Seized studs on discharged flange of Between bearing pump

[MechEngineer2012]

Dear Engineers,
I work as a shop Engineer for a pump repair shop and recently we received a Single stage-Between bearing-Radially split-Double suction impeller pump (BB2 per API 610). I found that some of the discharge flange studs were seized and customer (Refinery) had to cut them (see attached picture). I wanted to ask you if you have experience this problem before. What were the possible solutions? What can be the root cause of this issue. We will remove the studs and repair the threads but I wanted to bring this topic up for discussion. Thanks

 

[hydtools]

I would usually suspect corrosion. Perhaps reinstall new studs with an anti-corrsion compound.

Ted

 

[quadtracker]

Some pump companies will use a interference fit studs so that you can remove the nut without the stud coming out when maintenance is required on the pump. As far as removing the studs set the flange housing on the boring mill and drill out the studs without cutting the threads in the flange. If you remove most of the stud you should be able to use an extractor to remove the remaining stud. When putting in new studs check thread fit with a standard nut. You may want to reduce the interference by re-threading the studs with a split die to cut the threads for an easier thread fit. Depending how much of interference fit you need or want use some anti-sieze compound on the threads for easier removal next time.