hydrotest

[212197]

we supplied equipment after successful hydro.
At site it is found that few bolts have minor cracks. These bolts are pressure retaining bolts
We decided to replace all the bolts.

Does code (sec. VIII DIV 1) permit use of non hydro tested bolts on hydro tested equipment ?
If so, as per which clause ?

I did not find any reference of this in UG-99.

 

[Aub_Engineer]

I've never heard requirements for hydro/non-hydro tested bolts. PCC-1 appendix N gives information on reusing vs. replacing bolts.

In my experience pressure vessels, columns, strainers, etc. built to pressure vessel code are opened, inspected, filters replaced, etc. regularly. The flange bolting is replaced without an additional hydrotest if no repairs/alterations were performed.

 

[mk3223]

My experience is, if needed to replace the flange bolts after the hydro, to replace with a new set of bolts and follow the same bolting procedures for stud tightening.