Problems with the check valve on the liquid inlet line of the storage tank at the liquefied gas station
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Friends, I’ve recently come across a project to renovate a liquefied gas station. This station is quite old; it was likely built in the 1990s. During the renovation, a problem was identified: the inlet and outlet lines for the gas and liquid phases in the original station’s storage tanks were not equipped with check valves. I checked the \"Code for Design of Urban Gas Supply\" GB50028-1993, and indeed there are no requirements in this regard ； However, the Code for Design of Town Gas GB50028-2006 explicitly requires, in bold text, that a check valve must be installed on the liquid inlet line. Then, the latest \"Design Code for Liquefied Petroleum Gas Supply Engineering\" GB51142-2015 replaced the section on liquefied gas supply stations in Chapter 8 of the original \"Design Code for Urban Gas\" GB50028-2006; the bold text was removed from this section, but the wording used is \"shall\". The inlet and outlet lines at the site appear to be bidirectional in operation and can be switched, so no check valves are installed on the inlet lines there. The problem now is that a new tank has been added in this renovation – is it okay not to install a check valve on the liquid inlet line? If a check valve is to be installed, the workload will be considerably greater, and the site does not currently have the conditions necessary for carrying out welding work.
As the original poster mentioned, the new rules have removed the bold text, but the wording used is “should,” so it clearly should be included. A new tank was added during the renovation, and it must meet the current regulatory requirements. The site does not meet the conditions for welding; it is possible to prepare the parts that need to be welded outside first, and then bring them back to the site for installation using flange connections.