BOP Test Stump Insert with XT-38 box thread material

[Bruce1983]

What material is suitable for a bop test stump insert with XT-38 box thread.

Our supplier recommended 120 ksi yield material (4145 or 4330v)?
Is 4130 75ksi material isn't suitable, if so please advise why it's not suitable?
Is it difficult to machine XT threads with 75 ksi yield material.

Appreciate your help

Thanks,
Harry

 

[bananapeople]

Hi Harry,

The make-up torque for API drilling connections is dependant on yield. Pretty sure that XT-38 would usually be S135 material, so 4130 75ksi material is half the strength. Depending on your box geometry you could fail the connection by box flaring or shoulder over-pressure if you torque it to the normal S135 value.

Don't think you would strictly need 135ksi material just to test a BOP, but you would need to be careful what loads you put into the box if it's lower yield material. Also there's a chance that you won't properly engage the pin if you reduce the make-up torque to suit the lower yield strength.