12" dia drum, SA-53 B - UNEVEN OD

[mihir5577]

Hi,
Pls. i want to know, that, if the 12" & 8" std. wall, SA-53 B PIPE was fell down and od changed to oblong, than is this allowed as per ASME IV?
what is allow for UNEVEN OD of pipes as per ASME IV????
Pls. reply me ASAP.
Thanks
MIhir5577

 

[metengr]

OK, after reviewing ASME B&PV Code, Section IV, Article 8, Fabrication Requirements, under paragraph HW-813 Distortion, the cylinder or barrel of a shell or drum shall be circular to within 1% of the mean diameter, based on the differences between the maximum and minimum mean diameters at any section...

The Code does not distinguish the causes of distortion, they could be thermal, handling, welding, etc.....

 

[mihir5577]

Hi,
Thanks for quick reply. Now i want to know, that if the distortion is more than 1% of the mean diameter?, than is it acceptable or can we fix it?
pls. guide me.
Thanks in advance
Mihir5577

 

[metengr]

mihir5577;
Do you have a copy of ASME B&PV code, Section IV? Yes, you can repair it by various fabrication methods.

 

[gr2vessels]

mihir5577,

The oblong shape you mentioned is not any longer a shell of revolution, hence it will end up with variable internal diameter. It is however, a pressure vessel able to contain pressure. This applies only for a reasonable, gradual change of the internal radius, not for a warp generated by the vessel falling of the crane hook. Provided also that the material was not damaged structurally and you can prove that with various testing methods, you can recalculate the shell thickness based on the maximum internal radius (ie the flat area of the shell). In absence of any dimensional detail of your vessel, it would be speculative to further advise what can you do (re-rate the vessel or discard it and build a new one, etc).
The bottom line is that you might have a reasonable chance to re-use it, but only with the help of a vessel engineer. There could be other issues related to insurance, local government regulations, compliance with the Code for repairs, etc.

Cheers,

gr2vessels

 

[deanc]

gr2vessels:

If I read your post right,you suggest by redesign you can wiggle away from the damage and use the vessel. If this was a used or in service item.....maybe. If it is a new item I doubt I would accept it,especialy if it was designed as a "round" vessel to begin with. Just not ethical in my book.

Now if you are talking lots of money,the customer has a deadline,it will not affect final use,and everybody and their brother buys it off in writing.....OK,We can talk.

Since it is pipe...scrap,reform it on a plate roll,jack the damaged area back in shape,or cut the damaged area out and use a flush patch.

Anyhow...just my opinion

 

[lostsailor]

mihir5577,
I concur with deanc's post. You would have to give pipe with the specifications you mentioned a serious drop to knock it out of round if you now describe it as oblong.
Regards,
RLS

 

[vpl]

metman and gr2vessels: You appear to be talking about vessels, the OP is talking about a pipe. Do your comments still apply? (This is for my own education)

Also, I rather agree with lostsailor. It seems it would take more than just a fall to distort a pipe - like maybe something heavy falling on top of it.

mihir5577: Out of curiousity, what diameter pipe, what's the application, how did it fall (or what fell on it)?

Patricia Lougheed

Please see FAQ731-376 for tips on how to make the best use of the Eng-Tips Forums.

 

[gr2vessels]

vpl,

You're right, I got carried away thinking of a PV. A small piece of CS pipe, deformed for any reason, doesn't warrant any effort in repair (unless it's flooding your house).
However, I don't regard inethical to try salvage an equipment where people put in there effort and value of design, fabrication, hopes of best performance. I also don't believe that using the Code requirements to salvage an equipment is immoral. It's also not much of an engineer discarding a damaged equipment (without confirmed irreparable damage) on emotional basis. Perhaps somewhere the money comes easy..

Best regards,

gr2vessels

 

[metengr]

vpl;

metman (metenger) and gr2vessels: You appear to be talking about vessels, the OP is talking about a pipe.

Section IV like other Sections of the ASME B&PV Code do not really single out specific wrought product forms for end use. In this case, the OP referred to pipe being used in reference to an ASME Section IV application. Section IV addresses pipe and tube products for use in pressure retaining applications. What was mentioned above is applicable in evaluating an out of round pipe, drum, header (cylinder) if it is fabricated from seamless pipe, forged pipe or forged and bored pipe.

 

[deanc]

gr2vessels:

Didn't say it was immoral,only my opinion on ethical practice.

Over the years I have seen all sorts of things take place and this has resulted in me being rather....well lets just say "skeptical".

deanc

 

[gr2vessels]

OK, all good.
However, where is mihir and details of his pipe. Afterall, he asked for help to doctor the sick pipe. Probably the repair solutions above have covered his requirements.
gr2vessels

 

[GenB]

I would not use a damage pipe in a PV construction specially ERW which can open unexpectedly.
one cure would be (if the damage is not sever:
formeit back then PWHT.