U. S. Department of Labor

Occupational Safety and Health Administration

Directorate of Science, Technology & Medicine

Office of Science and Technology Assessment

SHIB 12/05/05

Safety and Health Information Bulletin

This Safety and Health Information Bulletin

is not a standard or regulation, and it creates

no new legal obligations. The Bulletin is

advisory in nature, informational in content,

and is intended to assist employers in

providing a safe and healthful workplace.

Pursuant to the Occupational Safety and

Health Act, employers must comply with

hazard-specific safety and health standards

promulgated by OSHA or by a state with an

OSHA-approved state plan. In addition,

pursuant to Section 5(a)(1), the General

Duty Clause of the Act, employers must

provide their employees with a workplace

free from recognized hazards likely to cause

death or serious physical harm. Employers

can be cited for violating the General Duty

Clause if there is a recognized hazard and

they do not take reasonable steps to prevent

or abate the hazard. However, failure to

implement any recommendations in this

Safety and Health Information Bulletin is not,

in itself, a violation of the General Duty

Clause. Citations can only be based on

standards, regulations, and the General Duty

Clause.

Preface

Recent fatalities during releases at anhydrous

ammonia loading stations illustrate the potential

hazards associated with transfer operations if the

transfer system is not adequately protected from hose

severance or an inadvertent pull-away during transfer.

Anhydrous ammonia storage facilities and nurse tank

loading stations are considered anhydrous ammonia

systems and are covered by a variety of Federal,

State, and consensus standards. The most recent

American National Standards Institute (ANSI)

standard for storage and handling of anhydrous

ammonia (K61.1 – 1999) and several State

regulations include provisions that specifically address

hose severance and pull-away protection. This

Safety and Health Information Bulletin highlights these

provisions and illustrates their use in complying with

existing Federal Occupational Safety and Health

Administration (OSHA) standards that cover

anhydrous ammonia systems. These standards

include 29 CFR 1910.111, Storage and handling of

anhydrous ammonia [1] and 29 CFR 1910.119,

Process Safety Management (PSM) standard. [2]

Purpose

• examples of devices, work practices, and

training that employers and employees can

use to eliminate or reduce the likelihood of

these incidents.

The purpose of this Safety and Health Information

Bulletin (SHIB) is to increase awareness about:

• the potential for an uncontrolled anhydrous

ammonia release during transfer operations at

loading stations and other anhydrous

ammonia systems/processes without certain

safety mechanisms, and

Preventing the Uncontrolled Release of Anhydrous

Ammonia at Loading Stations
2

Background

OSHA’s Bismarck, North Dakota Area Office

recently investigated an anhydrous ammonia release at

a loading station in a grain handling facility. The

release occurred when an employee pulled a nurse

tank away from a fixed storage installation with

transfer hoses still attached. Because the loading

risers were not equipped with excess flow valves to

limit the uncontrolled release of anhydrous ammonia,

approximately four (4) tons of anhydrous ammonia

were released. As a result of the release, a grain

facility employee driving the truck and a customer

were hospitalized. The customer died while in the

hospital.

Applicable OSHA Standards

The loading station involved in the investigation

and other systems where anhydrous ammonia is used

or stored are covered by OSHA’s Storage and

handling of anhydrous ammonia standard (29 CFR

1910.111) provided they are not ammonia

manufacturing plants or refrigeration plants where

ammonia is used solely as a refrigerant. If the system

contains more than 10,000 pounds (lbs.) of anhydrous

ammonia it would be covered by OSHA’s Process

Safety Management (PSM)standard (29 CFR

1910.119). Although the loading station investigated

was not part of a larger system or process and it did

not involve sufficient anhydrous ammonia to be

covered by PSM, many similar facilities may be

covered by 29 CFR 1910.119 depending on the

amount of anhydrous ammonia contained in the

process.

OSHA’s Storage and handling of anhydrous

ammonia standard generally requires that all transfer

systems include certain types of protective devices.

Paragraph (b)(12)(vii) states:

“Loading and unloading systems shall be

protected by suitable devices to prevent the emptying

of the storage containers in the event of severance of

the hose. Backflow check valves or properly sized

excess flow valves shall be installed where necessary

to provide such protection. In the event that such

valves are not practical, remotely operated shutoff

valves may be installed.” [1]

As a performance standard, 29 CFR

1910.111(b)(12)(vii) does not state where the devices

must be installed, only that once installed the devices

will prevent the emptying of a container if hose

severance should occur.

OSHA’s Process Safety Management standard

includes several general requirements that pertain to

transfer system equipment. Paragraphs (d)(3)(ii) and

(iii) state:

“The employer shall document that equipment

complies with recognized and generally accepted

good engineering practices.

For existing equipment designed and constructed

in accordance with codes, standards, or practices that

are no longer in general use, the employer shall

determine and document that the equipment is

designed, maintained, inspected, tested, and operating

in a safe manner.” [2]

The employer must first identify the “recognized

and generally accepted good engineering practices”

and then ensure that his/her equipment is compliant.

“Recognized and generally accepted good engineering

practices” can include Federal, State or local

government requirements, national consensus codes

and standards such as ANSI K61.1, recommended

practices from trade associations such as the

American Petroleum Institute (API), Center for

Chemical Process Safety (CCSP) guidelines,

corporate/facility standards/policies, insurance

company reports, and others. If the system was built

under an older code, then the employer must

determine the best way to document that it still

operates safely. Even if the transfer system is not a

PSM-covered “process,” the requirements in the

PSM standard and the recommendations in this SHIB

can assist the employer in effectively managing and

implementing measures that will protect employees

during transfer operations at all anhydrous ammonia

systems, including loading stations.
3

Other Standards

North Dakota and many other States have

adopted ANSI K61.1 (1989 or 1999). The most

recent version of ANSI K61.1 (1999) and the North

Dakota regulations (as amended in 2004) include

language that may be useful to employers in

understanding and complying with 29 CFR 1910.111.

These standards may also need to be evaluated by

employers as “recognized and generally accepted

good engineering practices” for compliance with 29

CFR 1910.119. ANSI K61.1 (1999) includes

general provisions for the protection of all covered

systems in Section 5.10 Basic Rules, Transfer of

Liquids. The provisions in 5.10.8 include:

• Suitable back-flow check valves in loading

lines for non-refrigerated containers.

• Suitable in-line excess flow valve in unloading

lines for non-refrigerated containers.

• Pipe sizing that does not restrict flow rates.

• Emergency shutoff or backflow check valves

in liquid and vapor fixed piping of transfer

system within 5 ft. or a reasonable distance

from where hose/swivel piping is attached to

fixed piping (stationary storage systems >

4000 gal.). Installed so that a break due to

pull-away will occur on hose or swivel type

piping side (not fixed piping side). This may

be accomplished by using a bulkhead or

equivalent anchorage, or by using breakaway/

shear fittings.

• Emergency shutoff valve with manually

activated shutoff from a remote location and at

the installed location. [3]

These provisions address hose severance and provide

protection for other system/process components

during pull-away incidents.

In response to the incident in Bismark, the North

Dakota Department of Agriculture modified the State

regulation so that it would include clear provisions for

protective systems to prevent releases from severance

of hoses and other system components during pullaway incidents. The North Dakota regulation now

includes the following provisions in section 7-12-01-

05.3:

• Approved bulkheads or breakaways, or both

at nurse tank fill stations. Emergency shutoff

valves must be in place in liquid and vapor

piping before the bulkhead or breakaway, or

both. Approved cables must be connected to

the emergency shutoff valves and these cables

can be activated both at the valves and at a

remote location. Breakaway action will close

the valves.

• Approved bulkheads and breakaways at

truck unloading stations. Emergency shutoff

valve on the vapor piping on system side of

the bulkhead and a back-check valve installed

on the liquid piping on the system side of the

bulkhead. Approved cables must be

connected to the emergency shutoff valve and

these cables must be activated both at the

valve and at a remote location.

• Excess flow protection for nurse tank filling

station risers:

• For facilities using bulkheads with

emergency shutoff valves below the

bulkhead – install the required excess

flow valves integral with the riser shutoff

valves or as in-line excess flow valves.

An approved installed location cable must

be used between the emergency shutoff

valve actuator and the riser shutoff valve.

• For facilities using breakaway devices

with positive closure – install excess flow

valve integral with the riser shutoff valve

or as approved in-line excess flow valve

installed prior to the positive closure

device.

• Installer must verify operation of any

excess valve covered. [4]
Other States that identify similar types of protection

include Illinois and Minnesota. [6,7]

Figure 1 shows a transfer system with the

protection devices identified in the North Dakota

regulation and recommended in the ANSI standard:

• excess flow valves are located in the “riser”

integral with shutoff.

• risers are anchored through a bulkhead and

have emergency shutoff valves below the

bulkhead.

• a location cable runs between the emergency

shutoff valve actuator and the riser shutoff

valve.

The excess flow valve protects against the

emptying of the storage tank if the hose is severed.

During a severance, the pressure differential would

result in a release from the tank through the piping.

If the flow in the pipe exceeds a predetermined

level, the valve is triggered and will automatically

close. The piping around the excess flow valve

must be large enough to ensure that the valve will

close when needed. A smaller diameter pipe will

provide more resistance to the flow, potentially

reducing the flow rate below the actuation rate of

the valve. The diameter of the pipe and the excess

flow valve must be matched accordingly. The

bulkhead provides protection to the risers during a

pull-away, and the cable ensures that the emergency

shutoff is triggered if the top portion of the riser is

dislodged or severed during a pull-away.

Figure 2 shows an example of a loading platform

from bulk storage. Nurse tanks can be loaded from

both sides of the platform simultaneously.

Figure 3 shows a breakaway device that may be

used in place of the protection offered by the

bulkhead and location cable. It is a quick release

device that uncouples during a pull-way to protect the

hoses and risers. The breakaway device includes

double backflow check valves to minimize the release

of anhydrous ammonia when it breaks away. It is not

sensitive to the direction of the pull-way and is similar

to the device used on pumps at gas stations.

4

Bulkhead 

Riser 

Excess 

Flow 

Valves 

Emergency 

Shut-off 

Valves 

Cable to 

Shut-off 

Figure 1 

Figure 3

Figure 2
In addition to provisionsthat specifically address

protective devices, OSHA and ANSI standards, and

the North Dakota regulation identify work practices

and protective equipment for use during transfer

operations, equipment for use on vehicles transporting

anhydrous ammonia, and training that can provide

additional protection for workers conducting transfer

operations at loading stations and other anhydrous

ammonia systems/processes.

Recommendations

• Determine if the loading station or other anhydrous

ammonia system is covered by the PSM standard.

If it is, then many of the following recommendations are also required under the PSM standard.

[2] If not, implementing the following recommendations will provide additional protection to

workers during anhydrous ammonia transfer

operations.

Protective Devices

• Identify appropriate “recognized and generally

accepted good engineering practices” that address

protection for hose severance and vehicle pullaway. Several alternatives are described in the

Other Standards section of this SHIB, above.

[2]

• Based on selected and documented “recognized

and generally accepted good engineering

practices,” evaluate, select, and install a

combination of protective devices that protect the

entire system, including the risers, during pullaway incidents. Several alternatives are described

in the Other Standards section of this SHIB,

above.

Work Practices and Equipment Design

• Document the applicable codes and standards

used for equipment in the process, including the

transfer station equipment. This is one of the first

steps in managing the equipment integrity of the

process. [2]

• Document that the equipment in the loading station

and other areas of the process comply with

applicable “recognized and generally accepted

good engineering practices.” [2]

• Conduct a process hazard analysis and identify,

evaluate, and control the hazards associated with

the entire system/process. [2]

• Develop written operating procedures that include

step-by-step procedures for transfer and a

checklist that must be completed for each transfer.

These should be used during training to establish

competency (see, training requirement, below). [2,

9]

• Inspect, test, and maintain all system/process

equipment, including the protective devices

installed to prevent releases during hose severance

and pull-away incidents. Include this information

in the written standard operating procedures. [2]

• Ensure that an attendant is physically present

throughout the entire transfer operation. Assure

that a qualified operator, experienced in the

procedures, is present from the time the

connections are first made until they are finally

disconnected. [1, 3, 4, 9]

• Chock/block all vehicles involved in transfer

operations; make removing the chock/block the

last step when shutting down operations and

getting ready to allow a vehicle to pull away.

[1,3,4]

• Require that the attendant conduct a walk-around

inspection once transfer is completed. Attendant

should walk around tanks and storage containers

and ensure that hosing has been uncoupled and

secured and that all steps of the transfer operation

are complete. [4]

• Manage any changes in the system/process to

ensure that any new hazards introduced by the

changes are identified, evaluated and controlled.

Also, any subsequent changes to the process will

then have documentation showing the history of

the equipment which evaluators can use to

5
determine the technical basis for subsequent

changes and the safety and health impacts of those

changes. [2]

• Develop and implement an emergency action plan

for the facility and include procedures for handling

small releases. The requirements of this type of

plan are detailed in OSHA’s Emergency Action

Plansstandard 29 CFR 1910.38 and Hazardous

Waste Operations and Emergency Response

(HAZWOPER) standard 29 CFR 1910.120. [2]

• Perform a pre-start-up safety review for new and

modified facilities to assure that the design and

construction is in accord with the design

specifications. Note: The design specifications

should comply with “recognized and generally

accepted good engineering practices.” [2]

• Check and inspect to assure that the equipment in

the process, including the transfer station, are

installed properly and consistent with design

specifications and the manufacturer’s

recommendations. [2]

• The PSM standard includes other elements related

to mechanical integrity, incident investigation, and

compliance audits that should be reviewed and

implemented as necessary. These elements are

mandatory for systems that are covered by the

PSM standard. [2]

Personal Protective and Other Equipment

• Select and provide personal protective equipment

that will adequately protect employees during

routine transfer operations and anticipated

emergencies. At a minimum, the following should

be easily accessible during an emergency: gloves,

protective slicker or protective pants and jacket

(impervious to ammonia); goggles and/or face

shield; and full-face respiratory protection with

appropriate cartridges. A Self-Contained

Breathing Apparatus (SCBA) may be required if

there is potential for entry into an atmosphere that

contains ammonia concentrations in excess of the

immediately dangerous to life or health (IDLH)

value. [1,3,4]

• Install, inspect, and maintain easily accessible

emergency shower and plumbed eyewash or at

least 150 gal. of clean water in an open top

container. [1,3]

Training

• Provide initial training to any person required to

handle, transfer, transport, or otherwise work with

ammonia in the system/process. Training should

enable the employees to understand the hazards of

the process, properties of ammonia and the

system/process, become competent in safe

operating practices, and to take appropriate

actions during an incident. [2,3,4,9]

• Conduct refresher training annually. [3,4]

Conclusion

As illustrated by the investigation in Bismark, even

though OSHA requires that employers provide

suitable protection from anhydrous ammonia releases

due to hose severance, the Agency still continues to

investigate serious accidents involving these types of

releases. In addition to the requirements identified by

OSHA in 29 CFR 1910.111 and 29 CFR 1910.119,

the ANSI K61.1 standard and the recently revised

North Dakota Anhydrous Ammonia regulation identify

additional steps that employers can take to provide

protection during hose severance and vehicle pullaway. Employers are encouraged to review these and

other applicable standards, install the protective

devices recommended, develop and implement

appropriate work practices, and provide the training

identified to ensure that employees are protected

during transfer operations.

References/Resources

1. Occupational Safety and Health

Administration. 29 CFR 1910.111, Storage and

Handling of Anhydrous Ammonia. http://

www.osha.gov/pls/oshaweb/

owadisp.show_document?p_table=STANDARDS&p_id=9757

6
7

2. Occupational Safety and Health Administration.

29 CFR 1910.119, Process Safety Management

(PSM). http://www.osha.gov/pls/oshaweb/

owadisp.show_document?p_table=STANDARDS&p_id=9760

3. American National Standards Institute. ANSI

K61.1 “American National Standard Safety

Requirements for the Storage and Handling of

Anhydrous Ammonia.” Arlington, VA: Compressed

Gas Association. 1999.

4. North Dakota Department of Agriculture.

Anhydrous Ammonia Regulation, Chapter 7-12-01,

Anhydrous Ammonia Standard. http://

www.agdepartment.com/PDFFiles/AARULESREGS-Amended10-2004.pdf [PDF, 37KB]

5. Occupational Safety and Health Administration.

“Recommendation for Issuance of a National Hazard

Alert on Anhydrous Ammonia (NH3

) Operations.”

Memorandum. September 5, 1980.

6. Illinois Department of Agriculture, “Anhydrous

Ammonia, Equipment, Containers, and Storage

Facilities” (Part 215). http://www.agr.state.il.us/Laws/

Regs/nitrogen.pdf [PDF, 606KB]

7. Minnesota Department of Agriculture,

Application for Permit to Install Anhydrous Ammonia

Storage. http://www.mda.state.mn.us/appd/nh3/

instructions.htm

8. OSHA’s online Ammonia Refrigeration e-Tool:

Plant Safety - Self Inspection Checklist. http://

www.osha.gov/SLTC/etools/ammonia_refrigeration/

safety/plant_safety.html. Though refrigeration plants

where ammonia is used solely as a refrigerant are not

covered under 29 CFR 1910.111, this checklist is a

useful summary of the types of emergency equipment

and placarding that should be present for anhydrous

ammonia systems.

9. Department of Transportation (DOT) HM225A: Transportation and Unloading of Liquefied

Compressed Gases. http://hazmat.dot.gov/regs/rules/

final/97_2718_4.htm

10. Environmental Protection Agency. 40 CFR

Part 68, Accidental Release Prevention Requirements:

Risk Management Programs Under the Clean Air Act,

Section 112(r)(7). http://yosemite.epa.gov/oswer/

ceppoweb.nsf/content/caa112r.htm#Regulation

11. Environmental Protection Agency. General

Guidance for Risk Management Programs (40 CFR

Part 68). http://yosemite.epa.gov/oswer/

ceppoweb.nsf/content/EPAguidance.htm

12. Environmental Protection Agency. Guidance

for Implementation of the General Duty Clause: Clean

Air Act Section 112(r). http://yosemite.epa.gov/

oswer/ceppoweb.nsf/vwResourcesByFilename/

gdcregionalguidance.pdf/$File/

gdcregionalguidance.pdf [PDF 367KB]