RE: [MW:6854] tempering temperature of P4 material

The use of UCS-56.1 is not permitted for P4 material.

john

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of N VENKATESWARA PRASAD
Sent: Friday, September 03, 2010 12:15 PM
To: materials-welding@googlegroups.com
Subject: Re: [MW:6852] tempering temperature of P4 material

Hi,

The PWHT temperature shall be always less than the temperature as the base material Tensile strength, Hardness etc will not affect much as long as your PWHT temperature is less than tempering temperature. So you can carryout PWHT at 645 deg. Centigrage. As per UCS 56.1 you can reudced PWHT temperature, but you need to increase soaking temp. as per the table given in UCS 56.1.

On Thu, Sep 2, 2010 at 12:57 PM, THAKSEN INGOLE <t_ingole@yahoo.co.in> wrote:

Dear all

There is a clause in Saudi Aramco documents stating as below

The maximum PWHT soaking temperature for quenched and tempered carbon steel and C-1/2Mo shall not exceed the temperature at which the test pieces were heat treated as shown on mill test reports or 650 deg C max for carbon steel ,690 deg C max for C-1/2 Mo and 700 for low Chrome alloy.

Our material is SA-387-Gr 12 cl2 (C -1/2Mo) which is P4 material. The min PWHT temp as per code (VIII Div 1-U stamp) is 650 deg C.

Now aramco has commented on our documents that they need a PWHT temperature to be 25 deg C less than tempering temperature as specified on MTC for the plates. So we need to have a tempering temp of min 680 deg C so we can carry out the PWHT at 650 deg C but he plates MTC shows the tempering temp as 660 so we are 15-20 deg below. The plates are already purchased which are 65,70,80 mm thick.

My first query is no where in the aramco document we can find a clause of have PWHT temp 25 deg C less than tempering then what is the reason for asking this requirement.
What is the solution that we can offer them.

Regards
Thaksen

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