TITLE:

ES&H Manual

 

DOCUMENT ID:

6150 Compressed Gases

 

 

1.0            Introduction

 

Jefferson Lab uses a variety of gases for fuels, research activities, refrigerants, fire-suppression agents, and other applications.  All of these gases are stored in a compressed or pressurized state.  Some are stored under extreme pressure.  All are capable of causing catastrophic property damage, personal injury, and death if they are not handled properly.

 

Compressed or liquefied gases that are in regular use at Jefferson Lab include the following:

 

 

These gases are enclosed in a variety of containers: small and large cylinders, tanks, dewars, and distribution piping systems.  Tank trucks make bulk deliveries of nitrogen and helium.

 

Text Box: NOTE: Compressed gases are regulated by an array of federal regulations, national and local codes, and industry standards. The applicability of these is often specific to the gas and operations in question. Jefferson Lab does not have the facilities nor the qualified staff to perform all of these operations. It is important for us to stay within our capabilities and procure special gas products and services when they are needed.

 

This chapter discusses the various gases used on site, how they are stored, and the general precautions that are necessary to prevent injury or property damage.  Other related chapters:

 

ES&H Manual Chapter 6152 Storage/Use of Flammable Gases addresses the special situations and work practices associated with target gases and other physics research applications.

 

ES&H Manual Chapter 6500 Cryogenic and ODH Safety provides additional information on helium and nitrogen gas systems.

 

Welding and cutting fuel gases are discussed in ES&H Manual Chapter 6122 Welding, Cutting, Brazing, and Grinding.

 

Pressure vessel design and procedures are covered in ES&H Manual Chapter 6151 Pressure Systems.

 

2.0            Key Terms

 

ASME American Society of Mechanical Engineers

compressed (or pressurized) gas Any gas enclosed in a container at a pressure higher than 40 psia at 68°F (20°C); also any flammable liquid enclosed in a container with a vapor pressure of 40 psia or higher at 100°F (37.8°C).

DOT U.S. Department of Transportation

flammable gas Any gas or gas mixture that will ignite in a 13% or lower concentration with air at 14.7 psia and 68°F.

lecture bottle A small, compressed gas cylinder, typically less than 10 liters gas volume (this does not include dewars, used for cryogenic fluids).

OSP/SOP/TOSP Operational Safety Procedure/Standard Operating Procedure/Temporary Operational Safety Procedure—work control documents.

Oxidizer A chemical that readily yields oxygen or that vigorously promotes oxidation reactions or combustion.

pressure-relief valve A calibrated, spring-loaded valve that will vent a container's contents if safe pressure is exceeded.  (Some gas containers use a rupture disc or a blow-out plug to relieve excessive pressure.)

psia/psi psi is an abbreviation for the “unit” pound-force per square inch, and psia is an abbreviation for a “property.”  In this case it is the pressure (“a” stands for absolute) at a given point in a medium expressed in units of psi.

transfill The transfer of compressed gas and/or cryogenic liquid from one portable container to another or from a bulk-storage vessel to a portable container.

 

3.0            Hazard Avoidance

 

3.1              Compressed gases can maim and kill!

Potential hazards include explosions, fires, asphyxiation, skin burns or tissue freezing, and violent motion if containers are damaged.  Do not attempt to use compressed gases unless you are trained and authorized to do so.

 

If you are trained and qualified, you must observe some essential precautions:

 

·         Never heat a compressed-gas container.

·         Never alter a container's pressure-relief vent system.

·         Never strike, damage, weld, or attempt to repair a compressed-gas container.

·         Never move a compressed-gas cylinder without its protective cap in place.

·         Never expose oils, greases, or other combustible materials to oxygen.  Never use oxygen to pressure-test a container or piping system.

·         Never perform work on a gas piping system without first isolating, blanking, and bleeding the system.  Refer to ES&H Manual Chapter 6110 Lock, Tag, Try (LTT) Policy. Do not cut or weld on a piping system unless these precautions are in place and you are certified to weld on pressure systems.

·         Make gas mixtures only in accordance with SOPs, OSPs, or other work control documents.

·         Do not refill (transfill) DOT-regulated gas containers.[1]

·         Use gases only for approved purposes.

·         Keep compressed gas containers out of confined spaces and other poorly ventilated areas.

·         Always store and handle gas containers according to Lab procedures: Work-control documents such as OSPs, SOPs, and ESH&Q Manual chapters.  Always:

o   Segregate flammable gases from oxidizers with approved fire barriers or at least 20 feet of distance

o   Secure gas cylinders with a chain or suitable strap and in an upright position.

 

Report damage to gas containers, valves, or piping to the appropriate line supervisor immediately, this may be a stop-work condition.

 

4.0            Process Steps or Expectations

 

Individual users or “owners” of compressed gases

 

Supervisors/Sponsors/SOTRs

 

Division ESH&Q staff

 

5.0            Procedures and Practices

 

In addition to the requirements in this chapter, all compressed gases on site at Jefferson Lab must be used and handled in accordance with the material safety data sheet (MSDS) information.  Also, the Compressed Gas Association publishes useful information and reference materials that are usually available through the gas supplier.

 

Specific practices for welding and cryogenic gases are described in their respective ESH&Q Manual chapters.  All other high-hazard (flammable, oxidizer, toxic, etc.) compressed gases may be used only under the conditions described in an approved work-control document (SOP, OSP, TOSP).  The development of these procedures is the responsibility of the operational group using the gases.

 

5.1              Container and system labeling

·      Label each compressed-gas cylinder, vessel, and piping system with the name of its contents.

·      Use conspicuous means such as tear-off tags to indicate whether gas cylinders are full, partially empty or empty.

·      If there are hazards with incompatible materials, describe these by suitable warning signs on or near the gas container.

 

 

5.2              Storage and handling

·         Do not store compressed gases near heat sources or in unventilated areas such as storage trailers and closets, or anywhere the temperature exceeds 125°F (52° C).

·         Store combustible or flammable gases at least 20 ft (6 m) from oxygen cylinders and other oxidizing chemicals, or separate them by a fire-rated partition.

·         Store bulk quantities of gases outside buildings, well away from building ventilation intakes.  Request guidance from your division ESH&Q staff on maximum quantities of compressed gases allowed in your work area.

·         Never store a flammable gas container in an unventilated cabinet.

·         Except when part of an apparatus specifically designed for the purpose, all cylinders in use shall be upright and secured with straps, chains, or other means to prevent tipping.  If cylinders of various sizes are stored together, ensure there are provisions for securing all of them.

·         Always store fuel-gas cylinders in an upright position.

·         Use special racks or cradles whenever moving gas containers by crane, forklift, or truck.  The containers must be upright and secured by chains or straps in the racks, and the protective caps must be in place.

·         Other compressed gas cylinders should also be stored upright.  In certain temporary or transient situations, or where upright storage is impractical, cylinders may be stored horizontally if they are secured to prevent rolling.  Be alert to extra hazards such as dropping cylinders while moving them from vertical to horizontal.

·         Label all storage areas for compressed gases as to contents, and identify empty and full cylinder storage racks with signs.  Individual cylinders or tanks must be labeled as to contents and important precautions.

·         Cylinder storage areas should be well drained to prevent bottom corrosion.

·         Gas cylinders will cause bone-crushing foot injuries if dropped.  Wear safety footwear when you are moving cylinders.

 

5.3              Transporting compressed gas cylinders

·         Use a gas cylinder hand truck (with securing strap or chain) to move individual containers to and from storage or in-service locations.  Do not roll or “walk” cylinders across the floor.

·         Use special racks or cradles whenever moving gas containers by crane, forklift, or truck.  The containers must be upright and well secured by chains or straps in the racks, and the protective caps must be in place.  Assume the cylinders will be subject to the forces of a vehicle collision.

·         Gas cylinders must be secured by chains or straps whenever the protective caps are removed.

 

5.4              Use of compressed gases

·         Do not use flammable or combustible gases near a source of ignition.  Be aware of a gas's tendency to rise or fall in air.  Heavy gases may “crawl” along the floor and reach a distant ignition source.  Refer to the MSDS for this information.

·         Do not use toxic or poisonous gases (chlorine, for example) unless you are equipped with suitable personal protective equipment, and you are specifically trained in proper handling techniques.

·         Never use a pressure regulator or piping system on a gas for which it was not made.  Do not modify cylinder fittings, regulators, or pressure-relief devices.  Do not use a damaged or defective regulator; tag it and remove it from service immediately.

·         When connecting regulators or piping to the cylinder valve, direct the opening away from your face and others in the vicinity, and wear eye protection while doing this.  Open the cylinder valve slowly.

·        Inspect gas cylinder before use.-Ensure it is the product you think it is.  Do not rely on cylinder color; look for labels.  Do not use a gas container if you cannot be certain of its contents.

o   Look for any serious damage to the container: cracks, dents, arc burns, excessive corrosion.

o   In warm-weather months, be alert to the possibility of wasp nests within cylinder caps – especially cylinders stored outdoors.

o   Look for foreign matter on the valve or cap threads.  Be especially alert to oil or grease on oxygen cylinders.

o   Check the valve threads for damage, and remove any debris before connecting the regulator.

 

·         Nozzles used for compressed air must have integral pressure-limiting features that reduce output pressure to 30 psi or less.  Do not use “shop-made” blower nozzles.

·         Close cylinder and manifold valves when they are not in active use.

 

5.5              Container refill (Transfilling)

·         Most gas products used on site are delivered by the supplier or by motor freight.  Do not transfill compressed gases unless the process has been specifically authorized by a work-control document.  (This does not apply to cryogenic liquids handled in accordance with the appropriate procedures.)

·         Propane tanks used for industrial trucks and powered lift platforms are refilled by local vendors, and they must be appropriately transported to and from the vendor.  These tanks must be transported in the designated enclosed rack secured in an approved vehicle.  For more information, contact the Jefferson Lab Material Handling Safety Representative (ext. 7406).

 

5.6              Container disposal

·         Most compressed gas containers must be returned to the supplier to be refilled.  Many have a required cash deposit.  Do not discard any refillable gas container.

·         Containers that are clearly labeled as disposable must be emptied completely of their contents and left open to the atmosphere.  If you are unsure what to do with a container (empty or not), contact your division ESH&Q staff for assistance.

·         Containers that cannot be returned to the supplier, and that contain hazardous substances, must be disposed as hazardous waste.  Refer to ES&H Manual Chapter 6761 Hazardous Waste Management.

 

5.7              Manifolds and gas distribution systems

Compressed gas piping must be labeled for its contents at regular intervals.  Use the ANSI Standard A13.1 for color schemes and other marking techniques.  Consult with your ESH&Q staff for this information.

 

Text Box: NOTE: Distribution systems for flammable gases will likely have additional requirements specific to the gas and the system location. Materials and components must be of an approved type. These systems also may have significant implications for building fire protection and occupant life safety. Consult with ESH&Q staff, Facilities Management, and other subject-matter experts before procuring or designing such systems.

 

5.8              Special situations

·         There are threshold quantities of certain gases (hydrogen, for example) that we cannot exceed without implementing major engineering measures and special handling techniques.

·         There are also gases which are extremely toxic or reactive and that may pose unacceptable risks.  Toxic gases usually must be stored in dedicated enclosures vented to the outdoors.  Consult with division ESH&Q staff before introducing any new toxic gases into the workplace—even small volumes like “lecture bottles”.

·         Compressed gases create serious additional hazards in poorly ventilated areas and confined spaces.  Do not use gases in these areas without first consulting with division ESH&Q staff.  Refer to ES&H Manual Chapter 6160 Confined Space Entry.

 

5.9              Environmental protection

·         Certain gases are atmospheric pollutants that must not be released into the air, or only under specific, controlled conditions.  Examples include many chlorofluorocarbon refrigerants, certain fire suppression agents, and some solvents.  The MSDS will usually have this information.

·         If you have any of these products, consult with your ESH&Q staff on proper handling and disposal.  Refer to ES&H Manual Chapter 6720 Outdoor Air Quality Management Program for additional information.

 

 

 

ISSUING AUTHORITY

CHAPTER AUTHOR

APPROVAL DATE

EFFECTIVE DATE

EXPIRATION DATE

REV.

 

 

 

ESH&Q Division

Jennifer Williams

02/01/06

02/01/06

02/01/09

0

 

This document is controlled as an on line file.  It may be printed but the print copy is not a controlled document.  It is the user’s responsibility to ensure that the document is the same revision as the current on line file.  This copy was printed on 8/14/2009.


[1] This does not apply to the proper use of approved refrigerant-reclamation.