[MW:8172] RE: 8169] RE: 8153] repair of erosion on steam turbine casing

Dear Azril ,

 

GS22Mo4 is a cast steel, nearest ASME/ASTM grade being SA-A-217-WC1(C-0.5Mo). As explained rightly by Mr. Henning , turbines are not with the jurisdiction of any boiler and pressure vessels codes. They're built to  OEM's specifications, hence they're outside the scope of any ASME codes. 

 

However following ASME Sec-IX qualified WPS and PQR for any repair of eroded areas would be a good practice and many cases the OEM's inspectors may insist on this This would ensure, that correct welding consumables are used for repair. the properties of the weld equals or exceed the base metal and meet clients requirements. A groove welded PQR qualified on C-0.5Mo steel ,i.e ASME Sec-IX-P3 material meeting all requirements would be the correct document for performing weld repairs.

 

Thanks.

 

Pradip Goswami,P.Eng.

Welding & Metallurgical Specialist & Consultant

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

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From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of John Henning
Sent: Tuesday, November 09, 2010 9:25 AM
To: materials-welding@googlegroups.com
Subject: [MW:8169] RE: 8153] repair of erosion on steam turbine casing

As far as ASME Codes are concerned, the turbine island is not considered to be within the scope/under the jurisdiction of these Codes – NOT Sc I, Sc VIII, nor B31.1.  All major turbine manufacturers;  GE, Westinghouse, Siemens, have been zealously defending this historical code break.  Therefore, you are not required by Code to weld to a WPS/PQR - however local authorities, the insurance agency, or the owner may require you to have a WPS/PQR prior to welding.  It is good practice to have a WPS (even if not supported by a PQR) so that your welder(s) know how the weld is expected to be performed. 

 

In regard to the WPS ( other than the turbine island ) if the weld build up is solely to restore thickness, then a suitable groove weld test will be sufficient as long as essential variables are met, particularly base metal thickness. 

 

John

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of Azril Johari
Sent: Monday, November 08, 2010 5:57 PM
To: materials-welding@googlegroups.com
Subject: [MW:8153] repair of erosion on steam turbine casing

 

Dear Friends,

We are requested to repair erosion on steam turbine casing. We will have to weld build up and machine back to specified dimension. The material of the casing is GS22Mo4. Client do not dictate any standard to be used.

I have a few fundamental questions:
1. Do we really need a WPS for this work since there is no joining (just weld build up)?
2. If we need a WPS, should we develop WPS using "groove" or "overlay"? We intent to use AWS B2.1.

Hope to get your feedback.

Thank you.

Azril Dahari

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