Are pads must for Platform clips???????
Are pads must for Platform clips???????
(OP)
Hi all,
Are pads must for platform clips/ Pipe support clips?
I referred ASME Sec.VIII Div.1 App.G, under the sub topic G-2. What i understand is, that clips are not necessary until our shell is strong enough to withstand the load.....but when used it may serve us to reduce the secondary stresses over the vessel
Please provide ur view over my understanding.
Thanks in advance
Are pads must for platform clips/ Pipe support clips?
I referred ASME Sec.VIII Div.1 App.G, under the sub topic G-2. What i understand is, that clips are not necessary until our shell is strong enough to withstand the load.....but when used it may serve us to reduce the secondary stresses over the vessel
Please provide ur view over my understanding.
Thanks in advance





RE: Are pads must for Platform clips???????
Now if you have large loads, WRC-107 may force you to use pads.
Alloy shell with carbon steel clips you may want to use pads
PWHT vessel you may want to use pads in case clips need to be mooved due to being located incorrectly or platform not matching.
RE: Are pads must for Platform clips???????
What is mandatory is that you, as the engineer/designer, consider and evaluate all of the loadings on the vessel. Based on my experience, if I were to put a 6' x 6' top platform on a vessel and I'm attaching it with vertical legs to a 4' diameter head/shell which is 3" thick and at 400°F - I will not need repads since it is a relatively light load and transferred into the shell through shear. Take the same platform with unusually high live loads (e.g. designed to set a heavy safety valve down on it for maintenance, etc.) and put it on a 20' diameter head which is 3/4" thick and I'll have to take a close look at putting repads on since it is a relatively heavy load transferred into a large diameter thin shell through radial loading.
As vesselfab pointed out, there may be other reasons to use repads such as changes in metallurgy or to allow a bit of margin for post-PWHT changes.
There are also reasons to avoid repads, such as on vessels subject to fatigue where a fillet weld is detrimental, vessels subject to thermal shock where the differential temperature between a shell and repad could be detrimental, and my personal favorite: It is impossible to determine wall thickness on the run via UT when a repad is blocking access to the head or shell.
jt
RE: Are pads must for Platform clips???????
Frankly, I don't want my minimum shell thickness dictated by structural attachment loadings. And I don't want my primary pressure containment envelope having to deal with point loads.
If the manager/engineer doesn't like the dollars involved, then we have the arm wrestle - but as far as I'm concerned, it's a good practice.
To those who have responded, what do you view as the down side of mandating compensation pads?
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RE: Are pads must for Platform clips???????
cheers,
gr2vessels
RE: Are pads must for Platform clips???????
RE: Are pads must for Platform clips???????