Use of RT plugs 30" od 2.25cr B31.1

[rmillercwi]

I am working on a repair procedure to replace a 2' section of 30" od, 375 wall 2.25 cr pipe. RT required to get by the hydrotest. B31.1

The previous installation had RT plugs installed. Are they nessesary in this application? I would like to not require them if possible. It appears they are not required but makes the RT process a one-shot deal vs having to rotate the camera 3 times. Correct?


The finished product is in a wide open location.

Thank you in advance.

 

[metengr]

Yes, for RT gamma plugs are the norm. You might want to consider ultrasonic examination (UT) for this application. TOFD or shear wave can be used depending on your procedure.

 

[stanweld]

We seldom if ever use gamma plugs for pipe welds that thin. We generally require gamma plugs for wall thickness > or = 3/4-inch and diameters > or = 10-inches.

 

[rmillercwi]

Thank you for the comments. Considered using UT in lieu of RT but had concerns of the 1/8" dead zone. The pipe is pretty thin. Agree?

 

[metengr]

A conventional shear wave technique with UT would work on a butt weld of this wall thickness. Check with a nondestructive testing company for specifics.

 

[rustbuster]

Time of Flight Diffraction or Phased array ultrasonic inspections are both capable of examining these welds.

 

[ndeguy]

I have not come across "RT plugs" before. I think I understand the (simple) principle of an entry port in the wall of a vessel or pipe for insertion of the gamma-ray guide tube (maybe Gamma plug would be a better description) in order to reduce exposure times (single panoramic possible versus multiple double wall exposures). I have searched this forum and got to the reference to the Pipe Fitting Institute PFI Standard ES-16 - but I dont have a copy. Can anyone direct me to any further technical information. Would be grateful.

Nigel Armstrong
Karachaganak Petroleum
Kazakhstan