Heat Treatment Condition as per UG-84 (h)(2)(-b)

[sushildwivedi16]

Hello to everyone.

As per my understanding, clause UG-84 (h)(2)(-b) refers to heat treatment conditions such as as-rolled, annealing, normalizing, normalizing+tempering, quenching+tempering, normalizing+accelerated cooling+tempering. In short this clause refers to quality heat treatment of the material to be welded. Any change in the heat treatment condition will require re-qualification of the welding procedure. Is stress relieving or second quality heat treatment (which is done after forming operation of dished heads) also included in this conditions ?

An example of this is as below

Shell thickness is 45 mm (as-supplied heat treatment condition is normalized). After long seam welding, stress relieving is carried out at 610°C x 2 hours. The dished head is 40 mm thick (as-supplied condition is normalizing + post forming heat treatment is normalizing because of client requirements). The circumferential seam between shell to dished head shall also undergo stress relieving at 610°C x 2 hours.

The PQR supported for Shell long seam & circ. seam welding is made between Normalized plate to Normalized plate with PWHT of 610°C x 2 hour as min. PWHT and 610°C x 10 hours as max. PWHT.

The authorized inspector insists that for circ. seam welding the PQR should be welded between Plate-1 which is Normalized+Stress Relieved to Plate-2 which is Normalized+Normalized. After completion of welding the PQR shall be subjected to PWHT requirements of the circ. seam i.e. 610°C x 2 hours. Impact test of both the HAZs shall be carried out. The stress-relieving cycle of Plate-1 shall be same as the PWHT cycle after shell long-seam welding and the second normalizing cycle of the Plate-2 shall be same as the Post-Forming normalizing of the dished head.

Is the authorized inspector's requirement justified as per code ?

 

[metengr]

Heat treatment as mentioned above is not the same as a subcritical post weld heat treatment. Typically, a subcritical PWHT is used to relieve stresses and to soften the weld heat affected zone with no effect on bulk properties. Whereas, heat treatment, like normalizing or normalize and temper, alters the bulk mechanical properties.

 

[fleischfresser]

Hi,

authorized inspector's requirement is justified acc. to the code requirements:
ASME VIII/1 UG-84 (h)(2)(-b)
ASME VIII/2 3.11.8.3(f)(2)

Please find below Interpretations for a better clarification:
Interpretation: VIII-1-92-51
Subject: Section VIII, Division 1 (1989 Edition, 1991 Addenda); UG-84(h)(3)(b)
Date Issued: March 9, 1992
File: BC88-434 (BC89-465 and BC89-467)
Question: Does the phrase “Same heat treated condition” in UG-84(h)(3)(b) of Section VIII, Division 1 mean that the following would be considered different heat treated conditions?
[ul]
[li]as rolled[/li]
[li]annealed[/li]
[li]normalized[/li]
[li]normalized and tempered[/li]
[li]Quenched and tempered[/li]
[/ul]
Reply: Yes.
Please note: The reference to UG-84(h)(3)(b) in the above Interpretation is paragaph UG-84(h)(2)(-b) in the current Code.

Interpretation: VIII-1-92-221
Subject: Section VIII, Division 1 (1992 Edition, 1993 Addenda); UG-84(h)(2)(b)
Date Issued: May 24, 1994
File: BC94-110
Question (1): A procedure qualification test plate has been welded using base material in the normalized condition, and meets the requirements of UG-84. Under the requirements of UG-84(h)(2)(b), is this PQR also applicable for a vessel production weld joining normalized material to quenched and tempered material?
Reply (1): No.
Question (2): If the Reply to Question (1) is “no,” then is it permitted to weld an additional procedure qualification test plate using quenched and tempered material for testing impact toughness of the heat affected zone only?
Reply (2): No.

Regards - Juergen

 

[sushildwivedi16]

Dear Fleischfresser,

Thanks for the interpretations. However, it does not answer my query in the original post.

The Interpretation: VIII-1-92-51 does not indicate stress-relieving as heat treatment condition. The Interpretation: VIII-1-92-221 is related to joining of two different heat treatment conditions (i.e. N to Q+T) supported by a procedure qualified only with one heat treatment condition (i.e. Normalized)

So why to qualify the PQR with Normalized+Stress Relieving to Normalized+Normalized ?

Post-Forming normalizing restores the original mechanical properties of the material. This is verified by testing a coupon subjected to same normalizing cycle as the head. Hence, this second normalizing is as good as the as-supplied normalizing.

 

[metengr]

Is the authorized inspector's requirement justified as per code ?

Yes.

 

[fleischfresser]

sushildwivedi16,

we have to keep apart:
• heat treatment conditions mentions by paragraph UG-84 (h)(2)(-b): conditions of the base metal before welding and PWHT and
• heat treatment conditions acc. to UG-85 with reference to UCS-85: all thermal treatments of the material during fabrication exceeding 900°F (480°C) – with some exemption e.g. for P. No. 1 material

Therefore acc. to UG-84(h)(2)(-b) the material heat treatment conditions (conditions before welding and PWHT) of your example are as follows:
• shell: normalized
• dished heads: normalized (all heat treatment conditions before normalizing (heat treatment above the upper transformation temperature) must not be considered
That means the heat treatment condition of test plates for the circumferential seam dished head/shell as well as for the longitudinal seam of the shell must be normalised.
PWHT is not addressed by UG-84(h)(2) and will be considered by ASME IX e.g. for all arc welding processes by paragraph QW-407.1, QW-407.2 and QW-407.4 and by UCS-85 as mentioned above.
That means as long as all essential variables and if applicable all supplementary essential variables for the above mentioned circ. Seam as well as for the long. seams are the same you need only one supporting PQR.


Regards - Juergen