Monday, May 6

Compressed Gas

Compressed gases can be toxic, flammable, oxidizing, corrosive, or inert.  In the event of a leak, inert gases can quickly displace air in a large area creating an oxygen-deficient atmosphere. Toxic gases can create poison atmospheres. Flammable or reactive gases can result in fire and exploding cylinders.  In addition, there are hazards from the pressure of the gas and the physical weight of the cylinder.  A gas cylinder falling over can break containers and crush feet.  The cylinder can itself become a missile if the cylinder valve is broken off. This week, we will talk about safe handling of compressed gas containers and safe use of compressed gas in our operations.

What is a compressed gas?

A compressed gas is a substance that is a gas at normal room temperature and pressure and is contained in a cylinder when under pressure.  Some compressed gases (i.e. Acetylene) are stabilized in the cylinder by dissolving the gas in a liquid or solid matrix. Compressed gas cylinders are used in many applications in the workplace.  Oxygen and acetylene cylinders are very common since they are used for welding and cutting operations. However, there are other types of welding that require the use of other gases, such as helium and argon.  Laboratories and R&D departments may require the use of various exotic or specialty gases as well.

“Compressed gas” means:

• A gas or mixture of gases having, in a container, an absolute pressure exceeding 40 psi at 70°F (21.1°C); or
• A gas or mixture of gases having, in a container, an absolute pressure exceeding 104 psi at 130°F (54.4°C); or
• A liquid having a vapor pressure exceeding 40 psi at 100°F (37.8°C) as determined by ASTM D-323-72
   

Main causes of incidents with compressed gas

• Inadequate training/supervision
• Poor installation
• Poor maintenance
• Faulty equipment and/or design (i.e. bad fittings or regulators)
• Poor handling
• Poor storage
   

Inadequately ventilated working conditions

Tuesday, May 7

Receiving Compressed Gas

If your facility uses compressed gas cylinders, it’s a good bet that outside vendors deliver full tanks and retrieve empty ones.  For the most part, these companies are well aware of the hazards associated with handling compressed gases and take the necessary precautions to protect their employees and customers.  However, in a given month, thousands of compressed gas cylinders are handled and pumped into storage tanks so it’s reasonable to expect a defect or two.  This is why we the customers must take the time to follow safety steps when receiving or surrendering cylinders:

• Perform a visual inspection of the cylinders.                                   
  • Dents, cracks, deep rust?
  • Leaks: do you hear gas escaping (hissing noise)?
  • Valve cap installed; valve undamaged?
  • Identifying label for the gas inside?  Reject unidentified gas.
• Do not rely on color to identify the gas, use the label.
• Make sure it’s the gas you need.  If not, reject it.
• Note the hydrostatic test date. 
  • Most cylinders should be tested every 5 years

• If a cylinder is damaged in your possession, segregate and label accordingly, then inform the vendor.
   

Wednesday, May 8

Compressed Gas Cylinder Storage

As you go through this list, identify any deficiencies in your work space and storage area.

DO:

• Store gas cylinders on concrete in an open or fenced area with weather protection.
• Store oxygen at least 10 feet (3 meters) from fuel gases, or separate them with a fire wall at least 6 feet high (2 meters).
• Store full and empty cylinders separately.  Use signs to designate those storage areas.
• Ensure ease of access into and around the storage area.
• Secure and properly restrain cylinders with straps or chains connected to a wall bracket on a fixed surface.
• Clearly label cylinders to show contents and associated hazards.
• Store all cylinders upright and secure on a level surface to prevent them from falling.
• Post appropriate “Warning” and “Danger” signs around perimeter of storage area.

DO NOT:

• Store extra cylinders.  Only keep what you need.
• Store other materials, such as flammable or corrosive liquids, or sources of ignition, with gas cylinders.
• Allow storage temperatures to exceed 125°F (52°C).
• Permit smoking or open flames in gas storage areas.
• Expose cylinders to corrosive materials such as ice melting compounds.
   

Thursday, May 9

Compressed Gas Handling

DO:

• Understand all of the hazards associated with the material and how to use it safely.  Consult the Safety Data Sheet (SDS).
• Move cylinders using a suitable hand truck or cart.
• Leave the valve protection cap and valve seal outlet in place until the cylinder is secured in place and ready for use.
• Secure cylinder when in storage, transit, or use.
• Ensure cylinder is not giving off odors or hissing sounds.
• Use in well-ventilated areas.
• When returning cylinders to the vendor, properly close the cylinder valve, replace and secure any valve outlet seals, and properly install the cylinder cap.
• Use a cylinder cage or cradle to lift a cylinder.

DO NOT:

• Drag, slide, or drop cylinders or allow them to strike one another.
• Subject cylinders to mechanical shocks that may cause damage to their valves.
• Use cylinders as rollers for moving materials or other equipment.
• Tamper with pressure-relief devices.
• Permit oil, grease, or other readily combustible substances to come in contact with cylinders, valves, or other equipment in oxidizer service.
• Remove any product labels or shipping hazard labels.
• Refill compressed gas cylinders. 
• Lift a cylinder by its cap using a sling or a magnet.
• Attempt to catch a falling cylinder.
• Use homemade adaptors or force connections between cylinder valve and gas handling equipment.
   

Open a damaged valve.

Friday, May 10

Discussion

Who would think those little fire extinguishers, mounted on the walls, could be deadly?  A fire extinguisher is, in fact, a compressed gas cylinder that can turn into an exploding bomb if stored or handled improperly.  No matter how large or small the cylinder, any misuse or mishandling can be deadly.  Even empty tanks can be dangerous. 

Are there other examples of compressed gas in your facility that could pose a hazard?  Use this morning to discuss any possibilities.

Tags: safety topics , industrial hygiene , osha compliance ,