Equation 6.3.1.1 in CGA S1.3 is based on modeling to API methods described in: Heitner, T. Trautmauis, and M. Morrissey, “Relieving Requirements for Gas Filled Vessels Exposed to Fire,” 1983 Proceedings-Refining Department, Volume 62, American Petroleum Institute, Washington, D.C., pp. 112-122.

This method considers the transient nature of the vessel warming in combination with the…

An annual inspection of safety devices is recommended. Testing requirements will be based on the type of device and a quantified risk analysis. Typical replacement or function testing of relief valves is between 5 and 10 years depending on the application within the industrial gas industry. Rupture discs are not tested but are frequently replaced on an interval based on manufacturer…

Based on the question, it’s not clear if the reference to stress corrosion cracking (SCC) has been proven or is only suspected. It can be difficult to identify the nature of the cracks (SCC vs H2 embrittlement without analysis and microscopy). In addition, the question does not mention that the cylinders contain hydrogen gas, but it’s assumed since it was submitted to the Panel. 

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It depends on the service. Variables include disk design, corrosion resistance, number of cycles, and how to close the operating pressure is to the rupture disc set pressure. One approach is to ask the manufacturer for their recommendation. Typical practice for U.S. Department of Transportation vessels and discs is to replace them at the tube requalification (i.e., every 5 to 10 years in the U…

The answer could be no devices at all, just a TPRD, just a PRD, or both. It depends on the potential overpressure scenarios identified during a hazard assessment. TPRDs typically are not used on ASME pressure vessels since they are not ASME compliant devices and since  system siting provides protection from engulfing fires. However, TPRDs are frequently used in portable applications for…

Liquid hydrogen is much less likely to pool than liquified natural gas (LNG) due to its low heat of vaporization. Very large facilities are often equipped with methods to enhance vaporization, such as crushed stone under tanks, as well as diversion systems to allow liquid hydrogen to spill and boil off in a safe area. Care needs to be taken that diversion systems do not create a hazardous…

By definition, liquid hydrogen can BLEVE, but this is highly unlikely. Liquid hydrogen is stored in a double wall tank with vacuum insulation. This protects the primary pressure vessel from direct impingement and the very cold liquid provides self-cooling of the vessel walls. Tanks are also equipped with redundant pressure relief systems that are sized for fire exposure.

In most cases, it is not necessary to depressurize hydrogen systems in an emergency. Pressure vessels are usually isolated in an emergency. The best actions to assure safety during an emergency should be identified during the hazard analysis.

Underground storage tanks can be either installed in a vault or directly buried. Both offer additional
protection from external impact and fire, but each has unique challenges. Vaults must be properly
ventilated and designed to not create an explosion or asphyxiation risk. Direct burial vessels should not
have any underground leak points and must be protected from corrosion. Both…

This can be a complex problem and response to insulation failure should be considered in the emergency response guidelines and procedures. 
First, a tank with an insulation failure may boil off at an elevated rate which applicable codes build into the relief device and vent system design.
Second, ice and oxygen enriched liquefied air can form where inadequately insulated surfaces…