The Code is not explicit about the use of 'non continuously welded'
stiffener though it talks about permitting intermittently staggered
welding at the stiffener to shell interface for which it gives the
following rule among others:
[UG-30 c): The total length of weld on each side of the stiffening
ring shall be:
(1) not less than one-half the outside circumference of the vessel for
rings on the outside; and
(2) not less than one-third the circumference of the vessel for rings
on the inside.]
Even Section III has the same wording for nuclear pressure vessel
stiffeners.
But, remember UG-29 e) says the following:
[Any internal stays or supports used as stiffeners of the shell shall
bear against the shell of the vessel through the medium of a
substantially continuous ring.]
The use of the phrase 'substantially continuous ring' is very
important here. A substantially continuous ring definitely cannot be a
ring that is fabricated by staggered welding.
So far as the Code goes, it is only concerned about the design of
pressure retaining components and gives minimum guidelines for the
same. Everything else is left to the engineering judgement of an
engineer who is supposedly sound in his or her engineering
fundamentals.
Per the Code [The Code is not a handbook and cannot replace education,
experience, and the use of engineering judgment. The phrase
engineering judgment refers to technical judgments made by
knowledgeable designers experienced in the application of the Code.
Engineering judgments must be consistent with Code philosophy and such
judgments must never be used to overrule mandatory requirements or
specific prohibitions of the Code.]
If I were your customer and if you were to use staggered welded
stiffener ring, I would certainly ask you to provide structural
calculations proving that this construction does not compromise the
design (the same way I would expect calculations for the saddle
support or lugs or legs, where seismic or wind loads apply over and
above the static and weight loads).
Regards
Johnson Madukayil, P.Eng.
Canada
On Mar 31, 12:57 am, "Devang Patel" <deva...@inoxindia.com> wrote:
> If that is the case than why ASME permit a staggered weld between shell to stiffeners weld? As per my opinion we can do staggered weld for stiffeners fabrication b'cas same redial pressure load + Redial shear load (please refer UG-30(e))acting on stiffener weld.
>
> Regards,
>
> Devang Patel
> Manager Engineering
>
> INOX INDIA Ltd.
> Ph :+91-265-3056392-3056100
> Fax :+91-265-2333398-2341449
> email : deva...@inoxindia.comwww.inoxindia.com
>
> ----- Original Message -----
> From: Yagnesh Desai
> To: materials-welding@googlegroups.com
> Sent: Tuesday, March 31, 2009 9:42 AM
> Subject: [MW:1850] Re: 1841] Re: 1838] Fabricated Stiffeners
>
> Its so because the design is guided by buckling and not induced stress.
>
> "Somesh Kumar Pandey" <Somesh.Ku...@kbr.com>
>
> "Somesh Kumar Pandey" <Somesh.Ku...@kbr.com>
> Sent by: materials-welding@googlegroups.com
> 03/30/2009 11:58 AM Please respond to
> materials-welding@googlegroups.com
>
> To
> <materials-welding@googlegroups.com>
>
> cc
>
> Subject
> [MW:1843] RE: 1841] Re: 1838] Fabricated Stiffeners
>
> Devang,
>
> As per ASME it is no where specified for external pressure design to use
> the staggered intermittent weld to fabricate the stiffeners. Hence, in
> my opinion it should not be used. You have to meet the required moment
> of inertia for the provided section. It is advisable to fabricate the
> stiffener with continuous welding only.
>
> Regards
>
> Somesh Kumar Pandey
> KBR Energy & Chemicals
> 79 Anson Road #20-01
> Singapore 079906
> Office: +65 6210 7459
> Fax: +65 6210 7250
> Email: Somesh.Ku...@kbr.com
>
> -----Original Message-----
> From: materials-welding@googlegroups.com
> [mailto:materials-welding@googlegroups.com] On Behalf Of Devang Patel
> Sent: March 30, 2009 1:48 PM
> To: materials-welding@googlegroups.com
> Subject: [MW:1841] Re: 1838] Fabricated Stiffeners
>
> Thanks, Somesh,
>
> Yes, you are write but my question is can we do staggered intermittent
> weld
> to fabricate the stiffeners?
>
> ASME Sec. VIII Div-1 told about the stiffeners to shell welding only.
>
> Regards,
>
> Devang Patel
> Manager Engineering
>
> INOX INDIA Ltd.
> Ph :+91-265-3056392-3056100
> Fax :+91-265-2333398-2341449
> email : deva...@inoxindia.com
> www.inoxindia.com
>
> ----- Original Message -----
> From: "Somesh Kumar Pandey" <Somesh.Ku...@kbr.com>
> To: <materials-welding@googlegroups.com>
> Sent: Monday, March 30, 2009 10:45 AM
> Subject: [MW:1840] RE: 1838] Fabricated Stiffeners
>
> Dear Devang,
>
> Fabricated stiffeners can be used in external pressure design of shell
> of
> pressure vessel as per ASME Sec. VIII Div.1. You can refer UG -29 , Fig.
> UG 29.1 , UG-30 & Fig. UG-30 of ASME Sec. VIII Div.1 for more details on
> the acceptable method of attaching stiffener rings
>
> Regards
>
> Somesh Kumar Pandey
> KBR Energy & Chemicals
> 79 Anson Road #20-01
> Singapore 079906
> Office: +65 6210 7459
> Fax: +65 6210 7250
> Email: Somesh.Ku...@kbr.com
>
> -----Original Message-----
> From: materials-welding@googlegroups.com
> [mailto:materials-welding@googlegroups.com] On Behalf Of Devang Patel
> Sent: March 30, 2009 12:24 PM
> To: materials-welding@googlegroups.com
> Subject: [MW:1838] Fabricated Stiffeners
>
> can we use fabricated stiffeners in external pressure design of shell of
>
> pressure vessel?
>
> If, yes than please tell, can we use staggered intermittent weld to
> fabricate T or Angle?
>
> Please reply.
>
> Regards,
>
> Devang Patel
> Manager Engineering
>
> INOX INDIA Ltd.
> Ph :+91-265-3056392-3056100
> Fax :+91-265-2333398-2341449
> email : deva...@inoxindia.com
> www.inoxindia.com
>
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