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 and regulations 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.
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  and 29 CFR 1910.119, Process Safety Management (PSM) standard. 
The purpose of this Safety and Health Information Bulletin (SHIB) is to increase awareness about:
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.
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." 
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." 
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.
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:
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 pull- away incidents. The North Dakota regulation now includes the following provisions in section 7-12-01-05.3:
Figure 1 shows a transfer system with the protection devices identified in the North Dakota regulation and recommended in the ANSI standard:
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.
In addition to provisions that 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.
Work Practices and Equipment Design
Personal Protective and Other Equipment
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 pull- away. 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.
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