POST WELD HEAT TREATEMENT OF API 2W GR 50/API 2MT1 PIPES WITH THK 3''

[Philip, Taiye (Lagos)]

Hello Gents,

Using AWS D1.1 as project code, is it wise/Professional to carry out

PWHT on joints made from (TMCP PLATES- API 2W Gr 50/ API 2MT1 Gr 50 rolled into pipes with thickness 3’’)

Used for TKY joints on jackets.

Note: TMCP - thermo-mechanical control process.

Regards

Philip Taiye

Principal QA/QC Welding Engineer

(EPCM-1 Quality Assurance/Control)

DeltaAfrik Engineering Limited

2nd Floor, City Express Bank Building

Plot 1637 Adetokunbo Ademola Street

Victoria Island, Lagos  Nigeria

Phone: +234-1-461-8508, +2341-461-6137 ext. 1257
Cell: +234-(0)-803-803-1396
Fax: +234-1-262-2418

e-mail: taiye....@worleyparsons.com

 

 

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[pgoswami]

Phillip,

 

API-RP 2A-WSD-Recommended Practice for Planning, Designing and Constructing Fixed Offshore Platforms—Working Stress Design and  AWS D-1.1 have restrictions for PWHT on the above steels.

 

In addition the spec for base metal, API -2W -2000, have the following precautionary note for such(TMCP) steels:-

• 1.2 POST MANUFACTURING HEATING

   

  Due to the inherent characteristics of the TMCP method, plates manufactured to this spec cannot be formed or post weld heat treated at temperatures above 1100°F (595°C) without some risk of sustaining irreversible and significant losses in strength and toughness. If warm-forming is to be required during subsequent fabrication, the tensile and notch toughness properties of the finished component shall be verified and the properties shall conform to the requirements of this specification. The procedure for verification shall be subject to mutual agreement. The plates may be post-weld heat treated at elevated temperatures not exceeding 1100°F (595°C) providing test coupons are subjected to a thermal cycle to stimulate such fabrication operations, as described in S9. Verification or simulation is not necessary for heating at temperatures not exceeding 400°F (205°C).

 

For a thickness of 3" if the design/ service conditions calls for PWHT, I would think the best option would be carry out  through the Simulated Heat Treatment ,see the base metal properties, and then to decide PWHT.

 

What're  the code or specifications for design and construction???

 

Thanks.

 

 

 

Pradip Goswami,P.Eng.IWE

Welding & Metallurgical Specialist & Consultant

Ontario,Canada.

Email-pgoswami@sympatico.ca,

pgos...@quickclic.net

 

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From: material...@googlegroups.com [mailto:material...@googlegroups.com] On Behalf Of Philip, Taiye (Lagos)
Sent: Thursday, July 21, 2011 8:08 AM
To: material...@googlegroups.com
Subject: [MW:11848] POST WELD HEAT TREATEMENT OF API 2W GR 50/API 2MT1 PIPES WITH THK 3''

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[Ramin Kondori]

Dear Philip:

Whenever you have high thickness + welding (structural grades) then after welding you have high 3D residual stresses that can tear the plate even before service...!!!

Be careful...!!!

1. Preheat shall be always controlled...
2. Interpass temperature too since in jackets you should not overheat such TMCP plates otherwise the strength and toughness will drop. you do not want that...!!!
   
3. For weld layers near to joint's sidewalls use low heat input process (or techniques) but for the other layers it's not that critical.
4. For cap run, first deposit weld metal on toes then deposit weld runs in between

• PWHT is a must but check with material certificate, do not exceed the tempeatures specified there...

Whatever you do be aware that:
HAZ toughness will drop if you overheat the base metal
and
High residual stress will be there because of the large amount of weld

Additionally:

Do not stop welding untill at least 30% to 50% of weld is completed
Maybe you Have to PWHT when 1/2 thickness was completed (they do this in critical cases)

 
Regards

Ramin  Kondori

   QC/Welding Engineer 

         IWE AT 0070

   

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