It's a because present stabilizing element as well high content of alloying element like Cromium.
On Tue, 8 Sept 2026, 15:21 Kannayeram Gnanapandithan, <kgpandithan@gmail.com> wrote:
What is the reason to do NDT after PWHT for alloy steel.
THANKS & BEST REGARDS,KG.PANDITHAN, BE, IWE,ISO 9712 Level 2 in VT,ASNT-Level II in PT,MT,RT & UT,LA ISO 9001-2015, ISO 3834, EN 1090 & EN 15085,International Welding Engineer.CONSULTANT-WELDING & QUALITYMobile no: +919940739349
--On Tue, 8 Sept 2026, 17:00 Bharath Kumar, <vbmkumar1988@gmail.com> wrote:
Hi--
The requirement for examination after PWHT usually comes from the construction code/specification, service requirements, or project specification, not simply from the P-No. designation.. in my understanding the material like Pno 3/5A,5B,5C basically a alloy materials it's metallurgical behaviour during welding and followed by heat treatment will be different than normal carbon steel material. These material may occur delayed cracks unlike carbon steel it could be a one of reason for NDT after PWHT . But normally carbon steel material it's not mandatory to do RT/UT before PWHT unless specified by client requirement. You can perform after PWHT but you should ensure the weld free from surface defects ( by PT/MPI) before PWHT.
BRV.Bharathkumar
On Tue, Sep 8, 2026, 8:34 AM 'ranajit chatterjee' via Materials & Welding <materials-welding@googlegroups.com> wrote:
Dear Sirs,
As per ASME B31.3 clause no.341.3.1(a) mentioned P Nos.3,4,5A,5B,5C AND 15 materials examination(RT/UT) shall be performed after completion of heat treatment. But no information for P1 material whether NDT performed before or after PWHT.
Please advise can we perform NDT(RT/UT) before PWHT activity for P1(NACE/H2 service) material or not.Regards,
Ranajit Chatterjee
9995018265
--
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