Fastener failure in huge pump cover. 2

[nasirqa1407]

I have a huge mud pump that has a big crank shaft case cover that installed 35 angeld degree. Originally, this cover is attached by 22 studs. As it is hard to install the cover we change those studs to standard fastener bolts. With 6 month later, we observed that most of the fastener bolts are fractured from the head & body joint. I would suggest to reuse the old design attachment. Could you please advise me?

 

[micalbrch]

I would suggest the same (reuse the old design attachment). If one could simply replace the studs by standard fasteners, the mud pump manufacturer would have done this.

 

[Artisi]

Can't see any real difference between studs and bolts, provided the bolts are the correct grade of steel and torqued correctly.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[hydtools]

nasirqa1407,
What is your 'standard' bolt? It may not have been the same strength as the studs.

Ted

 

[EdStainless]

Or it may have to do with slight bending loads.
A nut on a stud will be able to shift slightly while a head on a shank will not.

We used to test high strength bolts and tried all sorts of tricks to get failures in the threads instead of just breaking heads off.

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Plymouth Tube

 

[nasirqa1407]

Thank you all for you efforts.

hydtools,
They are the same grade type of strength.

Additional Information:

The main crankshaft bearing cover is attached by two big bolt 1 1/2" head size. Usually, I get one of them broken every 6 month PM. Consequently. the load in the main bearing will be transferred to the structure which it attached to this bearing cover meanwhile it trys to push the main crank shaft cover.