BE CAREFUL! Ensure that structure holding the Coke drum is designed to
take loads created by water weight which will be really HUGE.
Generally, equipment wall thicknesses are suitable for hydrotest or
pneumatic test whichever way you go but must confirm this bit with
coke drum manufacturer. Initiate discussions with client if they can
reduce pneumatic test pressure (most of the clients restrict air
pressure to 7 barg) and supplement with NDE inspection eg. radiography
after the test.
In my opinion, you should share this problem with client's consultant
(PMC) and client Technical Authority (TA) as risk involved is quite
high.
Thanks,
Jatin 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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>
> InspectionNon Destructive Testing-HSE.GOV.UK.pdf
> 258KViewDownload
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