LNG storage, plumbing, and other systems can’t be directly retrofitted to handle hydrogen. The LNG components and systems will need to be removed and replaced with equipment specifically designed for hydrogen. If the concept is to convert existing equipment or an existing ship, then it’s probably impossible. If it’s to convert an existing LNG design on paper, then it’s probably impractical. Much better to start from the ground up with an H2 design.

From a materials perspective, there would be issues related to both the lower temperature of hydrogen and hydrogen embrittlement.   The temperature of LNG is 113 K, so many materials specified for this temperature will not be suitable for liquid hydrogen’s temperature of 20 K. In addition, liquid hydrogen’s lower temperature will condense air, so insulation systems will need to be significantly different for vessels and piping.

Another consideration is that electrical classification for LNG is different than H2, so would likely require substantial retrofit of instrumentation and controls. LNG equipment also frequently has non-captured vents, which would not be acceptable for hydrogen. Much of the LNG equipment might be located in enclosed areas, in which case the properties of H2 are going to drive design changes. Enclosed areas may also be a hazard for LH2 systems since air may condense on the piping and create a localized oxygen rich environment, especially if poorly ventilated.

It is common to have combustible materials and fuels in a building during construction activities. Commissioning is typically considered part of construction. It is good to see that fire suppression is available. However, given the lack of alarm capabilities, it would seem prudent to have a fire watch posted when hazardous materials are present or being used. Regarding requirements, the International Building Code (Chapter 33) and the International Fire Code are the primary applicable codes. NFPA 241 also provides guidance but may not be required by the local jurisdiction. It may also be beneficial to contact the contractor’s or owner’s insurance company to see if they have any specific requirements as a result of the increased risk. 

In particular and with regard to hydrogen, it is unusual that H2 would be needed for construction activity in the same way that other gases such as propane, natural gas, or acetylene might be used for welding, brazing, or cutting.  When bringing H2 into a building for commissioning activity, the building and fire codes should be followed with respect to maximum allowable quantities (MAQ), control areas, and ventilation. Consult with the local authority having jurisdiction for specific requirements from the model fire code and associated codes for the hazardous materials and processes planned for the premises. Occupancy certificates are typically issued by the AHJ upon final inspection and approval by several code Officers such as building, electrical plumbing, Fire etc. Typically all life safety systems required by codes must be functional regardless if the premises is occupied or not.