[MW:5693] MW: 5659- SIMULATED PWHT FOR THE MATERIALS

Mr. Masthan,

 

Looking at your query it looks to me , you're enquiring about hydroprocessing reactors. Typically modern day reactors are fabricated to ASME SeC-VIII, DIV-2 (for  best design and  best fabricated product)  or SecVIII, DIV-1( as an alternative code).

 

In addition API-934A specifications (Hydrocrackers) and 934C(For Hydro treaters) are also applicable.

 

If you specify the following details:-

• Design Code, Additional Specifications
• Materials of constructions

 

then probably the best guidelines could be provided.

 

Both in SecVIII, DIV-1 and DIV-2 codes there are specific requirements for simulated heat treatment and test coupons for steels used for hydroprocessing reactors. In addition the above API Specs outlines how these simulated PWHT is to be perormed and how specimens have to be tested.

 

Thanks.

 

 

Pradip Goswami,P.Eng.

Welding & Metallurgical Engineer/Specialist

Ontario Power Generation Inc.

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

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From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of masthan
Sent: Saturday, June 19, 2010 2:22 PM
To: materials-welding@googlegroups.com
Subject: [MW:5659] SIMULATED PWHT FOR THE MATERIALS

We are manufacturer of pressure vessels and one of the major client specifications explains about the simulated heat treatment of material as under

 

“Materials with properties enhanced by heat treatment cycles such as tempering, intermediate stress relief (ISR) and the final post weld heat treatment shall be tested to verify that their mechanical properties have been retained after all heat treatment cycles. These tests shall also include two additional post weld heat treatment cycles to account for future repairs or alteration.”

 

 

Query: 1: My understanding is that the above paragraph is referring only to the materials for shells & heads of the equipment.

 

Query: 2: My understanding is that the above paragraph is referring only to the material undergoing PWHT in order to achieve certain properties like HIC resistance etc. (or) some specific metals which mechanical properties may enhance due to PWHT not due to thickness for PWHT (ie 38 mm above as per UCS-56).In this case, combined three cycles of SPWHT will fully satisfy the above paragraph requirement.

 

Query: 3: If for the above queries (1 & 2), suppose my understanding is not correct, Please check the below condition for the applicability of Para.

 

For example

·         Dish Head/Toricone of the pressure vessel requires Stress Relieving due to exceeding the allowable fiber elongation as specified in UCS-79(d)

·         Instead of heat treating separate petals of the dish head / toricone, the dish head/toricone petals are welded and also shell portions are welded to it. The complete assembly is then heat treated to relieve residual stresses of Dish head / toricone. (This is done to avoid any distortion caused during Stress relieving of separate petals of the dish head / toricone)

·         In this case, with reference to above Para, whether mechanical properties after one heat treatment cycle need to be tested only for dish head or for all the materials included in the assembly?

 

Please note due to some reason, we are not clarifying the above directly with client. I need opinion from experts.

 

Regards

M.M

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