NATIONAL

TRANSPORTATION

SAFETY BOARD

WASHINGTON, D.C. 20594

HAZARDOUS MATERIALS ACCIDENT REPORT

PB2001-917002

NTSB/HZM-01/01

DCA99MZ004

RUPTURE OF A RAILROAD TANK CAR

CONTAINING HAZARDOUS WASTE

NEAR CLYMERS, INDIANA

FEBRUARY 18, 1999

7329

Hazardous Materials Accident Report

RUPTURE OF A RAILROAD TANK CAR 

CONTAINING HAZARDOUS WASTE 

NEAR CLYMERS, INDIANA

FEBRUARY 18, 1999

NTSB/HZM-01/01

DCA99MZ004

PB2001-917002

Notation 7329

Adopted March 5, 2001

National Transportation Safety Board

490 LíEnfant Plaza, S.W.

Washington, D.C. 20594
National Transportation Safety Board. 2001. Rupture of a Railroad Tank Car Containing Hazardous

Waste Near Clymers, Indiana, February 18, 1999. Hazardous Materials Accident Report NTSB/

HZM-01/01. Washington, DC.

Abstract: About 12:05 a.m. on February 18, 1999, railroad tank car UTLX 643593, which was on the

west unloading rack at the Essroc Cement Corporation plant near Clymers, Indiana, sustained a sudden and

catastrophic rupture that propelled the tank of the tank car an estimated 750 feet and over multistory

storage tanks. The 20,000-gallon tank car initially contained about 161,700 pounds (14,185 gallons) of a

toxic and flammable hazardous waste that was used as a fuel for the plantís kilns. There were no injuries or

fatalities. Total damages, including property damage and costs from lost production, were estimated at

nearly $8.2 million.

 The safety issues discussed in the report are: sufficiency of safety requirements addressing the procedures

used for loading and offloading railroad tank cars and other bulk containers used to transport hazardous

materials; adequacy of inspection and testing requirements for pressure relief devices on railroad tank cars;

adequacy of provisions addressing changes in product service for railroad tank cars; and adequacy of the

U.S. Department of Transportation Hazardous Materials Regulations pertaining to the notification and

reporting of hazardous materials incidents.

As a result of its investigation, the Safety Board made recommendations to the Federal Railroad

Administration, the Research and Special Programs Administration, the Association of American

Railroads, the Railway Progress Institute, the Lyondell Chemical Company, the Olin Corporation, the

Essroc Cement Corporation, and CP Recycling, Inc., and Affiliated Companies. The Safety Board also

reiterated one recommendation to the Research and Special Programs Administration.

The National Transportation Safety Board is an independent Federal agency dedicated to promoting aviation, railroad, highway, marine,

pipeline, and hazardous materials safety. Established in 1967, the agency is mandated by Congress through the Independent Safety Board

Act of 1974 to investigate transportation accidents, determine the probable causes of the accidents, issue safety recommendations, study

transportation safety issues, and evaluate the safety effectiveness of government agencies involved in transportation. The Safety Board

makes public its actions and decisions through accident reports, safety studies, special investigation reports, safety recommendations, and

statistical reviews.

Recent publications are available in their entirety on the Web at <http://www.ntsb.gov>. Other information about available publications also

may be obtained from the Web site or by contacting:

National Transportation Safety Board

Public Inquiries Section, RE-51

490 LíEnfant Plaza, S.W.

Washington, D.C. 20594

(800) 877-6799 or (202) 314-6551

Safety Board publications may be purchased, by individual copy or by subscription, from the National Technical Information Service. To

purchase this publication, order report number PB2001-917002 from:

National Technical Information Service

5285 Port Royal Road

Springfield, Virginia 22161

(800) 553-6847 or (703) 605-6000

The Independent Safety Board Act, as codified at 49 U.S.C. Section 1154(b), precludes the admission into evidence or use of Board reports

related to an incident or accident in a civil action for damages resulting from a matter mentioned in the report. 
iii Hazardous Materials Accident Report

Contents

Acronyms and Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .vi

Factual Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Accident Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Preaccident Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1993 Loading and 1998 Shipment of Tank Car . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Heating and Offloading Attempts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Accident . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Emergency Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Injuries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

UTLX 643593 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Meteorological Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Tank Car Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

TDI Waste Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Lake Charles Plant Shipments of TDI Waste . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Operations Under Olin Ownership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Operations Under Arco/Lyondell Ownership . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Lake Charles TDI Waste Offloading and Processing Procedures . . . . . . . . . . . . . . . . . . . . . . 21

Olin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Arco/Lyondell . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Essroc TDI Waste Disposal Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Guidance on Processing TDI Waste Mixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Operational Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Configuration of Essroc Offloading Station . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Essroc Offloading Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Postaccident Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

FRA-Ordered Inspections and Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Disposition of TDI Wastes in Other Tank Cars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Postaccident TDI Matter Waste Offloading Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Inspections and Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Metallurgical Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Examination of the Pressure Relief Valve and Other Fittings . . . . . . . . . . . . . . . . . . . . . . 32

Pressure Tests and Teardown of Pressure Relief Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Chemical Analyses and Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Approved Cargoes and Components for DOT Specification Tank Cars . . . . . . . . . . . . . . . . 38

Federal Regulations and Oversight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Compatibility of Pressure Relief Device Components with TDI Waste Mixtures . . . . . 39

Change of Authorized Cargoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Hazardous Materials Incident Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Notification of Accident . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Notification Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Contents iv Hazardous Materials Accident Report

Regulatory Initiatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

 Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Accident . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Rupture of UTLX 643593 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Overpressure Condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Product Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Hazardous Materials Loading and Offloading Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

TDI Waste Shipments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Recent Safety Board Actions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

DOT Hazardous Materials Regulations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Pressure Relief Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Inspection Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Changes in Product Service for Railroad Tank Cars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Notification and Reporting of Hazardous Materials Incidents . . . . . . . . . . . . . . . . . . . . . . . . . 62

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Probable Cause . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

New Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

Previously Issued Recommendation Reiterated in this Report . . . . . . . . . . . . . . . . . . . . . . . . . 67

Appendixes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

A: Investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

B: U.S. Department of Transportation Hazardous Materials Incident Report Form . . . . . . . 70
v Hazardous Materials Accident Report

Acronyms and Abbreviations

AAR -- Association of American Railroads

ANPRM -- advance notice of proposed rulemaking

Arco -- Arco Chemical Company

ASTM -- American Society of Testing and Materials

Btu -- British thermal unit

cfm -- cubic feet per minute

CFR -- Code of Federal Regulations

cp -- centipoise

CPRIN -- CP Recycling of Indiana

EPA -- Environmental Protection Agency

Essroc -- Essroc Cement Corporation 

FRA -- Federal Railroad Administration

ksi -- thousand pounds per square inch

MCB -- monochlorobenzene

Midland -- Midland Manufacturing Corporation

MSHA -- Mine Safety and Health Administration

NPRM -- notice of proposed rulemaking

NRC -- National Response Center

Olin -- Olin Corporation

psia -- pounds per square inch, absolute

psig --pounds per square inch, gauge

RSPA -- Research and Special Programs Administration

RSST -- reactive system screening tool

TDI -- toluene diisocyanate

TSD -- transfer, storage, and disposal
vi Hazardous Materials Accident Report

Executive Summary

About 12:05 a.m. on February 18, 1999, railroad tank car UTLX 643593, which

was on the west unloading rack at the Essroc Cement Corporation (Essroc) Logansport

cement plant near Clymers, Indiana, sustained a sudden and catastrophic rupture that

propelled the tank of the tank car an estimated 750 feet and over multistory storage tanks.

The 20,000-gallon tank car initially contained about 161,700 pounds (14,185 gallons) of a

toxic and flammable hazardous waste that was used as a fuel for the plantís kilns. There

were no injuries or fatalities. Total damages, including property damage and costs from

lost production, were estimated at nearly $8.2 million.

The National Transportation Safety Board determines that the probable cause of

the accident was the failure of Essroc Cement Corporation and CP Recycling of Indiana

management to develop and implement safe procedures for offloading toluene diisocyanate

matter wastes, resulting in the overpressurization of the tank car from chemical self-reaction

and expansion of the toluene diisocyanate matter wastes. 

This report discusses the following safety issues:

ï Sufficiency of safety requirements addressing the procedures used for loading

and offloading railroad tank cars and other bulk containers used to transport

hazardous materials;

ï Adequacy of inspection and testing requirements for pressure relief devices on

railroad tank cars;

ï Adequacy of provisions addressing changes in product service for railroad tank

cars; and

ï Adequacy of the U.S. Department of Transportation Hazardous Materials

Regulations pertaining to the notification and reporting of hazardous materials

incidents.

As a result of its investigation of this accident, the Safety Board makes

recommendations to the Federal Railroad Administration, the Research and Special

Programs Administration, the Association of American Railroads, the Railway Progress

Institute, the Lyondell Chemical Company, the Olin Corporation, the Essroc Cement

Corporation, and CP Recycling, Inc., and Affiliated Companies. The Safety Board also

reiterates one recommendation to the Research and Special Programs Administration. 
1 Hazardous Materials Accident Report

Factual Information

Accident Summary

About 12:05 a.m.1 on February 18, 1999, railroad tank car UTLX 643593, which

was on the west unloading rack at the Essroc Cement Corporation (Essroc) Logansport

cement plant near Clymers, Indiana, sustained a sudden and catastrophic rupture that

propelled the tank of the tank car an estimated 750 feet and over multistory storage tanks.

(See figure 1.) The 20,000-gallon tank car initially contained about 161,700 pounds

(14,185 gallons) of a toxic and flammable hazardous waste generated from the production

of toluene diisocyanate (TDI). TDI is an intermediate product used in the manufacture of

polyurethane foam, a material commonly used to produce seat cushions. TDI matter waste

was used as a fuel for the Essroc plantís kilns.

In the 5 days before the accident, employees or contract personnel for the

hazardous material disposal firm CP Recycling of Indiana (CPRIN)2

 had applied steam to

heat the tank car for a total of 28.5 hours. Their goal was to make the material in the tank

sufficiently liquid to transfer to the plant piping and kilns for burning. (See figure 2 for an

aerial view of the Essroc plant layout.) The attempts to offload the TDI matter waste were

unsuccessful due to solidification of the waste in the plant piping to the kilns. 

There were no injuries or fatalities. Total damages, including property damage and

costs from lost production, were estimated at about $8.2 million. 

Preaccident Events

1993 Loading and 1998 Shipment of Tank Car

Railroad tank car UTLX 643593 (see figure 3) was loaded on October 1, 1993,

with approximately 161,700 pounds (14,185 gallons) of a TDI mixture designated as

ìTDI matter wasteî at the then-Olin Corporation (Olin) plant in Lake Charles, Louisiana.

The loaded tank car remained in storage at the Lake Charles plant until March 31 or

April 1, 1998, when it was shipped to the Essroc cement plant, near the towns of Clymers

and Logansport in north-central Indiana.3

 At Essroc, the TDI matter waste was to be used

as a fuel for the plantís kilns. UTLX 643593 was interchanged at the rail yard in

Logansport on April 20, 1998.

1 All times are eastern standard time.

2 CPRIN is a subsidiary of CP Recycling, Inc., and Affiliated Companies. 

3 The TDI matter waste stored in UTLX 643593 was classified as a hazardous waste when it was

shipped in April 1998 from the Lake Charles plant to Essroc. 
Factual Information 2 Hazardous Materials Accident Report

Figure 1. Accident location [not to scale]. (NTSB)

KENTUCKY

MICHIGAN

ILLINOIS INDIANA

Indianapolis

Lafayette

Logansport

OHIO

Accident Site

Clymers
Factual Information 3 Hazardous Materials Accident Report

Figure 2. Aerial view of Essroc plant (preaccident); areas of interest cited in report are 

labeled. (Photo provided by Essroc)
Factual Information 4 Hazardous Materials Accident Report

Figure 3. Photo and diagram showing tank cars of same design as UTLX 643593. 

(NTSB)

External Heating Coils

Dome Manway Coverplate (within dome) Jacket

A-end B-end

Hand

Brake
Factual Information 5 Hazardous Materials Accident Report

UTLX 643593 remained in the Logansport rail yard until December 7, 1998, when

it was delivered to the Essroc plant. UTLX 643593 was positioned on the west offloading

rack at the Essroc plant about 2:00 p.m. on February 12, 1999. The A-end of the tank car

was in the direction of ìplant north.î4 Essroc daily rail car inspection records from

December 7, 1998, through February 17, 1999, show no problems with the tank car.

Heating and Offloading Attempts

Before the TDI matter waste could be offloaded from UTLX 643593, it had to be

heated by circulating steam through the tank carís external heating coils to ensure that the

waste mixture was sufficiently fluid to be pumped to the plantís kilns, where it was to be

burned. (Essroc used the TDI matter waste and other hazardous wastes to fuel the plantís

kilns for cement production.)

On February 13, 1999, the Essroc transfer, storage, and disposal (TSD) facility5

supervisor, who supervised the plantís waste fuel technicians (the Essroc employees who

offload waste fuels) and oversaw the transfer of all waste fuels to the plantís kilns, met

with the customer service manager for CPRIN at the plant to discuss the steam heating of

the tank car. CPRIN was Essrocís on-site contractor for steam heating tank cars containing

waste fuels. In that capacity, either the CPRIN service manager or CPRIN contract

employees made the steam connections to the tank car and operated the boiler system that

produced the steam. Essroc employees made all the offloading connections to the valves

on the tank car and operated the pumps, valves, and other equipment to physically offload

the tank car and pump the waste to the kilns.

The connections for steam heating UTLX 643593 were completed about 5:00 p.m.

on February 13, and steam heating began about 6:00 p.m. At the time the steam

connections were made, internal tank pressure was reported to be 0 pounds per square

inch, gauge, (psig) and the ambient air temperature was about 30° F.6

As a standard practice and quality control measure, Essroc technicians would draw

a sample of the TDI matter waste before offloading any tank car. A contract laboratory

with on-site facilities would then analyze the sample to ensure that the waste was within

prescribed parameters before offloading commenced. One technician stated that he and a

second technician drew the quality control sample from UTLX 643593 before the end of

their shift at 11:30 p.m. on February 13. They left the sample with the facility supervisor.

The technician described the waste sample as being ìsomewhat thickerî than normal. The

sample was taken to the contract laboratory with on-site facilities at 12:20 a.m. on

February 14. The analysis was completed and the results reported to Essroc at 1:23 a.m.

on February 14. 

4 The true direction of ìplant northî is north to northwest. Directional references in this report will be

referenced to ìplant northî rather than true directions unless otherwise specified. 

5 A TSD facility transfers, stores, or disposes of hazardous wastes.

6 Essroc stated that its waste fuel technicians monitored the internal pressure of the tank car and the

temperature of the matter waste in the tank car between February 13 and the accident, but internal tank

pressures and temperatures of the waste mixture were not, as a matter of practice, measured at regular

intervals or required to be documented. Consequently, the internal tank pressures and cargo temperatures

cited in this report are those recalled by the facility supervisor and the waste fuel technicians.
Factual Information 6 Hazardous Materials Accident Report

The lab tested the sample for the presence of specific constituents, including

chlorine and water, and measured the heating value and density of the waste mixture. It

did not indicate the wasteís viscosity.7 The testing indicated that no water was present. The

sample had a density of 11.4 pounds per gallon and a heating value of 119,880 British

thermal units (Btu) per gallon. 

About the time the sample was drawn, the internal tank pressure was 0 psig. The

temperature of the matter waste mixture was 80° F at 12:30 a.m. As the steam heating

continued, the temperature of samples drawn from the tank car increased to about 120 to

150° F, at about 2:30 a.m., to 202° F at 6:00 a.m., when the steam heating ended.

About 9:00 a.m. on February 14, the Essroc facility supervisor spoke with a waste

fuel technician who was on duty. The technician advised the facility supervisor that the

steam heating of UTLX 643593 had ended about 6:00 a.m. that morning. The facility

supervisor and the waste fuel technician reviewed the procedures to finish offloading

operations from a just-emptied tank car, GATX 42585, on the east offloading rack

adjacent to UTLX 643593. The facility supervisor told the waste fuel technician to call

him if any problems developed in the offloading.

The waste fuel technician notified the Essroc facility supervisor about 11:00 a.m.

that he had attempted to begin offloading UTLX 643593 but was unable to do so because

the TDI matter waste was too thick. The waste had plugged the fixed plant piping between

the offloading rack and the kilns.8 The facility supervisor directed the technician to shut

down the pumping and piping system and to flush the piping from the kilns back to the

loading rack.9

 The internal tank pressure was about 10 psig at 11:00 a.m.; it was 40 psig at

1:00 p.m.

About 4:30 p.m., the Essroc facility supervisor received a telephone call from

another waste fuel technician on duty. This technician advised the facility supervisor that

the on-duty technicians had again tried to offload UTLX 643593 and pump the TDI matter

waste to the kilns, but the waste was too thick and had again plugged the piping. The

facility supervisor told the technician to flush the piping to the kilns and to shut down the

offloading effort. An on-duty product supervisor at the plant notified the facility

supervisor before 6:00 p.m. that it had been shut down. No further attempts to heat or

offload UTLX 643593 were made on February 14.

The facility supervisor arrived at the Essroc plant between 6:30 and 6:45 a.m. on

February 15. About 6:45 a.m., the internal tank pressure in UTLX 643593 was between

20 and 25 psig, and the temperature of a waste sample was 70° F. The facility supervisor

7 Viscosity is a measure of the resistance of a fluid to deformation or flow. A fluid with a high viscosity,

such as heavy syrup, tends to be thick and slow flowing. A fluid with a low viscosity, such as water, is thin

and flows easily.

8 The system of piping and pumps that fed the TDI waste directly from the tank car to the kilns was

designated as the TDI direct burn system. 

9 Essroc personnel indicated that toluene, a solvent for TDI, was used to flush and unplug the piping to

the kilns.
Factual Information 7 Hazardous Materials Accident Report

determined that the TDI matter waste was too thick to pump. (After the accident, the

facility supervisor stated no temperature was prescribed for offloading; he said the waste

product was considered ready for offloading when it was ìthinî enough to flow.)

The facility supervisor then contacted the CPRIN manager, told him the

temperature of the TDI waste sample, and said that the waste was much too thick to pump

from the tank car. The CPRIN manager responded that he would reheat the tank car. The

second round of steam heating UTLX 643593 began about noon on February 15 and

ended about 4:30 a.m. on February 16. The facility supervisor told the waste fuel

technicians to draw samples from the tank car every 30 to 60 minutes to check the wasteís

temperature and visually monitor its viscosity. The facility supervisor left it to the Essroc

technicians to advise the CPRIN personnel when the TDI matter waste was fluid enough

to pump. 

The Essroc facility supervisor checked the status of UTLX 643593 upon arriving

at the plant between 6:30 and 6:45 a.m. on February 16. The waste samples drawn from

the tank car at that time were 173° F and were thin and fluid. The facility supervisor also

noted that the pressure gauge on the nitrogen line used to measure internal pressure in the

tank car read 45 psig, which was higher than Essrocís desired pressure of 20 to 25 psig.

To relieve excess pressure in the tank car, Essroc technicians manually opened the

vapor valve on top of the tank car that was connected to a ìteeî fitting that allowed the

injecting of nitrogen into, or the venting of vapors from, the tank car with the alignment of

flow valves at the offloading station. The facility supervisor later told the Safety Board

that when the technician went to open the vapor valve on the tank car to relieve the

internal pressure, he found the pressure relief valve ìwhisperingî or discharging slightly

and not seating tightly. The facility supervisor attributed this condition to saturated carbon

filters in the offloading stationís vapor emission system.10 He directed the technicians to

clean the carbon filters so that they could absorb the pollutant vapors as intended.11

While the technicians cleaned the filters, vapors from the tank car were vented into

a water bath, which would absorb any pollutants. A 3/4-inch vent hose (about 100 feet

long) was connected to the vapor valve on the tank car and then run to a 300-gallon plastic

ìtoteî tank filled with about 275 gallons of water. The end of the vent hose was resting

underwater on the bottom of the tote tank so that vapors from the hose would be absorbed

in the water rather than emitted to the atmosphere. According to the facility supervisor,

Essroc technicians continued to clean the carbon filters throughout the day on

February 16, and vapors from the tank car continued to trickle through the water bath.

About 5:30 p.m. on February 16, the facility supervisor told the 3:30 to 11:30 p.m.

shift about the problems with the vent system and the carbon filters and directed the shift

to monitor the water bath and the internal pressure in UTLX 643593. He also told the

10 Saturation of the filters could have caused a back pressure in the tank car, which would have caused

the pressure relief valve to open so that ìwhisperingî could be heard. 

11 The carbon filters were designed to absorb pollutants in the vapors from the tank car to satisfy air

quality standards.
Factual Information 8 Hazardous Materials Accident Report

technicians to reconnect the nitrogen line to the tank car when the internal tank pressure

was between 20 and 25 psig and to try to offload the tank car. The facility supervisor also

checked the internal pressure in UTLX 643593 and noted that the pressure gauge

indicated 40 psig. 

The on-duty product supervisor notified the facility supervisor about 9:15 p.m. that

the technicians had attempted to offload UTLX 643593, but the product was very thick,

ìlike taffy.î The attempt to offload had begun about 7:30 p.m. but was stopped a ìvery

short timeî later, after a small amount of the TDI waste had been offloaded. The on-duty

product supervisor told the facility supervisor that the technicians had been unable to flush

the TDI waste from the pipeline to the kilns and that the TDI waste had ìfrozenî in the

pipeline. They shut down the offloading effort.

During a March 2, 1999, interview with officials from the Mine Safety and Health

Administration (MSHA), an Essroc laborer who worked this shift stated that he had seen

water bubbling and splashing in the tote tank after this last unsuccessful attempt to offload

the tank car on February 16. He said that the pressure in the tank car had been holding at

50 psig. 

Essroc later estimated that about 750 gallons of the TDI matter waste were

offloaded during the three attempts made to offload the tank car. 

The facility supervisor arrived at the plant between 6:30 and 6:45 a.m. on

February 17, and, as he had the 2 previous days, he checked UTLX 643593. He noted that

the pressure gauge measuring the internal pressure in the tank car indicated 40 psig. The

facility supervisor opened a valve in the vent line to begin relieving the pressure in the

tank car. The pressure was relieved until 10:00 a.m., when the pressure gauge indicated

3 to 5 psig. The vent line valve was closed at that time, and the nitrogen line was opened.

Nitrogen was injected into the tank car until about 3:00 p.m., by which time it had

increased the internal pressure to between 20 and 25 psig. The facility supervisor said that

the tank car was not steam-heated further or otherwise worked on before the explosion.

Accident

The waste fuel technicians and other employees, whose shifts began at 11:30 p.m.,

February 17, were in an on-site building that housed the techniciansí office when

UTLX 643593 ruptured. One of the waste fuel technicians was doing paperwork when the

accident occurred. About 12:05 a.m. on February 18, the technician heard what he later

described as a ìsmall bang.î He stated that he was looking out the window, but he did not

see any smoke, flame, or flash, and therefore was not sure where the sound originated.

Following the bang, he saw an orange fireball, which he estimated was 40 feet high,

moving toward the office and engulfing the entire area. According to the technician, the

fireball hit the window and was gone. Following the fireball, he felt a concussion. After

the fireball and concussion, the technician looked toward the tank car offloading area and
Factual Information 9 Hazardous Materials Accident Report

saw the entire area in flames. He said that ìclumps of fireî were raining down. The

technician said he was certain that the source of the explosion was the TDI tank car.

The technician said he heard three other explosions, but he could not estimate the

interval between them. He did not know what the first and second explosions were, but he

said that the third explosion was the cargo tank truck east of the diesel storage tanks. (See

figure 4 for postaccident view of the Essroc plant site.)

Emergency Response

The Logansport Fire Department received the alarm from the Essroc plant at

12:06 a.m. on February 18. The first responding units arrived on the scene at 12:21 a.m.

The Clymers Volunteer Fire Department, the Georgetown Fire Department, the Royal

Center Fire Department, and the Grissom Air National Guard Base Fire Department also

responded. Fire crews extinguished the fires without incident. Because of the potentially

hazardous smoke and the loss of area electrical power, residents of about 100 homes were

temporarily evacuated to shelters. The emergency had concluded by 7:30 a.m. on

February 18.

In addition to the fire departments, the following Federal, State, and local agencies

responded to the accident: the Federal Railroad Administration (FRA), MSHA, the

Indiana State Emergency Management Agency, the Indiana Department of Environmental

Management, the Indiana State Fire Marshal, the Indiana State Police, the Cass County

Office of Emergency Management, the Cass County Sheriffís Department and

Ambulance, the Carroll County Sheriffís Department, the Logansport Police Department,

and the local Red Cross.

The Indiana Department of Environmental Management reported that the

containment dike surrounding the offloading area and storage tanks was intact and held

fire suppression materials. Solid chunks of TDI matter waste from UTLX 643593 were

scattered as a debris field across the plant facility. Essroc confirmed that the following

fuels and solvents were released from the damaged storage tanks in the offloading area:

17,000 gallons of diesel fuel; 1,000 gallons of gasoline; 15,000 gallons of HAN 906

solvent; and 2,000 gallons of toluene. In addition to the TDI matter waste remaining in

UTLX 643593, the accident released about 4,200 gallons of a flammable and corrosive

waste from the nearby cargo tank truck. The Indiana Department of Environmental

Management monitored cleanup of the plant facility.

Injuries 

No fatalities or injuries were reported.
Figure 4. Essroc plant after the accident; #1 indicates preaccident position of UTLX 643593; #2 indicaof bulk of tank car after the accident. (Photo courtesy of Logansport Pharos-Tribune newspaper) 
Factual Information 11 Hazardous Materials Accident Report

Damage 

General

The Essroc plant is in a rural area with no residences in the immediate vicinity. The

cement plant sustained significant property damage and suspended operations for nearly

4 weeks. UTLX 643593 and a cargo tank trailer were destroyed. Two other tank cars

(GATX 42585 and UTLX 640738) in the offloading area were also damaged. Total

damages and lost business costs were estimated at nearly $3.4 million and $4.8 million,

respectively. 

At Essroc, two pairs of north-south train tracks led to the two offloading stations

for tank cars. The offloading platforms for the two tank car stations, the pipe rack between

the two sets of train tracks, and the offloading station for cargo tank trucks on the west

side of UTLX 643593 were completely destroyed. Sections of what appeared to be

structural steel from the offloading platforms were found on the far east side of the storage

tanks and the kilns adjacent to the east side of the offloading area.

Tank car GATX 42585, on the adjacent (east) loading rack, had been blown on its

side, away from the west loading station. The cargo tank trailer that had been on the west

side of UTLX 643593 had also been blown on its side, away from the west loading station.

Fixed storage tanks along the east and west sides of the offloading area exhibited

fire and heat damage, as well as impact damage from flying debris. The damaged areas on

all these tanks were directly exposed to the offloading station where UTLX 643593 had

been. The four tanks along the west side included two 12,000-gallon fuel oil tanks and two

7,500-gallon tanks containing a blending agent for the TDI matter waste. All four of these

tanks were destroyed. A 2,000-gallon tank containing toluene was blown from its original

position between UTLX 643593 and the cargo tank trailer into the fuel oil tanks on the

west side of the offloading area. Fire had blackened 4 of a group of 10 storage tanks on the

east side of the offloading area. The remaining six tanks, although partially shielded, also

had some blackening and heat damage. (See figure 5.)

UTLX 643593

Both truck (wheel) assemblies from the tank car had derailed adjacent to the west

track in the offloading area, in the approximate location of UTLX 643593 at the time of

the accident. Chemical debris and structural components from UTLX 643593 were

scattered to the east and west of the offloading station. Investigators did not locate the

dome lid from the tank car. Pieces from the metal jacket of the tank car were generally

found in the large field west and north of the offloading station. 

Most of the UTLX 643593 tank was found in one piece, upside down on the west

side of a plant building about 750 feet northeast of the offloading station, with the

remaining attached section A-end head next to the building. (See figure 6.) The only

section of the tank jacket with burned paint or indication of direct exposure to fire was the

jacket section found at this location. A piece of burned rubber hose was found facing and

next to the burned area on the jacket.
Factual Information 12 Hazardous Materials Accident Report

Figure 5. Essroc loading rack area after accident. (NTSB)
Figure 6. Remains of UTLX 643593 tank after accident. (NTSB)
Factual Information 14 Hazardous Materials Accident Report

There were fractures along the bottom centerline of the tank that had propagated

on a shear plane, typical of the shear-face tensile fractures in ductile materials.12 Toward

both head ends of the tank, transverse tearing through the tank plate was observed,

creating two sections of the tank barrel that appeared flattened. The fractures observed

were not along welds in the tank. The bottom portion of the tank toward the B-end had

crumpled and folded over on itself. Measurements of the plate thickness along the fracture

surfaces showed that ìnecking downî deformation had reduced the wall thickness below

the nominal thickness of 0.5625 inch.

No pitting, corrosion, blistering, or other visual signs of deterioration were

observed on the internal tank surface. No breaches or cracks were observed in the tank,

including the area of the tank covered by the external heating coils. The outline of the

external heating coils from discoloration of the tank metal was observed on the internal

tank surface at both the A- and B-ends. The discoloration was more pronounced at the

A-end.

Pieces of solid chemical residue were observed on what had been the interior

surface of the section of the A-end tank head. The chemical residue had a solid, glassy,

and brittle appearance. Other than this residue, the interior surface of the tank head was

clean. The tank head was deformed and dented. 

The eduction lines, gauging line, and thermometer well mounted on the manway

coverplate were bent at a 45- to 60-degree angle toward the top of the tank, along the

longitudinal centerline, and toward the B-end of the tank.

Chemical residue that was dark brown in color and of a solid, glassy appearance

filled about half of the dome nozzle. The residue had a top layer of loose chunks. Beneath

the chunks, the residue conformed to the shape of the dome nozzle and manway

coverplate as if poured into a mold. 

Numerous solid chunks of the TDI matter waste material were scattered

throughout the large field to the west and north of the offloading station. (See figure 7.)

Some pieces of these solids showed indications of burning while others did not. Samples

of these solids were obtained for analysis. A retired Olin/Arco employee who had

34 yearsí experience with the production and handling of TDI and who came to the

accident scene as a consultant for Olin told the Safety Board that he was surprised by the

number of small chunks of TDI waste on the ground. He identified these chunks as

polymeric TDI. He stated that for the polymeric TDI to be in that form, it had to have been

a solid block or slab in the tank car when the accident occurred. He further stated that if

the polymeric TDI had been in a fluid state in the tank car at the time of the accident, he

would have expected the polymeric TDI to have a ìstringyî appearance or to be ìsort of

strung out like youíd throw something out and itíd freeze in the air.î He also observed that

some of the polymeric TDI appeared to be burned and showed indications of exposure to

water, which he attributed to moisture in the air. He stated that he found the offloading

12 National Transportation Safety Board Materials Laboratory Factual Report No. 99-113, dated

May 12, 1999.
Factual Information 15 Hazardous Materials Accident Report

lines to UTLX 643593 and noted that they were elongated as ìif they was hooked to

somethingî at the time of the accident. He believed that the elongation of these lines

indicated they were attached to the tank car when it ruptured.

Meteorological Information

The National Climatic Data Center provided weather data for Lafayette, Indiana,

which is about 35 miles southwest of Logansport/Clymers. (Lafayette was the closest

weather reporting station to the accident site.) Between February 12 (the date UTLX 643593

was positioned at the loading rack) and February 18 (the accident date), the high

temperatures ranged from 32° F on February 13 to 57° F on February 15. The low

temperatures ranged from 13° F on February 13 to 35° F on February 16. The average daily

temperatures ranged from 23° F on February 13 to 45° F on February 15. No measurable

precipitation was recorded in the 7-day period.

The Essroc waste fuel technician who witnessed the February 18 accident said it

was cool at the time of the accident, and there was no rain, thunder, or lightning.

Figure 7. Solid TDI matter waste gathered from debris field after accident. (NTSB)
Factual Information 16 Hazardous Materials Accident Report

Tank Car Information

Union Tank Car Company built UTLX 643593, a U.S. Department of

Transportation (DOT) specification 111J100W1 tank car, in late 1992 or early 1993. It was

1 of 52 tank cars (UTLX 643546 through 643597, inclusive) ordered by Olin and designed

for TDI product transportation. The certificate of construction for UTLX 643593 and its

sister tank cars indicates that these cars were approved for carriage of TDI and 

Non-regulated commodities and commodities authorized in DOT Part 173

[49 Code of Federal Regulations (CFR) 173] for which there are no other

requirements and which are compatible with this design and class of car.

Each of these tank cars had a capacity of 20,000 gallons. They were approved to

carry a maximum of 181,400 pounds of cargo each. The tank was constructed of

American Society of Testing and Materials (ASTM) A-516-70 carbon steel. The thickness

of the tank shell was 0.563 inch and of the tank heads was 0.603 inch. Under sections

49 CFR 179.201-1 and 179.201-2 of the DOT Hazardous Materials Regulations, the

minimum required thickness of the tank shell and tank heads for this class of tank car are

both 0.438 inch. Union Tank Car calculated the burst pressure of the tank to be between

813 and 844 psia.13

The tank carís external heating coils14 were on the bottom half of the tank and ran

the tankís full length. The heating area of the external coils was about 274 square feet of

the tankís surface area. The inlet and outlet connections for the heating coils were just to

the A-end side of the blind flange covering the sump at the bottom center of the tank. The

tank was covered by 6 inches of insulation (1/2 inch of fiberfrax and 5 1/2 inches of

fiberglass), a 1/8-inch carbon steel jacket, and 1/2-inch-thick head shields.

All seven valves/fittings on the top of the tank car were mounted on a pressure

manway plate, which was bolted to the tank and enclosed in the type of housing used on

pressure tank cars that transport liquefied compressed gases. The seven fittings mounted

on the manway plate comprised a valve for each of the two liquid loading/offloading lines,

the valve to the tankís vapor space, the pressure relief valve, the vacuum relief valve, the

gauging device, and the thermometer well. (See figure 8.)

The valves to the two liquid loading/offloading lines were 2-inch Union Tank Car

stainless steel ball valves. 

The vapor valve was a 1-inch stainless steel Jamesbury ball valve.

13 Psia stands for pounds per square inch, absolute. For purposes of comparison, 0 psig = 14.696 psia =

1.0 atmosphere. 

14 The external heating coils were welded to the exterior of the tank. The coils were hidden from view

by insulation and the metal jacket, which held the insulation in place. (Refer to the figure 3 diagram

cutaway.)
Factual Information 17 Hazardous Materials Accident Report

The pressure relief valve had been made by the Midland Manufacturing

Corporation (Midland). The Midland model A-1479 pressure relief valve had a

start-to-discharge pressure of 75 psig. The rated flow capacity of the pressure relief valve

was 2,027 cubic feet per minute (cfm). (The DOT minimum flow capacity for this design of

tank car was 166 cfm.) The O-rings and gaskets for the pressure relief valve were of ethylene

propylene rubber and Teflon, respectively. 

The vacuum relief valve was a Midland model A-222W flanged valve made of

stainless steel with a standard set point15 of 0.75 psi vacuum. Midland found no record

indicating that the vacuum relief valve on the tank car had a nonstandard set point. 

Figure 8. Fittings on UTLX 643593 manway coverplate. (NTSB)
Factual Information 18 Hazardous Materials Accident Report

TDI Waste Information

Over the years, the Lake Charles plant shipped to Essroc (and other waste disposal

companies) two types of wastes generated from TDI production. The first type, designated

as ìsolvent blend waste,î was generated during the final purification and distillation of the

TDI product. The second type, designated as ìTDI matter waste,î was generated from an

intermediate product stream removed during the TDI production process. (Generation and

shipment of the solvent blend and TDI matter wastes from the Lake Charles plant are

discussed in the next section.)

The solvent blend wastes and the TDI matter wastes contained comparable

percentages of TDI and TDI polymers. For example, the TDI matter waste mixture in

UTLX 643593 (the accident tank car) was approximately (by weight) 42 percent

monomeric TDI and 38 percent polymeric TDI.16 Monomeric TDI is a clear to slightly

yellow liquid, and polymeric TDI is a dark brown to black liquid or a glass-like black

solid. Both the monomeric and polymeric forms of TDI present high ingestion and

inhalation hazards and are combustible, with flash points17 of 270° F.

Monomeric and polymeric TDI are stable at temperatures below 104° F. At higher

temperatures, monomeric TDI can ìself-reactî18 in two ways, either by combining to

generate polymeric TDI or by reacting to produce carbon dioxide gas and a type of

chemical compound known as a carbodiimide. At higher temperatures, the polymeric TDI

can decompose and release gaseous byproducts such as carbon dioxide, carbon monoxide,

and oxides of nitrogen. Both monomeric and polymeric TDI are reactive with water. TDI

will react slowly with water under 122° F; the reaction with water will accelerate rapidly

in the presence of alkaline materials and at higher temperatures. Olinís information

concerning ìTDI productî (TDI in its monomeric form) noted that TDI should not be

stored at temperatures above 104° F.

Solvent blend wastes and TDI matter wastes differ with respect to the blending

agent present in each that formed the balance of the waste mixture and served to reduce its

viscosity. The blending agent typically used for solvent blend wastes was HAN 906, a

mixture of flammable petroleum hydrocarbons, such as naphthalene and

trimethylbenzene. HAN 906 is combustible and has a flash point of 145° F.

Monochlorobenzene (MCB), the blending agent used in the TDI production process and

found in the TDI matter wastes, is also a flammable liquid and has a flash point of 82° F.

Both HAN 906 and MCB are chemically stable. 

15 The term set point applies to the pressure at which a device, such as the pressure relief valve, which is

designed to open at some specific pressure, opens. 

16 A monomer is a relatively simple molecule or compound of low molecular weight and simple

structure. A polymer is a relatively complex compound formed from the combination of some number of

molecules or groups of molecules to create a chainlike macromolecule.

17 A flash point is the temperature at which a liquid gives off a vapor sufficient to form an ignitable

mixture with the air near the surface of the liquid or within the test vessel. 

18 Self-reaction occurs when molecules of a chemical interact with each other (often because of

increased temperature) and combine to form a molecular chain.
Factual Information 19 Hazardous Materials Accident Report

Lake Charles Plant Shipments of TDI Waste

When UTLX 643593 was loaded in 1993, Olin owned and operated the Lake

Charles, Louisiana, plant where the company produced TDI (and generated TDI waste). In

December 1996, Olin sold its TDI production business, including the Lake Charles plant,

to Arco Chemical Company (Arco). In July 1998, Lyondell Chemical Company

(Lyondell) acquired Arco and its assets. Lyondell assumed Arcoís responsibilities under

the 1996 Olin/Arco purchase agreement and took ownership and operational control of the

Lake Charles plant. 

Operations Under Olin Ownership

Olin used tank cars to transport and store two distinct chemical streams generated

from the production of TDI ó solvent blend waste and TDI matter waste.

Solvent Blend Waste. The first stream, solvent blend waste, was generated by the

distillation and purification of the TDI product. The waste stream from the distillation

process contained monomeric TDI and polymeric TDI that were normally routed to an

incinerator on the plant site. When the incineratorís capacity was exceeded or the incinerator

was not operable, this waste stream would be pumped into a fixed storage tank where it was

mixed (blended) with HAN 906 solvent to reduce its viscosity. 

According to the waste profiles for solvent blend waste, after the blending with the

HAN 906 solvent, the viscosity of the solvent blend waste was about 150 centipoise (cp).19

Periodically, when the storage tank was filled, the solvent blend wastes in the fixed

storage tank were pumped into rail tank cars or highway cargo tanks for transportation to

an off-plant disposal site for thermal destruction. 

Olin contracted Chemical Waste Management, a waste management contractor, to

handle the transportation and disposal of its solvent blend waste. In late 1995, Chemical

Waste Management, on Olinís behalf, approached CPRIN and Essroc about burning

solvent blend waste at Essrocís Logansport cement plant. In a June 5, 1996, letter, CPRIN

advised Olin that the solvent blend wastes were acceptable for incineration at the Essroc

Logansport plant. Records of tank car shipments and offloading submitted by Olin and

Essroc indicate that 70 tank carloads of solvent blend waste were shipped from Olin to

Essroc between July 11, 1996, and April 29, 1998.20 Between July 31, 1996, and

July 21, 1998, 67 of these 70 tank cars were successfully offloaded at the Essroc plant, and

the solvent blend wastes were burned without incident. According to Essroc records, the

company rejected the three remaining tank cars in January and February 1998 because the

wastes they contained did not meet Essroc specifications. One of these three cars

(GATX 25412) was in the Logansport yard at the time of the February 1999 accident. 

19 Centipoise is the metric measurement unit for viscosity. 

20 Comparison of the shipping records from Olin and Essroc showed minor inconsistencies in the

shipment and offloading data. The figures cited in this report are the most accurate numbers that could be

obtained from the available data.
Factual Information 20 Hazardous Materials Accident Report

TDI Matter Waste. TDI matter waste was an intermediate product stream from

Olinís production of TDI. TDI matter waste was a mixture of monomeric TDI, polymeric

TDI, and MCB. The MCB in the TDI matter waste acted as a solvent for the substance,

which reduced its viscosity. Through reprocessing, Olin could recover both MCB and

monomeric TDI from the TDI matter waste. 

Beginning in October 1988, at various times, Olin stored the TDI matter waste in

tank cars rather than halting the production process when it experienced problems with the

processing equipment or the incinerator. Under this practice, Olin would later reintroduce

the TDI matter waste stored in the tank cars to the production process to recover the

monomeric TDI and MCB. Eventually, Olinís efforts to maximize production resulted in

the on-site accumulation of a growing number of tank cars that stored TDI matter waste. 

In early 1996, Olin increased its efforts to either reprocess the stored TDI matter

waste on-site or ship the tank cars to disposal sites where the TDI matter waste could be

incinerated. Olin continued to use tank cars for storing TDI matter waste until late 1996.

Olin loaded the last tank car carrying TDI matter waste on November 30, 1996. Olin

indicated that it used 144 tank cars for storing TDI matter waste and that it reused an

unspecified number of these tank cars for storage after loads of TDI matter waste had been

reprocessed at the plant. According to Lyondell, 234 tank carloads of TDI matter waste

were stored at the Lake Charles plant during the 8 years Olin followed this practice. Olin

and Lyondell both confirmed that the TDI matter waste was stored in tank cars only at the

Lake Charles plant.

Operations Under Arco/Lyondell Ownership

On October 9, 1996, Olin and Arco signed a purchase agreement for the Lake

Charles plant. Under the terms of the purchase, Arco agreed to assume control and

ownership of the TDI matter waste then stored in 128 tank cars at the Lake Charles plant,

if the Louisiana Department of Environmental Quality determined that the stored TDI

matter waste was in-process material and not a hazardous waste. When this condition was

satisfied, on or about December 6, 1996, the sale of the plant was completed. 

While purchasing the plant, Arco decided to discontinue the practice of using tank

cars for interim storage of the TDI matter waste when the company encountered operation

problems with the TDI production equipment. Arco elected to reduce the TDI production

rate or shut down production rather than continue to use tank cars for storage.

Consequently, the Olin-Arco purchase agreement included terms for processing the

128 tank cars then in storage at the Lake Charles plant. Under these terms, Arco was to

either reprocess the TDI matter waste stored in the tank cars at the plant or ship it offsite

for thermal destruction by June 30, 1998. This deadline was subsequently extended to

October 1, 1998. After October 1, 1998, any remaining tank cars were to be declared

ìexcess TDI matter rail cars.î Arco had two options for handling such tank cars. Arco

could either (1) ship the tank cars to an off-site disposal facility for thermal destruction of

the waste at Olinís expense, subject to monetary conditions, or (2) require Olin to take

possession of the tank cars, assume their leases, transport them to an off-site facility for

disposal of the waste, and permanently remove the tank cars from the Lake Charles site.
Factual Information 21 Hazardous Materials Accident Report

(Olin later indicated that Essroc and two waste disposal companies incinerated the excess

TDI matter waste.)

In early 1998, on behalf of Arco, Chemical Waste Management approached

CPRIN and Essroc about disposing of TDI matter wastes from the Lake Charles facility at

Essrocís Logansport plant. Initial shipment of tank cars carrying the TDI matter wastes to

Essroc began in early March 1998, and acceptance of the TDI matter wastes at Essroc was

approved in a June 10, 1998, letter from CPRIN to Arco. The waste profile sheet that

accompanied CPRINís June 10 letter stated that the viscosity of the TDI matter waste at

70° F ìvaries.î

Between early March 1998 and early November 1998, Arco/Lyondell shipped

40 tank cars containing TDI matter wastes from the Lake Charles plant to Essroc.

Between July 31, 1998, and the date of the accident, 14 of the 40 tank cars were offloaded

at the Essroc plant. The wastes from four tank cars were offloaded, blended in a fixed

tank, and pumped to the kilns and burned. The wastes from 10 tank cars were offloaded

and pumped directly to the kilns, without any blending. (This was termed the ìdirect

injectionî process.) The accident tank car, UTLX 643593, would have been the fifteenth

tank car to be offloaded at Essroc, and the eleventh offloaded by direct injection. Of the

remaining 25 of the 40 tank cars, Essroc was unsuccessful in blending the wastes from 1

tank car; this car was shipped to a transfer facility in Deer Park (Houston), Texas, before

the accident. Twenty-four of the original 40 tank cars remaining at Essroc were shipped to

the Deer Park facility after the accident.21

Lake Charles TDI Waste Offloading and Processing Procedures

Olin

Olin told the Safety Board that it heated the TDI matter waste at the Lake Charles

plant by slowly passing low-pressure (around 10 psig) steam through the coils in the rail

car. At times, heating the TDI matter waste in this manner took 2 to 3 days. Olin said its

procedure was to make sure that there was no back pressure on the steam coil and that the

exit line continued to produce warm water and a small amount of steam, ensuring that the

steam was not trapped.

Olin stated that during the steam heating, it mixed the TDI matter waste by a

process known as ìnitrogen spargingî to facilitate even heating. In this process, nitrogen

gas was injected through the eduction line at the top of the tank car. When the nitrogen

exited the end of the eduction line at the bottom of the tank car, the nitrogen would mix the

TDI matter waste, facilitating its even heating. Olin maintained the nitrogen line at a slight

positive pressure to avoid suctioning the TDI material from the railcar. Vapors and gases

21 Olin revised this accounting in August 2000. Thirteen tank cars were shipped directly from Lake

Charles and arrived in Deer Park between December 15, 1998, and April 1, 1999. A fourteenth tank car was

also shipped from Essroc to Deer Park about 2 weeks before the accident.
Factual Information 22 Hazardous Materials Accident Report

vented from the tank car flowed to a vapor emissions system and/or an incinerator.

Typically, Olin gradually heated the TDI matter waste in the tank car to 90 to 100° F

during the sparging process until the mixture was pumpable. Olin indicated that it never

heated the TDI matter waste above 110° F because of possible degradation of the

recoverable monomeric TDI. 

Olin said it monitored the temperature and pressure on at least an hourly basis

during the heating and nitrogen sparging processes. Through nitrogen sparging, the

contents of the tank car were gradually heated, mixed, and made less viscous. Olin also

added additional MCB to the tank car, if needed, to reduce the viscosity of the TDI matter

waste. During this process, Olin drew samples of the TDI matter waste to determine the

viscosity of the mixture. When the viscosity of the TDI matter waste was sufficiently

reduced, Olin would offload the waste from the tank car and reintroduce it into the TDI

production stream.

Olin stated that the on-site blending process with the HAN 906 solvent at the Lake

Charles plant for TDI matter waste to be shipped off-site for disposal followed the same

procedures for low-pressure steam heating and nitrogen sparging as were followed when

the TDI matter waste was offloaded from the tank cars and reintroduced into the plant

production stream. The one difference in the procedures was that the TDI matter waste to

be shipped off-site was occasionally heated to around 130 to 140° F. The higher

temperatures were permitted under the blending procedure because recovery of

monomeric TDI was no longer an objective; so heat-caused damage to the substance was

not a consideration. Olin also indicated that the temperature of the TDI matter waste in the

tank cars never exceeded 140° F. Olin added HAN 906 solvent to the TDI matter waste in

the tank cars until the TDI waste mixture met specifications for chlorine content of less

than 3 percent and viscosity of 400 to 500 cp, as prescribed by Essroc. The tank cars

containing the TDI matter waste were then shipped to Essroc for disposal.

Arco/Lyondell

When Arco assumed ownership of the Lake Charles plant, it determined that it

would not reintroduce the TDI matter waste stored in tank cars to the TDI production

stream but ship it all offsite for disposal. Arco said it typically blended the TDI matter

waste stored in the tank cars with HAN 906 solvent before shipping the waste to a disposal

site. According to Lyondell, contractors for Olin blended the stored TDI matter waste with

HAN 906 solvent. 

Lyondell stated that Arco/Lyondell did not have specific written procedures for

on-site blending of the TDI waste mixtures and offloading them from tank cars because

Olin or Olin contractors blended and disposed of this TDI waste. Arco/Lyondell said it had

written procedures for producing solvent blend wastes in a fixed blending tank at the Lake

Charles plant site and then transferring the solvent blend wastes from the blending tank

into tank cars. These procedures set the temperature and viscosity limits for the solvent

blend wastes in the fixed blending tank. The viscosity of the solvent blend wastes in the

blending tank was to be less than 200 cp at a reference temperature of 78° F. The

temperature of the solvent blend wastes in the blending tank was to be maintained at
Factual Information 23 Hazardous Materials Accident Report

125° F (± 5° F). Further, if the ambient air temperature were below 45° F, the temperature

of the solvent blend wastes was to be increased to 145 to 155° F before the solvent blend

wastes were transferred to a tank car, to prevent the wastes from plugging the transfer

piping. 

Apart from these procedures, neither Olin nor Arco/Lyondell had written operating

procedures or limitations that addressed the potential for gas generation or product

expansion, the maximum temperature and time for heating the TDI wastes, or the

maximum product viscosity for offloading tank cars. Lyondell also noted that the

company did not conduct any tests on the effects of heating the TDI wastes.

Essroc TDI Waste Disposal Operations

Guidance on Processing TDI Waste Mixtures

Solvent Blend Wastes. During the evaluation of the 1996 proposal to burn solvent

blend wastes at Essrocís Logansport plant, Essroc and CPRIN personnel visited the Lake

Charles plant to observe Olinís process for handling and incinerating the solvent blend

wastes. According to CPRIN, most of the information discussed addressed the risks from

exposure to the solvent blend wastes and the necessary equipment to protect Essroc and

CPRIN employees who would be involved in processing the solvent blend waste mixtures.

Olin also discussed with Essroc and CPRIN the reactivity of the solvent blend wastes with

water.

CPRIN stated that it advised Chemical Waste Management that the viscosity of the

solvent blend wastes had to be less than 500 cp before they could be shipped to Essroc.

According to CPRIN, Olin indicated that, to meet this standard for viscosity, the solvent

blend wastes would only have to be heated to about 90 to 100° F for Essroc to offload and

pump the wastes directly to the kilns. 

Essroc stated that because CPRIN was responsible for heating and delivering the

solvent blend wastes in sufficiently fluid states, any operational procedures or limits for

heating the waste mixtures were directed toward CPRIN. CPRIN indicated to the Safety

Board that Essroc retained ultimate authority over heating, handling, and offloading the

wastes; therefore, any change in procedures for heating the wastes would require Essroc

approval.

TDI Matter Wastes. In early 1998, Chemical Waste Management approached

CPRIN and Essroc about incinerating TDI matter wastes at the Logansport plant. Between

March and June 1998, Olin, Chemical Waste Management, CPRIN, and Essroc evaluated

the proposal and determined that TDI matter wastes could be processed and incinerated at

the Essroc plant. Under this plan, the TDI matter wastes would be offloaded from the tank

car to a fixed tank where the wastes were to be blended with HAN 906 solvent. The blended

TDI matter wastes would then be pumped to Essrocís kilns and burned.
Factual Information 24 Hazardous Materials Accident Report

Before Essroc agreed to accept the TDI matter wastes in spring 1998, a TDI expert

who worked at the Lake Charles plant22 visited the Essroc plant to meet with Essroc and

CPRIN personnel and to instruct them about handling and processing the TDI matter

wastes. According to the Lake Charles TDI expert, he told the Essroc and CPRIN

personnel that the TDI matter wastes would have to be heated to 125° F before they could

be offloaded from the tank car and transferred to the blending tank. In response, Essroc

and CPRIN expressed concerns about the generation of the poisonous chemical phosgene

and the heating of the TDI matter wastes above 110° F, which was the maximum

recommended temperature for pure TDI cited in Olinís product literature. 

According to CPRIN, the Lake Charles TDI expert advised that the 110° F

temperature limit applied only to the pure monomeric TDI product, which, if heated above

that temperature, could not be sold as a usable product. Because Essroc never intended to

recover the monomeric TDI from the waste materials in the tank cars sent it for disposal,

degradation of the monomeric TDI in the wastes was no longer a concern. Essroc and

CPRIN both indicated that the Lake Charles TDI expert said that the TDI matter was

heated to temperatures as high as 350° F at the Lake Charles plant, and that the

concentration of phosgene in the TDI matter at elevated temperatures was not sufficient to

present a hazard. As a result, CPRIN stated it was ìgiven the impression that we should

not be concerned about how hot we heated the TDI material.î CPRIN further stated that

Olin provided no guidance or information about the potential for gas generation and/or

product expansion during heating, nor did Olin provide a recommended viscosity for

offloading. 

According to Essroc, Olin advised Essroc personnel that expansion of the TDI

matter wastes during heating was ìnormalî and that phosgene gas would not likely be

generated if the wastes were heated over 125° F. Essroc said that the Lake Charles TDI

expert also told its personnel that heating the wastes before offloading them was intended

to make the wastes sufficiently fluid to be transferred, not to enable the wastes to meet an

established viscosity threshold. 

Essroc acknowledged that the Lake Charles TDI expert said that a long, slow

heating process, possibly taking 2 to 3 days, would sometimes be necessary before the

TDI matter wastes would flow. During a December 1999 Safety Board interview, the Lake

Charles TDI expert who had met with Essroc and CPRIN personnel stated that he had

discussed the various handling and offloading procedures with them. He said that the

procedures discussed had included heating the tank car with low-pressure steam, using

nitrogen sparging to facilitate even heating of the TDI matter wastes, and keeping the

temperature of the TDI matter wastes below 130 to 140° F. The Lake Charles TDI expert

also stated that he discussed the chemical properties of the TDI matter waste, including its

reactivity with water and the possible generation of phosgene and carbon dioxide, with

Essroc and CPRIN personnel. 

22 This employee worked at the Lake Charles TDI plant under the successive managements of Olin,

Arco, and Lyondell as the TDI production facility changed ownership between 1993 and 1999. This report

will refer to this employee as the ìLake Charles TDI expert.î
Factual Information 25 Hazardous Materials Accident Report

In response to Safety Board inquiries about the guidance it provided to Essroc and

CPRIN, Olin said that it told Essroc and CPRIN (through its company expert) about using

low-pressure steam and nitrogen sparging to evenly heat the TDI matter wastes in the tank

cars. Olin also stated that it told Essroc and CPRIN to keep the temperature of the wastes

from exceeding 130 to 140° F. 

Responding to a Safety Board request for copies of any written guidance provided

to Essroc and CPRIN, Olin stated in a January 14, 2000, letter that ìto the extent that a

written policy or procedure exists for heating TDI matter, it was turned over to Arco as

part of the business sold to Arco.î In response to the same Safety Board request, Lyondell

stated in a January 24, 2000, letter that ìsince Olin interfaced with Essroc, Arco or

Lyondell recommended no guidance or operational limits for heating railcars for

unloading.î

Operational Problems

Soon after Essroc began accepting the TDI matter wastes in May 1998, the

company began to experience problems with the on-site blending process. Sediment from

the unblended wastes built up in the fixed blending tank. In addition, Essroc was unable to

pump the blended waste from the blending tank to the kilns because the blended waste

was solidifying in the pipelines that ran from the blending tank to the kilns. According to

the Essroc facility supervisor, Essroc stopped using the storage tank for blending in

September or October 1998. 

In November 1998, the Lake Charles TDI expert again visited the Essroc plant to

determine the cause of the problem with the blending system, but he could not pinpoint it.

According to the Essroc facility supervisor, the Lake Charles TDI expert advised Essroc

during this visit that the TDI matter wastes could be burned by direct injection from the

tank cars to the kilns rather than blending the wastes before feeding them to the kilns. 

The Lake Charles TDI expert told the Safety Board that, as part of his November

1998 visit to the Essroc plant, he and two CPRIN employees checked the fluidity of the

TDI matter wastes in UTLX 643593 (the accident car), UTLX 643560, and possibly one

other tank car. They checked the fluidity by lowering a rod into the tank cars and sensing

the resistance to withdrawing the rod. The Lake Charles TDI expert stated that

UTLX 643593 had retained a ìslightî positive pressure in the tank. He described the

condition of the wastes in the three tank cars as ìpretty stiff.î He stated that a sample of

the TDI matter waste was normally drawn from each tank car at the Lake Charles plant

before the car was shipped from the plant. The viscosity of the sample was routinely

measured to ensure that it was within customer specifications. If the viscosity were too

high, HAN 906 solvent would be added to bring it within specifications before the tank

car was shipped. 

The Lake Charles TDI expert acknowledged that, for some unknown reason, the

three tank cars he examined at Logansport in November 1998 had been shipped from the

Lake Charles plant without samples being drawn or verification being made that the

viscosities were within Essroc specifications (400 to 500 cp). Lyondell later confirmed
Factual Information 26 Hazardous Materials Accident Report

that tank cars UTLX 643593 (the accident car), UTLX 643560, and UTLX 643562 were

shipped on the same date from Lake Charles. (Shipping records from Olin and Essroc

indicate that UTLX 643562 was offloaded by late September 1998.) In response to Safety

Board inquiries about how this occurred, Olin responded that it was their understanding

that ìArco decided not to add HAN 906 solvent,î based on the original analysis of the TDI

matter waste in each tank car at the time of loading. Lyondell responded that 28 tank cars

containing TDI matter waste were shipped to Essroc between March and September 1998,

including UTLX 643593, UTLX 643560, and UTLX 643562, because blending of the

wastes was to be performed on-site at Essroc. Lyondell stated that the tank cars were

shipped ìunblended at the request of Olin.î 

Configuration of Essroc Offloading Station

The Essroc plantís offloading area had two stations for tank cars, one on the west

side of the kilns and one near the fixed storage tanks. The offloading area also included a

station west of the tank car stations; this western station was used to offload cargo tank

trucks.

To offload a tank car, connections to the fixed plant piping were made at the tank

carís vapor valve and one of its two loading line valves. The connection to the vapor valve

on the tank car controlled the nitrogen system and the vapor emissions system. Nitrogen

gas was injected into the tank carís vapor space to maintain a positive pressure of 20 to

25 psig and to provide a nonflammable mixture in the vapor space. The vapor emissions

system passed the vapors vented from the tank car through a series of filters before any

vapors were released to the atmosphere.23 The single line from the vapor valve on the tank

car contained a shutoff valve and a coupler to the tee fitting that was connected to a

coupler for the nitrogen system and a coupler for the vapor emissions system. The

nitrogen supply line and the vapor emissions line were also equipped with isolation

valves. With this configuration, nitrogen could be injected into the tank car or vapors

vented from the tank car through the vapor emissions system. (Nitrogen could not be

injected while vapors were being vented.)

The nitrogen was stored in a bulk tank located in the offloading area. The nitrogen

was cycled through two heaters before it flowed into the tank car. According to the vendor

that supplied the nitrogen to Essroc, the specifications for the nitrogen stipulated a purity

of 99.999 percent and a maximum water content of 1.5 parts per million (0.00015 percent

by volume). The Essroc TSD facility supervisor indicated during a postaccident interview

that Essroc had had no problems with the nitrogen system before the accident.

A section of flexible hose equipped with a coupler and a valve was connected to

one of two loading line valves on the tank car. The coupler on this flexible hose could be

connected to one of three fixed pipelines: (1) a pipeline serving as a direct feed to the

kilns, (2) a pipeline from the storage tanks containing HAN 906 solvent, and (3) a pipeline

from the storage tanks containing toluene. Cross-connections between the three pipelines

and the placement of pumps and valves enabled Essroc to blend the TDI matter wastes

23 To ensure compliance with air quality standards. 
Factual Information 27 Hazardous Materials Accident Report

with the HAN 906 solvent in a fixed tank and to flush the plant piping from the kilns back

to the tank car. 

The facility supervisor also said, in a postaccident interview, that the offloading

stations had no water lines. An air line led to the offloading station; the air line could not

be cross-connected to the nitrogen line.

The boiler used to generate the steam to heat the wastes in the tank cars was in a

truck trailer north of the tank car offloading station. The CPRIN service manager at the

Essroc plant said that the boiler was automatic. The main valve on the boiler controlled the

amount of steam delivered to the tank car; it was the only valve manipulated in the

steam-heating process. The valve was normally open about halfway. The steam flowed

through a 75-foot-long feed line from the boiler to the inlet connection on the bottom

center of the tank car. The pressure of the steam discharged from the boiler was between

100 and 125 psig; the maximum design pressure of the boiler was 150 psig. After the

steam circulated through the heating coils on the tank car, it flowed through a return line to

a steam trap or condensate tank located in the same trailer as the boiler. According to the

CPRIN manager, the water in the return line was about 180° F. 

Essroc Offloading Procedures

Essrocís plant procedures manual contained written instructions for moving and

unloading any tank car containing any type of waste fuel and standard operating

guidelines that applied specifically to the tank cars carrying TDI wastes. The guidelines

addressed receiving and positioning such cars, drawing samples from them, offloading the

TDI wastes to a fixed tank, and purging the flow lines after the offloading was complete.

The Essroc facility supervisor said that Essroc developed these written procedures in 1995

before the company began to burn standard solvent blend wastes. The facility supervisor

also stated that Essroc had written procedures on how to blend TDI wastes in the fixed

tank after they were offloaded from a tank car and before they were pumped to the kilns

for incineration. The waste fuel technicians had no written procedures or checkoff lists for

directly feeding TDI wastes from the tank car to the kilns (the process used for offloading

UTLX 643593).

The Essroc written procedures that applied to all tank cars and those specific to the

tank cars carrying TDI wastes addressed subjects such as the sequence for opening and

closing valves, the means of connecting and disconnecting nitrogen lines, and the ways of

increasing and decreasing internal tank car pressures to specific limits. The procedures did

not address heating the waste cargoes, limiting temperatures, or limiting maximum

viscosities (to ensure the cargo was sufficiently fluid for offloading). 

The Essroc facility supervisor stated during postaccident interviews that Essroc

personnel would not allow CPRIN to heat TDI wastes to more than 200° F because of a

concern that phosgene might be released. The facility supervisor also stated that Essroc

workers determined that the TDI wastes were ready for offloading when the wastes were

thin enough to flow, rather than when they reached some specific temperature.
Factual Information 28 Hazardous Materials Accident Report

The CPRIN manager stated that CPRIN had no written procedures or checkoff lists

addressing the steam heating of rail tank cars containing TDI wastes or other waste

cargoes. He said that the criteria that CPRIN used for steam heating the tank cars was to

conduct steam heating until the viscosity of the TDI wastes was reduced and the waste

was in a pumpable state. According to the CPRIN manager, it was not unusual to apply

two steam cycles to a tank car containing TDI waste fuels. He also indicated that they

applied more heat to UTLX 643593 than to other tank cars. 

Postaccident Actions 

FRA-Ordered Inspections and Tests 

When the accident occurred, 24 tank cars containing TDI matter waste either were

stored in the Logansport rail yard or had been delivered to the Essroc plant. Olin advised

the FRA on March 23, 1999, that an additional 10 cars containing TDI wastes were at the

Deer Park transfer facility in Houston, Texas.

Following the rupture of UTLX 643593, Olin and Lyondell determined that the 24

tank cars in the Logansport area should be sent to Deer Park for offloading. Because of the

possibility that UTLX 643593 had failed from overpressurization, the FRA ordered the

testing of the pressure relief valves from a representative sample of four of the tank cars in

the Logansport area to ensure the valves were functioning properly before the tank cars

could be moved. The pressure relief valves from tank cars UTLX 643560, UTLX 643588,

GATX 36571, and GATX 92907 were removed and tested at the Midland Manufacturing

production facility in Skokie, Illinois, on March 18 and 25, 1999. Because UTLX 643560

and UTLX 643588 were sister tank cars of UTLX 643593, they were equipped with the

same model pressure relief valve, a Midland model A-1479 ER relief valve. Tank cars

GATX 36571 and GATX 92907 were equipped with Midland model A-1775-P and A-2085

(respectively) pressure relief valves. 

Federal regulations at 49 CFR 180.509 require that pressure tests be conducted

every 10 years for the pressure relief valves on these tank cars. The pressure relief valves

on UTLX 643560, UTLX 643588, and UTLX 643593 had last been tested in 1993 and

were due for retesting in 2003. The pressure relief on GATX 36571 had last been tested in

1989 and was due for retesting in 1999. The pressure relief valve on GATX 92907 had last

been tested in 1993 and was due for retesting in 2003.

The four valves were pressure-tested on March 18, 1999, in accordance with the

procedures in appendix D of the Association of American Railroads (AAR) Specifications

for Tank Cars (M-1002).

24 The FRA reported that all four valves, which were to have

discharge pressures of 75 psig, failed to meet the tolerances for the start-to-discharge

24 Association of American Railroads, Specifications for Tank Cars, In: Manual of Standards and

Recommended Practices, Section C - Part III, Specification M-1002, Washington, DC, 1996.
Factual Information 29 Hazardous Materials Accident Report

pressure25 and vapor-tight pressures required under Federal regulations for tank cars

transporting hazardous materials. 

Although the start-to-discharge pressures recorded for the valves from

UTLX 643560 and UTLX 643588 ranged from 83 to 90 psig, each valve began leaking at

2 to 3 psig. Over three test cycles, the model A-2085 valve from GATX 92907 had a

start-to-discharge pressure ranging from 84 to 94 psig, and a vaportight pressure of

20 psig. The model A-1775-P valve from GATX 36571 had a start-to-discharge pressure

of 250 psig on its first test, and 120 and 130 psig on two subsequent tests. The vaportight

pressure could not be determined.

The O-rings from each valve were examined and tested for brittleness. According

to Midland representatives, the O-rings should have durometer26 readings ranging from

70 to 75 for the relief valve to function properly. Durometer readings for the O-rings were

generally in the mid-90s. (Durometer readings increase as a substanceís brittleness

increases.) The O-rings also exhibited varying degrees of brittleness, swelling, hardness,

and cracking. The condition of the metallic components varied widely: heavy rust, scale,

pitting, and grit were observed on some valve components from GATX 36571 and

GATX 92907. The valve components from UTLX 643560 and UTLX 643588 either had

light scale and rust or exhibited no visible deterioration.

Based on these test results, the FRA required that Olin and Lyondell either replace

the pressure relief valves on the remaining tank cars in Logansport (24 cars) and Deer

Park (10 cars) or prove that the pressure relief valves on the remaining tank cars complied

with Federal regulations before any of the tank cars could be moved in commerce.

Disposition of TDI Wastes in Other Tank Cars

In response to the FRA directive, Olin and Lyondell had the pressure relief valves

replaced on all 24 tank cars in the Logansport rail yard before moving any of the tank cars

to Deer Park, Texas, where they were to be offloaded. By June 22, 1999, the 24 tank cars

shipped from Logansport had arrived in Deer Park, where they were staged until they were

individually offloaded at the terminal. 

Olin contracted a waste disposal firm to dispose of the TDI matter wastes in the

24 tank cars shipped from Logansport and the other tank cars sent to Deer Park. The waste

disposal firm was to blend the TDI matter waste with HAN 906 solvent as needed to

reduce the viscosity of the waste below a prescribed level before transloading the wastes

from the tank cars to tank trucks. The blending agent was added to the TDI matter waste to

reduce the wasteís viscosity to ensure that it would be sufficiently fluid to allow it to be

offloaded into tank trucks. The tank trucks delivered the wastes to incineration sites in

Houston, Texas, and Baton Rouge, Louisiana. 

25 The start-to-discharge pressure is the pressure at which the spring-loaded valve begins to lift,

allowing vapor to flow through the valve and vent from the tank. 

26 Tool for measuring the degree of brittleness or hardness of a gasket. 
Factual Information 30 Hazardous Materials Accident Report

The blending and offloading of the wastes in these tank cars began on August 2,

1999. Olin reported that by August 9, 2000, five cars remained to be offloaded. Since

August 2000, two tank cars have been successfully offloaded. In the three remaining cars,

the TDI matter waste has solidified and cannot be successfully pumped from the tanks. An

attempt to offload two of the three cars by mechanical extraction (grinding) is planned for

2001. Experts believe that the final car may have to be cut apart to remove the solidified

waste.

UTLX 643560, which had a loading history and waste composition most similar to

UTLX 643593, had been offloaded on December 2, 1999. The initial viscosity of the TDI

matter waste in UTLX 643560 was 2,160 cp at 75° F. Slightly more than 2,500 gallons of

toluene were blended with the waste in UTLX 643560 to reduce the viscosity to 325 cp at

75° F. Because of the reduction in the viscosity from blending with the toluene, steam

heating of the waste was not required before offloading UTLX 643560. Olin also stated

that no problems were encountered with increased pressures or temperatures concerning

any of the tank cars offloaded at Deer Park.

Postaccident TDI Matter Waste Offloading Procedures

Following the accident (and before offloading began), Olin, with the assistance of

waste disposal companies, developed written offloading procedures for the 24 tank cars

that contained TDI matter wastes and had been stored in Logansport and for the 10 tank

cars stored at Deer Park. Under these procedures, a sample of the TDI matter waste would

first be drawn to determine its viscosity, which had to be less than 400 cp at 120° F before

offloading could begin. If the viscosity of the TDI matter waste in an individual tank car

exceeded this limit, the amount of HAN 906 solvent needed to lower the viscosity below

the 400 cp threshold was calculated.27

Before any TDI matter wastes were transferred from the tank car to a cargo tank

truck, technicians were required to conduct the following sequence of operations: 

ï (To prevent overheating from high-pressure steam) Use low-pressure steam to

heat the TDI wastes by connecting the steam supply to the inlet pipe for the

heating coils on the tank car, leaving the discharge pipeline for the heating

coils open; 

ï Sparge the TDI waste mixture by injecting nitrogen through the eduction line

to agitate the TDI waste while heating; 

ï Continuously steam heat and mix until the temperature of the TDI waste

reaches 125° F, at which time the steam heating and sparging are stopped; 

ï Inject the previously calculated amount of HAN 906 solvent through the

eduction line; 

ï Recommence sparging of the TDI waste with nitrogen for 1 hour; 

27 Although these procedures specified the use of HAN 906, toluene (a hydrocarbon) could be used as a

solvent to reduce the viscosity of the wastes. As noted earlier, toluene was used to reduce the viscosity of the

wastes in UTLX 643560. 
Factual Information 31 Hazardous Materials Accident Report

ï Draw a sample of the TDI waste from the tank car and measure its viscosity. (If

the viscosity were less than 400 cp, the TDI wastes were to be offloaded from

the tank car to cargo tank trucks. If the viscosity exceeded 400 cp, the cycle of

steam heating, sparging, and adding HAN 906 solvent was to be repeated until

the specifications for viscosity were met.)

The written procedures also specified that the temperature of the TDI matter waste

should be maintained at 125° F, ± 10° F.

Inspections and Tests

Metallurgical Examination

After the accident, three sections were cut from UTLX 643593 and sent to the

Safety Boardís materials laboratory for further examination. The sections were: (1) a

35-inch-long section of the fracture surface along the tankís bottom center toward the

A-end, (2) a section from the top center that appeared to be unaffected by the tank rupture,

and (3) a section from the bottom center containing a tear in the exterior tank wall.

The 35-inch-long section of the fracture surface was taken from a tank location

with the lowest wall thickness, based on field measurements. Measurements of the wall

thickness along the fracture face ranged from 0.285 to 0.338 inch. Plastic deformation

(necking) of the tank wall along the fracture was observed. The fracture face in the area

where the tank wall was thinnest contained shear lips on both the exterior and interior

surfaces and a small flat fracture region between the shear lips. The fracture features were

typical of ductile tensile overload fractures in low-carbon steels. X-ray energy dispersive

analysis indicated that the chemical composition of the steel was consistent with the

ASTM A516 grade 70 steel specified for the tank material.

The tank wall in the section removed from the top center of the tank (which had

appeared to be unaffected by the rupture) had an average thickness of 0.545 inch.

According to Union Tank Car, the thickness of the shell plate before it was rolled into the

tank cylinder ranged from 0.569 to 0.580 inch. The microstructure of the tank material

was typical of ASTM A516 grade 70 steel in a hot-rolled condition. Based on hardness

tests, the ultimate tensile strength was about 89,000 pounds per square inch (ksi). The

specified tensile strength of the tank plate was 70 to 90 ksi. The reported tensile strength

of the plate from which this tank was manufactured was 78.8 ksi.

Plastic deformation was found on the section removed from the bottom of the tank

car that had tearing damage on the exterior surface. Hardness tests indicated that this

section had an ultimate tensile strength of 89 ksi.
Factual Information 32 Hazardous Materials Accident Report

Examination of the Pressure Relief Valve and Other Fittings

The dome assembly, including the manway cover, valves, piping, and surrounding

tank shell, was cut from UTLX 643593ís tank on February 24, 1999. The dome assembly

was taken in April 1999 to Marsh Railcar Services in St. Peters, Missouri. Testing and

examination of the pressure relief valve and the other valves mounted on the manway

were conducted on May 18, 1999.

Solid TDI waste material filled about half of the interior of the dome nozzle. Loose

pieces of the solid waste were removed to expose a portion of the manway coverplate. The

remainder of the manway coverplate interior was covered with a layer of solid,

glassy-looking TDI matter waste that was molded into the dome nozzle. The thickness of

this layer was 4 to 5 inches. This layer was chipped out to expose the complete interior

side of the manway coverplate.

Some TDI waste residue was also on the exterior side of the manway coverplate,

between the base of the pressure relief valve and the valve for the B-end loading line. An

information card about the health hazards of pure TDI and a plastic bag containing an Olin

rail car complaint form were also found within the dome housing. These two items had no

apparent heat or thermal damage. The pressure relief valve, the vapor valve, the vacuum

relief valve, and the two loading line valves were removed and examined. The Teflon

gaskets used to seat these valves on the manway coverplate were clean and had no visible

deterioration. The condition of each valve is detailed below.

Pressure Relief Valve. The pressure relief valve was unbolted and removed from

the manway coverplate. The orifice in the manway coverplate for the pressure relief valve

was completely plugged with solid TDI waste. The solid TDI waste had also flowed onto the

exterior of the manway coverplate below the base of the pressure relief valve, between the

orifice opening and the Teflon seating gasket. TDI waste filled and plugged the throat of the

pressure relief valve. (See figure 9.) The vertical alignment of the pressure relief valve was

measured. No misalignment was noted or observed. Dirt, grease, and some corrosion were

observed on the exterior surfaces. (The pressure tests and teardown are detailed in the next

section.)

Vapor Valve. The handle for the 1-inch vapor valve was not in the fully open

position. The orifice through the manway coverplate was completely plugged with TDI

waste. When investigators removed the valve, they noted that the inlet at the base of the

valve was completely plugged with TDI waste. They disassembled the valve. TDI waste was

molded to the interior of the valve; the waste completely plugged the valve from the inlet

flange to the outlet flange. (See figure 10.)

Vacuum Relief Valve. The orifice through the manway plate was plugged with TDI

waste. The waste did not completely fill the orifice and came to within 1 inch of the exterior

side of the manway coverplate. (Refer to bottom photo of figure 10.) No waste material was

observed in the body of the valve.
Factual Information 33 Hazardous Materials Accident Report

Figure 9. Top photo shows plugged opening in UTLX 643593 manway coverplate for 

pressure relief valve as viewed from the interior of the tank. Bottom photo shows view of 

plugged valve from the dome side of the manway cover. (NTSB)
Factual Information 34 Hazardous Materials Accident Report

Figure 10. Top photo shows plugged opening in UTLX 643593 manway coverplate for 

vapor valve as viewed from the interior of the tank. Bottom photo shows plugged openings in manway coverplate for vapor (higher) and vacuum relief (lower) valves from the 

dome side of the manway cover. (NTSB)
Factual Information 35 Hazardous Materials Accident Report

A-end Loading Line Valve. The valve handle was in the closed position. The

threaded cap used to cover the valve outlet was in place and secure. When the valve was

removed from the coverplate, it was seen to contain waste with a taffy-like consistency. 

B-end Loading Line Valve. The valve handle was in the closed position. The

threaded cap used to cover the valve outlet was unscrewed and dangling from a chain

attached to the valve. When the valve was removed from the coverplate, liquid trapped in the

valve began to drip. During the inspection, one party representative remarked that the liquid

had an odor similar to MCB. (The liquid and other viscous materials trapped in the valve

were drained into a glass jar with a screw-on lid. These substances were subsequently sent to

an independent laboratory for analysis. See section on ìChemical Analysis and Tests.î) The

orifice in the manway coverplate was plugged to a depth of about 1 inch below the exterior

surface of the coverplate with wet and very soft waste residue. After this residue was

removed, a length of pipe was inserted to a depth of 14 inches through the manway plate

opening into the loading line to determine whether TDI waste was in the loading line. No

waste product was detected using the pipe probe.

Thermometer Well. The cap was off. No other observations were noted.

Pressure Tests and Teardown of Pressure Relief Valve

The pressure relief valve was mounted on a test bench, and air pressure was

applied to determine (1) if the start-to-discharge pressure was within the tolerance of

± 3 psi for the 75-psig set point and (2) if the valve, upon closing, was vaportight at not

less than 80 percent of the start-to-discharge pressure. Five test runs were conducted.

During the first two tests, the valve began to discharge at less than 10 psig and to

continuously discharge as the air pressure was increased to 100 psig. For the third test, the

TDI waste in the throat of the pressure relief valve was removed, and air pressure was

again applied to the valve. The valve began to leak air at less than 10 psig. Before the

fourth test, the pressure relief valve was disassembled without changing the spring setting.

Debris on the valve seat was observed but left in place. (See figure 11.) After new O-rings

were installed, the valve was reassembled, and, without cleaning the debris from the valve

seat, air pressure was applied. The valve discharged at 3 psig. For the fifth test, the

pressure relief valve was again disassembled and the debris was cleaned from the valve

seat and all sealing surfaces. The new O-rings were lubricated, and air pressure was

applied. The valve began to discharge at 73 psig, reseated when the air pressure was

reduced, and was vaportight at 68 psig. This cycle was repeated twice more with

comparable results.

Following the pressure tests, the pressure relief valve was completely

disassembled. The interiors of the valve and the spring were free of chemical debris and

exhibited no indications of mechanical damage or corrosion. The two O-rings that had

been removed from the pressure relief valve were examined and tested for brittleness. The

large O-ring had a permanent set or deformation on the sealing surface with the valve. No

set or deformation was noted on the small O-ring. Durometer measurements on the new

O-rings and the two O-rings removed from the relief valve were taken and compared.

Durometer readings for the new O-rings ranged from 70 to 74 (considered normal); the
Factual Information 36 Hazardous Materials Accident Report

reading for the O-rings removed from the pressure relief valve ranged from 80 to 97

(indicating increased hardness and brittleness). 

Chemical Analyses and Tests

Samples. Nine chemical samples, including a sample of the TDI waste matter

drawn from UTLX 643593 before the accident, were recovered and shipped to the Lake

Charles plant for analysis and testing. The other eight samples were recovered after the

accident from the remnants of the tank car, debris on the plant grounds, and a cutout

section of plugged pipe to the kilns. Heating tests were conducted on the preaccident

sample drawn from UTLX 643593 (designated as the "retain" sample), the sample from

the plugged pipe section (designated as the "pipe cutting" sample), and a waste sample

from the Lake Charles plant. The tests were designed to analyze the effects of heating the

samples similarly to the heating of the waste mixture that had been in UTLX 643593.

Testing. The apparatus for the heating tests, known as the reactive system

screening tool (RSST), monitored and recorded the temperature and pressure as a 10-cubic

centimeter glass vial approximately 2/3 full of each test sample was heated in a closed

chamber. The liberation or generation of gas would be indicated in a test run if there were

a net increase in the pressure in the test chamber after the chamber had cooled to its initial

temperature. The first four test runs were to be conducted following normal RSST

methods of increasing the temperature at a controlled rate to the programmed cutoff

temperature of 662° F. However, the sample in the first run could not be heated to the

Figure 11. Pressure relief valve fitting. Arrows show debris on the valve seat. (NTSB)
Factual Information 37 Hazardous Materials Accident Report

cutoff temperature because the glass vial shattered from expansion of the test sample. The

sample was heated and held to a temperature range of 428 to 446° F for the maximum test

time of 7.3 hours. In the fifth and final run, 10 grams of the preaccident sample drawn

from UTLX 643593 were heated to 353° F and held at this temperature for 25.7 hours to

approximate the maximum possible temperature of the steam used to heat UTLX 643593

and the total heating time of UTLX 643593. See table 1 for the results of the five test runs.

The sample in each test run exhibited an increase in volume by the conclusion of

the test run. The volume increase of the samples in two of the glass vials was sufficient to

exceed the volume of the glass vial and cause the vial to break. The volume of the samples

from the three remaining test runs expanded from 2/3 of the volume of the vial to fill the

vial completely. The test results did not establish whether the volume increase was the

result of the expansion of the sample or the entrapment of gas bubbles within the waste.

Gas chromatographic analysis was conducted on the retain sample, the pipe cutting

sample, and the typical waste sample to identify specific chemical compounds in each

sample. The results of this analysis indicated that each sample contained TDI, chlorinated

TDI impurities, and carbodiimides (byproduct of a self-reaction of the monomeric TDI). 

An independent laboratory conducted several analytical tests from December 1999

through February 2000 on the waste sample recovered from the B-end loading valve of

UTLX 643593 during the inspections at Marsh Railcar Services in May 1999. The sample,

when recovered, was a mixture of a viscous material and liquid. Although the sample had

been placed in a glass jar and sealed, virtually all the liquid had evaporated when it was

delivered to the laboratory for testing. The purpose of these tests was to identify the

chemical components of the sample and to test specifically for the presence of toluene and

amines. (Toluene was the solvent used by Essroc to flush the plugged piping to the kilns.

Amines are a class of chemical compounds that would be byproducts of the reaction of

TDI and water.)

Infrared spectrometry and gas chromatography indicated the presence of toluene,

amines, and MCB in the sample. Based on additional testing to determine the types of

amines detected, the laboratory concluded that the amines present were ìprimaryî amines

that would be generated with the reaction of TDI and water. 

Table 1. Results of RSST runs on TDI waste matter samples

Run Number Sample Source

Net Pressure Increase 

(psi)

1 10.11 g of retain w/200 mg of water 9.4

2 10.10 g of retain 4.4

3 9.10 g of pipe cutting 20.0

4 10.00 g of typical waste 9.9

5 10.20 g of retain 3.5
Factual Information 38 Hazardous Materials Accident Report

Approved Cargoes and Components for DOT Specification Tank 

Cars

Federal Regulations and Oversight

Under 49 CFR 179.15 of the DOT Hazardous Materials Regulations, the pressure

relief device on a DOT class 111A tank car, such as UTLX 643593 and the four other tank

cars tested at Midland in March 1999, must be made of materials that are compatible with

the lading transported in the tank car. Paragraph A3.02 of appendix A of the AAR Manual

of Standards for tank cars28 reads, ìIt is the shipperís responsibility to assure that materials

used for gaskets or valve seals are compatible with the lading and the service

temperature.î The 49 CFR 179.15 compatibility requirement does not reference, or

explicitly require conformance with, the AAR standard.

In a February 9, 2000, response to Safety Board inquiries concerning the FRA

hazardous materials safety program and issues involved in the Clymers accident,29 the

FRA told the Safety Board that the DOT Hazardous Materials Regulations place the

responsibility for ensuring that a package is appropriate for transportation on the ìofferorî

(typically the shipper) of the material. The FRA further stated that the selection should be

made with input from the tank car owner, to ensure that the gasket configuration is

appropriate for the device and that other entities have similar responsibilities in relation to

the tank carís maintenance. The FRA noted that the tank car manufacturer and tank car

repair facilities each have a responsibility to ensure that the approved materials are used

during the assembly of the tank car and for repairs or replacement. Nevertheless, the FRA

stated that the DOT regulations require the offeror to ensure that the components on the

tank car are correct before offering the tank car for transportation.

The DOT Hazardous Materials Regulations also contain provisions regarding a

change in the approved cargoes for a DOT specification tank car.

Paragraph 49 CFR 173.31(a)(2) of the Hazardous Materials Regulations reads:

Tank cars and appurtenances may be used for the transportation of any commodity

for which they are authorized in this part and specified on the certificate of

construction (AAR Form 4-2 or by addendum on Form R-1)... Transfer of a tank

car from one specified service on its certificate of construction to another may be

made only by the owner or with the ownerís authorization. A tank car proposed

for a commodity service other than specified on its certificate of construction must

be approved for such service by the AARís Tank Car Committee.

The FRA, in response to Safety Board inquiries, indicated that, under the

provisions of 49 CFR 173.31(a)(2), the offeror must secure approval from the tank car

owner before making a change in product service. The offeror must also ensure, with the

28 Association of American Railroads, Specifications for Tank Cars. In: Manual of Standards and

Recommended Practices, Section C - Part III, Specification M-1002. Washington, DC, 1996.

29 Letter from FRA Hazardous Materials Staff Director Edward W. Pritchard to the Safety Board,

February 9, 2000.
Factual Information 39 Hazardous Materials Accident Report

assistance of the tank car owner, that the materials and components that constitute the tank

car are appropriate for carriage of a new product. In the case of UTLX 643593 and the

other tank cars used to transport the TDI waste mixtures, the FRA stated that the addition

of constituents other than TDI would comprise a change in service if the additional

constituents substantially changed the chemical makeup of the material or changed its

hazard class.30

The FRA further stated that no information or guidance regarding gasket and

fitting compatibility in conjunction with changes in product service has been issued. The

FRA noted, however, that, in an advance notice of proposed rulemaking (ANPRM)

published under docket HM-175A in May 1990, the FRA and the Research and Special

Programs Administration (RSPA) sought comments regarding performance standards for

the gaskets used on tank cars. Because it received numerous comments citing the technical

complexities in developing a performance standard for gaskets, RSPA removed the gasket

issue from the docket. The FRA stated that it continues to participate in the AAR Tank Car

Committee and the North American Non-accident Release Prevention Committee, which

have addressed compatibility issues concerning gaskets and fittings in nonaccident

releases. 

Compatibility of Pressure Relief Device Components with TDI Waste 

Mixtures

Union Tank Car provided the Safety Board with excerpts from the Chemical

Resistance Guide for Elastomers, which contains guidance about the resistance of available

gasket, O-ring, and sealing materials to degradation upon exposure to various chemicals.

According to this guide, ethylene propylene rubber, the material that constituted the O-rings

in the pressure relief valves from UTLX 643593 and the four tank cars tested at Midland,

offers good to excellent resistance to chemical attack from pure TDI at temperatures up to

70° F and should not exhibit more than minor swelling, softening, or surface deterioration.

The guide recommends against using ethylene propylene rubber with either MCB or

naphthalene, one of the primary components of the HAN 906 solvent. Teflon is rated as

providing excellent resistance to degradation for TDI, MCB, and the naphthalene.

Midland indicated that, because it is the manufacturer rather than the user of the

pressure relief valves, the company does not recommend, prescribe, or influence the

selection of valve materials. Midland further stated that it is rarely cognizant of the

intended service of the valves and fittings it sells. The company provides its customers, in

this instance the tank car builder Union Tank Car, with the valves, gaskets, and O-rings

specified by the customer. (Olinís construction order to Union Tank Car specified ethylene

propylene rubber O-rings for the pressure relief valves on UTLX 643593 and its sister

tank cars.) 

In response to Safety Board inquiries about the chemical compatibility of the TDI

matter wastes with the components of the tank cars used to store them, Olin stated that, at

various times since the 1970s, the company had had its tank cars evaluated to ensure their

30 FRA February 9, 2000, letter.
Factual Information 40 Hazardous Materials Accident Report

suitability for storing and transporting TDI, TDI matter wastes, and solvent blend wastes.

Olin stated that the results of such evaluations would have been turned over to

Arco/Lyondell as part of the sale of the business. Olin indicated that the company has not

been able to locate documentation on any such tests and could not provide any additional

details. In response to the same inquiry, Lyondell responded that Arco and Lyondell did

not conduct any evaluations of the chemical compatibility of the TDI waste mixtures with

gaskets, O-rings, and other components on the tank cars used to store these wastes, but

ìtypicallyî verified the compatibility of the gaskets and O-rings with ìvendor-supplied

information.î Lyondell stated that the company had no reason to investigate use of the

gasket materials with the TDI wastes because no in-plant incidents or releases from tank

cars had occurred.

Change of Authorized Cargoes

Because of concerns involving the chemical compatibility of the O-rings with the

MCB and the HAN 906 solvent in the TDI waste cargoes, the Safety Board also asked

Olin and Lyondell whether they considered that the storage and transportation of the TDI

matter wastes in UTLX 643593 and the other tank cars constituted a change in product

service from the transportation of pure TDI.

Olin responded that it did not consider the storage and transportation of the TDI

wastes in these tank cars to constitute a change in product service. Olin acknowledged that

the TDI matter (blended and unblended) and the solvent blend wastes differed from pure

TDI but considered that UTLX 643593ís and the other tank carsí approval for carriage of

pure TDI to be sufficient for carriage of the mixtures of monomeric and polymeric TDI,

MCB, and HAN 906 solvent. Olin noted that, under the certificate of construction,

UTLX 643593 and its sister tank cars were approved for the carriage of ìnon-regulated

commodities and commodities authorized in DOT Part 173 (49 CFR 173) for which there

are no other requirements and which are compatible with this design and class of car.î

Olin considered that the MCB, the polymeric TDI, and the HAN 906 solvent were within

the approved commodity service on the certificate of construction. Consequently, Olin did

not seek AAR approval for a change in product service.

Lyondell responded to the Safety Boardís inquiry that, although the TDI waste

mixtures would have to be identified under a new DOT proper shipping name (hazardous

waste, toxic liquid, flammable, organic n.o.s. [not otherwise specified]) rather than as pure

TDI, the shipment of these TDI waste mixtures did not constitute a change of product

service. Lyondell noted that, under the DOT Hazardous Materials Regulations, the bulk

containers, such as tank cars, authorized to transport pure TDI were the same containers as

those authorized to transport commodities under the new proper shipping name, and that

no applicable special provisions in the DOT Hazardous Materials Regulations precluded

the use of the same type of tank car. Consequently, Lyondell did not seek AAR

authorization to change the approved cargoes.
Factual Information 41 Hazardous Materials Accident Report

Hazardous Materials Incident Reporting

Notification of Accident

The Essroc plant manager notified the National Response Center (NRC) about the

accident by telephone shortly after 3:00 a.m. on February 18, 1999, about 3 hours after the

accident. The NRC report summarizing the telephonic notification indicated that a rail car

containing ìhazardous wastesî had ruptured and was on fire.

The Essroc plant manager believed that, in providing telephonic notification to the

NRC, he was complying with applicable Environmental Protection Agency (EPA)

regulations.31 According to Essroc, the plant manager and other Essroc personnel are

generally aware of applicable DOT requirements. Essroc further stated that the company

is not a carrier and is not responsible for submitting a written DOT Hazardous Materials

Incident Report. Essroc did not submit a written incident report to the DOT.

The rail carrier that delivered UTLX 643593 to the Essroc plant was the Central

Railroad of Indianapolis, which was managed by the Indiana and Ohio Rail Company. The

parent company for both the Central Railroad of Indianapolis and the Indiana and Ohio

Rail Company is Rail America. The general manager for the Central Railroad of

Indianapolis and the Indiana and Ohio Rail Company indicated that the rail carrier did not

submit a written incident report to RSPA because the tank car had been delivered to and

left at the Essroc plant, the accident occurred on Essroc property, and the railroad was not

involved in the accident. To date, no written incident report has been received by RSPA.

Notification Requirements

Immediate Notification. Under section 49 CFR 171.15 of the DOT Hazardous

Materials Regulations, a carrier must notify the NRC by telephone ìat the earliest

practicable momentî about incidents that occur during ìthe course of transportationî in

which the release of a hazardous material results in a fatality, injuries requiring

hospitalization, property damage exceeding $50,000, evacuations of the general public, and

other criteria. 

EPA regulations contain multiple requirements throughout 40 CFR for immediate

notification following releases of those materials it designates as ìhazardous

substances,î32 ìhazardous wastes,î and oil (both ìusedî and crude) from vessels, offshore

and onshore facilities, and hazardous waste management facilities operating under EPA

permits, as well as TSD facilities such as Essroc. Under DOT and EPA regulations, the

telephonic or immediate notifications are made to the NRC, which then disseminates the

report to the appropriate Federal agencies, including the EPA, RSPA, the FRA, and the

31 The EPA regulations for TSD facilities (40 CFR 264) include notification requirements in the event of

a release of a hazardous waste. The regulations for emergency planning and community right-to-know

programs (40 CFR 302) also have notification requirements for chemical releases. 

32 Specific materials or chemicals designated under the Comprehensive Environmental Response,

Compensation, and Liability Act (42 USC 9601) as harmful to the environment if released in a quantity

exceeding the reportable quantity for the material.
Factual Information 42 Hazardous Materials Accident Report

Safety Board. A single notification to the NRC often satisfies the notification

requirements of several Federal agencies.

The NRC, in processing all telephonic notifications, regardless of the nature of the

release, collects information of a general nature necessary to understanding and

responding to a current or recent emergency. The information sought by the NRC typically

includes such information as the location of the incident, the date and time it occurred, the

type of material released, the source of the release, the quantity of material released, the

names of the parties involved, the damage to the area, and other information immediately

obtainable. Such reports are preliminary in nature and are not designed to be

comprehensive. 

Written Reports. Section 49 CFR 171.16 of the DOT regulations requires that each

carrier that transports hazardous materials submit a written DOT Hazardous Materials

Incident Report to RSPA within 30 days of discovery of each incident that occurs ìduring

the course of transportationî in which there has been an unintentional release of a hazardous

material. DOT regulations define a ìhazardous materialî as including both EPA-designated

hazardous substances and hazardous wastes. Section 49 CFR 171.16 also requires that the

carrier submit a DOT Hazardous Materials Incident Report for any incident that must be

telephonically reported under section 49 CFR 171.15. Both 49 CFR 171.15 and 171.16

specify that ìthe course of transportationî includes loading, unloading, and temporary

storage. The regulations define a carrier as ìa person engaged in the transportation of

passengers or property by land or water as a common, contract, or private carrier or by civil

aircraft.î In response to Safety Board inquiries, the FRA stated that, in letters of clarification

concerning these requirements, RSPA has indicated that a carrier has a duty to report

releases of hazardous materials in accordance with 49 CFR 171.16 when it has knowledge of

such releases. The FRA stated that a rail carrier must ìreport to the Departmentî within

30 days of the date of discovery.

The DOT Hazardous Materials Incident Report form (see appendix B), contains

45 specific categories of information, including background facts about the incident

(mode of transportation, date and time of incident, description of carrier and materials

shipped, etc.) and specific details concerning the type of container involved, conditions at

the incident site, packaging of the material released, and sources of packaging failures.

RSPA uses the information obtained through these written incident reports as the input for

its Hazardous Materials Information System, which serves as RSPAís accident database,

which RSPA uses to conduct accident analyses.

The EPA requires the submission of written reports for certain types of hazardous

waste and oil releases, under certain conditions. Under 40 CFR 264.56(j) and 279.52(b)

the owner/operator of a TSD facility or a used-oil processing facility must file a written

report to the EPA regional administrator within 15 days after a release, fire, or explosion

involving a hazardous waste or used oil that could threaten human health or the

environment outside of the facility. The written report must include seven categories of

information:
Factual Information 43 Hazardous Materials Accident Report

1. The name, address, and telephone number of the owner or operator,

2. The name, address, and telephone number of the facility,

3. The date, time, and type of incident,

4. The name and quantity of hazardous waste or oil involved,

5. The extent of injuries (if any), 

6. An assessment of the actual or potential hazards to human health or the

environment, where this is applicable, and 

7. The estimated quantity and disposition of recovered hazardous waste or oil that

resulted from the incident.

The EPA also requires a transporter of hazardous waste under 40 CFR 263.30 or

used oil under 40 CFR 279.43 to file a DOT Hazardous Materials Incident Report in

accordance with 49 CFR 171.16 when hazardous waste or used oil is released during

transportation.

With respect to those materials that the EPA designates as ìhazardous substances,î

the EPA does not require that a written report be submitted to the agency when a

hazardous substance release occurs.

Essroc submitted a report dated March 4, 1999, concerning the Clymers accident

to the Indiana Department of Environmental Management. Essroc forwarded a copy of

this report and cover letter to the EPA Region 5 office on March 4, 1999.

Regulatory Initiatives

RSPA issued an ANPRM on March 23, 1999, which concerned revising the incident

reporting requirements (49 CFR 171) and the DOT Hazardous Materials Incident Report

form.33 According to RSPA, the purpose of any revisions would be to increase the usefulness

of the accident/incident data in evaluating the effectiveness of existing regulations,

determining the need for regulatory changes to address changing transportation safety

problems, and identifying major problem areas requiring additional DOT resources. The

ANPRM sought comments and information about numerous issues, including:

ï Should the hazardous materials incident reporting requirements be extended to

persons other than carriers (such as freight forwarders, warehouse operators,

consignees, etc.)?

ï If an incident requiring immediate telephonic notification occurs at the

location of an offeror or consignee, should the offeror or consignee be required

to provide the notification?

33 RSPA. March 23, 1999. ANPRM ìRevisions to the Incident Reporting Requirements and the Detailed

Hazardous Materials Incident Report DOT Form F 5800.1.î Docket number RSPA-99-5013 (HM-229).

64 Federal Register 13943.
Factual Information 44 Hazardous Materials Accident Report

The Safety Board commented on the ANPRM in a July 26, 1999, letter and urged

RSPA to:

Require that undeclared shipments of hazardous materials found in transportation

be reported; telephonic and written notification be improved; a report be filed for

any hazardous materials container failure; shippers be notified when a release

involving their cargo occurs; and information be collected that will help identify

patterns of container and equipment failure.

In its comments, the Safety Board cited specific deficiencies in current reporting

requirements. Among those problems the Safety Board detailed was that:

Öwhen failures of DOT specification containers or releases of hazardous

materials from such containers occur at either the loading or unloading facility, a

carrier may not be directly involved, as the Clymers accident demonstrates,

thereby increasing the likelihood that such accidents will go unreported to RSPA. 

The FRA made no official comments on the ANPRM but stated that the agency

addresses its concerns and recommendations through its participation as an active member

of the rulemaking team.
45 Hazardous Materials Accident Report

Analysis

General

About 12:05 a.m. on February 18, 1999, railroad tank car UTLX 643593, which

was on the west unloading rack at the Essroc cement plant near Clymers, Indiana,

sustained a sudden and catastrophic rupture that propelled the tank carís tank about

750 feet and over multistory storage tanks. Essroc had been attempting to transfer the

substance in the tank car, TDI matter waste, to its kilns, where it was to be burned as a

fuel. TDI matter waste is a flammable, toxic, and hazardous substance that must be

disposed of in accordance with EPA regulations. This tank car of TDI matter waste had

been sent to Essroc by the Arco Chemical Company (later purchased by the Lyondell

Chemical Company), which owned the Lake Charles, Louisiana, facility that had

generated the TDI matter waste as a byproduct of TDI production. 

Lyondell had contracted with Essroc to dispose of the TDI matter waste. The TDI

production facility already had a relationship with Essroc for the disposal of hazardous

TDI waste, as Essroc had disposed of TDI solvent blend waste from the Lake Charles

plant for 2 years before agreeing to take shipment of the TDI matter waste for disposal.

When Essroc began accepting TDI matter waste for disposal in May 1998, it initially used

a process by which the waste from the rail car tanks was first blended in a fixed tank with

solvents (to reduce its viscosity) and then pumped to Essrocís kilns from the fixed tank.

When, in fall 1998, Essroc encountered problems with this process, it began using a new

procedure to transfer the TDI matter waste from its shipping tank cars directly to the kilns.

This was known as the direct injection process. Essroc did not develop, in cooperation

with Lyondell, specific written instructions for unloading the waste or disposing of it

safely using the direct injection process.

Because of the complex circumstances and nature of the accident, the Safety Board

considered several potential causes of the rupture during the investigation. The first

section of this analysis will address each of the potential causes of the accident. The

succeeding sections will address, in turn, the four major safety issues identified during the

investigation, which are:

ï Sufficiency of safety requirements addressing the procedures used for loading

and offloading railroad tank cars and other bulk containers used to transport

hazardous materials;

ï Adequacy of inspection and testing requirements for pressure relief devices on

railroad tank cars;

ï Adequacy of provisions addressing changes in product service for railroad tank

cars; and 
Analysis 46 Hazardous Materials Accident Report

ï Adequacy of the U.S. DOT Hazardous Materials Regulations pertaining to the

notification and reporting of hazardous materials incidents.

Accident

Rupture of UTLX 643593

The catastrophic rupture of tank car UTLX 643593 was the result of pressurization

that exceeded the burst pressure of the tank, which Union Tank Car calculated to be

between 813 and 844 psia. The upright position and orientation of both tank car wheel

assemblies at the loading station after the accident, the torsion damage to the rails at the

loading station, the upward trajectory of the UTLX 643593 tank over the fixed storage

tanks, the extended fracture along the bottom centerline of the tank, and the flattening of

the tank were all consistent with a failure originating along the bottom centerline of the

tank.

Safety Board investigators observed ìnecking downî deformation in the tank wall

at the fracture that extended along the bottom center of the tank. Laboratory measurements

of the plate thickness along the fracture indicated that deformation of the plate from

ìneckingî had reduced the plate thickness to as little as 0.285 inch, a 50 percent reduction

in the original plate thickness of 0.5625 inch. In addition, metallurgical examination of a

35-inch long section of the fracture along the bottom center of the tank identified features

on the fracture surface typical of ductile tensile overload in low-carbon steels. The

deformation from necking and the presence of fracture features indicating tensile overload

could have resulted only from an overpressurization of the tank.

The absence of pitting, corrosion, and other visual signs of tank deterioration

indicated that no structural defects or deficiencies might have caused the tank to rupture,

or weakened the tank such that it would have ruptured at pressures within its design limits.

Further, based on the results of the laboratory analysis of the steel plateís microstructure

and hardness tests, the steel used in the tankís construction met the specifications for

ASTM A516 grade 70 steel and had sufficient tensile strength and thickness for the tank

car to easily withstand its maximum operating pressure of 100 psig. Consequently, the

Safety Board concludes that no evidence indicates that the tank of railroad tank car

UTLX 643593 had any structural or material defects that either caused or contributed to

the rupture of the tank. Therefore, in the absence of any structural or material defects to

weaken the tank, the Safety Board concludes that the internal pressure in tank car

UTLX 643593 increased and eventually exceeded the burst pressure of the tank, resulting

in the catastrophic rupture of the tank car. 

Overpressure Condition

Given the offloading configuration that Essroc employed, internal pressure in

UTLX 643593 could be relieved in two ways: (1) controlled venting through the vapor

valve on the tank car to the vapor emissions system for the plant and (2) venting through
Analysis 47 Hazardous Materials Accident Report

the pressure relief valve on the tank car. The pressure relief valve was designed to

discharge when the internal pressure reached 75 psig, but during postaccident testing, it

began to discharge at pressures below 5 psig. Consequently, an overpressure and eventual

rupture of the tank could have occurred only if the flow of vapor or other material through

the vapor valve/vapor emissions system or the pressure relief valve had been completely

stopped or if the pressure in the tank had increased at a rate that exceeded the flow

capacity of the pressure relief valve to vent.

The Safety Board examined whether the generation of pressure at a rate that

exceeded the flow capacity of the pressure relief valve to vent could have caused the

overpressure and rupture of UTLX 643593. Essroc employees noted that the pressure

relief valve was ìwhisperingî or discharging slightly on the morning of February 16. The

Essroc employees attributed the whispering to the saturation of the filters in the vapor

emissions system, which prompted them to use a water bath for venting the vapors from

the tank car. The facility supervisor described the vapors from the tank car as ìtricklingî

through the water bath on February 16, and a second Essroc employee observed water

ìbubblingî and splashing in the tote tank on the night of February 16. The Essroc facility

supervisor stated that on the morning of February 17, he reduced the pressure in the tank

car and then injected nitrogen until the pressure was 25 psig. According to Essroc

personnel, no other work was performed on the tank car before the accident. 

The trickling of vapors through the water bath and the bubbling of the water bath

indicate that only low-pressure venting of vapors was occurring. If pressure in the tank car

had been increasing at a rate exceeding the pressure relief valveís capacity to vent, the

venting vapors would have severely agitated the water bath, and such agitation would

have been conspicuous. Also, the pressure relief valve would have been fully open, and

the vapors passing through the relief valve would have made a loud and noticeable noise.

Further, if the capacity of the pressure relief valve had been exceeded, the valve would

have remained open, so noise from any escaping vapors would have been continuous and

particularly loud. Under such conditions, it would have been virtually impossible for plant

employees to fail to notice the severe agitation of the water bath and the continuous noise

from the pressure relief valve. However, no Essroc employee mentioned noticing either

condition before the accident. Therefore, the overpressure in UTLX 643593 did not result

from the pressureís rate of increase exceeding the flow capacity of the pressure relief

valve to vent the tank.

During postaccident examination of the valves and fittings of ULTX 643593,

however, investigators found TDI matter waste molded to the interior of the carís manway

coverplate. The TDI matter waste completely plugged the openings through the manway

coverplate for the pressure relief, vacuum relief, and vapor valves. The inlet to each of

these three valves opens to the vapor space at the top of the tank car. Further, the TDI

matter waste was molded into the bodies of the pressure relief and vapor valves.

For the TDI matter waste to completely plug and fill these openings and valves in

this manner, it must have flowed into them through expansion of the waste before the tank

car ruptured. If the TDI matter waste had been blasted into these openings in the manway

coverplate and the valve bodies when the tank ruptured, it would not have been molded to
Analysis 48 Hazardous Materials Accident Report

the contours of the openings and valve bodies. Rather, the TDI matter waste would have left

void spaces in the openings through the manway coverplate and the valve bodies.

Consequently, the Safety Board concludes that the expansion of TDI matter waste that

occurred before the accident blocked the vapor and pressure relief valves of tank car

UTLX 643593, which effectively removed any means of relieving the build-up of internal

pressure. 

The Safety Board cannot determine exactly when the vapor and pressure relief

valves became plugged. On the morning of February 16, Essroc employees noted that the

pressure relief valve was ìwhisperingî (discharging vapors at a low pressure), which they

attributed to saturation of the carbon filters in the plantís vapor emissions system.

Following the final attempt to offload the tank car on the night of February 16, an Essroc

laborer observed water bubbling from the end of the submerged hose in the tote tank. The

bubbling indicated that vapors were venting from the tank car at that time.

Although the Essroc facility supervisor and other Essroc employees checked and

adjusted the internal pressure on UTLX 643593 throughout the 5 days that UTLX 643593

was at the offloading station, the reliability of these pressures is suspect. The whispering

of the pressure relief valve, which was first noted by Essroc personnel on the morning of

February 16 and later replicated during postaccident testing of the valve in May 1999,

indicates that the pressure relief valve very likely was continuously discharging vapors

from the tank until it became plugged by TDI matter waste.

Product Expansion

The initial volume of TDI matter waste in the 20,000-gallon tank car after loading

was 14,185 gallons, which was about 71 percent of tank capacity. Therefore, between the

loading date in March 1993 and the accident date in February 1999, the TDI matter waste

must have expanded to fill the remaining 29 percent of the tank, leading to the rupture. 

The Safety Board considered several possible causes for the expansion of the TDI

matter waste. These included exposure of the tank car to fire from an unknown external

source; gradual instability in the waste material over the 6-year period it was stored in the

tank car; chemical reactions initiated from the steam heating of the tank car, resulting in

the liberation and entrapment of gaseous byproducts in the waste mixture; and chemical

reaction with water that would have liberated gases within the tank.

The Safety Board was able to discount the possibility of the tank carís experiencing

direct exposure to fire. The external jacket from UTLX 643593 did not exhibit any

evidence of flames affecting it, other than an isolated section found on top of a burned rubber

hose.

The Board found no significant evidence that the TDI matter wasteís stability had

gradually degraded (causing expansion) while the tank car was stored between 1993 and

1999. Essroc personnel working around and with the tank car did not report any usual

events or problems with it, apart from the plugging of the plant piping to the kilns. The

waste had been stored in the tank car for nearly 6 years with no problems. In addition,
Analysis 49 Hazardous Materials Accident Report

chemical data for the monomeric TDI, polymeric TDI, and MCB found in the TDI waste

do not indicate that any of these materials were unstable. Nevertheless, the tank car

catastrophically ruptured 5 to 6 days after it had been heated with steam on two occasions

for a total of 28.5 hours and three attempts to offload the TDI matter waste from it had

been made. Therefore, some aspect of the offloading operation most likely led to the

rupture.

Heating tests conducted in April 1999 on the TDI matter waste samples drawn

from UTLX 643593 before the accident demonstrated that significant expansion of the

waste occurred when a waste sample was heated under conditions similar to those

experienced by the accident tank car in the days before the accident. Expansion also

occurred when a sample was heated and exposed to water. Both these test conditions

resulted in the generation of sufficient quantities of carbon dioxide gas to have

theoretically increased the pressure in the tank car above its burst pressure.

The most likely means of introducing water into the tank car would have been

from the tote tank that was being used as a temporary measure to provide a vapor

emissions system while the carbon filters were being cleaned or replaced. No other likely

source of water was identified. Essroc employees noted water bubbling in the tote tank

throughout the day on February 16, indicating that vapors were venting from the tank car.

One Essroc employee also observed water bubbling in the tote tank following the final

attempt to offload UTLX 643593 on the evening of February 16. However, no Essroc

employee commented on the condition of the tote tank from that time forward. 

Based on engineering calculations, water from the tote tank could have been

siphoned into the tank car only if a vacuum of 4 to 5 psi (equivalent to a total internal

pressure of 10 to 11 psi) had developed in the vapor space within the tank car because of

the cooling of the vapors and/or the contraction of the TDI matter waste mixture. The

heating tests on samples from UTLX 643593 clearly demonstrate that the waste expanded

when it was heated, but it did not contract after cooling. Therefore, the generation of any

vacuum would have to have been caused by the vapors cooling in the air space at the top

of the tank car. Engineering calculations indicate that vapors initially at 150° F would

have to have been cooled to less than -30° F to create a sufficient vacuum in the tank car.

More importantly, water drawn into the tank car from the tote tank would have spilled into

the TDI matter waste at the point of liquid/vapor interface within the tank car. Any gases

from a reaction occurring at the liquid/vapor interface would have entered the vapor space

within the tank car and readily been vented. Such venting would have precluded

overpressurization of the tank car.

Chemical analyses conducted between December 1999 and February 2000 on the

TDI matter waste sample recovered from the B-end loading valve detected the presence of

chemical byproducts from the reaction of TDI and water. The analysis could not quantify

the amounts of these byproducts. Although the presence of these chemical byproducts

suggests that the waste sample from the loading valve reacted with water, it cannot be

determined when or how much water came into contact with this sample. Between the

accident date and the recovery of the sample in May 1999, the dome assembly from

UTLX 643593, including the B-end valve, was kept in indoor storage at Essroc and then at
Analysis 50 Hazardous Materials Accident Report

the St. Louis testing facility. After the recovery of the sample in May 1999, the sample

was in a glass jar, which, although sealed, proved not to be airtight, as evidenced by the

evaporation of the liquid portion of the sample. The waste sample may have been exposed

to moist air between the time it was recovered and analyzed, which might have caused the

formation of the chemical byproducts detected in the analysis. Nevertheless, the other

evidence (as previously discussed) does not support the theory that the overpressurization

was the result of a sufficient quantity of water being introduced into the tank car.

Therefore, the overpressurization of the tank car from product expansion and the

plugging of the pressure relief and vapor valves most likely occurred as a result of the

steam heating of the waste mixture before offloading was attempted. The portion of the

TDI matter waste mixture in contact with the tank wall in the bottom half of the tank

received the heat from the steam circulating through the heating coils. Because the

samples were drawn through one of the eduction lines that extended to the bottom of the

tank car, the temperatures of samples drawn by Essroc personnel while the steam heating

was performed are good indicators of the temperatures of the waste mixture that was in

contact with the heating coils. According to Essroc employees, the temperatures of the

samples drawn from UTLX 643593 ranged from 120 to 202° F early on February 14, at

the end of the first steam-heating cycle, and reached at least 173° F during the second

heating cycle on February 15 and 16. These temperatures are well above the maximum

safe temperature range of 130 to 140° F that Olin used for processing the TDI matter

wastes at the Lake Charles plant and reported to the Safety Board during the investigation.

In the absence of any means to mix the wastes to facilitate uniform heating

throughout the tank, localized overheating of the TDI matter waste in contact with or near

the tank wall adjacent to the heating coils most likely caused the TDI to self-react,

resulting in the generation of carbon dioxide gas at the bottom of the tank and eventual

expansion of the waste. Additionally, because the tank was insulated (and would retain

heat), the self-reaction and expansion of the TDI matter waste could have continued after

the steam heating was completed. Thus, the TDI matter waste continued to expand until

the dome was completely filled and the vapor and pressure relief valves were plugged.

Because the tank did not have any room to accommodate continued expansion of the

waste or any outlet by which it could relieve the increasing pressure, the tankís burst

pressure was exceeded, and the tank car ruptured.

Consequently, the Safety Board concludes that tank car UTLX 643593 was

overpressurized from the chemical self-reaction and expansion of the TDI matter waste

that was initiated and sustained by localized overheating of the mixture at the bottom of

the tank car. 
Analysis 51 Hazardous Materials Accident Report

Hazardous Materials Loading and Offloading Practices

TDI Waste Shipments

Essroc Plant Operations. In 1996, Essroc began to accept TDI solvent blend

wastes as fuel for its Logansport plant. Blending agents, such as HAN 906 solvent, were

added to the TDI solvent blend wastes at the Lake Charles plant before they were shipped to

Essroc, to increase the fluidity of the wastes. However, beginning in spring 1998, nearly all

the TDI wastes shipped to Essroc were TDI matter wastes. Unlike the solvent blend wastes

that had been ìthinnedî before shipment to Essroc, the TDI matter wastes were to be heated

and offloaded from the tank car to a blending tank at the Essroc plant, where the wastes

would be mixed with solvents to ìthinî them before they were pumped to the kilns and

burned. However, problems with the blending tank operation led Essroc to resort to

offloading the TDI matter wastes from the tank cars and pumping them directly to the kilns

(direct injection process). Essroc was using the direct injection process to offload the TDI

matter wastes from UTLX 643593. 

Whereas the waste profile for the solvent blend waste specified a maximum

viscosity of 500 cp, the profile for the TDI matter waste indicated that its viscosity

ìvaries.î Because the TDI matter wastes in UTLX 643593 and the other tank cars were to

be blended at the Essroc plant, they typically were more viscous than the solvent blend

wastes. Consequently, the TDI matter wastes probably had to be heated for longer periods

and to higher temperatures than the solvent blend wastes, to make the TDI matter wastes

sufficiently fluid for offloading from a tank car and pumping directly to the kilns.

The heating standard jointly employed by Essroc and CPRIN personnel was to

heat the TDI matter waste until it was sufficiently fluid to flow. While CPRIN conducted

the steam-heating operation, Essroc personnel drew samples from UTLX 643593 to

measure the temperature of the wastes and to determine if the waste mixture was

sufficiently fluid for offloading. Although Essroc and CPRIN personnel said they knew

that the TDI matter wastes had to be heated to higher temperatures than the solvent blend

wastes, Essroc and CPRIN claim they were unaware that Olin recommended a maximum

safe temperature range of 130 to 140° F for heating the TDI matter wastes. The Essroc

facility supervisor said he was under the impression that the TDI matter wastes could

safely be heated to 200° F; whereas CPRIN stated that, although the TDI product should

not be heated above 110° F because of possible quality control problems, these concerns

did not apply to the TDI matter wastes because no TDI product recovery would be

attempted.

Further, the offloading and steam-heating procedures used by Essroc and CPRIN

did not include three critical heating and offloading practices that Olin used at the Lake

Charles plant: steam heating with low-pressure steam, nitrogen sparging while steam

heating, and keeping the temperature of the waste mixture below 140° F. Through steam

heating with low-pressure steam, the waste mixtures could be heated more slowly and

could more easily be maintained at a temperature below the 130 to 140° F threshold

recommended by Olin. Performing nitrogen sparging during the steam-heating process

would cause the waste mixture at the bottom of the tank car to agitate, which would
Analysis 52 Hazardous Materials Accident Report

facilitate a more even distribution of heat throughout the entire waste mixture. The Safety

Board concludes that, if Essroc and CPRIN had employed low-pressure steam to heat the

wastes, used nitrogen sparging to facilitate even heating throughout the tank car, and

maintained the temperature of the wastes below 140° F, the risk of localized overheating

and expansion of the waste mixture would have been minimized, and the accident likely

would not have occurred. 

Guidance and Instruction on Heating and Offloading Procedures. To

determine why Essroc and CPRIN did not employ the procedures used at the Lake Charles

plant, the Safety Board asked Olin, Lyondell, Essroc, and CPRIN to describe the information

they exchanged about the heating of all TDI waste mixtures, the generation of gas from

chemical self-reaction, the expansion of the wastes if overheated, nitrogen sparging, the

establishment of temperature limits for the waste mixtures, and other special handling

procedures. 

Each company provided a different account regarding its responsibilities and the

information it either provided or requested. All agreed that the Lake Charles TDI expert

met with Essroc and CPRIN personnel at the Essroc plant in spring 1998 to provide

instruction on handling and processing TDI matter wastes. The Lake Charles operators,

Essroc, and CPRIN agreed that the TDI matter wastes could safely be heated to 125° F,

compared to the 90 to 100° F range for the TDI solvent blend wastes. Essroc also

acknowledged that the Lake Charles TDI expert had stated that a long, slow heating

process was sometimes required to heat the TDI matter wastes. However, neither Essroc

nor CPRIN acknowledged that the Lake Charles operators had set a maximum

temperature limit or that the Lake Charles operators had recommended using nitrogen

sparging and low-pressure steam-heating procedures. The Lake Charles operators,

however, maintained that their TDI expert discussed nitrogen sparging, heating with

low-pressure steam, and heating limits with Essroc and CPRIN personnel.

As can be seen from this diversity of opinion and recollection as to what was

communicated between the producers and receivers in this instance regarding the

appropriate procedures for offloading the TDI matter wastes, considerable confusion and

misapprehension appears to have been prevalent among those parties that handled the

waste mixtures. Given the potentially hazardous nature of TDI matter wastes, such

ambiguity is unacceptable.

The investigation also revealed other areas of imprecision. For instance,

responsibility for offloading at the Essroc plant seems to have been unclear. Essroc stated

that CPRIN was responsible for steam heating the TDI product so that it was sufficiently

fluid that it could be pumped to the cement kilns. CPRIN, however, stated that Essroc

retained operational authority over the heating and offloading process. 

Further, no one at the Essroc plant had comprehensive, written instructions on the

offloading procedures to be used. Although Essroc had written procedures for offloading

the TDI matter wastes to a fixed blending tank, these procedures did not include details

about heating practices, nitrogen sparging, or maximum temperature limits. Then, when

Essroc adopted the direct injection procedure in place of blending in a fixed tank, even
Analysis 53 Hazardous Materials Accident Report

less information was available. Neither Essroc nor CPRIN had any written procedures for

heating and offloading the TDI matter wastes for direct injection of these wastes to the

kilns. 

Therefore, based on the discrepancies between Essrocís and CPRINís accounts of

their respective roles and responsibilities for handling and disposing of TDI matter wastes

and the absence of specific, written procedures for heating and offloading these wastes by

direct injection, the Safety Board concludes that Essroc and CPRIN failed to develop and

implement appropriate heating and offloading procedures for the TDI matter wastes at the

Logansport plant, which resulted in the use of unsafe offloading practices at the plant. 

With respect to the Lake Charles operationís procedures, Olin stated, in its response

to Safety Board inquiries about whether it had written procedures for heating and offloading

TDI wastes, that any written procedures that might have existed had been turned over to

Arco (later Lyondell). Lyondell stated that Arco/Lyondell did not have specific, written

procedures for on-site blending of the TDI waste mixtures and offloading them from tank

cars. Arco/Lyondell had written procedures for blending solvent blend wastes in a fixed tank

and then transferring them from the fixed tank into tank cars. These procedures set the

temperature and viscosity limits for the solvent blend wastes in the fixed blending tank.

However, neither Olin nor Arco/Lyondell had written operating procedures or limitations

that addressed the potential for gas generation or product expansion, the maximum

temperature and time for heating the TDI wastes, or the maximum product viscosity for

offloading tank cars. Therefore, no one at Lake Charles appears to have had

comprehensive, written procedures for handling the TDI wastes. 

The Safety Board also considers that the implementation of comprehensive,

written procedures for loading and offloading chemicals or waste materials exhibiting

properties that require special handling must incorporate methods that will detect internal

tank conditions and accurately reflect the thermophysical state of all of the material in the

tank vessel. The written procedures should specify values or ranges for important material

properties, such as melting temperature, flash point, maximum allowable product

temperature, and viscosity. Further, offloading procedures developed and validated under

certain environmental conditions may lead to or cause catastrophic failures or other

potential problems in offloading the material when the environmental conditions vary

from the baseline conditions.

Partially because there is no written record to which it may refer, the Safety Board

cannot decisively determine what information and guidance were provided by the Lake

Charles operators to Essroc and CPRIN on heating and offloading TDI matter from tank

cars or what consideration, if any, was given to detection of internal tank car conditions

that were potentially catastrophic. Nor can the Safety Board be sure what guidance may

have been provided by the Lake Charles operators but not implemented by Essroc and

CPRIN. Nevertheless, given the differences between the accounts offered by these

companies about the guidance given or requested and the lack of comprehensive, written

procedures at Lake Charles for handling TDI wastes, the Safety Board concludes that Olin

and Arco (now Lyondell) did not provide Essroc with comprehensive, written information

about safe handling procedures for TDI matter wastes. 
Analysis 54 Hazardous Materials Accident Report

The Safety Board considers that the producer/shipper and the consignee/end-user

of any chemical or waste material have joint responsibility for determining and

implementing comprehensive, written procedures for the transfer of any chemical or waste

material to and from a tank car, highway cargo tank, or other bulk container when the

chemical or waste material exhibits properties that require special handling. Such

properties would include those identified with the TDI matter wastes involved in this

accident, such as temperature and heating effects, means of self-reaction, and the

byproducts of reaction, including the generation of gases and product expansion. 

In the Safety Boardís view, both parties to the transport of a hazardous material

have information vital to its safe transfer. The producer/shipper has detailed knowledge

about the properties of the chemical or waste material, while the consignee/end-user has

specific information about the transfer facilities at the destination. Ideally, the result of the

collaboration between the producer/shipper and consignee/end-user should be the

development and implementation of specific, written transfer procedures that address each

unique property of the chemical or waste material in the context of the physical layout of a

given plant or facility.

The importance and effectiveness of such cooperation is evidenced by what

happened when the TDI waste materials had to be moved after the Clymers accident took

place. Following the accident at the Essroc plant, Olin and the waste disposal companies

that were contracted to unload the remaining tank cars at a transfer facility in Deer Park,

Texas, jointly developed comprehensive, written procedures that established viscosity and

temperature limits and called for nitrogen sparging. Consequently, the transfer and

offloading took place without incident. Therefore, the Safety Board believes that Essroc,

CPRIN, Olin, and Lyondell should each collaborate with applicable producers, shippers,

consignees, and end-users in the development and implementation of specific and written

procedures for the loading or offloading of any chemical or waste material from a railroad

tank car, highway cargo tank, or other bulk transportation vessel when the chemical or waste

material exhibits properties that require special handling or processing during the loading or

offloading operation. 

Recent Safety Board Actions

The catastrophic rupture of UTLX 643593 in February 1999 at the Essroc plant is

the fifth nonaviation accident investigated by the Safety Board since June 1998 in which

deficient offloading procedures or operations caused or contributed to an accident and the

release of hazardous materials. 

The first of the five accidents took place on June 29, 1998, at Stock Island, Key

West, Florida.34 A Dion Oil Company driver was on top of a straight-truck cargo tank

checking its contents and preparing to transfer cargo from a semitrailer cargo tank when

explosive vapors ignited within the straight-truck cargo tank. The ignition caused an

34 National Transportation Safety Board, Fire and Explosion of Highway Cargo Tanks, Stock Island, Key

West, Florida, June 29, 1998, Hazardous Materials Accident Report NTSB/HZM-99/01 (Washington, DC:

NTSB, 1999).
Analysis 55 Hazardous Materials Accident Report

explosion that threw the driver from the truck. The fire and a series of at least three

explosions injured the driver and destroyed the straight truck, a tractor, the front of the

semitrailer, and a second nearby straight-truck cargo tank. Damage was estimated at more

than $185,000. 

The Safety Board concluded from its investigation that (1) the carrier did not have

written procedures to ensure safe cargo handling, (2) the carrier did not adequately train its

drivers to ensure safe cargo handling, and (3) Federal training programs for Federal and

State motor carrier inspectors did not adequately address the need for inspectors to

evaluate the training that motor carriers give their drivers on loading and unloading cargo

tanks. Consequently, the Safety Board recommended on October 1, 1999, that the Federal

Highway Administrationís (FHWAís) Office of Motor Carrier Safety (now the Federal

Motor Carrier Safety Administration [FMCSA]): 35

H-99-30

Add elements to training programs for Federal and State inspectors that include

instruction on determining whether motor carriers have adequate written

procedures for and driver training in loading and unloading cargo tanks.

H-99-31

Evaluate the adequacy of cargo-tank loading and unloading procedures of and

driver training for hazardous-materials motor carriers and require changes as

appropriate. 

To date, the Safety Board has not received a response to either recommendation

from the FMCSA. On December 14, 2000, the Safety Board sent a follow-up letter to the

FMCSA requesting an update on the status of these two recommendations.

Another accident concerning a transfer of hazardous materials took place on

August 9, 1998, in Biloxi, Mississippi.36 A truckdriver was transferring gasoline from a

highway cargo tank to underground storage tanks at a gasoline station-convenience store

when an underground storage tank containing gasoline overflowed. An estimated

550 gallons of gasoline flowed from the storage tank, across the station lot, and into the

adjacent highway and intersection. The gasoline ignited, and fire engulfed three vehicles

near the intersection. Five occupants of the vehicles were killed, and one occupant was

seriously injured. Property damages were estimated at $55,000.

As a result of its Biloxi investigation, the Safety Board concluded that the carrierís

operating manuals for its new employees and driver-trainers lacked the specificity that

employees need to ensure that they practice correct and safe cargo unloading procedures.

35 The December 9, 1999, enactment of the Motor Carrier Safety Improvement Act of 1999 established

a new DOT agency, the FMCSA, to oversee and enforce motor carrier safety regulations, which had

previously been handled by the FHWA.

36 National Transportation Safety Board, Overflow of Gasoline and Fire at a Service

Station-Convenience Store, Biloxi, Mississippi, August 9, 1998, Hazardous Materials Accident Report

NTSB/HZM-99/02 (Washington, DC: NTSB, 1999).
Analysis 56 Hazardous Materials Accident Report

The Safety Board also concluded that to help drivers follow safe loading and unloading

procedures, Federal regulations should require carriers that transport hazardous materials

in cargo tanks to have specific, written procedures for loading and unloading.

Consequently, the Safety Board recommended that RSPA:

H-99-57

Promulgate regulations requiring motor carriers that transport hazardous materials

in cargo tanks to develop and maintain specific written cargo loading and

unloading procedures for their drivers. 

In a February 24, 2000, response to Safety Recommendation H-99-57, RSPA stated

it is evaluating options to amend the general training requirements and the current

specialized requirements for motor carriers in the DOT Hazardous Materials Regulations.

On April 4, 2000, the Safety Board classified Safety Recommendation H-99-57 ìOpenñ

Acceptable Response,î pending RSPAís development of regulations that meet the intent of

the recommendation. On January 5, 2001, the Safety Board sent a letter to RSPA

requesting an update on the actions RSPA has taken on this recommendation since

February 2000.

Following the Biloxi accident, the Safety Board also recommended that the

FHWA:

H-99-59

Once the Federal regulations requiring motor carriers that transport hazardous

materials in cargo tanks to provide written cargo loading and unloading

procedures are promulgated, ensure that the motor carriers are in compliance with

the regulations.

The FHWAís Office of Motor Carrier Safety stated in a November 23, 1999,

response to Safety Recommendation H-99-59 that it would develop procedures to ensure

that motor carriers comply with regulations promulgated to address Safety

Recommendation H-99-57. The Safety Board classified Safety Recommendation H-99-59

ìOpenñAcceptable Responseî on February 22, 2000. On January 10, 2001, the Safety

Board sent a letter to the FHWA requesting an update on the actions taken on this

recommendation since February 2000.

On November 19, 1998, at the Ford Motor Company truck plant in Louisville,

Kentucky, a cargo tank truck arrived with a delivery of a liquid mixture of nickel nitrate

and phosphoric acid. A plant employee inadvertently connected the truckís transfer hose

to the wrong connection and then departed the area, leaving the truckdriver to complete

the delivery alone. The truckdriver did not check that the connection was correct and

began unloading the product into a storage tank that contained a chemically incompatible

material. The resulting chemical reaction generated a vapor cloud of toxic gases that

forced the evacuation of 2,400 plant employees and caused $192,000 in damages.37
Analysis 57 Hazardous Materials Accident Report

Another transfer-related accident occurred in Whitehall, Michigan, on June 4,

1999, after a cargo tank truck arrived at the Whitehall Leather Company with a delivery of

sodium hydrosulfide solution. At the direction of a Whitehall shift supervisor, the

truckdriver connected the transfer hose from the cargo tank truck to the wrong storage

tank; the tank contained a chemical that reacted with the solution in the cargo tank truck.

The resulting chemical reaction released hydrogen sulfide gas that resulted in the death of

the truckdriver and $411,000 in damages. 38

The Safety Boardís investigation of both the Louisville and Whitehall accidents

showed that the companies had significant problems with their loading and unloading

processes for hazardous materials. The Whitehall Leather Company did not have written

instructions and procedures for unloading hazardous materials from bulk cargo tanks and

did not have a training program for those employees who might be involved in loading

and unloading such materials. The Ford Motor Company had written instructions and

procedures for unloading hazardous materials and maintained a training program on these

procedures, but Ford failed to provide the plant employee involved in the Louisville

accident with the latest unloading instructions for hazardous materials, which might have

prevented the accident.

As a result of its investigations of the Louisville and Whitehall accidents, the

Safety Board determined that safety requirements were needed for loading and unloading

hazardous materials involved in transport and recommended on June 29, 2000, that RSPA:

I-00-06

Within 1 year of the issuance of this safety recommendation, complete rulemaking

on Docket HM-223, ìApplicability of the Hazardous Materials Regulations to

Loading, Unloading, and Storage,î to establish, for all modes of transportation,

safety requirements for loading and unloading hazardous materials.

In its July 21, 2000, response to Safety Recommendation I-00-06, RSPA stated that

it is drafting a notice of proposed rulemaking (NPRM) under Docket HM-223 and expects to

publish the NPRM in early 2001. RSPA anticipates issuance of a final rule by the end of

2001. The Safety Board wrote to RSPA on September 25, 2000, indicating its concern over

the slow progress of the rulemaking and urging that a final rule be issued by July 2001. In

light of the continuing slow pace of action on this important safety issue indicated by RSPAís

letter, the Safety Board classified Safety Recommendation I-00-06 ìOpenñUnacceptable

Response.î 

37 National Transportation Safety Board, Chemical Reaction During Cargo Transfer, Louisville,

Kentucky, November 19, 1998, Hazardous Materials Accident Brief HZB/00/02 (Washington, DC: NTSB,

2000).

38 National Transportation Safety Board, Chemical Reaction During Cargo Transfer, Whitehall,

Michigan, June 4, 1999, Hazardous Materials Accident Brief HZB/00/03 (Washington, DC: NTSB, 2000).
Analysis 58 Hazardous Materials Accident Report

DOT Hazardous Materials Regulations

The rupture of UTLX 643593 at the Essroc plant near Clymers and the accidents in

Stock Island, Biloxi, Louisville, and Whitehall can all be attributed to deficient unloading

operations that occurred because of inadequate training, or a lack of comprehensive,

specific, and written unloading procedures, or both. In the Clymers accident, the failure of

the producer/shippers and end-users to collaborate in the development and

implementation of comprehensive, written loading and offloading procedures, customized

to the characteristics of the TDI matter wastes and the specific facility, resulted in the use

of unsafe unloading practices that ultimately caused the tank car to rupture. 

Although the DOT Hazardous Materials Regulations include general and

mode-specific requirements about the loading and unloading of bulk containers such as

tank cars, highway cargo tanks, and intermodal tanks, the current requirements only

address procedures common to most loading and offloading operations, such as which

personnel must attend the transfer, when brakes must be set on the tank car, when tank car

wheels must be blocked, and when and how warning signs must be placed. The DOT

Hazardous Materials Regulations do not include requirements for loading and unloading

procedures to be written based on any unique or particular properties of the hazardous

materials that would necessitate the implementation of special handling requirements or

on the conditions specific to an individual facility. As demonstrated in the Clymers

accident, the use of unloading practices that are not based on such thorough and

comprehensive standards can have catastrophic consequences. Therefore, the Safety

Board concludes that the DOT Hazardous Materials Regulations are deficient because

they fail to require the development and implementation of comprehensive, written

loading and unloading procedures for hazardous materials. 

The Stock Island, Biloxi, Louisville, Whitehall, and Clymers accidents all

involved the loading and unloading of transport containers carrying hazardous materials.

Of the five accidents, however, only the Clymers accident involved rail rather than motor

carrier transportation. Recently, therefore, the Safety Boardís safety recommendations

concerning loading and unloading regulations have focused primarily on highway

transportation. 

For instance, following the Biloxi accident involving the unloading of a motor

carrierís cargo tank containing a hazardous material, the Safety Board recommended that

RSPA promulgate regulations requiring motor carriers that transport hazardous materials

in highway cargo tanks to develop and maintain specific and written cargo loading and

unloading procedures. The Safety Board also recommended that the FHWA ensure that

motor carriers comply with the regulations once they are enacted. Both these safety

recommendations (H-99-57 and H-99-59) are currently ìOpenñAcceptable Response.î 

The Clymers accident, however, showed that swift action is needed to improve the

safety of hazardous material loading and unloading operations involving rail tank cars as

well as highway cargo tanks. Therefore, to ensure that loading and unloading safety

provisions are equivalent throughout transportation modes, the Safety Board considers

that action is needed to address the deficiencies in the loading and unloading regulations
Analysis 59 Hazardous Materials Accident Report

for rail transport of hazardous materials. Such multimodal action is implicit in Safety

Recommendation I-00-06, which the Safety Board issued following the Whitehall and

Louisville accidents, which called for RSPA:

I-00-06

Within 1 year of the issuance of this safety recommendation, complete rulemaking

on Docket HM-223, ìApplicability of the Hazardous Materials Regulations to

Loading, Unloading, and Storage,î to establish, for all modes of transportation,

safety requirements for loading and unloading hazardous materials. (Emphasis

added. )

Despite the need to carry out this recommendation promptly, as evidenced by the

recent Stock Island, Biloxi, Louisville, Whitehall, and Clymers accidents, RSPA has not

yet completed action on it or indicated that RSPA intends to accomplish the

recommendation before the end of 2001. The Safety Board is concerned that such slow

progress on Safety Recommendation I-00-06 could negatively affect the safety of

hazardous materials transportation in all modes. Therefore, to ensure that comprehensive,

written safety requirements are established without delay for all carriers, including rail

carriers, that transport hazardous materials in cargo tanks, the Safety Board reiterates

Safety Recommendation I-00-06.

Pressure Relief Valves

Performance

After the Clymers accident, the FRA mandated that the pressure relief valves from

4 of the 24 tank cars containing the TDI matter wastes in storage at the Logansport rail

yard be pressure-tested in accordance with the DOT Hazardous Materials Regulations

before any of the tank cars could be transported for unloading. When these tests were

performed in March 1999, three of the four valves were not due for retesting until 2003.

Each valve had 4 years remaining of its 10-year test cycle. The fourth valve, also on a

10-year test cycle, was due for a retest in 1999. The pressure relief valve from

UTLX 643593 was on a 10-year test cycle and not due for a retest until 2003. This valve

was also examined and tested in May 1999. All five pressure relief valves failed to meet

the tolerances for the start-to-discharge pressure and vapor-tight pressure as required

under the regulations.

Because the valve from UTLX 643593 began to discharge at pressures around

5 psig during the postaccident tests and Essroc personnel heard the valve discharging

before the accident, the valve was likely venting vapors whenever a minimal positive

pressure developed in the tank. The frequent discharging would have resulted in continual

venting of harmful or flammable vapors to the atmosphere and possible exposure of

personnel working near the tank car until the valve was plugged from expansion of the

TDI matter waste.
Analysis 60 Hazardous Materials Accident Report

Inspection Requirements

The teardown and inspection of the pressure relief valves from these five tank cars

(the four cars that the FRA required to be tested and UTLX 643593) demonstrated that the

valves were in a deteriorated condition. The ethylene propylene rubber O-rings showed

evidence of swelling, hardness, and brittleness, and the metallic components exhibited

varying degrees of rust, scale, pitting, and grit. Replacement of the deteriorated O-rings in

the pressure relief valve from UTLX 643593 with new O-rings did not, by itself, bring

about proper operation of the valve. Even with the new O-rings, the pressure relief valve

from UTLX 643953 was within the tolerances for the start-to-discharge and vapor-tight

pressures only after all dirt, grit, and other debris had been removed from the sealing

surfaces of the valve. Consequently, it appears that the accumulation of rust, scale, and dirt

caused the five pressure relief valves to fail to meet the required start-to-discharge and

vapor-pressure standards. Therefore, the Safety Board concludes that, based on the

deteriorated condition of the pressure relief valves examined in this investigation and the

failure of these valves to activate as required, the pressure relief valves on tank cars that

transport hazardous materials may require more frequent and rigorous testing to ensure

that they remain functional. 

The testing interval for a tank car and its components under the Hazardous

Materials Regulations depends in part upon the types of products that are transported in

the tank car. Tank cars that transport corrosive materials must be inspected and retested

every 5 to 10 years, whereas tank cars that transport noncorrosive materials must be

inspected and retested every 10 years. The regulations also require testing and inspection

if there is evidence of damage, corrosion, cracks, dents, or deformation or if the tank car is

involved in an accident and is repaired. However, the deterioration of the pressure relief

valves from UTLX 643593 and the other four tank cars was only detected when the valves

were disassembled and inspected. The Safety Board believes that RSPA and the FRA

should, with the assistance of the AAR and the Railway Progress Institute, evaluate the

deterioration of pressure relief devices through normal service and then develop

inspection criteria to ensure that the pressure relief devices remain functional between

regular inspection intervals. They should also incorporate these inspection criteria into the

DOT Hazardous Materials Regulations. 

Changes in Product Service for Railroad Tank Cars 

Even when appropriate test intervals are established and followed, carriage of

cargoes that chemically attack gaskets and O-rings in valves and fittings can undermine

the integrity of valves and fittings. Data provided by Union Tank Car Company indicated

that ethylene propylene rubber is subject to chemical attack when it is exposed to MCB

and naphthalene, a primary constituent of the HAN 906 solvent. The swelling, hardness,

and brittleness of the ethylene propylene rubber O-rings in the pressure relief valves from

UTLX 643593 and the four other tank cars that were tested likely resulted from exposure

to the MCB in the TDI matter waste. 
Analysis 61 Hazardous Materials Accident Report

The addition of a new chemical constituent to a commodity approved for

transportation in a tank car changes the chemical composition of that commodity and

results in the exposure of gaskets and seals on the tank car to a new mixture. The

concentration of a newly added chemical constituent may be sufficiently diluted as to

present little or no risk of chemical attack to gaskets and seals, but the risk level can best

be ascertained by tests or verification through technical literature that the new chemical

constituent is compatible with the gaskets and seals on the tank car. 

The AAR Manual of Standards for tank cars clearly places the responsibility on

the shipper to ensure that the materials used for gaskets and valve seals are compatible

with the lading and the service temperature. Under 49 CFR 173.31(a)(2), a tank car may

be transferred from one specified commodity service (listed on the tank carís certificate of

construction) to another only by the owner or with the ownerís authorization. In addition,

under 49 CFR 179.15, the pressure relief device on DOT class 111A tank cars must be

made of materials that are compatible with the commodity being transported. Further, the

FRA interprets the addition of new constituents to TDI to represent a change in service if

the additional constituents substantially change the chemical makeup of the TDI or change

the hazard class of the TDI. 

Olin and Lyondell did not consider that the presence of MCB and HAN 906 solvents

in the TDI waste mixtures might adversely affect the O-rings in the pressure relief valves

and other gaskets on the tank cars used to store and transport these wastes. Consequently,

Olin and Lyondell did not find that the presence of these chemicals constituted a substantial

change in product service from the transport of pure TDI. The investigation, however,

showed that the presence of MCB and HAN 906 solvent in the TDI waste mixtures was

sufficient to chemically attack the O-rings in the pressure relief valves on tank cars carrying

TDI waste mixtures. Therefore, the Safety Board concludes that the transportation of the

solvent blend wastes and TDI matter wastes in UTLX 643593 and the other tank cars

approved for the transport of pure TDI constituted a change in product service that resulted

in the transport of a commodity incompatible with components of the tank car.

The FRAís interpretation that a change in product service occurs when the

chemical makeup is substantially changed is subjective and may account for the

misinterpretations of Olin and Lyondell that the solvent blend wastes and TDI matter

wastes were not ìsubstantially differentî from pure TDI. Although the criteria in the AAR

Manual of Standards for tank cars and 49 CFR 179.15 seem clear that tank car valves and

components must be compatible with the commodity being transported, the mistaken

beliefs of Olin and Lyondell suggest that other producers that ship hazardous materials

may hold similarly incorrect views regarding the interpretation of these criteria. 

The Safety Board knows, for example, that other tank cars used for shipping both

solvent blend wastes and TDI matter wastes are equipped with pressure relief valves with

ethylene propylene rubber O-rings. The Safety Board does not know, however, whether the

shippers using these cars have considered that the MCB and HAN 906 solvents in the TDI

waste mixtures might adversely affect the O-rings in the pressure relief valves. Therefore,

the Safety Board believes that the FRA should issue an advisory bulletin reminding

shippers of hazardous materials that any time a change is made in the chemical
Analysis 62 Hazardous Materials Accident Report

constituents of hazardous materials shipped, they should verify the compatibility of all

tank car components, such as valves and gaskets, with all of the commodities to be

transported. 

Notification and Reporting of Hazardous Materials Incidents

When the Clymers accident occurred, the Essroc plant manager immediately notified

the NRC by telephone, in compliance with Federal regulations, about the releases of

hazardous wastes. According to 40 CFR 264.56(j) the owner/operator of a TSD facility that

experiences a hazardous waste incident must also submit a written report to the EPA regional

administrator within 15 days of the incident. Essroc sent a report concerning the Clymers

accident to the EPA Region 5 office on March 4, 1999. However, neither the written report

to the EPA required under 40 CFR 264.56(j) nor the immediate telephone report to the NRC

comprise the high level of detail regarding a hazardous materials incident reflected in the

DOT Hazardous Materials Incident Report form. Neither would contain, as would the DOT

Hazardous Materials Incident Report, detailed information concerning the container and

packaging used to transport the hazardous material, the specific circumstances of the failure,

or the transportation environment in which the incident occurred. Consequently, neither

could provide the in-depth information that RSPA needs to maintain its Hazardous Materials

Information System, which is crucial to RSPAís ability to carry out meaningful analyses of

reported accident data.

The requirements in 49 CFR 171.16 of the DOT Hazardous Materials Regulations

place the responsibility for submitting the written DOT Hazardous Materials Incident Report

on the carrier. The requirements apply to releases of hazardous materials that occur during

the course of transportation, which has been defined under 49 United States Code

Section 5102 to include ìthe movement of property and the loading, unloading, or storage

incidental to the movement.î

In the case of the Clymers accident, it seems reasonable that the Central Railroad

of Indianapolis, the carrier that delivered UTLX 643593 and the other tank cars to the

Essroc plant, assumed it was not responsible for filing a written DOT Hazardous Materials

Incident Report with RSPA. The railroad had delivered the tank car to the Essroc plant on

December 7, 1998, more than 2 months before the accident took place. The accident

occurred on the plant property, and the railroad was not involved in the accident. The

Central Railroad of Indianapolis thus had good reason to suppose it was no longer

responsible for filing a written report with RSPA. Essroc likewise did not provide a DOT

Hazardous Materials Incident Report to RSPA because it is a TSD facility operator, not a

carrier.

Consequently, no DOT Hazardous Materials Incident Report has been filed for this

accident with RSPA, even though a DOT specification tank car used in revenue service

and containing a regulated hazardous waste catastrophically ruptured. The Safety Board

concludes that, because the requirements of 49 CFR 171.16 place the responsibility for

filing the written DOT Hazardous Materials Incident Report solely upon the carrier, the
Analysis 63 Hazardous Materials Accident Report

current requirements do not ensure that RSPA receives the information the Safety Board

believes it needs to develop safe practices. 

Of the parties involved, the carrier is least likely to have knowledge of or be

involved in an accident or incident that occurs at a shipper or consignee facility where

loading and unloading operations are carried out, and where hazardous materials

containers are temporarily stored. As a result, many loading and unloading accidents may

not be reported to the DOT.

The written DOT Hazardous Materials Incident Reports provide the input for the

Hazardous Materials Information System, which is RSPAís accident database. Because

this database is used (among other things) to carry out trend analyses, the failure to capture

data about incidents at loading and offloading facilities may skew accident analyses

conducted using these data and obscure industry performance and operational

deficiencies. Further, a review of EPA regulations demonstrated that the comprehensive

data required are collected only by the written DOT Hazardous Materials Incident

Reports. 

The Safety Board has previously expressed its concern about this issue to RSPA,

most recently through its July 26, 1999, comments on the March 23, 1999, ANPRM that

RSPA issued on revising the incident reporting requirements and the DOT Hazardous

Materials Incident Report form. Citing reporting deficiencies identified in the Clymers,

Louisville, and Biloxi hazardous materials accidents, the Safety Board noted that when

accidents involving releases of hazardous materials from DOT specification containers

occur at loading or unloading facilities, a carrier may not be directly involved, increasing

the likelihood that such accidents will go unreported to RSPA. The Safety Board stated

that it believed that ìÖa complete and accurate accident database requires that incident

reports be filed for any failure of hazardous material containers or the unintended release

of a hazardous material during any transportation-related operationÖ.î 

To repair this gap in the notification and reporting standards, the Safety Board

believes that RSPA should develop and implement policies and procedures to ensure that

comprehensive reports concerning all significant failures of DOT specification tank cars,

highway cargo tanks, and intermodal bulk containers containing hazardous materials are

provided in writing to RSPA. 
64 Hazardous Materials Accident Report

Conclusions

Findings

1. No evidence indicates that the tank of railroad tank car UTLX 643593 had any

structural or material defects that either caused or contributed to the rupture of the

tank. 

2. The internal pressure in tank car UTLX 643593 increased and eventually exceeded

the burst pressure of the tank, resulting in the catastrophic rupture of the tank car.

3. The expansion of toluene diisocyanate matter waste that occurred before the accident

blocked the vapor and pressure relief valves of tank car UTLX 643593, which

effectively removed any means of relieving the build-up of internal pressure.

4. Tank car UTLX 643593 was overpressurized from the chemical self-reaction and

expansion of the toluene diisocyanate matter waste that was initiated and sustained by

localized overheating of the mixture at the bottom of the tank car.

5. If the Essroc Cement Corporation and CP Recycling of Indiana had employed

low-pressure steam to heat the wastes, used nitrogen sparging to facilitate even

heating throughout the tank car, and maintained the temperature of the wastes below

140° F, the risk of localized overheating and expansion of the waste mixture would

have been minimized, and the accident likely would not have occurred.

6. The Essroc Cement Corporation and CP Recycling of Indiana failed to develop and

implement appropriate heating and offloading procedures for the toluene diisocyanate

matter wastes at the Logansport plant, which resulted in the use of unsafe offloading

practices at the plant. 

7. The Olin Corporation and the Arco Chemical Company (now the Lyondell Chemical

Company) did not provide the Essroc Cement Corporation with comprehensive, written

information about safe handling procedures for toluene diisocyanate matter wastes.

8. The U.S. Department of Transportation Hazardous Materials Regulations are

deficient because they fail to require the development and implementation of

comprehensive, written loading and unloading procedures for hazardous materials. 

9. Based on the deteriorated condition of the pressure relief valves examined in this

investigation and the failure of these valves to activate as required, the pressure relief

valves on tank cars that transport hazardous materials may require more frequent and

rigorous testing to ensure that they remain functional. 
Conclusions 65 Hazardous Materials Accident Report

10. The transportation of the solvent blend wastes and toluene diisocyanate matter wastes

in UTLX 643593 and the other tank cars approved for the transport of pure toluene

diisocyanate constituted a change in product service that resulted in the transport of a

commodity incompatible with components of the tank car.

11. Because the requirements of 49 Code of Federal Regulations 171.16 place the

responsibility for filing the written U.S. Department of Transportation Hazardous

Materials Incident Report solely upon the carrier, the current requirements do not ensure

that the Research and Special Programs Administration (RSPA) receives the

information the National Transportation Safety Board believes RSPA needs to develop

safe practices.

Probable Cause

The National Transportation Safety Board determines that the probable cause of

the accident was the failure of Essroc Cement Corporation and CP Recycling of Indiana

management to develop and implement safe procedures for offloading toluene diisocyanate

matter wastes, resulting in the overpressurization of the tank car from chemical self-reaction

and expansion of the toluene diisocyanate matter wastes. 
66 Hazardous Materials Accident Report

Recommendations

New Recommendations

As a result of its investigation, the National Transportation Safety Board makes the

following safety recommendations:

To the Federal Railroad Administration

Issue an advisory bulletin reminding shippers of hazardous materials that

any time a change is made in the chemical constituents of hazardous

materials shipped, they should verify the compatibility of all tank car

components, such as valves and gaskets, with all of the commodities to be

transported. (R-01-01)

Evaluate, with the assistance of the Research and Special Programs

Administration, the Association of American Railroads, and the Railway

Progress Institute, the deterioration of pressure relief devices through

normal service and then develop inspection criteria to ensure that the

pressure relief devices remain functional between regular inspection

intervals. Incorporate these inspection criteria into the U.S. Department of

Transportation Hazardous Materials Regulations. (R-01-02)

To the Research and Special Programs Administration

Evaluate, with the assistance of the Federal Railroad Administration, the

Association of American Railroads, and the Railway Progress Institute, the

deterioration of pressure relief devices through normal service and then

develop inspection criteria to ensure that the pressure relief devices remain

functional between regular inspection intervals. Incorporate these

inspection criteria into the U.S. Department of Transportation Hazardous

Materials Regulations. (R-01-03)

Develop and implement policies and procedures to ensure that

comprehensive reports concerning all significant failures of U.S. Department

of Transportation specification tank cars, highway cargo tanks, and

intermodal bulk containers containing hazardous materials are provided in

writing to the Research and Special Programs Administration. (I-01-01)
Recommendations 67 Hazardous Materials Accident Report

To the Association of American Railroads (R-01-04)

To the Railway Progress Institute (R-01-05)

Assist the Federal Railroad Administration and the Research and Special

Programs Administration in the evaluation of the deterioration of pressure

relief devices through normal service and the development of inspection

criteria to ensure that the pressure relief devices remain functional between

regular inspection intervals. 

To the Essroc Cement Corporation (I-01-02)

To CP Recycling, Inc., and Affiliated Companies (I-01-03)

To the Olin Corporation (I-01-04)

To the Lyondell Chemical Company (I-01-05)

Collaborate with applicable producers, shippers, consignees, and end-users

in the development and implementation of specific and written procedures

for the loading or offloading of any chemical or waste material from a

railroad tank car, highway cargo tank, or other bulk transportation vessel

when the chemical or waste material exhibits properties that require special

handling or processing during the loading or offloading operation. 

Previously Issued Recommendation Reiterated in this Report

To the Research and Special Programs Administration 

I-00-06

Within 1 year of the issuance of this safety recommendation, complete

rulemaking on Docket HM-223, ìApplicability of the Hazardous Materials

Regulations to Loading, Unloading, and Storage,î to establish, for all

modes of transportation, safety requirements for loading and unloading

hazardous materials.

BY THE NATIONAL TRANSPORTATION SAFETY BOARD

CAROL J. CARMODY

Acting Chairman

JOHN J. GOGLIA

Member

JOHN A. HAMMERSCHMIDT

Member

GEORGE W. BLACK, JR.

Member

March 5, 2001

69 Hazardous Materials Accident Report

Appendix A

Investigation

The National Response Center notified the Safety Board of the accident at

8:30 a.m., February 18, 1999. The Safety Board immediately dispatched a team of two

hazardous materials investigators from Washington, D.C., to the scene. 

A metallurgist from the Safety Boardís D.C. office joined the on-scene

investigation several days after the accident occurred. No Board Member participated in

the on-scene investigation. 

No hearings were held on the accident, and no depositions were filed concerning

it. 

The Federal Railroad Administration, the Lyondell Chemical Company, the Olin

Corporation, the Essroc Cement Corporation, CP Recycling of Indiana, Union Tank Car

Company, and Midland Manufacturing Corporation were all parties to the investigation.

(The Safety Board also provided information about the investigation on an ongoing basis to

the Mine Safety and Health Administration.)
70 Hazardous Materials Accident Report

Appendix B

U.S. Department of Transportation Hazardous Materials Incident 

Report Form
Appendix B 71 Hazardous Materials Accident Report