Raised face finish....... Acceptable or not?

[Thirlmere]

Just after some feedback on this valves raised face......... the black was applied to show up the finish a little better.
My question is simple.

Acceptable or not, and if not... why not?

Cheers

 

[BJI]

Thanks for the picture but it is hard to assess the average surface roughness by eye. Is it within the range of ASME PCC-1 Appendix C?

 

[IRstuff]

It looks intentional; so is it non-conforming to your spec?

And, does it matter? Is it part of the functional surface of the valve?

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[mk3223]

Was the fabrication followed the design Code? And, what's the comment from the inspection?
IMO, it isn't the Engineer's responsibility to decide if it's deviated from the Code.

 

[0707]

What is behind of your question?


luis

 

[Thirlmere]

My question really is does this finish conform to that specified in ASME B16.5 for raised face surface finish.
I know if mentions a certain roughness, but isn't that roughness supposed to be done with a round nosed or 90 degree tool, which this obviously isn't.

Reject or accept?

Cheers

 

[saplanti]

It does not look metal, it seems textile from the photo. Are you sure that photo shows a metal surface?

 

[BJI]

Looks to possibly be chatter during machining, likely caused by a blunt tool. With the blackened contrast it look ok, for a visual inspection of a picture that is. It looks like you have a continuous groove, and none of the imperfections appear deep enough to be classed as radial defects. So provided it meets the average roughness requirements, and it has passed a pressure test, then I would think it should be suitable. However, depends on the gasket type, pressure class, service conditions, contract specifications, purchaser (who assumes the risk), etc, so we can't tell you whether to accept or reject.

If you are looking for a reason to reject, B16.5 states the following to assess if it meets code (under 6.4.5):

The finish of the gasket contact faces shall be judged by visual comparison with Ra standards (see ASME B46.1) and not by instruments having stylus tracers and electronic amplification.

So a visual comparison to a surface finish gauge might be enough to demonstrate that it hasn't met the requirements of 6.4.5.3, therefore, reface or replace.

 

[Thirlmere]

Thanks guys..... Firstly YES it's definitely a metal part I'm looking at... .... Secondly, is the surface "finish" all that counts?. I was under the impression that finish had to be achieved using a certain tool that allowed it to bite into the gasket.
Would you accept a brand new valve with that finish?

 

[The Obturator]

If this is the surface finish of a RAISED FACE Flange acc. to B16.5, the finish should be 3.2 to 6.3 micro meters, unless a different finish is specified to satisfy a gasket requirement. From the photo I don't know whether this is a small section or larger. You need to use a Surface Finish Comparator set to determine acceptance or not. The picture may look like rough grooves, but if it at X 5 magnification or so, it might even appear smooth. Can't tell from a picture.

Per ISO-4126, only the term Safety Valve is used regardless of application or design.

 

[Thirlmere]

The trouble with using a surface finish comparator is they only have standard machining finishes like turning and milling.

This finish is such that's its difficult to determine how it was acheived

Regards