According to 32-SAMSS-004 paragraph 13.2.14,heat treatment such as
normalizing,annealing,normalizing and tempering or quench and
tempering shall be performed after forming operation for heads or
other double –curvature components with nominal thickness exceeding 50
mm and / or any hot formed components.
This requirement may cause a problem when tempering operation is done
at mill because subsequent teat treatment above tempering temperature
at mill will ruin the mechanical properties certified at mill. Many
mills produce heavy wall plates using tempering process to meet
mechanical properties required by project specifications.
Recently ARAMCO revised the same paragraph of 32-SAMSS-004 to allow
PWHT as the heat treatment for the parts.
The temperature of PWHT can be set below the tempering temperature ,so
it will not be a problem.
Thanks & regards,
On Feb 6, 9:58 am, asad azmi <azmiasada...@gmail.com> wrote:
> Dear All,
> A Vessel has to be fabricated as per ASME SEC VIII DIV 1. Vessel requires
> SPWHT as per Client requirment.
> A Dished head of material SA 387 GR 12 CL2, Normalized and Tempered - 80
> mm Thickness, has been *HOT Formed at temperature 920 deg. Celsius*.
> As per Hot Forming Procedure after reaching soaking temperature of 920 deg
> celsius and holding for 1 hour, Hot forming operation was performed
> outside the furnace and immediately after hot forming dished head was put
> back in the furnace and temperature was again increased upto 920 dec
> celsisus before transferring dished head in Shop Floor for cooling.
> *As per ARAMCO Standard Noramilizing and tempering shall be perforemd as
> seprate operation after Hot forming as per below clause.*
> 184.108.40.206 Heat-treatment, as a separate operation, shall be performed after
> a forming operation (hot or cold) for any of the conditions listed below.
> The heat treatment shall be annealing, normalizing, normalizing and
> tempering, or quench and tempering, as required.
> Please be informed that as per hot forming procedure Noramalizing after
> forming has to be performed at 920 Deg Celsius.
> Contractor has not performed Normalizing sepratley after Hot forming. as
> per reports test coupon has also undergone only ONE Normalizing Cycle.
> *Please advise whther Normalizing can be avoided as the hot forming was
> done at Normalizing temperature. *
> *As per ARAMCO requirement Heat treatment cycle for Dished head & Test
> coupon should be Hot forming + Normalizing + tempering + SPWHT.*
> *Please suggest.*
> *Thanks in advance.*
> *Asad Azmi*
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