Re: [MW:11852] POST WELD HEAT TREATEMENT OF API 2W GR 50/API 2MT1 PIPES WITH THK 3''

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...!!!

Preheat shall be always controlled...
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...!!!
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.
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

On Thu, Jul 21, 2011 at 4:38 PM, Philip, Taiye (Lagos) <Taiye.Philip@deltaafrik.com> wrote:

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.philip@worleyparsons.com

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