Compressed gases construction materials

Pneumatic testing involves the hazard of released energy stored in compressed gas. Particular care must therefore be taken to minimize the chance of brittle failure during a pneumatic leak test. Test temperature is important in this regard and must be considered when the designer chooses the material of construction. See para. IP-10.6.2(b)(3) and Nonmandatory Appendix B. 

Section 4.2 consolidates the requirements for on-site transport of specific materials, including compressed gas cylinders, cryogenic liquid containers, and acetylene cylinders. This section covers such subjects as cylinder construction, labeling/marking, securing and lifting, and protection caps. 

Compressed gas in pressure vessels New materials have allowed pressure vessels and storage tanks to be constructed that can store hydrogen at extremely high pressures. 

Rupture disk devices installed on compressed gas cylinders may either be an integral part of the cylinder valve assembly or may be installed on the cylinder as an independent attachment. To minimize corrosion, the materials of construction selected must be compatible with the contents of the cylinder, as well as the cylinder valve materials with which the rupture disk device comes in contact. 

Requirements for stamp marking a portable compressed gas container are in the Hazardous Materials Regulations of the DOT and the regulations of Transport Canada (TC) [1, 2]. Such containers are constructed in accordance with a particular specification of the recognized authority. Depending on the particular type of container under consideration and the country, the recognized authorities may include DOT, TC, CSA, or the American Society of Mechanical Engineers (ASME), which publishes the ASME Boiler and Pressure Vessel Code [5]. 

Retest periods may vary depending upon use, material of construction, and the cylinder specification. Many steel cylinders must be retested every five years. DOT and TC regulations allow for Specification 3A and 3AA cylinders to be retested every 10 years provided the cylinder meets the regulatory criteria in 49 CFR 173.34, which are summarized in CGA P-15, Filling of Industrial and Medical Nonflammable Compressed Gas Cylinders [1] and [23] Aluminum cylinders must be retested every five years and fiber-reinforced high pressure cylinders every three years. 

If a fire occurs in a building, the occupants should be evacuated promptly and safely. Other emergencies requiring prompt evacuation are chemical spills and leaking compressed gas cyhnders. Obstruction to passageways can create serious hazards in case of fire, explosion, loss of light, or other emergency situations. Corridors are specifically constructed to retard the spread of fire and to provide a protective envelope to allow people to evacuate therefore, flammable materials should not be stored in corridors. 

Materials of construction depend on the metallurgical requirements and pressure of the gas being compressed hut usually the more popular materials include cast iron, cast steel, alloy steel, or forged steel (high pressure). Figure 12-42 illustrates the extent of damage internally when materials of construction are not resistant to possible effects of internal corrosion. 

CNF is an industrially produced derivative of carbon formed by the decomposition and graphitization of rich organic carbon polymers (Fig. 14.3). The most common precursor is polyacrylonitrile (PAN), as it yields high tensile and compressive strength fibers that have high resistance to corrosion, creep and fatigue. For these reasons, the fibers are widely used in the automotive and aerospace industries [1], Carbon fiber is an important ingredient of carbon composite materials, which are used in fuel cell construction, particularly in gas-diffusion layers where the fibers are woven to form a type of carbon cloth. 

Thermodynamic exergy analyses of gas-turbine cycles show that the major losses occur neither during the compression of air nor during the expansion of hot combustion products, but rather during the combustion reactions. Main reasons for these losses stem from the peak temperature limitations imposed by the materials of construction, coupled with the very high thermodynamic quality of the fuel source. 

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