Pump flange threaded hole

[Jungpao]

Dear Pump Experts,

Disclaimer, i am still new to the design of pumps. I have two ANSI/ASME B73.1 Pump with sizing 1.5" x 1" x 8" . One pump will handle diesel (Q : around 11 Usgpm H: around 100 ft) while the other pump will handle water (Q: around 10 Usgpm H: around 36 ft).

I am aware that ASME B73.1 (see attached) allow for some pump sizes to have tapped holes due to limitation of space for nuts however Vendor did not mention it in their sectional / GA Drawing. My concern is that during commissioning, when there is leak on the nozzle, Commissioning team may tighten the bolt and broke the thread (either stud bolt thread or flange hole thread)

Have you any experience for this design of pump? Any inputs would be very appreciated. Thank you

Best Regards,
Jungpao

 

[GBTorpenhow]

One approach (as a backstop to experienced installers and proper torqueing methods) is to specify bolts with low enough strength and enough thread engagement such that the bolt shank will fail before the threads do. Will depend on the depth of the tapped holes present, material strength of the casing material, etc. whether this is feasible or not.

One of the reasons I prefer cap screws for this type of application vs studs is because of the more positive control of thread engagement lengths.

The various flavors available of low stress or "multi-swell" type gasketing might help as well to keep bolt loads down.

 

[LittleInch]

Usually the key uncertainty is making sure that the studs are actually embedded the full depth of the flange and also not cross threaded or galled during installation. If the studs are correctly sized, inserted to at least the depth of the flange and made from similar material to a nut then there really should not be an issue.

Or make the nut on the other side of the flange thinner so it strips or fails first.

The flange material needs to be a similar strength to a that of a nut and at least the same thickness.

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