Introduction
Hydrogen is a colorless, odorless, tasteless,highly flammable gas. It is also the lightest weight gas. Since hydrogen is noncorrosive, special materials of construction are not usually required. The American Society of Mechanical Engineers (ASME) code and the American National Standards Institute (ANSI) Pressure Piping code specify vessel and piping design requirements for the pressures and temperatures involved. Applicable Dangerous Goods regulations specify requirements for vessels used for transportation.
Flammability
The wide flammability range, 4% to 75% in air, and the small amount of energy required for ignition necessitate special handling to prevent the inadvertent mixing of hydrogen with air. Sources of ignition such as sparks from electrical equipment, static electricity, open flames, or extremely hot objects should be eliminated. Hydrogen and air mixtures within the flammable range can explode and may burn with an almost invisible flame.
Manufacture
Hydrogen is produced primarily by the steam reforming of natural gas.
The steam reforming process produces syngas, which is a mixture of hydrogen and carbon monoxide. The product stream is separated into its components and the hydrogen is dried, purified, and compressed into cylinders, pipelines or tubes for transportation.
Uses
Hydrogen is used in manufacturing processes for producing petroleum, steel, chemicals, foods and electronics. Refineries use hydrogen to produce cleaner burning gasoline and low sulfur diesel fuel, helping to reduce air pollution.
In the metallurgical industry, hydrogen is used to reduce metal oxides and prevent oxidation when heat-treating certain metals and alloys. It is also used as a fuel in alternative energy vehicles and may be used when welding and cutting metals. Hydrogen is also used by semiconductor manufacturers, primarily to form reducing atmospheres, and it is used in the chemical industry to synthesize ammonia and methanol.
Health
Hydrogen gas is odorless and nontoxic but may induce suffocation by diluting the concentration of oxygen in air below levels necessary to support life. The amount of hydrogen gas necessary to produce oxygen-deficient atmospheres is well within the flammable range, making fire and explosion the primary hazards associated with hydrogen and air atmospheres.
Containers
Gaseous hydrogen may be supplied in cylinders or in tubes that are designed and manufactured according to applicable codes and specifications for the pressures and temperatures involved. The pressure rating and internal volume of a container determines the quantity of hydrogen it can hold. Cylinders may be used individually or can be manifolded together to allow for a larger gas storage volume.
Tubes are mounted on truck-trailer chassis or in ISO frames for transportation and are referred to as tube trailers or tube modules, respectively. Stationary tube (also called hydril tube) modules store large quantities of hydrogen at customer location.
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