Compressed Gas Cylinder Safety

Contents

• Introduction
• Notice Summary
• Applicability
• Definitions
• Events Summary
• Significance of Events
• Lessons Learned and Recommendations
• Cylinder Storage
• Special Gases
• Final Evaluation
• Regulations and Guidelines
• References
• Notices Previously Issued

Introduction

This notice is one in a series of publications issued by the Office of Nuclear and Facility Safety to share nuclear safety information throughout the Department of Energy complex. For more information, contact Richard L. Trevillian, Office of Operating Experience Analysis and Feedback, Office of Nuclear and Facility Safety, U.S. Department of Energy, Washington, DC 20585, telephone (301) 903-3074. This Safety Notice should be processed as an external source of lessons- learned information as described in DOE-STD-7501-95, Development of DOE Lessons-Learned Programs.

Safety Notices are distributed to U.S. Department of Energy Program Offices, Field Offices, and contractors who have responsibility for the operation and maintenance of nuclear and related facilities, and to other organizations involved in nuclear safety. Written requests to be added to or deleted from the distribution of Safety Notices should be sent to: Christine Crow, RPI, 20251 Century Blvd., Germantown, MD 20874 or by fax, (301) 540-2499.

The ESH Office of Information Management maintains a file of Safety Notices and supporting information. Copies can be obtained by contacting the Office of Information Management at (301) 903-0449 or by writing to the Office of Information Management, U.S. Department of Energy, EH-72/Suite 100, CXXI/3, Washington, DC 20585.

Notice Summary

This Notice describes events at Department of Energy (DOE) facilities involving compressed gas cylinders. These events resulted in injuries to employees, damage to equipment, and adversely affected facility operations. The causes and significance of the events are described along with corrective actions and lessons learned.

Applicability

This Notice applies to DOE facilities that use, store, or transport cylinders containing compressed gases. The Notice should be processed as an external source of lessons-learned information as described in DOE-STD-7501-95.⁽¹⁾ The Office of Nuclear and Facility Safety encourages DOE managers to examine their cylinder safety procedures, emergency plans, and safety analyses in light of this information.

Definitions

Compressed Gas — Material or mixture that is in a cylinder with a pressure exceeding 40 psia at 70 degrees Fahrenheit; or, regardless of pressure at 70 degrees Fahrenheit, with an absolute pressure exceeding 104 psi at 130 degrees Fahrenheit; or flammable liquid with a vapor pressure exceeding 40 psia at 100 degrees Fahrenheit as determined by American Society for Testing and Materials Test D-323-94.⁽²⁾

Compressed Gas Association — Association formed in 1913 and dedicated to developing and promoting safety standards and safe practices in the industrial gas industry; composed of more than 200 companies.

Compressed Gas Cylinder — Container with a maximum water capacity of 1,000 pounds that meets the shape, size, and material of construction and design standards of the American Society of Mechanical Engineers and the Department of Transportation.

Corrosive Gas — Gas that deteriorates living tissue or cylinder system components by chemical action.

Flammable Gas — Gas that when mixed with air in a concentration of 13 percent or less by volume forms a flammable mixture; or has a flammable range with air wider than 12 percent regardless of the lower limit.

Toxic Gas — Compressed gas that has a median lethal concentration in air of more than 200 and less than 2,000 parts per million by volume of gas; or vapor that is lethal when continuously inhaled for an hour by albino rats weighing between 200 and 300 grams.

Highly Toxic Gas — Compressed gas with a median lethal concentration in air of 200 parts per million or less by volume of gas; or vapor that is lethal when continuously inhaled for an hour by albino rats weighing between 200 and 300 grams.

Pressure Regulator — Mechanical device that is used to control discharge pressure of compressed gas from a cylinder.

Pressure Relief Device — Pressure- or temperature-activated device that prevents pressure from rising above a predetermined maximum to preclude rupture of a normally charged cylinder.

Valve Protection Cap — Device that is attached to the neck ring or body of a cylinder to protect the cylinder valve from damage if the cylinder falls or is struck.

Events Summary

Operating Experience Analysis and Feedback engineers reviewed the Occurrence Reporting and Processing System (ORPS) data base and found 203 reports related to compressed gas cylinders. Most of these events can be classified in the following categories.

• High-energy hazards
• Breathing-air hazards
• Hazardous and corrosive gases
• Radiological contamination

High-Energy Hazards

On September 20, 1995, at the Oak Ridge Y-12 site, a 100-pound-capacity cylinder containing carbon dioxide discharged its contents and became airborne after two fire department workers incorrectly manipulated a discharge-valve, hand-lever attachment. The cylinder narrowly missed the workers as it was propelled out of the storage enclosure. The cylinder hit a paved parking area and traveled an additional 30 feet before striking an inclined concrete ramp.⁽³⁾

The workers were examining the cylinder assembly in preparation for dismantling a fire suppression system. Investigators determined that the event was caused by inadequate planning for the removal of an obsolete fire suppression system, the workers' general lack of knowledge regarding the design of the cylinder discharge valve, and the worker's failure to notice that the cylinder was inadequately restrained.

Corrective actions included the following.

• Y-12 Fire Department personnel developed procedures for uniform systematic evaluation of maintenance activities.
• Y-12 Fire Department personnel developed a process to ensure that the building shift manager reviews all work conducted on the fire protection and suppression systems.

On May 7, 1993, at Los Alamos National Laboratory, office employees smelled gas coming from a propane storage area. Two employees went to investigate and heard an intermittent hissing noise coming from one of eight 100-pound propane storage cylinders. They tried to remove the valve protection cap to determine if the shut-off valve was fully closed. In the process, the valve protection cap vented, and a stream of liquefied petroleum gas sprayed from the two openings on the valve protection cap and struck both employees on their forearms. They were treated for minor, first-degree cold burns and released. Following the incident, the Los Alamos Hazardous Materials Team took the cylinder to an isolated area and vented the excess pressure.⁽⁴⁾

Investigators determined that the propane tank had been overfilled by an off-site vendor, and, when the cylinder was exposed to the sun, the propane was released through the relief valve. The cylinders were not stored in accordance with the administrative procedure that required hazardous gas to be in a dry, cool, well-ventilated area and protected from direct sunlight.

Corrective actions included the following.

• Laboratory inspectors toured the vendor facilities and discussed the event with vendor personnel including their responsibility to check for cylinder overfilling and leaks.
• The Laboratory receiving procedure was revised to require inspections of incoming cylinders for overfill and damage.
• The cylinder storage area was modified to block direct sunlight.

Breathing-Air Hazards

On May 2, 1994, at the Hanford T-Plant, four employees were exposed to unknown fumes from breathing air supplied by a contaminated cylinder as they repackaged drums of soil. The contaminated cylinder of compressed air was a replacement from a supply station for an exhausted cylinder of breathing air. As the employees began to breath air from the replacement cylinder, they became light-headed and nauseated.⁽⁵⁾

Investigators cut the cylinder open and found a residue coating along with areas of rust. The odor was offensive. Corrective actions included replacing breathing-air cylinders older than 20 years and implementing a sniff test of breathing-air cylinders for offensive odors before use.

Hazardous and Corrosive Gases

On March 13, 1996, four employees at the Ames Laboratory were exposed to hydrogen sulfide fumes when a regulator connected to a cylinder assembly leaked. A researcher, attempting to transfer the gas to a flow rate column, opened the valve to the cylinder when the regulator relief device leaked. He tried to close the valve with a wrench, then placed the cylinder inside a walk-in hood. After closing the hood sash, the researcher lost consciousness and slumped to the floor. A second researcher pulled him out of the area. Two others were exposed to the fumes while providing assistance.⁽⁶⁾

Investigators postulated that a spring in the regulator relief device was damaged by stress-induced corrosion from pressure on the spring and the corrosive properties of hydrogen sulfide gas.

On April 15, 1994, 40 people were exposed to chlorine gas at the Argonne National Laboratory—West when a Plant Services custodian attempted to remove a cylinder from service. Because he was not properly trained on cylinder operations, he did not close the cylinder valve before disconnecting the yoke and regulator. As he started to remove the screw securing the yoke to the cylinder, the seal broke, releasing chlorine gas. The cylinder leaked until a member of the Hazardous Material Team closed the cylinder valve approximately 41 minutes later. The custodian and 39 others were exposed to the gas, and 900 people were evacuated from the area. Investigators determined that about 20 pounds of chlorine were released to the atmosphere.^(7),(8),(9)

A Type A Accident Investigation Board found that the custodian had no specific training for disconnecting the cylinder. Also, there was no written, approved procedure. The Board also determined there was neither a system safety analysis nor a specific task safety analysis for the operation.

Corrective actions for this event included training Plant Services personnel on operating and maintenance procedures and on hazards associated with chlorine. Also, an administrative limit of 170 pounds was established to limit the maximum quantity of chlorine on site.

Radiological Contamination

On April 8, 1993, at the Los Alamos National Laboratory, two technicians in the Plutonium Process and Handling facility were working on a storage drum when one technician accidentally dropped an oil can on an assembly connecting two tritium/argon gas cylinders. The can struck a fitting, loosening it and allowing gas to escape. Technicians tightened the fitting approximately one minute later. The technicians were internally exposed, and tritium was released to the environment.^(10),(11)

Corrective actions for this event included counseling the careless technician on attention to detail when working with radioactive materials or contaminated equipment. Guidelines on working with tritium operations were updated, and emergency procedures for evacuation of personnel were added.

Significance of Events

Because gas cylinders are so commonly used, workers tend to overlook the hazards. The Computerized Accident Information Reporting System (CAIRS) data base lists 155 cylinder accidents with a cost to DOE in excess of $2.5 million. A review of the accidents indicates a downward trend in cost and number of accidents since 1990 (figure 1).

Figure 1. Number and Cost of Compressed Gas Cylinder Accidents

Following is a list of some of the more common hazards of using compressed gas cylinders.

• Practically all gases, including inert gases, can act as simple asphyxiants by displacing oxygen in the air. Some gases also have a toxic effect on the human system either through inhalation or high vapor concentrations. Also, liquefied gas can be toxic on contact with the skin or eyes.
• Flammable gases present the potential for fire or explosion.
• Cylinders that rupture can result in injury or damage by becoming airborne or by forcefully ejecting contents.
• Because cylinders can be large, heavy, bulky, and difficult to handle, they can cause injury by falling or rolling on personnel. Approximately 80 percent of the injuries listed in the CAIRS data base are caused by lifting, maneuvering, or transporting cylinders.
• Because cylinders are often needed for cutting, welding, or respiratory protection, workers are usually allowed to transport them to most areas of a facility. These areas may have safety-related equipment and instrumentation. In many cases, the components were designed to have redundant instruments in separate control cabinets and spatial separation of redundant cable trays. Compressed gas cylinder missiles have sufficient force to traverse this spatial separation and damage redundant safety channels and equipment.

Lessons Learned and Recommendations

Most cylinder events are avoidable. Only 16 percent of the cylinder-related events listed in ORPS involved equipment or material problems, and almost half occurred during normal operations or activities. Approximately 13 percent involved cylinders that were contaminated or caused contamination. Figure 2 shows a breakdown by nature of occurrences.

Figure 2. Gas Cylinder Events Nature of Occurrence

The most frequent root cause of these events was attributed to management issues (36 percent). Figure 3 shows a breakdown of root causes.

Figure 3. Root Causes of Gas Cylinder Events

The following measures are recommended to prevent cylinder events.

Cylinder Descriptions and Labels

• Labels applied by gas manufacturers to identify cylinder contents should not be defaced or removed.
• Prescribed stamped markings on cylinders should be legible and maintained. Users should not remove or alter prescribed markings. Cylinders with illegible markings should not be used.
• The primary identifier of cylinder contents is the label. Color should not be used to identify contents.

Cylinder Storage

• The cylinder storage area should be dry, well ventilated, and of fire-resistant construction. Area temperatures should not exceed 125 degrees Fahrenheit. Cylinders should not be stored where other objects may strike or fall on them or near highly ignitable substances such as gasoline. Cylinders should not be exposed to corrosive chemicals or fumes.
• Storage areas should be designed to accommodate various gases required by the user. Adequate spacing or segregation should be provided to allow cylinders to be grouped by the hazard class of the contents.
• Cylinders should not be placed where they may contact energized equipment or become part of an electrical circuit.
• Cylinders should not be exposed to extreme temperatures.
• Empty cylinders should be segregated from full ones.
• Stored cylinders should be secured to prevent falling.
• Liquefied-gas cylinders should be stored and used with the valve end up, so the pressure-relief device remains in contact with the gas phase as designed.
• "No Smoking" signs should be placed near flammable gas cylinders. Fire-suppression equipment using carbon dioxide or dry chemicals should be available. Spark-proof tools should be used when working with flammable gas cylinders.
• Areas where corrosive gases are filled or used should be equipped with emergency showers and eye-wash fountains.

Cylinder Use

• Cylinder valves should be opened slowly. Valves that are hard to open or frozen because of corrosion should not be forced. The cylinder valve should be closed except when the cylinder is in use.
• Cylinders must be retested in accordance with the requirements of 49 CFR.34.⁽¹²⁾
• Users should keep valve protection caps on containers except when cylinders are secured or connected to dispensing equipment.
• Only trained personnel should handle compressed gases.
• If a cylinder is contaminated or suspected to be so, it should be removed from service and identified as contaminated, and the vendor should be informed.
• Large cylinders should be transported on a cylinder hand-truck. Rolling or "walking" cylinders is extremely hazardous. Always protect the valve during transport and when not in use by installing the valve cover.

Special Gases

• Compressed oxygen, while not combustible itself, will cause some materials to burn violently. Never use grease, cleaning solvents, or other flammable material on an oxygen valve, regulator, or piping.
• Only steel or wrought iron pipe should be used with systems carrying acetylene gas because, under certain conditions, acetylene forms explosive acetylide compounds when in contact with copper, silver, or mercury.
• Critical components in corrosive or toxic gas systems should be inspected at regular intervals as determined by analysis and service use.
• Facilities where cylinders containing toxic, corrosive, or highly toxic gases are used should have a prepared emergency response plan that defines emergency response procedures and specified responsibilities for emergencies involving particular gases.

Final Evaluation

A review of the CAIRS database indicates that gas cylinder accidents have cost DOE over $2.5 million since 1984. This figure does not include costs associated with program corrective actions, such as training, procedure enhancements, and hazards analysis.

Hazards associated with compressed gas cylinders at DOE facilities are similar to those encountered in industrial plants. However, because many DOE facilities contain nuclear material, there is an extra concern that the cylinders do not become a secondary nuclear hazard.

Compressed gas cylinder safety should be an integral part of a facility safety program. Elements of cylinder safety should be included in the safety manual. Employees using, manipulating, or transporting cylinders should be trained in cylinder safety and operation.

Potential industrial, process, or operational hazards associated with compressed gas cylinders should be analyzed to define the risks posed to personnel and the environment. This should include identification and implementation through emergency plans and normal operational procedures.

Regulations and Guidelines

The following documents apply to compressed gas cylinders used at DOE facilities.

· Department of Energy — DOE O 440.1⁽¹³⁾ requires a written worker-protection program that provides a place of employment free of recognized hazards and cites Occupational Safety and Health Administration (OSHA) regulations. Attachment 1, section 6, provides requirements for a pressure-safety program.

· DOE 5480.23⁽¹⁴⁾ establishes the requirements for contractors responsible for design, construction, operation decontamination, or decommissioning of nuclear facilities to develop safety analyses that establish and evaluate the adequacy of the safety bases of the facilities.

· Department of Transportation — Interstate transportation of compressed gas cylinders is regulated by 49 CFR 100 to 179.⁽¹⁵⁾ These regulations refer to Compressed Gas Association CGA P-1-1991 for transportation of compressed gas cylinders.

· Occupational Safety and Health Administration — Employee safety is governed by the Department of Labor. Marking, storage, labeling, and handling are governed by OSHA regulations as stated in 29 CFR 1910.⁽¹⁶⁾ The requirements of 29 CFR 1910.101,⁽¹⁷⁾ state that in-plant handling, storage, and use of compressed gases in cylinders shall comply with Compressed Gas Association CGA P-1-1991.⁽¹⁸⁾

Additional Information

Additional information on compressed gas cylinder safety can be found in the Handbook of Compressed Gases⁽¹⁹⁾ and the Guide to Safe Handling of Compressed Gases.⁽²⁰⁾

References

1. DOE-STD-7501-95, Development of DOE Lessons-Learned Programs
2. American Society for Testing and Materials (ASTM), D-323
3. ORPS Report ORO--MMES-Y12SITE-1995-0025
4. ORPS Report ALO-LA-LANL-SERVICESS-1993-0014
5. ORPS Report RL--WHC-TPLANT-1994-0012
6. ORPS Report CH--AMES-AMES-1996-0001
7. Type A Accident Investigation Report - Argonne National Laboratory West Site - Release of Chlorine Gas, April 15, 1994
8. OE Weekly 95-21
9. ORPS Report CH-AA-ANLW-ANLW-1994-0004
10. OE Weekly 93-15
11. ORPS Report ALO-LA-LANL-TA55-1993-0009
12. Code of Federal Regulations 49 CFR 173.304, Qualification, Maintenance and Use of Cylinders
13. DOE O 440.1, Worker Protection Management For DOE Federal and Contractor Employees,
14. DOE 5480.23, Nuclear Safety Analysis Reports
15. Code of Federal Regulations 49 CFR 100-170, Transportation
16. Code of Federal Regulations 29 CFR 1910, General Industry
17. Code of Federal Regulations 29 CFR 1910.101,
18. Compressed Gas Association, CGA P-1 -1991 Safe Handling of Compressed Gases in Containers
19. Handbook of Compressed Gases, Third Edition, Compressed Gas Association, Arlington, VA, Van Nostrand Reinhold, NY 1990
20. Guide to Safe Handling of Compressed Gasses, Third Printing, Matheson Products, Inc, 1983

Notices Previously Issued

• Technical Notice 94-01, "Guidelines For Valves in Tritium Service," September 1994.
• Safety Notice 91-1, "Criticality Safety Moderator Hazards," September 1991.
• Safety Notice 92-1, "Criticality Safety Hazards Associated With Large Vessels," February 1992.
• Safety Notice 92-2, "Radiation Streaming at Hot Cells," August 1992.
• Safety Notice 92-3, "Explosion Hazards of Uranium-Zirconium Alloys," August 1992.
• Safety Notice 92-4, "Facility Logs and Records," September 1992.
• Safety Notice 92-5, "Discharge of Fire Water Into a Critical Mass Lab," October 1992.
• Safety Notice 92-6, "Estimated Critical Positions (ECPs)," November 1992.
• Safety Notice 93-1, "Fire, Explosion, and High-Pressure Hazards Associated with Drums and Containers," February 1993.
• Safety Notice 93-02, "Control of Temporary Modifications," September 1993.
• Safety Notice 94-01, "Contamination of Emergency Diesel Generator Fuel Supplies," July 1994.
• Safety Notice 94-02, "High-Efficiency Particulate Air Filters," August 1994.
• Safety Notice 94-03, "Events Involving Undetected Spread of Contamination," September 1994.
• Safety Notice 94-04, "Uninterruptible Power Supplies," November 1994.
• Safety Notice 95-01, "Decision Analysis Techniques," August 1995.
• Safety Notice 95-02, "Independent Verification and Self- Checking," September 1995.
• Safety Notice 95-03, "Lessons Learned Programs," October 1995.
• Safety Notice 95-04, "Post-Maintenance Test Programs," December 1995.
• Safety Notice 95-05, "Department of Transportation Non- Conformances by Vendor Shippers," December 1995.
• Safety Notice 96-01, "Chemical Spills During Loading," April 1996.
• Safety Notice No. 96-02, "Risk-Based Analysis of Electrical Hazard," May 1996.