Painting before hydrotesting per B31.1

[qualitypro]

Can the weld joints be painted prior to hydro testing? Is there a Code requirement for this? I understand that the B31.1 Code mentions that all joints shall be left exposed during testing.

 

[rneill]

You would need to consult the particular design code you're working to but for B31.3: All joints shall be left uninsulated and exposed for examination... all joints may be primed and painted prior to leak testing unless a sensitive leak test is required.

On the other hand,B31.1 says: All joints shall be left uninsulated and exposed for examination during the test. By prior agreement the complete system or portions thereof subject to test may be insulated prior to the test period provided an extended holding time pressurization of the system is performed to check for possible leakage through the insulation barrier.

Unfortunately B31.1 does not explicitly address the issue of painting although there may be an interpretation on the subject ?

 

[metengr]

Can the weld joints be painted prior to hydro testing? Is there a Code requirement for this? I understand that the B31.1 Code mentions that all joints shall be left exposed during testing.

Reply; No.
Rationale; ASME B31.1 , Section 137.2.1 the key words are uninsulated AND exposed joints. If an insulation layer is applied and by prior agreement a longer hold time may be used to check for leaks.

For weld joints, strip the paint for the inspection.

 

[rneill]

Well, I did take a quick look at what B31.1 interpretations I had (I don't have them all though) and couldn't find anything on this subject. Since it's not explicitly addressed, I'd go with metengr's advice.

What caused me to wonder a bit is that B31.3 has the same language regarding uninsulated and exposed but then goes on to say that painting is okay. However, the B31.1 committee would no doubt know what the B31.3 requirement was so probably made a conscious decision to not include this language.