Regarding light-transmitting holes and manholes
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This post was last edited by kareale88 on 2019-5-6 at 15:28. bg4.png: What are the current **standards** regarding these two structures on storage tanks? ? ? ? Could you give a rough estimate? Additionally, regarding the manholes on large LNG storage tanks, it is specified that manholes must be installed at the bottom of the side walls of the tank. However, the annular space of an LNG storage tank (the area between the two layers of tank walls) is entirely filled with insulation material (including perlite and elastic felt); how can manholes be installed in such a situation? Thank you, website~~
Thank you here to Kareale88~~
If the standard specifies that it must be installed, then it must indeed be installed; if it only says \"may\", then installation is optional. In the case of models with insulation, sufficient overhang length must be provided, as specified in 20583.
LNG storage tanks generally feature a dual-sealing design; aside from the tank roof and process requirements, the inner tank and the outer tank are completely separated, primarily to ensure the safety of personnel and the medium, as well as to provide low-temperature resistance and reliable insulation. Unlike ordinary storage tanks, it is a special device. Manholes should not be provided on the tank wall. In the domestic market, there is only engineering design experience but no standards. Design is generally based on API620, NFPA-59A, and BS7777. The relevant domestic standards are GB50028\GB50183.
The design structure of conventional storage tanks shall comply with the provisions of GB50341; where nothing is specified, it is not mandatory and can be determined based on the process characteristics of the equipment. That is, the manholes on the tank wall and the light-transmitting holes on the tank top can be omitted. Temporary holes can be drilled during the construction phase. Other measures can be taken during stages such as use to ensure the various functions of manholes and light-transmitting holes.
I would like to thank all the netizens upstairs for their generous help as well. In addition, there is now a specific standard for low-temperature storage tanks such as those used for LNG, namely GB 26978. However, it is quite simple and not as detailed as the API standards.