Hazardous Materials Accident Report

Hazardous Materials Release

From Railroad Tank Car With

Subsequent Fire at

Riverview, Michigan

July 14, 2001

National 

Transportation 

Safety Board

Washington, D.C.

A

A

N TION

L TRA SPOR

ATIO

N

B OARD

SAF E T Y

N

T

E PLURIBUS UNUM 

NTSB/HZM-02/01

PB2002-917002

Hazardous Materials 

Accident Report

Hazardous Materials Release 

From Railroad Tank Car With 

Subsequent Fire at 

Riverview, Michigan

July 14, 2001

NTSB/HZM-02/01

PB2002-917002 National Transportation Safety Board

Notation 7400A 490 LíEnfant Plaza, S.W.

Adopted June 26, 2002 Washington, D.C. 20594
National Transportation Safety Board. 2002. Hazardous Materials Release From Railroad Tank Car

With Subsequent Fire at Riverview, Michigan, July 14, 2001. Hazardous Materials Accident Report

NTSB/HZM-02/01. Washington, DC.

Abstract: About 3:45 a.m., eastern daylight time, on July 14, 2001, at the ATOFINA Chemicals, Inc.,

(ATOFINA) plant in Riverview, Michigan, a pipe attached to a fitting on the unloading line of a railroad

tank car fractured and separated, causing the release of methyl mercaptan, a poisonous and flammable gas.

About 4:09 a.m., shortly after the Riverview Fire Department chief arrived on scene, the methyl mercaptan

ignited, engulfing the tank car in flames and sending a fireball about 200 feet into the air. Fire damage to

cargo transfer hoses on an adjacent tank car resulted in the release of chlorine, a poisonous gas that is also

an oxidizer. The fire was extinguished about 9:30 a.m. Three plant employees were killed in the accident.

There were several other injuries; most of the injured were treated for respiratory symptoms and released.

About 2,000 residents were evacuated from their homes for about 10 hours. Two tank cars, railroad track,

and plant equipment (including hoses and fittings) were damaged in the fire.

The major safety issues identified in this investigation are the adequacy of ATOFINAís procedures for

unloading tank cars containing hazardous materials and the adequacy of Federal regulations and oversight

for cargo transfer operations involving bulk containers transporting hazardous materials.

As a result of its investigation of this accident, the Safety Board makes safety recommendations to the U.S.

Department of Transportation, the Federal Railroad Administration, the Environmental Protection Agency,

and the Occupational Safety and Health 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 PB2002-917002 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

Executive Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

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

Accident Synopsis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

The Accident and Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Injuries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Tank Car Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Unloading Apparatus Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Metallurgical Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Erosion-Corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Hazardous Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Methyl Mercaptan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Chlorine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Personnel Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Toxicological . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Plant Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Process 46 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Methyl Mercaptan Unloading Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Chlorine Unloading Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Emergency Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Federal/State Oversight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Federal Railroad Administration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

DOT Regulations on Loading and Unloading Hazardous Materials . . . . . . . . . . . . . . 16

Environmental Protection Agency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Occupational Safety and Health Administration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Emergency Preparedness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Other Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Postaccident Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Industry Use of Excess Flow Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Exclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

The Accident . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Inspection, Maintenance, and Use of Cargo Transfer Equipment . . . . . . . . . . . . . . . . . . . . 26

ATOFINA Policy Regarding Use of Personal Protection Equipment . . . . . . . . . . . . . . . . . 27

Reliance on the Tank Carís Excess Flow Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Federal Oversight of Loading and Unloading Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

EPA and OSHA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

FRA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Previous Safety Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Probable Cause . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Contents iv Hazardous Materials Accident Report

Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Appendixes

A: Investigation and Hearing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

B: NTSB Response to NPRM Docket HM-223 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
v Hazardous Materials Accident Report

Executive Summary

About 3:45 a.m., eastern daylight time, on July 14, 2001, at the ATOFINA

Chemicals, Inc., (ATOFINA) plant in Riverview, Michigan, a pipe attached to a fitting on

the unloading line of a railroad tank car fractured and separated, causing the release of

methyl mercaptan, a poisonous and flammable gas. About 4:09 a.m., shortly after the

Riverview Fire Department chief arrived on scene, the methyl mercaptan ignited,

engulfing the tank car in flames and sending a fireball about 200 feet into the air. Fire

damage to cargo transfer hoses on an adjacent tank car resulted in the release of chlorine, a

poisonous gas that is also an oxidizer. The fire was extinguished about 9:30 a.m. Three

plant employees were killed in the accident. There were several other injuries; most of the

injured were treated for respiratory symptoms and released. About 2,000 residents were

evacuated from their homes for about 10 hours. Two tank cars, railroad track, and plant

equipment (including hoses and fittings) were damaged in the fire.

The National Transportation Safety Board determines that the probable cause of

the accident involving the release of methyl mercaptan from a tank car at the ATOFINA

Chemicals, Inc., plant in Riverview, Michigan, was a fractured cargo transfer pipe that

resulted from (1) the failure of ATOFINA to adequately inspect and maintain its cargo

transfer equipment, and (2) inadequate Federal oversight of unloading operations

involving hazardous materials. Contributing to the accident were ATOFINAís reliance on

a tank car excess flow valve to close in the event of a leak from cargo transfer equipment

and the companyís failure to require appropriate safety equipment for employees involved

in tank car loading and unloading operations.

As a result of its investigation of the accident, the National Transportation Safety

Board identified the following safety issues:

ï The adequacy of ATOFINAís procedures for unloading tank cars containing

hazardous materials.

ï The adequacy of Federal regulations and oversight for cargo transfer

operations involving bulk containers transporting hazardous materials.

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

recommendations to the U.S. Department of Transportation, the Federal Railroad

Administration, the Environmental Protection Agency, and the Occupational Safety and

Health Administration.

1 Hazardous Materials Accident Report

Factual Information

Accident Synopsis

About 3:45 a.m., eastern daylight time, on July 14, 2001, at the ATOFINA

Chemicals, Inc., (ATOFINA) plant in Riverview, Michigan, a pipe attached to a fitting on

the unloading line of a railroad tank car fractured and separated, causing the release of

methyl mercaptan, a poisonous and flammable gas. About 4:09 a.m., shortly after the

Riverview Fire Department chief arrived on scene, the methyl mercaptan ignited,

engulfing the tank car in flames and sending a fireball about 200 feet into the air. Fire

damage to cargo transfer hoses on an adjacent tank car resulted in the release of chlorine, a

poisonous gas that is also an oxidizer. The fire was extinguished about 9:30 a.m. Three

plant employees were killed in the accident. There were several other injuries; most of the

injured were treated for respiratory symptoms and released. About 2,000 residents were

evacuated from their homes for about 10 hours. Two tank cars, railroad track, and plant

equipment (including hoses and fittings) were damaged in the fire.

The Accident and Response

From 2:00 until 3:00 a.m. on July 14, 2001, employees at the ATOFINA plant in

Riverview, Michigan, (see figure 1) removed three empty1 tank cars from the Process 462

loading area and replaced them with three full tank cars. Two of the loaded tank cars were

filled with chlorine, a poisonous gas, and one was filled with methyl mercaptan, a

poisonous and flammable gas. In the Process 46 area, the tank cars were to be used to feed

the chlorine and methyl mercaptan into the production process for the production of

several other materials. (See figure 2.)

1 These cars likely still contained a residue of product.

2 The term Process 46 refers to an area of the Riverview facility that is devoted to the production of

methane sulfonyl chloride and methane sulfonic acid through a multi-step synthesis of methyl mercaptan

with chlorine. Greater detail concerning Process 46 operations is provided in the ìPlant Informationî section

of this report.
Factual Information 2 Hazardous Materials Accident Report

According to one of the employees who had placed the loaded tank cars, once the

cars were positioned, two operators were assigned the task of attaching and leak-testing

the unloading apparatus that connected the tank cars into the plant piping. According to

the employee, the two full chlorine tank cars were attached first. The attachments were

completed about 3:00 a.m., and the A operator3

 began attaching the unloading apparatus to

Figure 1. Accident site.

Figure 2. Accident site. (The circled area is the area of greatest fire damage.)

85

12

Taylor

Trenton Trenton

Amherstburg Amherstburg

Glen Eden

Bar Point

Sinasac Corners

Eureka Rd

Northline Rd

Eloise

32

34b

36

40

Riverview Riverview

Southgate Southgate

Ecorse

Gibraltar Gibraltar

Lincoln Park Lincoln Park

Grosse Ile Grosse Ile

3

River Rouge River Rouge

24

26

28

Maple Beach

Detroit

Michigan

Southwick

McGregor Junction

Malden

Romulus Romulus
Factual Information 3 Hazardous Materials Accident Report

the methyl mercaptan tank car. ATOFINA operators told investigators that it takes about

15 minutes to attach and leak-test the tank car fittings.

ATOFINA employees first became aware of a problem in the Process 46 area at

3:45 a.m. when someone activated a fire alarm for the area.4 Shortly afterwards,

ATOFINA employees heard the shift superintendent5 on the two-way radio asking that 911

be called. At 3:47 a.m., a methyl mercaptan sensor in the control room on the second floor

of the Process 46 operations center registered an elevated level of methyl mercaptan. A

process operator in the control center said she became aware of a product release when she

smelled methyl mercaptan and then heard the alarms sounding at the plant. She looked out

of her building and saw the shift superintendent lying on the ground near a manually

operated area fire alarm about 50 feet from the tank car unloading area. She then began

securing her process in accordance with company emergency response procedures.

When the Process 46 area fire alarm sounded, ATOFINA employees from two

other plant process areas put on self-contained breathing apparatus (SCBA) and went to

the area. Because methyl mercaptan is a flammable gas that could ignite at any time, this

initial rescue attempt had to be performed quickly. The employees found the B operator

and the shift superintendent and removed them from the Process 46 area. The A operator

was not found at that time. The two injured employees were transported by ambulance to

Riverside Osteopathic Hospital (about 2.7 miles from the plant), where they were

pronounced dead.

Also in response to the fire alarm, the ATOFINA fire crew drove the plant fire

engine to the Process 46 area. Once there, an employee on the fire crew reported seeing

fumes coming out of the top of the methyl mercaptan tank car. The fire crew began

spraying water toward the tank car to knock down the fumes.

At 3:48 a.m., the Riverview 911 dispatcher received a call from an ATOFINA

employee reporting ìa man downî at the ATOFINA facility. By 3:52 a.m., the Riverview

Fire Department was en route to the scene. About the same time, the 911 dispatcher

received a second call from the ATOFINA plant reporting a release of methyl mercaptan.

By 3:58 a.m., the first two units of the Riverview Fire Department were on scene. At

4:08 a.m., the dispatcher received a third call from the ATOFINA plant reporting ìat least

four people down,î the need for several ambulances, and the need for responders to wear

SCBAs.

At 4:09 a.m., the leaking methyl mercaptan ignited, completely engulfing the tank

car in flames. The Riverview fire chief, who witnessed the ignition, said the ignition

3 Employees designated as operators perform various tasks within a production process. They are

identified as ìAî and ìBî operators, with the ìAî designation being given to the more experienced

employee.

4 The fire alarm was likely being used as a general alarm, since the first evidence of a fire was when

the escaping gas ignited some 19 minutes later.

5 The shift superintendent supervises the work of the entire plant during off shifts and is not directly

involved in tank car loading and unloading operations.
Factual Information 4 Hazardous Materials Accident Report

resulted in a fireball that extended an estimated 200 feet into the air. When the fireball

occurred, the Riverview fire chief requested mutual aid from the surrounding

communities. Riverview Fire Department responders began applying water to the tank

cars involved in the fire and to the adjacent tank cars to keep them cool. (See figure 3.)

Units from the Wyandotte, Trenton, and Brownstown Fire Departments, and the

Downriver Mutual Aid HAZMAT Team6 responded.

About 5:00 a.m., the Grosse Ile Police Department advised the Riverview fire

chief that strong odors were detected in Grosse Ile. At that time, according to the

Riverview fire chief, the wind direction was out of the northwest to the southeast at about

12 to 15 mph. Grosse Ile is southeast of the ATOFINA plant. At first, the Riverview fire

chief advised the Grosse Ile Police Department to have the residents shelter-in-place.7

However, about 5:19 a.m., after re-evaluating the situation, the Riverview fire chief

requested the evacuation of residents of parts of Riverview, Trenton, Grosse Ile, and

Wyandotte. In all, about 2,000 residents of the surrounding communities were evacuated

from their homes and businesses.

Figure 3. Overview of accident site and emergency response.

6 The Downriver Mutual Aid HAZMAT Team comprises 30 personnel from 17 local fire departments

specifically trained in handling hazardous materials emergencies.

7 Shelter-in-place is an emergency response action used after the release of potentially dangerous gases

or vapors from a source outside a building. It involves having occupants remain within their building with

the air circulation turned off until the area is determined to be safe.
Factual Information 5 Hazardous Materials Accident Report

The methyl mercaptan tank car fire was allowed to burn itself out while the water

streams continued to cool the tank cars. Records of the exact time the fire went out vary;

however, there was general agreement that it occurred after 8:30 a.m. The Riverview Fire

Departmentís report stated that ìat 12:47 p.m. the methyl mercaptan leak and fire had

stopped,î but the Riverview fire chief later stated that the fire was out between 8:30 and

9:30 a.m. After the fire was out, a reconnaissance team equipped with SCBAs and

protective suits entered and examined the site. The team found the partially burned body

of the A operator on the tracks near the south end of the methyl mercaptan tank car.

Several entry teams were sent into the accident area after the reconnaissance team

to search the site and close any open valves. One entry team found that the

1-inch-diameter transfer pipe in the unloading apparatus attached to the unloading valve

for the methyl mercaptan tank car, UTLX 900558, had failed and separated. The failure

occurred in the threaded section of the pipe where it entered a 2-inch to 1-inch reducer

mounted on the tank carís unloading valve. The unloading valve was open, and the tank

carís full load of 147,350 pounds of methyl mercaptan had been released. Both valves on

the flexible hose that connected the unloading apparatus to the plant process were closed,

and the hose itself was burned through. The team closed the tank carís unloading valve.

The flexible hose that connected the unloading apparatus on the adjacent chlorine

car (DCTX 27444) to the plant process was found burned through. The tank car unloading

valve and all in-line valves between the tank car and the plant piping were open when the

entry teams arrived. These valves were then closed. Because of the relatively short time

that elapsed between the damage to the flexible hose and the closing of the valves, only

about 26,500 of the 178,560 pounds of chlorine in the tank car were released. At

2:48 p.m., all the plant and tank car valves were confirmed closed, and at 3:07 p.m., the

evacuation was lifted.

About 1:30 p.m. on July 15, 2001, all Riverview Fire Department active units were

released, with the exception of one engine and two firefighters. Riverview Fire

Department personnel remained on scene until July 17, 2001, monitoring the accident site

for residue of hazardous materials to ensure that it was safe to allow investigators to enter

the area.

Injuries

According to the Wayne County Deputy Medical Examiner, the B operator and the

shift superintendent sustained fatal injuries consisting of methyl mercaptan intoxication.

The A operator had fatal injuries consisting of thermal burns and methyl mercaptan

intoxication.

One ATOFINA employee was injured when, after inhaling methyl mercaptan

fumes, he fell to the ground and fractured three ribs. Five other employees sustained minor

injuries, including muscle strains, abrasions, and/or inhalation injuries. Three emergency

responders sustained minor inhalation injuries, including nasal irritation. At least 40
Factual Information 6 Hazardous Materials Accident Report

residents of the communities surrounding the ATOFINA plant complained of sore throats,

headaches, and/or dizziness; they were treated and released from local hospitals. (See

injury table.)

At 5:04 a.m. on the day of the accident, some 5 to 10 minutes after the arrival of

the shift supervisor and the B operator, employees at the Riverside Osteopathic Hospital

began to report feeling sick. Later that day, the Western Wayne County hazardous

materials response team determined that the emergency department and external area had

been contaminated with methyl mercaptan, and they were closed until they could be

decontaminated. The decontamination was completed at 11:45 p.m.

Tank Car Information

The methyl mercaptan car involved in the fire was UTLX 900558, a DOT

105J300W specification tank car manufactured by Union Tank Car Company in October

1988. The car was a carbon steel pressure car, with thermal protection and insulation

covered by a steel jacket. The tank carís water capacity was 24,983 gallons.

The adjacent chlorine tank car also involved in the fire was DCTX 27444, a DOT

105A500W specification tank car manufactured by North American Tank Car in 1973.

This car was a carbon steel pressure car, with thermal protection and insulation covered by

a steel jacket. The tank carís water capacity was 17,300 gallons.

Both tank cars had liquid and vapor valves, and they each had a pressure relief

device mounted within a protective dome on the top of the tank. The liquid valve opening

on the methyl mercaptan tank car had a 2-inch inside diameter; the liquid valve opening

on the chlorine tank car had a 1-inch inside diameter. The liquid valves were used for

unloading the methyl mercaptan and chlorine from the tank cars.

Table 1. Injuries.

Injury Scalea

ATOFINA 

Employees

Emergency 

Responders Others Total

Fatal 3 0 0 3

Serious 1 0 0 1

Minor 5 3 40 48

Total 9 3 40 52

a

49 Code of Federal Regulations 830.2 defines fatal injury as ìany injury which results in death within 30 days of the 

accidentî and serious injury as ìan injury which: (1) requires hospitalization for more than 48 hours, commencing 

within 7 days from the date the injury was received; (2) results in a fracture of any bone (except simple fractures of 

fingers, toes, or nose); (3) causes severe hemorrhages, nerve, or tendon damage; (4) involves any internal organ; or 

(5) involves second or third-degree burns, or any burn affecting more than 5 percent of the body surface.î
Factual Information 7 Hazardous Materials Accident Report

Excess flow valves for each unloading (liquid) valve were installed in the eduction

pipe8

 inside each tank car. According to Federal regulations, an excess flow valve is

designed as a device that ìcloses automatically against the outward flow of the contents of

the tank in case the external tank car closure valve is broken off or removed during

transit.î9

 According to the Chlorine Instituteís Chlorine Manual, an excess flow valve

ìmay close if a catastrophic leak involving a broken connection occurs but it is not

designed to act as an emergency shut-off device during transfer.î10 The excess flow valve

will not activate if, as in this accident, the flow rate does not exceed the normal transfer

rate by a sufficient margin.

Unloading Apparatus Information

The first component of ATOFINAís unloading apparatus consisted of a

1-foot-long, 1-inch-diameter steel pipe with a 2- to 1-inch reducer threaded onto one end

and a four-bolt flange threaded onto the other. In preparation for product transfer, the

reducer end of the pipe was passed through an access hole on the side of a tank car dome,

and the reducer was threaded onto the tank carís unloading valve. The 1-inch pipe was the

one that, in this accident, failed and separated, releasing the methyl mercaptan.

Additional cargo unloading components were then attached to the 4-bolt flange.

These components included a pressure gauge, a 90-degree elbow, a gate valve, two

T-fittings, several lengths of 1-inch pipe, and a flexible hose that attached to the plant

process piping. (See figure 4.) The total weight of the unloading apparatus was about

53 pounds. With the exception of the downstream end of the flexible hose, which was

attached to the plant piping, the unloading apparatus was supported only by the reducer and

the 1-inch pipe mounted in the tank car unloading valve.

8 An eduction pipe is a long steel pipe attached to the liquid valve that extends to the bottom of the

tank. The pipe is used to unload liquid material from the tank car.

9 Title 49 CFR 179.100-13(d).

10 The Chlorine Institute, Chlorine Manual, Sixth Edition, Washington, DC. January 1997. Section

3.2.3.3, page 14.
Factual Information 8 Hazardous Materials Accident Report

Damage

Visible damage to methyl mercaptan tank car UTLX 900558 consisted of fire

damage to the jacket, wheels, axles, bearings, brake components, and safety appliances.

The fire affected approximately 90 percent of the car. The visible damage to chlorine tank

Figure 4. Overhead view of unloading apparatus. (For clarity, the pressure gauge, 

valves, and scrubber line have been rotated into the horizontal plane.)
Factual Information 9 Hazardous Materials Accident Report

car DCTX 27444 consisted of fire damage to the jacket and running components on the

left side (facing the B-end) of the car. This side was facing tank car UTLX 900558.

As noted earlier, a 1-inch-diameter steel pipe in the unloading apparatus of

UTLX 900558 was separated at the point the pipe threads exited a 2- to 1-inch reducer

installed in the tank carís unloading valve. The flexible hoses attached to the unloading

apparatus on both tank cars were melted and partially consumed by the fire.

Damage to the plant was limited to fire exposure on the methyl mercaptan

unloading station, which resulted in melting or damaging most of the non-ferric fittings,

gauges, and other apparatus; fire exposure and warping of the track under the methyl

mercaptan tank car; and scorching of track ties and nearby wooden planking.

Metallurgical Examination

The Safety Boardís metallurgical examination of the separated steel pipe in the

unloading apparatus (figure 5) did not identify any evidence of preexisting cracks on the

fracture surface; the fracture features were typical of an overstress separation.

Examination of the pipe revealed evidence of corrosion, including deposits of iron oxide

(rust) and pitting on both interior and exterior surfaces. (The interior surfaces of the pipe

were exposed to the weather whenever the unloading apparatus was not in place on a tank

car.)

Figure 5. Separated transfer pipe.
Factual Information 10 Hazardous Materials Accident Report

Measurements of the interior and exterior diameters at several locations on the

length of the pipe were compared with interior and exterior diameters for new pipe. These

comparisons revealed that the outside diameter was comparatively the same as that of new

pipe; however, the inside diameter near the end of the pipe where the failure occurred

showed evidence of erosion-corrosion damage (discussed in the next section) that reduced

the wall thickness near the fracture by about 23 percent as compared to the inside diameter

of new pipe.

Calculations made using the weight of each of the unloading apparatus

components, their distances from the pipe separation, the standard (as manufactured) wall

thickness of 1-inch pipe, and standard piping design and engineering formulas indicate

that bending stresses on a new pipe at the point the pipe entered the reducer would have

been 20,800 pounds per square inch (psi). The wall thickness reduction of the accident

pipe that resulted from erosion-corrosion resulted in a 20-percent increase in the

calculated bending stress on the pipe, to 25,100 psi at the point of fracture. Comparing the

bending stress to the strength of the material, Safety Board metallurgists estimated that an

additional force of about 175 pounds (added to the existing force represented by the

weight of the unloading apparatus), if applied at the outer end of the unloading apparatus,

would cause an overstress failure (fracture) of the pipe.

Erosion-Corrosion

ASM International, a society for materials engineers and scientists, in its Metals

Handbook,

11 defines ìerosionî as the ìdestruction of metals or other materials by the

abrasive action of moving fluidsÖ.î ìErosion-corrosionî is defined as ìa conjoint action

involving corrosion and erosion in the presence of a moving corrosive fluid, leading to the

accelerated loss of material.î It should be noted that, while methyl mercaptan is not

considered to have a significant corrosive effect on steel, exposure of steel to the

atmosphere does produce corrosion. And while corrosive products (rust on steel) tend to

form a protective layer that retards further corrosion, ASM International notes in its

Metals Handbook that:

Turbulence [in the fluid] has the ability to physically disrupt and tear away the

various types of protective filmsÖexposing the bare metal for subsequent

corrosion.Ö Turbulent conditions are created by changes in diameter in piping

systems. Bends and elbows likewise create conditions conducive to changes in

velocity that create turbulent conditions, sometimes called cavitation, wherein

bubbles of air contained in the fluid can collapse and exert an abrasive action

against any protective films formed on the pipe surface.

11 ASM International, Metals Handbook, Ninth Edition, Volume 13 (Materials Park, Ohio: 1987).
Factual Information 11 Hazardous Materials Accident Report

Hazardous Materials

Methyl Mercaptan

Methyl mercaptan is a U.S. Department of Transportation (DOT) hazard

Division 2.3 (poison gas) material that is also flammable. According to U.S. Coast Guard

chemical and hazardous response information system (CHRIS) data,12 the IDLH value13

for methyl mercaptan is 150 parts per million in air (ppm). The flash point is 0° F. Methyl

mercaptan is a colorless gas that has a garlic or rotten cabbage odor. Inhalation and skin

contact are the primary routes of exposure. Methyl mercaptan is irritating to the skin, eyes,

mucous membranes, and respiratory tract. Persons coming in contact with methyl

mercaptan may experience nausea, vomiting, headache, or dizziness, especially when

exposure occurs without adequate ventilation. High concentrations may produce central

nervous system effects such as staggering gait, muscular weakness, convulsions, paralysis

of the respiratory center, and death. The ATOFINA material safety data sheets state that

where airborne exposure to methyl mercaptan is likely, approved respiratory protection

equipment is appropriate. Contact with combustible materials may enhance the risk of

fire, and exposure to solid bleach or strong oxidizers may cause a violent reaction and fire.

Chlorine

Chlorine is a DOT hazard Division 2.3 (poison gas) material that is also corrosive.

Chlorine is a greenish-yellow gas with a distinctive odor. According to U.S. Coast Guard

CHRIS data, the IDLH value for chlorine is 10 ppm. Exposure to chlorine gas can cause

severe irritation of eyes and respiratory tract with shortness of breath, choking sensation,

dizziness, lung edema, and blindness. Inhalation is the primary route of exposure. The

material may be fatal if inhaled. The ATOFINA material safety data sheets state:

When airborne exposure limits are exceeded, use NIOSH [National Institute for

Occupational Safety and Health] approved respiratory protection equipment

appropriate to the material and/or its components (full facepiece recommended).

Personnel Information

The A operator for Process 46 was hired by Pennwalt Corporation (which later

became ATOFINA) on January 5, 1983, as a utility person. In 1986, he began working as a

process operator in the production department. At ATOFINA, he completed safety training

in such areas as firefighting, SCBA, respirator, hazardous waste operations and emergency

response (HAZWOPER), and hazard communication.

12 United States Coast Guard, United States Coast Guard Chemical and Hazardous Response

Information System, COMDTINST 16465.12C, Version 1.0, January 2000.

13 The IDLH (immediately dangerous to life and health) value is an atmospheric concentration of any

toxic, corrosive, or asphyxiate substance that poses an immediate threat to life or would cause irreversible or

delayed adverse health effects, or would interfere with an individualís ability to escape from a dangerous

atmosphere. The Environmental Protection Agency uses 10 percent of the IDLH value when determining

that a release has reached a level of concern for public exposure.
Factual Information 12 Hazardous Materials Accident Report

The B operator for Process 46 was hired on July 31, 1987, and began working as a

process operator in the production department. He had completed the same safety training

as the A operator.

The two operators had worked for about a week on this same shift. ATOFINA

co-workers who saw the operators the night of the accident told Safety Board investigators

that the operators appeared to be in good condition, and they noticed nothing unusual

about the operatorsí performance.

Toxicological

Postaccident drug and alcohol tests were conducted on the bodies of the

A operator, the B operator, and the shift superintendent who died as a result of injuries

sustained during the accident. All test results were negative.

Plant Information

ATOFINA Chemicals, Inc., formerly Elf Atochem North America, Inc., is

headquartered in Philadelphia, Pennsylvania. ATOFINA produces and markets chemical

intermediates and performance polymers. Chemicals have been produced at the

Riverview, Michigan, plant under a variety of owners since 1898. Elf Atochem North

America, Inc., took over ownership after a company merger in 1990. Today, the plant

manufactures 47 products and produces approximately 70 million pounds of organic

chemicals annually. Approximately 190 persons are employed at the plant. Most raw

hazardous materials used at the facility arrive by rail. Finished hazardous products are

shipped from the plant by rail and truck. The plant has 5 processes that load or unload tank

cars and 10 processes that load or unload highway cargo tanks.

Process 46

The area of the Riverview facility designated as ìProcess 46î produces methane

sulfonyl chloride by a multi-step synthesis of methyl mercaptan with chlorine. Methane

sulfonyl chloride is an intermediate material used in the photographic, agricultural, and

pharmaceutical industries. Process 46 also produces methane sulfonic acid. Methane

sulfonic acid is used as an intermediate chemical in the agricultural, electronics, and

pharmaceutical industries. The methyl mercaptan and chlorine are offloaded from tank

cars and fed to the plant process as needed.

At any given time, five tank cars are situated on tracks inside the Process 46 area.

Two of the five tank cars contain methyl mercaptan. They are attached to the plant piping

and are used, one car at a time, to supply the material to the process. When one car is

empty, it is removed and replaced with a full one while the other car supplies material.

Two chlorine tank cars are used in a similar manner, except that they are not attached
Factual Information 13 Hazardous Materials Accident Report

directly to the process plant piping. Instead, their piping is connected to a chlorine

ìanchorî tank car that is positioned permanently on a track scale. Chlorine is then fed to

the process through piping from the anchor tank car.

According to the Riverview plant production supervisor, pipes and fittings for the

methyl mercaptan and chlorine transfer equipment are not inspected or replaced on a

routine or scheduled basis. According to ATOFINA management, a search through about

5 years of records did not reveal any inspection or replacement records for the failed

1-inch-diameter steel pipe that was inserted in the reducer on methyl mercaptan tank car

UTLX 900558.

Methyl Mercaptan Unloading Procedures14

A Process 46 operator not on duty at the time of the accident described how two

operators for this process connect the tank car to the plant piping. As soon as a new tank

car is moved into position, one operator climbs to the top of the tank car using the stairs on

the working platform while the other connects a ground wire to the car to protect against

static electricity. No SCBAs or escape hoods are worn or carried by either operator. The

operator on the top of the car then opens the cover assembly for the tank carís protective

dome. If methyl mercaptan is leaking from the tank car, the operator on the car can detect

its odor as soon as the dome lid is opened. If a leak is detected, the operator closes the lid

and notifies the plantís emergency response team. If no leak is detected, the operators

visually check all valves to verify that they are closed. Next, one of the operators removes

the plug in the tank carís vapor valve opening15 and threads a nitrogen line into the vapor

valve. The nitrogen line provides additional pressure to the tank car, as needed, to assist in

unloading the methyl mercaptan. An operator then removes the plug for one of the two

unloading valves and passes the first component of the unloading apparatus (which

includes the 1-inch-diameter pipe that failed in this accident) through an access hole in the

side of the protective dome and threads the reducer into the unloading valve opening. The

operators then connect the other components of the cargo unloading apparatus to the first

component using the four-bolt flange on the other end of the 1-inch-diameter pipe. These

components are attached to a flexible hose that leads to the plant piping.

According to the operator who provided the description of the connection process,

once the attachment has been completed, the operators check the connections for leaks.

First, they test the vapor connection to the tank car by turning on the nitrogen feed from

the plant with the tank carís vapor valve closed; any leaks of nitrogen are audible. If they

detect no leaks, the nitrogen feed is left on and the vapor valve is kept closed. Next, they

test the unloading connection to the tank car. With the downstream valve on the unloading

apparatus closed, the operators slowly open the tank carís unloading valve, allowing 20 or

30 psi of methyl mercaptan to enter the unloading apparatus and register on its pressure

gauge. Once the desired 20 to 30 psi of pressure is reached in the unloading apparatus,

14 Variations in tank car design may require slight modification of these procedures. The operator

described the procedures that would have been used for the tank car involved in the accident.

15 A plug is threaded into the valve opening to prevent the release of material from the tank car in case

the valve opens or fails during transportation.
Factual Information 14 Hazardous Materials Accident Report

they close the unloading valve. The operators can detect by odor any leak of the poisonous

methyl mercaptan gas from the fittings on the tank car.

Once the operators have made all connections and verified that there are no leaks,

they close the tank car valves, and the tank car sits idle, grounded and ready for use.

According to the operator who provided this information, all connections are rechecked

just before the actual transfer process begins.

ATOFINA has written step-by-step instructions for these procedures in its Standard

Practice Instructions Manual. The manual describes the sequence of actions necessary to

connect the transfer piping to a methyl mercaptan tank car and to test the piping for leaks

before the tank car is unloaded. The instructions do not require operators to wear SCBAs

while working on methyl mercaptan tank cars. Further, they do not address carrying an

escape hood with an emergency (5- to 10-minute) air supply when in the area of

Process 46 tank cars, nor were such hoods carried by plant personnel. (In the event of

release of poisonous gas such as occurred in this accident, emergency hoods can be

donned and should provide sufficient oxygen to permit individuals to escape the area.)

ATOFINAís operators are provided with copies of the Standard Practice

Instructions Manual as part of their training. Operators also go through on-the-job training

with an experienced operator to reinforce these procedures.

Chlorine Unloading Procedures

The procedures used at ATOFINA for unloading chlorine from tank cars are

similar to those used for unloading methyl mercaptan, with the following exceptions:

ï Operators unloading chlorine are required to wear SCBAs when opening the

tank car dome cover and making the connections.

ï A spray bottle of ammonia solution is used to detect chlorine leaks from the

fittings. (Ammonia reacts with chlorine to form a visible white powder.)

ï Chlorine tank cars have two vapor valves; connection may be made to either

valve.

ï A high-pressure dry air (instead of nitrogen) line is attached to one of the two

vapor valves to provide additional pressure, as needed.

ï Connections are made between chlorine tank cars and the anchor tank car

rather than directly to the process.

Emergency Systems

Six methyl mercaptan sensors were installed at various fixed locations throughout

the Process 46 area. The sensors monitored the concentration of methyl mercaptan in the

air and recorded the data. The methyl mercaptan sensors were set to detect the material

and record concentrations ranging from 0 to 30 ppm.
Factual Information 15 Hazardous Materials Accident Report

One of the six methyl mercaptan sensors was on the tank car transfer platform

where the methyl mercaptan tank car (UTLX 900558) was positioned. A review of the

readout for that sensor revealed that it displayed either ì0î or a signal indicating a

malfunction for the 24-hour period reviewed (from about 3:15 p.m. on July 13 to

3:15 p.m. on July 14). The only sensor of the six in the Process 46 area that provided data

for that 24-hour period was the one in the second-floor Process 46 control room. That

sensor read ì0.12î (ppm) from 3:13 p.m. on July 13 until 3:47 a.m. on July 14, at which

time the readout changed to ì29.88 HIHIî (indicating that the reading had exceeded a

preset maximum). This reading remained until 5:12 a.m., at which time it began to

gradually decline to a level of ì0.94î at 3:13 p.m. on July 14.

Explosion-proof emergency switches to shut down production pumps within the

process were mounted on the Process 46 transfer platforms for the methyl mercaptan and

chlorine tank cars, the Process 45/46 control room, and the northeast exit door of the

Process 46 building. These switches did not and were not designed to close the valves on

the methyl mercaptan tank cars. The methyl mercaptan tank car was not equipped with a

plant-installed remote or automatic mechanism to stop the flow of product during an

emergency.

Federal/State Oversight

Federal Railroad Administration

The Federal Railroad Administration (FRA) is responsible for ensuring railroad

safety throughout the Nation. FRA inspectors are assigned to one of five disciplines, one

of which is hazardous materials.16 FRA hazardous materials inspectors are responsible for

ensuring that offerors17 and transporters of hazardous materials by rail comply with

applicable provisions of the hazardous materials regulations.18 Of the approximately 450

FRA inspectors in the United States, about 50 are dedicated to enforcement of the

hazardous materials regulations.

FRA hazardous materials inspectors conduct compliance reviews at offerorsí

facilities that ship hazardous materials, as well as at rail yards and tank car

manufacture/repair facilities. Because end users of hazardous materials, such as

ATOFINA, become offerors when they return tank cars containing a residue of hazardous

materials to the rail carriers, the FRA also inspects end-user facilities. A single FRA

hazardous materials inspector has oversight responsibility for the State of Michigan. This

inspector stated that on average he inspects each of the approximately 90 offerorsí

16 The other four disciplines are track, operating practices, signal and train control, and motive power

and equipment.

17 An offeror is the entity (person, company, corporation, association, etc.) that offers a hazardous

material for transportation.

18 The hazardous materials regulations (49 CFR Subchapter C) are promulgated by the DOTís Research

and Special Programs Administration. The FRA consults with the Research and Special Programs

Administration on rulemakings specifically involving the transportation of hazardous materials by rail.
Factual Information 16 Hazardous Materials Accident Report

facilities within his region at least once per year. Additionally, the inspector stated he

might return to a facility and conduct additional inspections during the year if an incident

occurs there or if his office receives complaints about the facility.

The FRA regulations concerning loading and unloading tank cars, found in

49 CFR 174.67, require that:

ï The tank car brakes are set.

ï Wheels are properly chocked.

ï Caution signs are placed on the track.

ï Internal pressure in the tank car is relieved, as appropriate.

ï All unloading apparatus, lines, and other equipment items are securely

attached before tank car valves are opened.

ï All connections are disconnected after the tank car is unloaded or when

unloading is discontinued for any reason.

ï The tank car is attended during unloading operations.

ï Employees are properly trained to perform hazardous materials functions.

The FRA has issued hazardous materials bulletins that explain FRA hazardous

materials policy and provide guidance about various regulated activities, including tank

car unloading, attendance requirements during the unloading of tank cars, and hazardous

materials training. Such bulletins are advisory in nature.

According to the FRA hazardous materials staff director, FRAís jurisdiction

concerning the hazardous materials regulations encompasses hazardous materials ìin

transportationî by rail, but the FRA has no oversight responsibility with respect to any

piece of cargo transfer equipment used to unload hazardous cargo from tank cars unless

that piece is a permanent part of the car. Consequently, FRA inspectors do not inspect

hazardous materials cargo transfer equipment at loading and unloading facilities. Between

1996 and June 2001, FRA inspectors performed seven inspections or audits at ATOFINAís

Riverview facility. Of the seven inspections or audits, six listed some type of deficiency

concerning the hazardous materials regulations. Among the problems noted were

inadequate training records, inadequate markings, inadequate placards, and failure to

secure all closures on tank cars, which resulted in a leak of hazardous materials. Of these

violations, the FRA formally addressed onethe failure to secure tank car closuresby

issuing a notice of probable violation and assessing a fine.

DOT Regulations on Loading and Unloading Hazardous Materials

The definitions of ìin transportationî in both 49 United States Code, Section 5102,

and 49 CFR 107.3 specifically identify loading and unloading of hazardous materials as

part of transportation for all modes.

The DOT has developed regulations and oversees the area of loading and

unloading hazardous materials. These regulations include:
Factual Information 17 Hazardous Materials Accident Report

ï 49 CFR 173.30 concerns the loading and unloading of transport vehicles in all

modes of transportation.

ï 49 CFR 174.67 concerns tank car unloading.

ï 49 CFR 174.101 ñ 174.115 concerns the loading of explosive materials being

transported by rail.

ï 49 CFR 177.834 concerns the general loading and unloading of highway

vehicles.

On June 14, 2001, the DOTís Research and Special Programs Administration

(RSPA) issued a notice of proposed rulemaking (NPRM), HM-223, entitled Applicability

of Hazardous Materials Regulations to Loading, Unloading, and Storage.

19 The NPRM

proposed, for the purposes of the hazardous materials regulations, to define

ìtransportationî for all modes of transportation, including rail, as beginning from the

moment a carrier accepts a container or package of hazardous materials to the moment the

carrier relinquishes it to the consignee. In its October 29, 2001, response to the NPRM, the

Safety Board expressed its concern about the proposed rulemaking and stated that ìthe

proposed rules may result in the elimination of effective Federal oversight of hazardous

materials loading/unloading operations of bulk transportation containers.î

Environmental Protection Agency

The Environmental Protection Agencyís (EPAís) mission is ìto protect human

health and to safeguard the natural environmentóair, water, and landóupon which life

depends.î One part of that mission, safeguarding the air, is addressed in 40 CFR

Subchapter C, Parts 50ñ99, which incorporates provisions of the Clean Air Act of 1970.20

EPAís ìGeneral Guidance for Risk Management Programsî21 states that:

If you handle, manufacturer, use, or store any of the designated toxic or

flammable substances listed in 40 CFR 68.130Öabove the specified threshold

quantities in a process, you are required to develop and implement a risk

management program.Ö

Both methyl mercaptan and chlorine are designated substances; methyl

mercaptanís threshold quantity22 is 10,000 pounds, and chlorineís threshold quantity is

2,500 pounds. The risk management program requirements became effective in June

1996.

19 Docket No. RSPA-98-4952, 66 Federal Register 32420, June 14, 2001.

20 Title 42 United States Code, Sections 7401 et. seq.

21 EPA, General Guidance for Risk Management Programs (40 CFR Part 68), EPA 550-B-00-008,

Washington, DC. May 2000.

22 Threshold quantity is the minimum amount of toxic or flammable material in a process above which

a facility is required by the EPA to develop a risk management program.
Factual Information 18 Hazardous Materials Accident Report

The EPA general guidance document also states that:

[T]he goal of part 68ñthe risk management program−is to prevent accidental

releases of substances that can cause serious harm to the public and the

environment from short-term exposures and to mitigate the severity of releases

that do occur.

Each risk management program must contain a hazard assessment that includes an

offsite consequence analysis and a release prevention program. The EPA considers tank

cars and highway cargo tanks that are interconnected with the plantís fixed equipment as

parts of the plant process equipment and thus subject to EPA regulations.

The offsite consequence analysis is intended to provide information about the

potential consequences of accidental releases. The analysis generally consists of a

worst-case release scenario23 involving one substance selected from all the regulated toxic

substances handled at a facility, a worst-case scenario for each of the regulated flammable

substances handled at a facility, an alternative release scenario for each regulated toxic

substance over the threshold limit, and an alternative release scenario that represents all

flammable substances over the threshold limit. Among the items included in a scenario are

the quantity of the hazardous material released and the measures used to prevent or

mitigate the release.

The release prevention program consists of 12 separate requirements.24 These

elements include a requirement to develop and follow a mechanical integrity program for

piping systems, such as the unloading apparatus, as well as for pressure vessels, storage

tanks, relief and vent systems/devices, emergency shutdown systems, controls, and

pumps. The equipment covered by the mechanical integrity element must be inspected and

tested using good engineering practices and must, at a minimum, be inspected in

accordance with the manufacturerís recommended inspection schedule. Each mechanical

integrity inspection and test must be documented.

In addition, each company must describe the risk management program in a risk

management plan that must be registered with the EPA. The risk management plan does

not contain all the information required in the risk management program; however, it

provides the EPA with key information. The worst-case and alternative release scenarios

must be included in this plan. Regulated facilities had until June 1999 to submit their first

risk management plans to the EPA.

Approximately 15,000 risk management plans have been submitted to the EPA.

The EPA uses a software program entitled ìRMP Submitî to review the risk management

plans, but this program only helps ensure that all required fields within the document

contain information. Neither the EPA staff nor the software program reviews the data for

content or accuracy. EPA regional staff indicated that some risk management plans (fewer

23 The EPA defines worst-case scenario as the release of the largest quantity of a regulated substance

from a single vessel or process line that results in the greatest distance to an endpoint.

24 Facilities regulated under the risk management program are subject to one of three prevention

program levels. Level 3 facilities, such as Riverview, are subject to the largest number of requirements.
Factual Information 19 Hazardous Materials Accident Report

than a dozen) have been thoroughly reviewed and that others may be audited at a later

date.

The EPA received the current ATOFINA Riverview facility risk management plan

on July 3, 2000. At the time the plan was submitted, 14 production processes within the

facility were subject to these regulations, including Process 46.25 The alternative toxic

release scenarios for both the methyl mercaptan and chlorine tank cars involve the failure

of the flexible hose that connects the unloading apparatus to the plant piping. Each

scenario lists the tank carís excess flow valve as an active mitigation measure.

The release prevention program for Process 46 also cites tank car ìexcess flow

devicesî as one of the prevention methods. In addition, one of the mitigation systems

involves planned and periodic inspections of critical equipment. The executive summary

for the risk management plan specifically identifies the need for frequent inspection of the

unloading lines. The risk management plan also lists the process gas monitoring/detection

systems as methods for preventing or mitigating a release.

On-site inspection of facilities to verify the compliance with the EPA regulations

has been left to discretion of each EPA region. Interviews with EPA Region V personnel,

whose jurisdiction includes the State of Michigan, revealed that, between the initiation of

the EPAís oversight program in June 1996 and the July 14, 2001, accident, three on-site

inspections covering the requirements of the risk management program had been

conducted of the approximately 2,800 facilities that submitted risk management plans

within the region. ATOFINAís Riverview plant was not one of the three facilities

inspected. After the accident, EPA regional personnel initiated an inspection of the portion

of ATOFINAís risk management program concerning the Process 46 location of the plant.

Occupational Safety and Health Administration

The mission of the Occupational Safety and Health Administration (OSHA) is ìto

prevent fatalities, injuries, and to protect the health of Americaís workers.î The

Occupational Safety and Health Act of 1970 (Public Law 91-596) was enacted ìto assure

safe and healthful working conditions for working men and women.î The general duty

clause requires that ìeach employer shall furnish to each of his employees employment

and a place of employment which are free from recognized hazards that are causing or are

likely to cause death or serious physical harm to his employees.î To achieve that goal,

Congress delegated broad, general authority to the Secretary of Labor to regulate the

working conditions that affect the occupational safety and health of the Nationís

employees. OSHA is preempted from exercising its authority under this act if another

Federal agency has been granted statutory authority to regulate the relevant working

conditions and if the other Federal agency has exercised its authority in a manner such as

to exempt the cited working conditions from OSHAís jurisdiction. As an example, vehicle

operators (truckdrivers or train crews) who are regulated by the DOT are not subject to

OSHAís regulations.

25 After July 3, 2000, 1 of the 14 processes was eliminated.
Factual Information 20 Hazardous Materials Accident Report

The Occupational Safety and Health Act of 1970 also gives States an opportunity

to assume responsibility for occupational safety and health standards and enforcement

through the mechanism of an OSHA-approved State plan. Twenty-one States, including

Michigan, have assumed this responsibility for private and public employees.

OSHA regulations are codified in 29 CFR. Section 1910.119 implements the

program designated as the ìprocess safety management of highly hazardous chemicals.î

Section 1910.119 contains requirements for preventing or minimizing the consequences of

catastrophic releases of toxic, reactive, flammable, or explosive chemicals. The OSHA

process safety management program preceded, and was used as a model for, the EPAís risk

management program. Like the EPA, OSHA has certain threshold quantity limits for these

materials, but the EPA and OSHA limits are not identical. In this case, OSHAís threshold

quantity limits are less than the EPAís: OSHA limits are 5,000 pounds for methyl

mercaptan and 1,500 pounds for chlorine.

OSHAís Process Safety Management program emphasizes the management of

risks associated with highly hazardous chemicals. One requirement of the Process Safety

Management program is the development of a process hazard analysis for each plant

process that involves quantities of a hazardous material in excess of the OSHA threshold

quantity limit. Each process hazard analysis must identify potential hazards and propose

recommendations to reduce the potential risks associated with those hazards. OSHA

defines a ìprocessî as follows:

[A]ny activity involving a highly hazardous chemical including any use, storage,

manufacturing, handling, or the on-site movement of such chemicals, or

combination of these activities. For purposes of this definition, any group of

vessels which are interconnected and separate vessels which are located such that

a highly hazardous chemical could be involved in a potential release shall be

considered a single process.

OSHA considers tank cars that transfer product to and from a process to be part of

that process. The Process Safety Management program requirements apply to all

activities, including loading and unloading operations, that are part of a regulated process.

Once completed, the process hazard analysis must be retained at the employerís facility.

Unlike EPA requirements, the analysis does not have to be submitted to either Federal or

State OSHA.

OSHA is authorized to conduct workplace inspections to determine whether

employers are complying with its standards for safe and healthful workplaces. OSHA

safety and health officers perform workplace inspections to ensure compliance. States

with OSHA-approved programs use qualified State officers as inspectors.

Because some 6.2 million workplaces are covered by the Occupational Safety and

Health Act of 1970, which represents a challenge to the agencyís resources, OSHA has

established a system of inspection priorities. First, imminent danger situations are given

top priority. OSHA considers an ìimminent dangerî to be any condition in which there is

reasonable certainty that a danger exists that can be expected to cause death or serious
Factual Information 21 Hazardous Materials Accident Report

physical harm immediately or before the danger can be eliminated through normal

enforcement procedures. Second priority is given to investigation of fatalities and

accidents resulting in the hospitalization of three or more employees. Third priority is

given to employee complaints of alleged violations of standards or unsafe/unhealthy

working conditions and to referrals from other government authorities about specific

workplace hazards. Lastly, programmed inspections aimed at specific high-hazard

industries, workplaces, occupations, health substances, or other industries are considered

and identified in OSHAís current inspection scheduling procedures. Follow-up inspections

may be conducted to determine whether previously cited deficiencies have been corrected.

In Michigan, the responsibility for workplace safety falls to an entity designated

the MIOSHA program office, which is within the Michigan Department of Consumer and

Industry Services, Bureau of Safety and Regulation. The MIOSHA program office has 76

compliance officers who enforce the workplace standards for 4 million employees

working for 200,000 employers in Michigan. MIOSHA conducted 6,874 inspections in

fiscal year 2000.

Within MIOSHA, the General Industry Safety Division is responsible for

overseeing process hazard analysis at chemical plants. This division has two officers

dedicated to compliance at chemical plants and three others who assist with chemical

plant oversight as a part of their duties. In 1993, while establishing a program of chemical

plant oversight, MIOSHA developed a list of the 100 facilities within Michigan that utilize

the largest quantity and/or most dangerous chemicals within their processes. From the list

of 100, each year since 1993, about 10 facilities, on average, have been selected at random

for a scheduled program quality verification audit. This type of audit was developed to

ensure comprehensive and planned compliance inspections in large petrochemical

manufacturing plants with a high potential for catastrophic release. As part of the program

quality verification audit, the OSHA process safety management requirements for selected

plant processes were reviewed. Compliance was determined by reviewing written

programs, observing the process areas, and interviewing management, union, and hourly

personnel. The MIOSHA inspector for this program stated that, as of May 2002,

approximately 85 of the 100 facilities on the 1993 list had been inspected.

According to MIOSHA, the ATOFINA facility in Riverview was the first of the

100 facilities inspected from the 1993 list. ATOFINAís program quality verification audit

began on September 8, 1994. Audit team members were on site on a daily basis at the

Riverview facility through November 2, 1994, and on an intermittent basis until

December 20, 1994. The audit team comprised four MIOSHA inspectors. According to

information provided by MIOSHA, a total of 960 work hours were dedicated to the

inspection. The audit reviewed all processes at the Riverview facility, but only two

processes received in-depth inspections. Process 46 was not one of those two processes.

The audit found that the Riverview facility had a process safety management

program in place but that it contained significant deficiencies. The initial citation

identified 31 ìserious,î 4 ìother than serious,î and 1 ìwillfulî violations. Eighteen of the

serious violations were related to process safety management standards. One of the serious

violations was that reactors, tanks, vent systems, and process piping systems were not
Factual Information 22 Hazardous Materials Accident Report

being inspected or tested as required. Further, the inspection report described the

Riverview facilityís overall mechanical integrity program by stating:

The employer failed to establish and implement a program to inspect and test

process equipment, such as pressure vessels and storage tanks that contained

highly hazardous chemicals, using inspection and test procedures which followed

recognized and generally accepted good engineering practices.

To correct this deficiency, MIOSHA recommended that ATOFINA:

[D]evelop a comprehensive list of process equipment covered by the mechanical

integrity program. The list should include the equipment identity, the inspection or

test reference (such as external and internal visual examination, bench tests,

non-destructive tests, etc.) and an inspection and test schedule. An appropriate

reference document should then exist for each inspection and test to be based on

the consensus standards and codes, industry practice, plant experience or other

reference sources. Inspections and tests must be properly documented as required.

According to the abatement agreement26 submitted by ATOFINA, the company

agreed to ìdevelop written procedures to address mechanical integrity and inspection and

testing of equipment and piping.î ATOFINA also stated that it would ìon or before

November 26, 1997, document that not less than 100 percent of the process equipment

and piping systems regulated by 29 CFR 1910.119 (Process Safety Management

Standard) have been inspected and tested.î MIOSHA conducted no follow-up inspection

to ensure that ATOFINA had corrected the cited violations.

In fulfilling the abatement agreement, ATOFINA developed a mechanical integrity

program. The program required periodic inspections of the wall thickness of plant piping,

including the transfer piping at all of the tank car platforms. The inspection procedures did

not establish specific inspection cycles but stated that inspections should be conducted

ìoftenî where deterioration is ìextremeî and ìseldomî where deterioration is ìminimal.î

The mechanical integrity program also contained procedures relating to the support of

cargo transfer equipment, but these procedures focused on detecting equipment distortion

and broken anchors on plant piping.

Following the July 14, 2001, Riverview accident, MIOSHA inspectors audited

ATOFINA and identified 22 probable violations of OSHA regulations. The enforcement

action was settled on May 1, 2002, without admission of liability. The company paid a

penalty of $500,000 and agreed to provide about $5 million more to make additional plant

improvements to enhance employee safety, to enable local emergency response agencies

to enhance the safety of the local communities, and to perform audits of other ATOFINA

facilities to improve employee safety.

26 MIOSHA defines an abatement agreement as a means of rapidly reducing or eliminating (abating) a

hazard whereby ìan employer who appeals a citation within fifteen working days of receipt of the citation,

who shows good faith to comply with MIOSHA standards, and who cooperated with the department during

the audit may receive a monetary penalty reduction of up to fifty percent,î provided the employer abates the

cited problems, provides proof of the abatement, pays the penalties, and abides by all agreed-upon actions.
Factual Information 23 Hazardous Materials Accident Report

Emergency Preparedness

On March 1, 2000, ATOFINA implemented an extensive general emergency plan

for the Riverview facility that included emergency procedures specific to Process 46. The

purpose of the plan was to minimize hazards to public health or the environment caused

by fires, explosions, or releases of hazardous waste or hazardous waste constituents to the

air, soil, or surface waters. A copy of the emergency plan was given to the Riverview Fire

Department and the fire departments of the surrounding communities, and periodic tours

and training were provided to the Riverview and Wyandotte Fire Departments.

The emergency plan also stated that the plant nurse maintains an open dialogue

with the local hospitals. However, before July 14, 2001, interactions between ATOFINA

and the Riverside Osteopathic Hospital focused on communications pertaining to the

hospitalís treatment of ATOFINA employees injured while working. After the accident,

ATOFINA conducted a presentation for Riverside Osteopathic Hospital staff regarding

chemical exposure, basic toxicology, decontamination, and basic hazardous materials

training and recommended minimum requirements for a hazardous materials room where

victims of hazardous materials accidents could be isolated. The hospital has developed

procedures and identified a room to be used in the event of a future hazardous materials

incident to prevent the type of contamination that occurred in this accident.

Other Information

Postaccident Activities

Since the accident, ATOFINA has made a number of changes to its plant

procedures and equipment to address problems identified during the investigation.

ATOFINAís mechanical integrity/preventive maintenance program now requires that the

cargo unloading apparatus, including the integral piping, be removed from service every 2

years and undergo non-destructive testing to ensure that it is still safe to be used.

ATOFINA has redesigned the unloading apparatus and has added a remotely operated

shutoff valve. Operators are now required to wear SCBAs when working on the methyl

mercaptan tank cars, and they are required to carry an escape hood with an emergency air

supply when in the area of the tank cars. In addition, operators now perform leak tests on

the unloading apparatus before opening the valve to the tank car. To perform the test,

operators attach the apparatus to the tank car, pressurize it with nitrogen gas, and use a

soap solution to visually detect leaks. ATOFINA has also redesigned the transfer

connection to the methyl mercaptan tank cars. The redesigned apparatus consists of a

2-inch-diameter pipe about 1-foot long that is mounted vertically to the loading line valve

on the tank car. A remotely actuated shutoff valve, which is connected to the downstream

end of the 1-foot pipe section, can be closed from multiple locations during an emergency.
Factual Information 24 Hazardous Materials Accident Report

Industry Use of Excess Flow Valves

Following the accident, Safety Board investigators interviewed a sampling of

domestic chemical companies that receive materials in tank cars concerning their use of

excess flow valves. Telephone interviews with personnel responsible for the company risk

management plans required by the EPA and OSHA revealed that six of nine companies

surveyed rely on the tank car excess flow valves as a method of stopping or limiting a leak

in the transfer equipment. Two of the nine companies did not respond to this question, and

the remaining company indicated that it has remotely operated shutoff valves on the

unloading piping just outside the tank car dome.
25 Hazardous Materials Accident Report

Analysis

This analysis is presented in three main parts. In the first part, the Safety Board

identifies factors that can readily be excluded as causal or contributory to the accident. In

the second part, the Board analyzes the causes and factors contributing to the severity of

the accident. In the final part, the Board discusses the safety issues arising from the

investigation:

ï The adequacy of ATOFINAís procedures for unloading tank cars containing

hazardous materials.

ï The adequacy of Federal regulations and oversight for cargo transfer

operations involving bulk containers transporting hazardous materials.

Exclusions

The following issues were examined but were not found to be factors in this

accident: the tank car design, the experience and condition of the personnel involved in the

accident, the failure of the methyl mercaptan sensor on the tank car platform, and the

emergency response. The equipment failures that resulted in the accident occurred in the

unloading apparatus, which were not part of the tank cars, and both tank cars withstood

the fire without catastrophic failure. Both the operators who were working on the tank car

had 14 to 15 years of experience unloading methyl mercaptan from tank cars for use in

Process 46. Evidence suggests that both operators were behaving normally on the night of

the accident, and postaccident drug and alcohol test results were negative. The Safety

Board was concerned that the methyl mercaptan sensor on the platform near the accident

tank car malfunctioned; however, ATOFINA had multiple sensors, and no action that

could have been taken in response to an alarm from the platform sensor would have

prevented the accident or reduced its severity. (See the discussion of the tank carís excess

flow valve.) Since the accident, ATOFINA has replaced the entire alarm system and has

installed additional sensors. The plant emergency response team reacted immediately to

the emergency, the local emergency response agencies arrived within 10 minutes, and both

sets of responders took reasonable measures to prevent the spread of the fire and the

release of other hazardous materials. Additionally, the decision to evacuate local residents

likely prevented their being exposed to the poisonous methyl mercaptan gas. Therefore,

the Safety Board concludes that the tank car design, the experience and condition of the

personnel preparing the methyl mercaptan tank car for unloading, the failure of the methyl

mercaptan sensor on the tank car platform, and the on-scene emergency response were not

factors in the accident.
Analysis 26 Hazardous Materials Accident Report

The Accident

This accident occurred as a result of a broken transfer pipe that allowed poisonous

and flammable methyl mercaptan gas to escape and contaminate the local area. While that

much is known, because neither of the two employees directly involved in this accident

survived, some questions about the events surrounding the accident cannot be answered

with certainty. For example, it could not be determined when during the hookup operation

the fractured pipe failed or what exactly caused it to fail; that is, how force was applied to

the pipe sufficient to cause it to fail. Nor could it be determined why, after the leak was

detected, the tank carís unloading valve was not shut off in time to prevent all three

employees in the area from being overcome by the poison gas. The locations of the three

employees and their specific activities at the time of the accident also could not be

determined.

Despite these uncertainties, enough information about the accident could be

gathered to lead investigators to examine ATOFINAís plant procedures for the inspection,

maintenance, and use of cargo transfer equipment and for the unloading of methyl

mercaptan tank cars. Investigators also examined ATOFINAís procedures and

requirements regarding protective equipment as well as Federal oversight of chemical

transfer activities.

Inspection, Maintenance, and Use of Cargo Transfer Equipment

Metallurgic examination of the failed transfer pipe revealed evidence of

erosion-corrosion resulting in a significant thinning of the pipe wall. The flow of the

liquefied methyl mercaptan through the pipe caused a gradual erosion of the metal. The

erosion was accelerated during each exposure of the interior of the pipe to the weather,

when atmospheric corrosion converted small amounts of the steel to iron oxide (rust).

Subsequent liquid flow during unloading eroded, or swept away, the iron oxide on the

interior of the pipe, revealing clean steel that readily corroded during its next exposure to

the atmosphere. The consequence of such cyclic action is the gradual wearing away of the

interior surface of the pipe wall, which reduces the strength of the pipe.

During use, the failed pipe was subjected to bending forces by the attachment of an

unloading apparatus that weighed about 53 pounds. The Safety Boardís metallurgy staff

estimated that about 175 pounds of additional downward force applied on the outer end of

the apparatus would have resulted in the failure of the pipe; however, this is only an

estimate, and the actual force required may have been different. The Safety Board

concludes that erosion and corrosion had weakened the transfer pipe such that application

of a force such as an individualís falling, leaning, or stepping on the pipe or dropping an

object on it, in combination with the weight of the unloading apparatus, could have caused

the pipe to break and release the methyl mercaptan.

ATOFINAís Process 46 general operating instructions specified that operators

perform a visual, external inspection of transfer piping each time unloading connections
Analysis 27 Hazardous Materials Accident Report

were made to a methyl mercaptan tank car. However, external visual inspections would

not have detected the reduction in wall thickness caused by the erosion-corrosion that led

to the transfer pipe failure in this accident.

ATOFINAís mechanical integrity program included written procedures that

covered the inspection and maintenance of all plant equipment used in the handling of

hazardous materials, including the transfer pipes used to unload hazardous materials from

tank cars. But the inspection procedures under the mechanical integrity program did not

establish specific inspection cycles. Instead, the procedures set out subjective and vague

inspection standards such as ìoftenî when deterioration is ìextremeî and ìseldomî when

deterioration is ìminimal.î

While ATOFINA could not provide data or records to confirm whether or when the

transfer pipe that failed in this accident had last been inspected under the mechanical

integrity program, the erosion-corrosion that was found within the failed pipe indicated

that the program had clearly not been effective. The Safety Board concludes that

ATOFINAís failure to implement effective procedures for inspection and maintenance of

its unloading pipes and fittings allowed the transfer pipe in this accident to gradually

deteriorate and ultimately fail.

Procedures relating to the physical support for cargo transfer equipment while in

use were also included in the mechanical integrity program. The procedures focused on

detection of such factors as equipment distortion and broken anchors on plant piping, but

they did not establish standards to ensure the transfer piping was adequately supported.

Since the accident, ATOFINAís mechanical integrity/preventive maintenance program has

been changed to require that the cargo unloading apparatus, including the integral piping,

be removed from service every 2 years and undergo non-destructive testing to ensure that

it is still safe to be used in the process. ATOFINA has also redesigned the unloading

apparatus to reduce mechanical stress.

ATOFINA Policy Regarding Use of Personal Protection 

Equipment

The fatal injuries to the ATOFINA employees caused by methyl mercaptan

intoxication raised concerns about ATOFINAís procedures for ensuring the safety of its

employees working on or around tank cars containing poisonous gases. None of the

employees was prepared to cope with a serious gas leak. Had they had personal protective

equipment available, they may have been able to close the unloading valve and stem the

flow of gas or, at a minimum, escape the area.

ATOFINAís procedures at the time of this accident did not require that employees

wear SCBAs while performing cargo transfer operations on methyl mercaptan tank cars.

In fact, ATOFINAís procedure for leak-testing the unloading apparatus by having the

operator pressurize it with the methyl mercaptan and attempt to detect the odor of this

poisonous gas actually required the operator to be unprotected to perform the test. This
Analysis 28 Hazardous Materials Accident Report

procedure subjected employees to the risk of injury. In contrast, the companyís procedures

for transfer operations involving tank cars containing chlorinealso a poisonous gasdid

require that operators wear SCBAs.

Because methyl mercaptan, like chlorine gas, is toxic by inhalation, the use of

approved respiratory protection equipment is appropriate to prevent inhalation exposure

that could lead to incapacitation and death. An operator wearing such equipment when the

release occurred would not have been incapacitated and would have had time to escape the

area and/or respond successfully to the emergency. Even an escape hood with an

emergency air supply that can be donned in the event of a sudden and unexpected release

of poisonous gas would have provided sufficient oxygen to permit an individual to escape

the area in the case of such an emergency. Therefore, the Safety Board concludes that the

use of proper personal protective equipment, such as SCBAs or escape hoods, would

likely have allowed the employees in this accident to survive the initial release of methyl

mercaptan and either safely evacuate the area or close the unloading valve and stop the

leak.

Since the accident, ATOFINA has implemented procedures that require operators

to wear SCBAs when making cargo transfer connections to methyl mercaptan tank cars.

ATOFINA has also changed its leak-testing procedures and now tests the tank car

unloading apparatus by pressurizing it with nitrogen gas and using a soap solution to

detect leaks before the unloading valve on the tank car is opened. In addition, all workers

in the area of tank cars containing poison gases must now carry an escape hood with an

emergency air supply.

Reliance on the Tank Carís Excess Flow Valve

Both the EPA and OSHA required ATOFINA to develop and document safety

plans for the Riverview facility that included safeguards intended to reduce the risk and

consequences of catastrophic releases of hazardous materials. ATOFINAís risk

management plan (mandated by the EPA) and process hazard analysis (mandated by

OSHA) included an accident scenario that involved the failure of a flexible hose on the

unloading apparatus for a methyl mercaptan tank cara scenario similar to this accident.

Under both plans, ATOFINA indicated that the release of methyl mercaptan would be

stopped by the automatic closure of the tank carís excess flow valve. Further, ATOFINAís

risk management plans explicitly noted that excess flow valves on the tank car would

activate in the event of a pipeline or unloading hose rupture. However, when the transfer

pipe failed on July 14, 2001, the excess flow valve on the tank car did not close and stop

the release of the methyl mercaptan.

Calculations made by Safety Board engineers and parties to the investigation

indicated that the flow rate of methyl mercaptan through the broken transfer piping was

insufficient to cause the excess flow valve to close. Excess flow valves are designed to

close and stop the release of product from the tank car in the event a tank car valve or

fitting is broken or sheared off during transit. Attaching cargo transfer apparatus to a tank
Analysis 29 Hazardous Materials Accident Report

car can change product release rates and flow rate characteristics and can prevent the

excess flow valve from closing in the event of an emergency. As noted by the Chlorine

Institute in its Chlorine Manual and by the Safety Board in its investigation of a

July 30, 1983, accident at the Formosa Plastics plant in Baton Rouge, Louisiana27 tank car

excess flow valves are not designed to act as an emergency shutoff device during cargo

transfer.28

Therefore, the Safety Board concludes that reliance on tank car excess flow valves

to stop leaks during tank car cargo transfer operations is inappropriate.

To determine whether reliance upon tank car excess flow valves as safety

mechanisms during transfer operations is restricted to ATOFINA or is a broader problem,

Safety Board investigators interviewed a sampling of domestic chemical companies.

Interviews with personnel responsible for company safety plans revealed that six of nine

companies surveyed rely on tank car excess flow valves as a method of stopping or

limiting a leak in the transfer equipment. Only one company reported having remotely

operated shutoff valves on the unloading piping just outside the tank car dome. (The other

two companies did not respond to the Safety Boardís inquiry.) Although the Safety

Boardís sampling was limited, the results suggest that the inappropriate use of tank car

excess flow valves may be a widespread practice in the chemical industry. To address this

issue, the Safety Board believes that the FRA should issue a hazardous materials bulletin

to warn companies involved in tank car loading and unloading operations that tank car

excess flow valves cannot be relied upon to stop leaks that occur during those operations.

The Safety Board further believes that the EPA should notify all facilities that are

required to submit risk management plans to the EPA that tank car excess flow valves

cannot be relied upon to stop leaks that occur during tank car loading and unloading

operations and that those companies that have included reliance on such valves in their

risk management plans should instead identify and implement other measures that will

stop the uncontrolled release of product in the event of a transfer line failure during tank

car loading or unloading.

Federal Oversight of Loading and Unloading Operations

Several Federal agencies, including DOT modal agencies, the EPA, and OSHA,

provide safety oversight for elements of hazardous material bulk container loading and

unloading operations. None of these programs provided the level of oversight necessary to

prevent the Riverview accident.

27 National Transportation Safety Board, Vinyl Chloride Monomer Release From a Railroad Tank Car

and Fire, Formosa Plastics Corporation Plant, Baton Rouge, Louisiana, July 30, 1983, Hazardous Material

Accident Report NTSB/HZM-85/08 (Washington, D.C.: NTSB, 1985).

28 Although excess flow valves are routinely used as safety mechanisms in the piping systems of fixed

facilities, those excess flow valves are designed and constructed for specific piping systems and the

properties of the material flowing through the pipe.
Analysis 30 Hazardous Materials Accident Report

EPA and OSHA

The EPA and OSHA each have multiple program responsibilities mandated by

several statutes. Under the authority of the Clean Air Act and the Occupational Safety and

Health Act, the EPA and OSHA exercise some oversight at chemical plants, which

includes oversight of hazardous materials transfer operations involving tank cars, highway

cargo tanks, and other bulk containers. However, oversight of hazardous materials cargo

transfers is only a minor element of these agenciesí chemical plant oversight programs,

which are themselves elements of still larger programs.

Also, the number of inspectors each agency has assigned to oversee these

operations is limited compared to the number of chemical facilities and plants that fall

under the agenciesí respective programs. The EPA estimates that its risk management

program regulates at least 15,000 facilities within the United States; about 2,800 facilities

are in Region V, which covers a five-State area that includes Michigan. The EPA had only

three inspectors to oversee its risk management program in Region V, and those personnel

had conducted only three inspections between the inception of the program in 1999 and

the 2001 Riverview accident.

Because of the scope of its oversight responsibilities, OHSA delegates some of

those responsibilities to State agencies. MIOSHA, the Michigan agency that has been

delegated to provide OSHA oversight within the State, has only two chemical plant

inspectors for the entire State. Since 1993, MIOSHA inspectors have conducted

approximately 85 plant inspections. Thus, after more than 8 years, the agency has not been

able to inspect all of the 100 facilities that, because of the quantities and types of

chemicals they use, were identified in the 1993 OSHA oversight program plan as the

highest priority plants.

The inspections that EPA and OSHA inspectors must conduct are complicated and

intensive because, according to Federal requirements, each EPA or OSHA inspector is

expected to oversee all plant operations for each of the regulated facilities. With a

chemical plant the size of ATOFINA, this could mean inspecting more than a dozen

processes, each with numerous procedures and employees, and hundreds of pieces of

equipment. Each piece of equipment may be subject to as many as 12 different safety

requirements. For example, the 1994 MIOSHA audit of the ATOFINA Riverview plant

took approximately 960 hours to conduct, yet it covered only 2 of the 14 processes at the

facility in depth. In addition, although 35 violations were noted during the audit (including

ATOFINAís failure to implement a mechanical integrity program for its plant piping

system), MIOSHA conducted no follow-up inspection to ensure that ATOFINA had

corrected the cited violations.

The EPA and OSHA oversight programs have additional weaknesses. For instance,

although the EPA and OSHA both require each facility to develop a written plan that

describes the procedures and mechanisms in place under each safety program, neither

agency routinely evaluates the plans to determine the effectiveness or appropriateness of

the procedures and mechanisms. Also, other than such reviews as take place during the
Analysis 31 Hazardous Materials Accident Report

rare plant inspections, neither agency verifies that the plants comply with the standards

identified in their own plans.

FRA

The FRA has 50 inspectors to determine compliance with the hazardous materials

regulations. Although the single FRA inspector responsible for the State of Michigan has

approximately 90 facilities to oversee, he generally has been able to inspect all of those

facilities annually. In fact, the FRA has inspected the Riverview plant seven times in the

past 6 years. The FRA inspectors are able to perform more frequent inspections than either

the EPA or OSHA because, at least in part, FRA inspections focus on the limited

requirements relating to tank car loading and unloading that are contained in the

hazardous materials regulations. These regulations cover the setting of tank car brakes, the

chocking of wheels, the placing of caution signs on the track, and attendance during

unloading operations. They do not address the inspection, maintenance, and support of

cargo transfer fittings; the development of safe unloading procedures, including leak-test

procedures for fittings; or the use of personal protection equipment by the operators

unloading the tank car.

The Safety Board therefore concludes that effective oversight of hazardous

materials loading and unloading operations from tank cars and other bulk containers is not

provided by the FRA, the EPA, or OSHA.

Previous Safety Recommendations

Over a number of years, the Safety Board has attempted to address the safety

problems associated with hazardous materials loading and unloading operations from bulk

containers by making individual recommendations to the various Federal agenciesó

including the EPA, OSHA, the FRA, RSPA, and the DOTóthat share elements of the

responsibility for providing safety oversight of these operations.

For example, many of the deficiencies with Federal oversight identified during this

investigation are almost identical to the safety issues the Safety Board noted in its report

on the previously referenced accident at the Formosa Plastics plant in Baton Rouge,

Louisiana. That accident involved the release and ignition of a toxic gas from a tank car

during transfer operations at a petrochemical facility. As a result of its investigation, the

Safety Board concluded that contributing to the accident was the fact that Federal

regulations concerning working conditions and the equipment used at the transfer station

were not being enforced at the plant because neither the FRA nor OSHA had inspected the

plant between 1977 and 1983.
Analysis 32 Hazardous Materials Accident Report

As a result of its investigation, the Safety Board issued the following safety

recommendation to RSPA:

R-85-70

Establish safety standards and inspection procedures for loading facilities at

petrochemical plants.

In a March 27, 1987, response to Safety Recommendation R-85-70, RSPA agreed

that further refinements to the regulations pertaining to the operation of safe loading and

unloading facilities would lead to safety improvements at those facilities. RSPA

subsequently provided details on how it intended to specify training requirements for

critical functions relating to the transportation of hazardous materials (including the

loading process) and use safety regulations published by OSHA to develop and implement

specific loading standards and procedures. Based on this information, the Safety Board

determined that this framework met the objective of the recommendation and classified

Safety Recommendation R-85-70 ìClosedóAcceptable Alternate Actionî on

December 20, 1993.

The Safety Board also issued the following safety recommendation to the FRA:

R-85-68

Establish a program to inspect rail loading facilities at petrochemical plants on a

regular basis.

In a March 15, 1989, response to Safety Recommendation R-85-68, the FRA

stated that its hazardous materials inspectors would inspect the entirety of the loading and

unloading areas during their on-site inspections and notify OSHA of any conditions

presenting potential hazards. The FRA stated that its hazardous materials inspectors would

devote 40 percent of their time to inspections at facilities where loading and unloading of

tank cars was conducted. Accordingly, the Safety Board classified Safety

Recommendation R-85-68 ìClosedóAcceptable Actionî on May 21, 1991.

In addition, the Safety Board recommended to OSHA:

R-85-71

Evaluate your ability to conduct inspections of petrochemical plant loading

facilities and your method for establishing inspection priorities for general

inspection and make necessary changes to provide for regular inspection.

In responses to Safety Recommendation R-85-71, OSHA described a ìspecial

emphasisî program for the chemical industry that became effective in November 1985.

OSHA stated that the program would be conducted in areas with the greatest

concentration of petrochemical plants. OSHA also pledged to notify the FRA of any

potential violations of the DOT hazardous materials regulations. Based on these
Analysis 33 Hazardous Materials Accident Report

responses, the Safety Board classified Safety Recommendation R-85-71 ìClosedó

Acceptable Alternate Actionî on September 24, 1986.

Other accidents, including the October 7, 1986, fire on board the Panamanian tank

ship Shoun Vanguard in Deer Park, Texas,29 and the March 6, 1984, release of hazardous

waste acid from a cargo tank truck in Orange County, Florida,30 heightened the Safety

Boardís concerns about the transfer of hazardous materials between and within all modes

of transportation. Because this concern involved several modes of transportation, the

Safety Board issued the following intermodal safety recommendation on March 14, 1988,

to the DOT:

I-88-2

Strengthen minimum safety requirements for loading and unloading of hazardous

materials to provide adequate, uniform safety in all modes of transportation.

In a September 30, 1988, response, the DOT stated that it was examining issues

related to the loading and unloading of hazardous materials at intermodal facilities

through several rulemaking activities, but the DOT did not complete action on most of

these initiatives. After the Safety Board requested an update on the status of its actions, the

DOT indicated in a September 2000 response that it had focused primarily on a proposed

rule under docket HM-223 that would be published within the upcoming fiscal year (FY

2001). According to the DOT, HM-223 would address the applicability of the hazardous

materials regulations to loading, unloading, and storage. The DOT stated that the goal of

the rulemaking under HM-223 was to ìclarifyî the applicability of the hazardous

materials regulations and the jurisdictional relationship between the hazardous materials

regulations and regulations promulgated by the EPA and OSHA. On December 5, 2000,

the Safety Board determined that, although the DOT was undertaking a strategic

realignment of the management of the departmentís hazardous materials program, there

had not been any significant progress on the recommendation in more than 12 years.

Consequently, the Safety Board classified Safety Recommendation I-88-2 ìClosedó

Unacceptable Action.î

On June 14, 2001, RSPA published its NPRM under docket HM-223, Applicability

of Hazardous Materials Regulations to Loading, Unloading, and Storage. Under the

rulemaking, RSPA proposed to limit the definition of ìtransportationî to include only the

period from the moment a carrier accepts a container or package of hazardous materials

until the carrier relinquishes it to the consignee. The proposed rule would thus apply to

loading and unloading operations only if those operations are performed by the carrier.

The Safety Board is concerned that, because the loading of tank cars and other bulk

29 National Transportation Safety Board, Fires on Board the Panamanian Tank Ship Shoun Vanguard

and the U.S. Tank Barge Hollywood 3013, Deer Park, Texas, October 7, 1986, Marine Accident Report

NTSB/MAR-87/08 (Washington, D.C.: NTSB, 1987).

30 National Transportation Safety Board, Release of Hazardous Waste Acid from Cargo Tank Truck,

Orange County, Florida, March 6, 1984, Hazardous Materials Accident Summary Report

NTSB/HZM-85/01 (Washington, D.C.: NTSB, 1985).
Analysis 34 Hazardous Materials Accident Report

containers is typically performed by the offeror before the carrier accepts the vehicle or

bulk container and because unloading is frequently performed by the consignee after the

carrier relinquishes it, these operations would, in most cases, not be covered by the

regulations or be subject to DOT oversight. The Safety Boardís October 29, 2001, letter to

RSPA concerning the NPRM expressed these concerns in detail. (See appendix B.)

The Safety Board believes that hazardous materials cargo loading and unloading

operations deserve more oversight and that therefore the DOT should, with the assistance

of the EPA and OSHA, develop safety requirements that apply to the loading and

unloading of railroad tank cars, highway cargo tanks, and other bulk containers that

address the inspection and maintenance of cargo transfer equipment, emergency shutdown

measures, and personal protection requirements. The Safety Board further believes that

the DOT should, once these safety requirements are adopted, implement an oversight

program to ensure compliance with the requirements.
35 Hazardous Materials Accident Report

Conclusions

Findings

1. The tank car design, the experience and condition of the personnel preparing the

methyl mercaptan tank car for unloading, the failure of the methyl mercaptan sensor

on the tank car platform, and the on-scene emergency response were not factors in the

accident.

2. Erosion and corrosion had weakened the transfer pipe such that application of a force

such as an individualís falling, leaning, or stepping on the pipe or dropping an object

on it, in combination with the weight of the unloading apparatus, could have caused

the pipe to break and release the methyl mercaptan.

3. ATOFINAís failure to implement effective procedures for inspection and maintenance

of its unloading pipes and fittings allowed the transfer pipe in this accident to

gradually deteriorate and ultimately fail.

4. The use of proper personal protective equipment, such as self-contained breathing

apparatus or escape hoods, would likely have allowed the employees in this accident

to survive the initial release of methyl mercaptan and either safely evacuate the area

or close the unloading valve and stop the leak.

5. Reliance on tank car excess flow valves to stop leaks during tank car cargo transfer

operations is inappropriate.

6. Effective oversight of hazardous materials loading and unloading operations from

tank cars and other bulk containers is not provided by the Federal Railroad

Administration, the Environmental Protection Agency, or the Occupational Safety

and Health Administration.

Probable Cause

The National Transportation Safety Board determines that the probable cause of

the accident involving the release of methyl mercaptan from a tank car at the ATOFINA

Chemicals, Inc., plant in Riverview, Michigan, was a fractured cargo transfer pipe that

resulted from (1) the failure of ATOFINA to adequately inspect and maintain its cargo

transfer equipment, and (2) inadequate Federal oversight of unloading operations

involving hazardous materials. Contributing to the accident were ATOFINAís reliance on

a tank car excess flow valve to close in the event of a leak from cargo transfer equipment

and the companyís failure to require appropriate safety equipment for employees involved

in tank car loading and unloading operations.
36 Hazardous Materials Accident Report

Recommendations

As a result of its investigation of the July 14, 2001, accident at Riverview,

Michigan, the National Transportation Safety Board makes the following safety

recommendations:

To the U.S. Department of Transportation:

Develop, with the assistance of the Environmental Protection Agency and

the Occupational Safety and Health Administration, safety requirements

that apply to the loading and unloading of railroad tank cars, highway

cargo tanks, and other bulk containers that address the inspection and

maintenance of cargo transfer equipment, emergency shutdown measures,

and personal protection requirements. (I-02-1)

Implement, after the adoption of safety requirements developed in response

to Safety Recommendation I-02-1, an oversight program to ensure

compliance with these requirements. (I-02-2)

To the Federal Railroad Administration:

Issue a hazardous materials bulletin to warn companies involved in tank

car loading and unloading operations that tank car excess flow valves

cannot be relied upon to stop leaks that occur during those operations.

(R-02-16)

To the Occupational Safety and Health Administration:

Assist the U.S. Department of Transportation in developing safety

requirements that apply to the loading and unloading of railroad tank cars,

highway cargo tanks, and other bulk containers that address personal

protection requirements, emergency shutdown measures, and the

inspection and maintenance of cargo transfer equipment. (I-02-3)

To the Environmental Protection Agency:

Assist the U.S. Department of Transportation in developing safety

requirements that apply to the loading and unloading of railroad tank cars,

highway cargo tanks, and other bulk containers that address personal

protection requirements, emergency shutdown measures, and the

inspection and maintenance of cargo transfer equipment. (I-02-4)
37 Hazardous Materials Accident Report

Notify all facilities that are required to submit risk management plans to

the Environmental Protection Agency that tank car excess flow valves

cannot be relied upon to stop leaks that occur during tank car loading and

unloading operations and that those companies that have included reliance

on such valves in their risk management plans should instead identify and

implement other measures that will stop the uncontrolled release of product

in the event of a transfer line failure during tank car loading or unloading.

(R-02-17)

BY THE NATIONAL TRANSPORTATION SAFETY BOARD

MARION C. BLAKEY

Chairman

CAROL J. CARMODY

Vice Chairman

JOHN A. HAMMERSCHMIDT

Member 

JOHN J. GOGLIA

Member

GEORGE W. BLACK, JR.

Member

Adopted: June 26, 2002

Recommendations

39 Hazardous Materials Accident Report

Appendix A

Investigation and Hearing

The National Transportation Safety Board was notified of the accident about

8:05 a.m., eastern daylight time, on July 14, 2001. A full go-team was dispatched from

Washington, D.C., to Riverview, Michigan. No Board Member went with the team.

Investigative groups were established for hazardous materials, survival factors, human

performance, railroad, and metallurgy.

Parties to the investigation were the Federal Railroad Administration; the

Environmental Protection Agency; the City of Riverview, Michigan; ATOFINA

Chemicals, Inc.; Union Tank Car Company; Midland Valve Company; and the Canadian

National/Illinois Central Railroad.

The Safety Board did not conduct a public hearing during this investigation.
40 Hazardous Materials Accident Report

Appendix B

NTSB Response to NPRM Docket HM-223
Appendix B 41 Hazardous Materials Accident Report



	 





 
 	 




  

	
 




	




	








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