suitable timing for post weld NDE

[mariolucas75]

Where is a reference / guidance for suitable timing for post weld nde - depending on various factors: thickness, low/high Hydrogen electrode, preheat / interpass temperatures etc etc ?

 

[ShabsRBI]

As far I know API-510 ( Pressure vessel Inspection code) in its para 8.3.4 Repairs to Stainless Steel Weld Overlay and Cladding refer the following point.

For vessels constructed with P-3, P-4, or P-5 base materials, the base metal in the area of repair should
also be examined for cracking by the UT in accordance with ASME Code, Section V, Article 4, Paragraph T-473.
This inspection is most appropriately accomplished following a delay of at least 24 hours after completed repairs
for alloys that could be affected by delayed cracking.

 

[r6155]

The 24-48 hour delay applies after welding, not after PWHT.
After PWHT, as soon as possible

 

[mariolucas75]

The 24-48 hour delay applies after welding, not after PWHT.
After PWHT, as soon as possible

r6155
If any delay is needed after welding for proper NDE... how does this requirement interfere when for example an "intermediate" NDE is required:
For example ASME B31.3 -

344.7 In-Process Examination
344.7.1 Definition. In-process examination comprises
examination of the following, as applicable:
(e) (for welding) condition of the root pass after cleaning — external and, where accessible, internal — aided by liquid penetrant or magnetic particle examination when specified in the engineering design.

If during an in-process examination after root pass is completed - normally PT or MPI will be done once it cools to ambient temperature ..so does it mean that root pass may not be ideally examined with immediate PT or NDE ?

 

[r6155]

You can make as many NDE as you want, even when you have completed half of the total weld thickness.
You can make a mock-up using the actual production material.

Regards

 

[racookpe1978]

Rational limits apply "first".
Example:
- Dye Pen exam or UT exam MUST WAIT until the weld zone has cooled down to near-room-temperature. The dye and UT lubricant/sound seal goop needs time on a relatively cool surface to soak, to not be burned off by a hot weld zone.
- VT? Often, can be done near-hot.
- RT? Needs time to set up, to apply the RT film or digital recorder to the weld zone. To position and setup the RT source or radioactive source in position.
If a Preheat blanket wraps or preheat heater is required, then those will likely interfere with the inspection either physically or by temperature.
PWHT may need 12 to 24 hours to come down from a 1250 deg F condition. Cracking inspection after that? See your company's spec's.
PWHT might have to come many hours or many days after several nearby welds all finish, then the whole assembly is brought back to temperature. Or be kept at high temperature for a long time. (Sagging? Droop? Movement damage?)