Re: [MW:3823] SS distortion control

Greeting All,

Distortion can be minimize by following on 300 series Austenitic stainless steel.

1.       Rap the water immersed cooton cloth on both side of the pipe(close to the joint).

2.       Add the water during subsequent pass on the cotton cloth( rap on the job close to joint).

3.       Clean the joint with  normal drinking water in-between subsequent pass.

(water have the dual benefit as it will control distortion plus control the sensitization (prohibited to from the chromium carbide)

 

 For control the internal protrusions ..

1.       control the back purging pressure.

 

 

Regards,

Bhaskar Kale

On Sat, Dec 12, 2009 at 1:18 PM, Darcy Morin <damorin@shaw.ca> wrote:

Especially on NPS 6 and above, heat input becomes problematic. One issue could be that your welders are using cosmetic 'wash' passes with GTAW on the cover pass of the weld. These welds should be performed with a maximum of 2 passes.  

Also, re-work in localized areas of welds (RT or PT failure for example) may neccesitate the cut-out of entire welds, piping sections and fittings in order to meet code requirements, material specifications or end user requirements in the finished weld. 

 

ASME B31.3 limits "internal protrusions".

The piping and fitting specifications will limit the acceptable ID of the components which can be extrapolated from measuring the OD.

 

The end user may have service conditions which require minimal turbulence.

Finally, when measuring and determining the extent of the distortion, be cautious to differentiate between misalignment and 'cave-in' type distortion. 

Best regards,

Darcy Morin

API 570 Refinery Piping Inspector   

 

On 2009-12-11, at 20:16, "Rajak, Sanjib  (Bantrel Constructors)" <RajakS@BantrelConstructors.com> wrote:

Hi Guys,

Can anybody through a light on how to control distortion in thin wall Stainless Sch10s piping welding. Fit up looks absolutely good but after welding we see cave in on weld upto 5/32".what is the acceptable limit or is there any acceptance critiria for cave in condition.

Thanks,

Sanjib

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