the area of bolt hole is not problem because it area is not in contact with other area, is more important the surface area of gasket, ever that it is in standart tolerance .
No ever we have that follow exactly the recomendation of the standart too we have use logic, common sense and pragmatism.
De: Bathula Raghuram (Mumbai - PIPING) <R.Bathula@ticb.com>
Para: "materials-welding@googlegroups.com" <materials-welding@googlegroups.com>
Enviado: mar, junio 8, 2010 3:20:32 AM
Asunto: [MW:5455] Flange back side surface roughness.
From: Yeleswarapu, Ravi [mailto:Ravi.K.Yeleswarapu@c-a-m.com]
Sent: Tuesday, June 08, 2010 1:14 PM
To: Bathula Raghuram (Mumbai - PIPING)
Subject: RE: Flange back side surface roughness.
Is there any standard reference/interpretation for acceptance of flanges machined surfaces other than raised face like these, could you post this in forum as I am not able to do this.
From: Bathula Raghuram (Mumbai - PIPING) [mailto:R.Bathula@ticb.com]
Sent: Tuesday, June 08, 2010 11:33 AM
To: Yeleswarapu, Ravi
Subject: RE: Flange back side surface roughness.
in my opinion you have right to reject these flanges as per para 12.2, though it is not a gasket seating surface, these serrations act like crevice and may cause corrosion.
However if the service is dry gas and flange connection is inside the building (I.e. protected from rain), you may accept in consultation with ur process designer, as I don' t see any other reason than crevice corrosion for this type of surface finish.
From: Yeleswarapu, Ravi [mailto:Ravi.K.Yeleswarapu@c-a-m.com]
Sent: Tuesday, June 08, 2010 12:16 PM
To: Bathula Raghuram (Mumbai - PIPING)
Subject: Flange back side surface roughness.
Dear Raghuram ,
We have a situation as below:
SS flanges are made as per dimensional standard ASME B16.5 and are rejected as per below clause.
Please refer to the attached specification SA 182, clause 12.2 the machined surfaces shall have a surface finish not to exceed 250 ARH. The surface finish of flanges is more than 250 AAH, hence not acceptable.
Could you please advise whether above is correct to apply, any reference to the overall machined surface acceptance standards for flanges.
| Regards,
Ravi Yeleswarapu |
| Quality Manager, HSSE - MR |
| Process Systems |
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