Re: [MW:7271] Re: FW: COKE DRUM PNEUMATIC TEST

Hi friends,

 

My apprehension is that, simply  pneumatic test  should not be used in lieu of hydrotest. Please read the qoute given below

 

As per  UG -100 (Pneumatic Test) of ASME Section VIII Division I,

 

pneumatic test may be used in lieu of the standard hydrostatic test prescribed in UG-99 for vessels:

 

(1) that are so designed and/or supported that they cannot safely be filled with water;

 

(2) not readily dried, that are to be used in services where traces of the testing liquid cannot be tolerated and the parts of which have, where possible, been previously tested by hydrostatic pressure to the pressure required in UG-99.

 

Moreover we have to follow UW-50

 

UW-50 NONDESTRUCTIVE EXAMINATION OF WELDS ON PNEUMATICALLY TESTED VESSELS

 

On welded pressure vessels to be pneumatically tested in accordance with UG-100, the full length of the following welds shall be examined7 for the purpose of detecting cracks:

 

(a) all welds around openings;

 

(b) all attachment welds, including welds attaching nonpressure

parts to pressure parts, having a throat thickness

greater than 1⁄4 in. (6 mm).

 

 

 

 

 

 

  

 

 

 

On Wed, Sep 29, 2010 at 2:35 PM, JP <jatin.patel@worleyparsons.com> wrote:

Hi,

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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