Hi I'm a Mechanical Engineer I w

[Wasula K]

Hi I'm a Mechanical Engineer

I want to know weather there is any code which mention about how the NDT should be done on a pipe line where the welding has been carried out by multiple welders where we only do NDT of a percentage of welds. Or how to select the weld for NDT.

Thanks in advance.

 

[david339933]

What Code is the pipeline being fabricated to?

 

[Wasula K]

The pipe line is Fabricated to B31.3.

 

[LittleInch]

Is specified in the code.

B31 3 is usually a poor code to use for a pipeline

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[mfgenggear]

Wasula
I am forgetting the correct terminology.
But was is the assessment for failure.
If not NDT circumferential on the pipe.
What are the allowable defects,
Is visual fine
Or does it require Magnetic particle inspect to fi

nd all allowable indications.
Does it require radio graphic inspection.
What are the allowable defects permitted.
Maybe that should be the questions.

Is the life or bodily harm to the environment or to personal.

 

[Wasula K]

Hi Little Inch,

I agree more details better answers. I should have asked more.

The line is 2" SS line for nitrogen at 9 bar. The line is designed to ASME B31.3. The line was welded by multiple welders and the contract have allowed 10% DPI as rule of thumb and good practice we do distribute the test weld among all the welders but what I want to know is whether it's mentioned in any of codes.

Yes the NDT is circumferential. It's SS316 hence the NDT method used is DPI.

Thank you in advance.

 

[DekDee]

Are you the Designer / Owner or Contractor ?
The Design pressure would allow it to be Category D piping so DP is sufficient.
However, there have been previous arguements on this forum as to whether Nitrogen is toxic or non-toxic ?
If deemed toxic it fallls under Category NFS (Normal Fluid Service) so radiography is required.
My current project has moved all Nitrogen lines from "In Service Leak Test" (Cat D) to Hydrotest with 5% RT (Cat NFS)

 

[LittleInch]

The codes don't normally get that prescriptive, it then depends on what you write into a construction or welding specification. They can't be expected to cover all possible circumstances of 1 welder, 10 welders or 100 welders...

I would normally look at 10% as a Minimum and make sure that I tested every welder at least once on a production weld, especially for something like Stl Stl

If its B31.3 then for a hydrotest you're supposed to be able to visually inspect each weld as well.

So is this a pipe or a pipeline?
A/G or buried?
Coated?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.