NDT performed after or before Hydrotest test

[mrmalcolm]

Dear colleagues,
Any code mentioned Non-destructive testing should be performed after or before the hydrostatic test?
If non-destructive testing is performed after the hydrostatic test, is it possible that the hydrostatic test could cause minor imperfection to expand into major defects?
If non-destructive testing is performed before the hydrostatic test, could the pressure of the hydrostatic test cause the pressure vessel to explode?
Thank you.

 

[JStephen]

Normal non-destructive testing wouldn't weaken or damage the part being tested, which is what your question seems to assume.
Just exactly what kind of non-destructive testing are you referring to?

 

[mfgenggear]

OP
Hydrostatic test with water will not explode.
I prefer to ndt before

 

[IdanPV]

Per ASME VIII-1 - UG-99(a)(2):

All examinations have been performed, except those required after the test

Per B31.1 - 137.1.5:

Pressure testing shall be performed following the completion of postweld heat treatment required by para. 132, nondestructive examinations required by Table 136.4.1-1, and all other fabrication, assembly, and erection activities...

 

[mfgenggear]

Here is the issue. Radio graphic inspection , penetrant inspection, or magnetic inspection will find imperfections. Depending on manufacturing and material. And what is specified on the drawing or quality contract requirement. If rework or repairs are required.
It must be performed prior to hydrostatic pressure testing.
Once these ndt procedures pass. Then hydrostatic test.
.

 

[mrmalcolm]

Thank you, colleagues. So,could pressure testing cause minor imperfection to become defects?

 

[mfgenggear]

Thank you, colleagues. So,could pressure testing cause minor imperfection to become defects?

Generally it's pass or catastrophic failure

 

[r6155]

What is minor imperfection?

 

[mfgenggear]

What is minor imperfection?

I should have said unacceptable indications.
Eg cracks, porosity ect

 

[r6155]

@ mfgenggear​

You're wrong and very confused.
You need to read more.
I'm sorry.

 

[mfgenggear]

@ mfgenggear​

You're wrong and very confused.
You need to read more.
I'm sorry.

Your answer is ridicules and has no merit.
It applicable to the contract, contract requirements , the specifications, and your insulting answer is un Profesional.

 

[EdStainless]

NDT (all methods) detects indications.
Whether or not these are of concern depends on your standards.
Verifying what these indications are requires some destructive examination.
We always did NDT prior to Hydro. for a couple of reasons.
1. Much easier to repair things while they are dry
2. To tell us if we need to do more inspection/testing before carrying on.

 

[r6155]

good luck.

 

[DekDee]

IdanPV has given you two examples.
Here is B31.3
345.1 Required Leak Test
Prior to initial operation, and after completion of the
examinations required by para. 341, each piping
system shall be tested to ensure tightness. The test
shall be a hydrostatic leak test in accordance with
para. 345.4 except as provided herein.

Forget the requirements of codes / standards for a moment and think basic common sense.
Fill the piping system with water, perform the test, drain all the water. Perform NDT and find you have a repair. Start all over again. Very costly and time consuming.

 

[r6155]

Although B31.3 is not applicable in this pressure vessel forum, I wish to comment that for normal service, B31.3, visual inspection is sufficient before hydraulic testing.

 

[mrmalcolm]

Thank you. Hydrostatic test is a pressure test. Will hydrostatic test produce new defects or expand existing defects?

 

[mfgenggear]

Thank you. Hydrostatic test is a pressure test. Will hydrostatic test produce new defects or expand existing defects?

Back in the late 70's my customers would require , penetrant inspect, radiographic inspection, and hydrostatic pressure testing.
To in sure weld integrity. As an apprentice level 1 then level 2 I did all three.
Don't remember the exact specifications.
It is an option for the design engineer if it's needed for application.
A pressure test will reveal if the tensile properties have been compromise.
I can tell you this if all of the inspect criteria
Passes, I never had hydrostatic failure..
A visual will not detect surface or sub surface fine cracks or porosity. Or un allowable metallic inclusions. You as the engineer have to decide what is necessary
For the application and intent.

 

[r6155]

Hydrostatic pressure test (HPT) is not considered NDE.
HDP can produce a permanent deformation, fracture, …...and more.

Remember

1. Conduct a thorough risk assessment before testing.​
2. Ensure supervisors and personnel are trained, competent, and qualified.​
3. Establish effective communication and limit access to the test area.​
4. Use calibrated pressure control devices and avoid leaving pressurizing equipment unattended.​
5. Check water temperature​
6. Check adequate supports​
7. Check air is vented​
8. Error in the “procedure for hydrostatic pressure test”
   
   This list is not all.
   
   ​

 

[mfgenggear]

Op
I wanted to add the the above procedure is for high hydrostatic pressure testing. 1000 psi or more. Nitrogen is acceptable for low pressure.
For verifying for leaks of joints with a meter.
Hydrostatic with the certified and qualified equipment is safe. No loud explosions. Just a leak failure. If the pipe leaks or bulges , it has failed the test.

 

[r6155]

“To in sure weld integrity”. : INCORRECT
Pressure test is to check a pressure vessel integrity, not only the welds
Hydrostatic pressure test for piping is different for pressure vessels.