Refer Para 4.1 (i) of UOP Spec 3-12-5 (Pressure Vessels – Low Alloy Steels) states, the tempering temperature for tempered material shall be at least 50 ºF (28 ºC) greater than the maximum intermediate or post weld heat treatment temperature.
Also if you refer note (a) of table 5 - API 582, which states that for QT or NT materials, the PWHT holding temp shall be at least 15° C below the original tempering temperature of the base metal unless the fabricator demonstrates that mechanical properties can be achieved at a higher PWHT temperature and holding time.
Regds/Jignesh
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of asad azmi
Sent: Friday, December 31, 2010 5:34 PM
To: materials-welding@googlegroups.com
Subject: Re: [MW:9040] Tempering Temp - IBR Cr-Mo Forged Steel valves
can you pls provide UOP para( Extract) which states --
Tempering temp shall be 28 °C higher than PWHT temp)
Regards
On Thu, Dec 30, 2010 at 12:58 PM, Bathula Raghuram (Mumbai - PIPING) <R.Bathula@ticb.com> wrote:
IBR regulation 282a: states tempering temperature for P11 shall be 620-660 °C and for P22 it shall be between 650-700 °C.
Whereas Minimum PWHT temperature for B31.3 piping is 704 °C, when we restrict the min tempering temp to (e.g. 730 °C), forging vendors are denying to meet the requirement (e.g. welded valves), quoting IBR regulation 282a.
However there is a note at the end "The tempering temperature may be varied by the Inspecting Authority to suit the steel being tempered".
My question is had anybody approached in the past and able to convince IBR for higher tempering temperatures?
Q: how forging vendors are meeting this requirement when PWHT temperature shouldn't exceed tempering temperature (for e.g. UOP states tempering temp shall be 28 °C higher than PWHT temp)
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