Opps, Ralph I fogot to answer your other question about flange facing
imperfections. There isnt a good guide for this other than B16.5 table 3.
This list the permissible imperfections in the flange face finish for new
flanges, but would be applicable for in-service flanges also. Its varies per
NPS flange size. Everett
> thank you. it is small (ok miniscule). but those few millimeter is
sometimes
> a killer if you're going to slip a test blind in a big cooler or reboiler
in
> terms of spreading those flanges. we learn our lesson last turnaround. i
> can still remember the cursing of our riggers and pipefitters because of
> those few millimeter. The hydro itself is not a problem. once you filled
it
> with water (ok with chloride not exceeding 50 ppm), it does not make a
> difference whether we test at 1.5 or 1.3.
>
> oops sorry. i have forgoten to mention, our plant is in the middle of the
> desert (wehre it take as long as 3 months to have those b16.5 flanges
> delivered). im from saudi arabia ( imean the place whre the complex is
> located). by the way, for the benifit of the other, the flange facing
> Everett has pointed out is normally serrated with 125 rms surface. this
> matches with the spiral wound gasket.
>
> thanks again. by the way nichols maybe you can help settle the issue
between
> our chief machinist and me. He says that a smooth surface (mirror
polished)
> is better than a serrated one (phonograph finish) in sealing the flange
> face. Is he correct? and ... have you come across a criteria in
determining
> damage sustain by a flange face (how many scratrches or goucges or nicks)
> before you start refacing (we're using Climax machine). damn those
> pipefitters and millwright.
>
> -----Original Message-----
> From: EVERETT W. NICHOLS [mailto:enichols@bbtel.com]
> Sent: 28 May, 2001 4:41 PM
> To: <a href="/group/PipingDesign/post?postID=6_OaJDkk65MuKbOgKtOCYUJPsySWH8qBJOUTv5cu_IzBLNlQf35hVuw7udaKOz1vjCB2wPM6kcdn6VnlGq14RNmcdX4bPw">PipingDesign@yahoogroups.com</a>
> Subject: Re: [PipingDesign] Hydro Test Pressure
>
>
> Go with the 1.5 value. If you use the ASME B31.3 equation to size your
line
> blind requirements you will find that by using the 1.5 x the PSIG design
> value and then use the 1.3 x the same value the material minimum thickness
> between the two is miniscule. Try it. You could also consider this 1.5 as
> an added safety factor. I would opt for going with off the shelf blinds
> versus homemade. Most manufactures of these blinds design them for full
> B16.5 pressure ratings. If someone was to forget or had a need for a
> permanent blind, then they would hold up to the working pressures. This
> saves from having to sketch, procure and fabricate. Plus the manufactured
> blinds also come with a gasket facing on the blinds. In the USA - Mack
Iron
> Works is a very good supplier. Everett Nichols
>
> ----- Original Message -----
> From: SARE, RALPH H. <SARERH@YANPET.SABIC.com>
> To: <PipingDesign@yahoogroups.com>
> Sent: Sunday, May 27, 2001 12:35 AM
> Subject: RE: [PipingDesign] Hydro Test Pressure
>
>
> > i can understand that Christopher. I don't have a copy of the latest
> B31.3,
> > but if you do - has there been a change in the b31.3 code allowables? Im
> > trying to save on the fabrication of blinds during the coming
turnaround.
> I
> > just want to have a blind that i can use either for piping, tanks,
> exchagers
> > or vessels using the 1.3 factor.
> >
> > -----Original Message-----
> > From: Christopher Wright [mailto:chrisw@skypoint.com]
> > Sent: 26 May, 2001 9:08 PM
> > To: ?
> > Subject: Re: [PipingDesign] Hydro Test Pressure
> >
> >
> > >Has there been any changed to the
> > >latest edition of the process piping code with regarrds to the material
> > >design factor and the hydro test rquirement ?.
> > The change was made to the ASME Code as a result of the increased
> > allowable stress made a couple of yous ago. The proof factor was
> > decreased from 1.5 to 1.3 to maintain the same margin against yielding
> > during the hydrotest. If the piping code allowables didn't change, then
> > the proof factor wouldn't change.
> >
> > Christopher Wright P.E. |"They couldn't hit an elephant from
> > chrisw@skypoint.com | this distance" (last words of Gen.
> > ___________________________| John Sedgwick, Spotsylvania 1864)
> > <a href="http://www.skypoint.com/~chrisw">http://www.skypoint.com/~chrisw</a>
> >
> >
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Received on Tue May 29 15:47:00 2001
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