PT / MPI for root Weld 1

[nktqc]

Hi friends,

Well , one question came in my mind while discussion with some inspection engineers , that , In a butt welding , ( Joint is single V and diameter is 43" ) we are doing the GTAW in root and hot pass , so after completion of Weld , Is we need to do PT / MPI from root side ? We are doing PT / MPI from face side ( top side not inside )

Is any code reference for the same if required or if not required then there is any code reference ?

Kindly help us ..

Regards

nAVIN

 

[nktqc]

Sorry its 42" Pipe to Pipe joint.

 

[racookpe1978]

A dye penet test - from any side of the weld, for any pass of the weld (root, hot pass, fill or cover pass) - can only tell you that "No pits or undercuts or surface-piercing cracks are present on this side of the weld at this time."

So, doing a DP NDE exam on the outside of the final pass does NOT tell you that there are no pits or holes (1) in the top or bottom layers of the root (2) in the top or bottom layers of the fill passes (3) in the bottom layers of the final cover pass.

A mag particle test (MT) test can find cracks or holes below the final layer of steel in the final pass, but they are not perfect either. I'd recommend a DP test after the root pass is complete. A DP test inside the pipe is not normally required (usually the inspector can't fit!) but should be done on the prep of welds that are back-ground and then welded from the back side to get a double penetration weld.

All of these requirements should be in your company's NDE spec's. Or in your client's NDE spec's for each different kind of piping and pipe material and service condition. NDE requirements are NOT generic, but specific to service, pipe material, temperature, pressure, etc.

 

[Duwe6]

racookpe, my only root ID penetrant testing was on the primary coolent loop at the Callaway Nuke while we were building it. Came out "snot-slinging drunk" due to the fumes.

Any PT in a confined space is dangerous, and requires forced ventilation and/or serious respiratory protection. Not to mention the flammability. One spark, you are a candle.

 

[nktqc]

101 % agree with racookpe.

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Any PT in a confined space is dangerous

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absolutely , there is No doubt.

=

Thanks to all

 

[EastCoastQC]

You main concern is cold cracking in the root due to the butted pipe acting as a heatsink. PT on a root before the hot pass is not going to work becase it is too hot, the dye will simply burn-off (can't be done on a hot surface anyway as per ASME V).

Dry MT is the most common NDE technique used for surface root inspection. It is immune to heat and is going to give you what your looking for- cracking.

This is all assuming that the material in question is non-ferrous.

Hope this helps.

East

 

[nktqc]

EastCoastQC

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Well there is NO such concern but as in code its not specified that PT need to carry from face side not from root side so during discussion it was came that PT / MT shall be carry out from both side if its accessible.

But normally we use to carry PT from out side only if its not specified in client specification or in approved procedure.

 

[EastCoastQC]

PT from root side of the weld (inside the pipe) could be achiveable and will give you an idea of any surface disct. up to 3mm, however, it would be the first time I've seen this practice used.

PT on the root, before hotpass is not a good idea. You have a much greater chance of inducing hydrogen in to the weld and you be asking for porosity. The welder will probably clobber you if you try this haha.

Dry MT is the only way to go for root NDE. The root cannot cool down too much before the hot pass or you are going to be a great risk for cracks.

Again, it depends on material type, size and sch.

Just my 2 cents.

East