We are one of the leading vessel manufacturers for Saudi Aramco/Sabic in K.S.A. I just got opinion from my material group regarding the surface finish issue. Refer the below reply
Regards
M.Masthan
From: Salman Farsi [mailto:sfarsi@olayandescon.com]
Sent: Thursday, June 10, 2010 7:38 AM
To: masthan; Muhammad Umer (QAQC)
Subject: RE: [MW:5469] Flange back side surface roughness.
As far as Sec IIA is concerned it states that machined surface finish (other than surfaces having special requirement) shall not exceed 250 AARH.
Which means that complete flange surface should be followed under 250 AARH condition.
However Saudi Aramco also sticks for the same.
Hence the flange cannot be accepted as shown in the picture as far as code point of view.
But in practical it can be accepted, as that (affected) area is not in the contact with the fluid, and can be accepted with client consultation.
Also refer to statement “other surfaces having special requirement” may denote to gasket face as for critical services (such as the one in SAFCO, where we have fabricated an ammonia exchanger) generally requirement for the gasket face restrict to 63 to 125 AARH.
This is what is my understanding.
Regards,
Salman Farsi.
From: masthan [mailto:sabreenbahira@hotmail.com]
Sent: Wednesday, June 09, 2010 9:02 PM
To: Salman Farsi; Muhammad Umer (QAQC)
Subject: FW: [MW:5469] Flange back side surface roughness.
Please check the acceptance & reply
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of AGUSTIN JIMENEZ
Sent: Tuesday, June 08, 2010 8:56 PM
To: materials welding
Cc: INSPECTORES DE EQUIPOS ESATICOS
Subject: Rv: [MW:5469] Flange back side surface roughness.
Hello.
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.
Agustin
----- Mensaje reenviado ----
De: Bathula Raghuram (Mumbai - PIPING) <R.Bathula@ticb.com>
Enviado: mar, junio 8, 2010 3:20:32 AM
Asunto: [MW:5455] Flange back side surface roughness.
Dear members, please share your opinion.
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
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, |
| Quality Manager, HSSE - MR |
| Process Systems |
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