On the design and manufacture of hydrogen buffer tanks
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There is now a hydrogen buffer tank with a nominal diameter of DN1000, featuring upper and lower elliptical end caps. The design pressure is 4.4 MPa, and the design temperature is 50°C. No inspection holes (manholes) have been provided in the design; is it necessary to include such holes? According to the standards, there are no options available for manholes with a pressure rating of PN6.3 Mpa. Furthermore, if inspection holes are not provided, how is the circumferential weld of the final head welded?
With a diameter of DN1000 and a hydrogen medium, it is recommended to provide inspection holes; for manholes with a pressure rating of PN6.3MPa, the standard manhole specified in HGT 21518-2014 with DN400 can be used.
With such high pressure, inspection holes must be provided.
Manholes should be installed. It is easy to manufacture as well as to maintain in the future. It is possible to design a non-standard manhole; as long as the calculations show it meets the requirements, that’s fine. With standard ones, it’s just that the cover and flanges are not taken into account
It is best to provide inspection holes for this; if no standard ones are available, custom ones can be used as long as the calculations show they are suitable! It is also possible to omit this setting; in that case, it is necessary to specify explicitly that the welding joint coefficient should be 1.0, that 100% non-destructive testing must be carried out, and to indicate the calculated thickness of the equipment as well as other specific requirements such as regular inspections.