Reuse old piping in a new plant, pressure test? 1

[Yasser Abu-elhassab]

If we are to reuse old piping in a new plant, after welding, we radiographed the new welds.
Shall we do a pressure test for these lines?

 

[LittleInch]

Generally a pretty good idea....

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

 

[TiCl4]

Yasser,

What is the design code of the piping for re-use? Piping is just piping. If you've verified the thickness and prior application (to ensure no SCC or other possible issues), then it's not much different than installing new piping.

 

[Yasser Abu-elhassab]

TiCl4,
Thanks,
I asked the question because those pipes are already hydrotsted in the previous plant in the construction phase.

 

[weldstan]

Is this not a new piping system using old pipe materials from a previous system? You have indicated that added circ welds that were made were RT'd.

 

[LittleInch]

Yes, but in practice, the test certificates are long gone, the pipe might be a bit damaged or corroded or suffered some strain, some fatgue, the odd bit of new pie might have been added, sometimes no one really knows what the actual pipe material was....

It's not that usual to do this so you need to take precautions.

B31.3 requires testing for new fabrications I believe.

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

 

[TiCl4]

Yasser,

The hydro is not usually done to just test piping integrity; it is also done to test the weld integrity of all welds. You are, of course, going to be cutting and rewelding this pipe. Thus, a hydro is needed, moreso now than before because instead of using new pipe you are using old, used pipe of unknown origin, quality, and corrosion status.

 

[KevinNZ]

What is the application and design and fabrication code?

If the reused pipe spools have been hydro tested previously, to the new system test pressure, (and other fabrication QA) then your piping code may allow you to skip the hydro if the new welds have RT or other NDT.

 

[weldstan]

A new piping system is subject to hydrostatic or pneumatic testing under both B31.1 and B31.3. I do hope that you have viiisually examined the old pipe to assure freedom from or acceptable corrosion and needed wall thickness.

 

[alchemon]

The short answer is yes, you should redo the pressure test. Be careful though. May be worth doing some low pressure leak testing beforehand. NDT of the welds will not pick up any issues on the pipe itself, as others have alluded to

 

[Dhurjati Sen]

There should have been a thorough Visual Inspection of the old piping to detect external damage, if any.

Ultrasonic thickness examination of the piping would have initiated the history card.

Alas, nothing seemed to have been done at the right time.

DHURJATI SEN
Kolkata, India