Pressure Boundry in API -650 tanks

[k7moorthi]

Dear Experts..............

Can you explain, what all are the pressure boundary in API-650 tank fabrication with reference from the code.

 

[M.M. Sunilkumar]

As stated in the Code, API 650 specifies  minimum requirements for the design, material, construction, and testing for aboveground, open and closed-top, cylindrical steel storage tanks in different capacities and sizes, roughly equating to the pressure of the atmosphere (not greater than the weight of the roof plates). For closed tops the roof may be cone, dome, umbrella or floating, with or without a fixed roof. If additional requirements are met, higher internal pressures are permitted.  API 650 only covers tanks that support the whole bottom evenly  and tanks in non-refrigerated service that have a maximum design temperature of 200 degrees F.  It stipulates  a minimum material thickness of 3/16 inch..

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On Mon, May 1, 2017 at 7:01 PM, k7moorthi <k7moo...@gmail.com> wrote:

Dear Experts..............

Can you explain, what all are the pressure boundary in API-650 tank fabrication with reference from the code.

 

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[k7moorthi]

Could you please explain about pressure boundaries instead of pressure parts.

On Tuesday, 2 May 2017 13:11:48 UTC+3, LINUS wrote:

As stated in the Code, API 650 specifies  minimum requirements for the design, material, construction, and testing for aboveground, open and closed-top, cylindrical steel storage tanks in different capacities and sizes, roughly equating to the pressure of the atmosphere (not greater than the weight of the roof plates). For closed tops the roof may be cone, dome, umbrella or floating, with or without a fixed roof. If additional requirements are met, higher internal pressures are permitted.  API 650 only covers tanks that support the whole bottom evenly  and tanks in non-refrigerated service that have a maximum design temperature of 200 degrees F.  It stipulates  a minimum material thickness of 3/16 inch..

Check out articles on Storage Tanks at www.linuserve.com

On Mon, May 1, 2017 at 7:01 PM, k7moorthi <k7moo...@gmail.com> wrote:

Dear Experts..............

Can you explain, what all are the pressure boundary in API-650 tank fabrication with reference from the code.

 

--
http://www.linkedin.com/groups/MaterialsWelding-122787?home=&gid=122787&trk=anet_ug_hm
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
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[M.M. Sunilkumar]

Obviously surfaces restraining pressure would form pressure boundaries. I think you need to be clear about what you want to ask.

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[k7moorthi]

Dear Mr.Sunilkumar,

In my project one of the contractor fabricating the API-650 tank for Fire water storage, he has submitted the WPS for all joints separately, but during the welding he has welded the bottom plate lap joints with E7024 (this WPS approved for roof welding)  instead of E7018 ( this WPS approved to weld bottom plate lap joint), while ask about this he says as per API-650 the bottom plates are not in the pressure boundaries. as he quoted that API-650 12th edition (2014) Para: 4.2.1.5 & 4.2.10.1.

kindly clarify.

[M.M. Sunilkumar]

Dear  Moorthi,,

Now I see the issue.

Your contractor is using  specious arguments to justify a deviation. 

Electrode selection depends on a lot of factors and not whether in the Contractor's opinion the component is pressure part or not.It may be noted that several non pressure pars are  also welded with E-7018.

The clauses he refers to relate to impact requirement. He is bound to follow approved WPS unless your inspection approves revised WPS.

Bottom plates though assumed to be uniformly supported at bottom are subject to static head and in cases where vacuum exists, bottom supported on grillage, double bottom tanks, possibility of settlement  etc, stress analyses are carried out.

The electrode he has selected seems suitable for downhand fillet welding if toughness is not an issue.

Regards,

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[k7moorthi]

Dear Mr.Sunilkumar,

Thanks for your clarification, and it's not having impact requirements. And we are not that department to approve the WPS, that is done by separate department, hence we escalated the issue to the concern department. But once again in our project specification holding the issue of F1 & F2 group electrodes not to be used in bottom plate welding. 

[M.M. Sunilkumar]

All others parameters remaining the same, qualification on F4 (7018) would also qualify welder for F1 and F2.. However if Project Specifications were available to Contractor at time of tendering, it takes precedence unless a deviation is accepted and contractor is bound to follow it.

Regards,

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