What are the requirements for the verticality of the equipment flanges on heat exchangers?
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Where can I find the requirements regarding the perpendicularity of the equipment flanges on the heat exchanger shell and those on the tube bank with respect to the main axis of the equipment? Paragraph 150 only mentions the requirements regarding the verticality and parallelism of the connection flanges and the equipment.
Generally, this is rarely specified in the drawings; it is determined based on machining and assembly experience, with the ultimate goal of ensuring no leaks during the hydrostatic test after assembly.
No special requirements are needed for this; the equipment flanges meet standard requirements regarding flatness, and for grade 150, there are specified requirements for the perpendicularity and parallelism of the flanges with respect to the equipment.
Which standard specifies the requirements for the parallelism of equipment flanges?
Generally, there are variations in the machining of the sealing surface in terms of height and roughness; it seems that there are no errors related to perpendicularity or parallelism as you mentioned. The precision of pressure vessels is very low; it’s not a purely mechanical design.
Equipment flange standards NB/T47020～47027-2012
Generally, the flanges on the tube box or shell are matched with the tube sheet, in accordance with the requirements regarding the verticality of the tube sheet.
It seems that there are only requirements regarding the verticality of the takeover and the deviation in the extension length. The levelness requirements for the flange