We have an pipe made from sa 672 cl 22 mat having dia 72" and thk 22 mm used for flair line in refinery. The construction people are taking devation not to do pwht on basis that they will check the hardness value if it comes under limets they will not do pwht.
i want to know that is hardness testing is substitute for avoiding sr or pwht
.
Its design base is asme 31.3
n Patel
> Worley Parsons, London
>
> On Sep 29, 12:14 am, "pgoswami" <pgosw...@quickclic.net> wrote:
> > Hi Sachin,
> >
> > Coke drum is a critical equipment for any refinery, which undergoes many
> > torturous operating cycle. A proper hydrotest after complete fabrication
> is
> > mandatory for the equipment integrity. Under UG-100, Sec VIII, DIV-1
> allows
> > pneumatic Test in lieu of hydro test, but there are hidden dangers in
> > pneumatic test for a vessel of such mammoth size as stated below:-
> >
> > . The pneumatic test pressure per UG-100(a) may be lower(1.1
> times
> > max) than the hydrostatic test pressure of UG-99(b) but it is not
> indicative
> > of a less hazardous test condition. The amount of energy stored in the
> > vessel during pneumatic test is far greater than that stored in a
> > hydrostatic test due to the compressibility of air. A vessel that may
> fail
> > catastrophically during a pneumatic test will be just like a bomb going
> > off; same event for a hydro test will be a little pop and a splash.
> Safety
> > precautions for a pneumatic test need to be far more stringent than those
> > for a hydro test; personnel should remain at a safe distance far away
> from
> > the vessel during the pneumatic test. Nearby equipment is at greater risk
> > during the pneumatic test than a hydro test.
> >
> > The design basis of ASME is on safe and sound manufacturing, not to
> endanger
> > any pressure vessel and human life. I've attached an extract
> fromwww.hse.gov.uk<http://www.hse.gov.uk/> . Look at page 13 of this
> document
> > on pneumatic test. This website has numerous guidelines on health and
> > safety, many related to pressure equipments.
> >
> > I would strongly feel that Hydro test in vertical condition would be
> ideal
> > for such large vessels.Wt of water may prove too much for vessel of this
> > size, if the foundation is not strong.
> >
> > Thanks.
> >
> > Pradip Goswami,P.Eng.
> > Welding & Metallurgical Engineer/Specialist
> > Ontario Power Generation Inc.
> > Email-pgoswami@ <mailto:sympatico.capgosw...@quickclic.net> sympatico.ca
> ,
> > pgosw...@quickclic.net
> >
> > From: materials-welding@googlegroups.com
> > [mailto:materials-welding@googlegroups.com] On Behalf Of Kavathekar,
> Sachin
> > Sent: Tuesday, September 28, 2010 6:49 AM
> > To: materials-welding@googlegroups.com
> > Subject: COKE DRUM PNEUMATIC TEST
> >
> > Hi all,
> >
> > My vendor has raised concession request regarding pneumatic test instead
> of
> > hydrotest of low alloy cladded coke drums to reduce cycle time.
> >
> > Coke drum size :- 10 M OD X 45 M overall length. As per specification/
> > contract they have to do hydrotest.
> >
> > Please share experts your suggestions for acceptance or rejection.
> >
> > Regards,
> >
> > Sachin A Kavathekar
> >
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> > Ontario Power Generation Inc.
> >
> > InspectionNon Destructive Testing-HSE.GOV.UK.pdf
> > 258KViewDownload
>
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