Pipe machined from Plate

[michigander]

If one needed a pipe 7" OD x 5" ID x 12"lg, could this be machined from a 7" thick slab of plate? Are there implications with the grain direction of the plate? I just have an unusual circumstance where I have a piece of plate available and the pipe is a long lead item.

Thanks in advance.

 

[eyec]

maybe if it is not to be used in high energy piping (due to seam welding)

not really enough information to give a reasoned answer though.

 

[SnTMan]

"Are there implications with the grain direction of the plate?"

Looks to me like any laminations would be subject to the hoop stress. Might be better to make the length run thru the plate thickness.

Regards,

Mike

 

[michigander]

I believe everything is there. There is no seam welding. If I take a piece of 7" thk plate and cut a piece that is 7" wide x 12" lg, and then I machine it round, and bore a hole in it, I now have a 7" OD seamless piece of pipe x 12" lg that has been machined from plate. Is this legal? If it is legal, are there issues or concerns with the orientation of the pipe as it is made from the plate regarding grain orientation within the plate? If I am still incomplete, please address specific questions so I can fill in any blanks.

Thanks again....

 

[SnTMan]

michigander, "legality" or lack of would depend on the Code of construction, if any.

You might consider the following:
1)Get a piece of your plate through-thickness tensile tested to confirm tensile strength.
2) UT your chunk before putting a lot of work in it.
3) Examine the heck out of the finished part, and also possibly in process, to confirm no laminations.

Regards,

Mike

 

[JStephen]

Nobody makes pipe that way, so there's not any specification for pipe made that way. So if you're needing to meet some pipe code, it probably won't. If you have some miscellaneous application that doesn't require compliance with any particular standard, you could do it that way, but it might be hard to predict the strength, if that was critical, in the through-plate direction.

It's not uncommon to roll pipe from plate and weld, although I have no idea what kind of equipment would be required to do that with small-diameter heavy-wall pipe.

 

[pvrerate]

Since your part is only 12" long could you purchase a 7" diameter forging and have it bored to the required ID? In the end this may be more economical and you would end up with a component that would meet some standard such as A-105 or whatever the required metallurgy would be.

 

[stanweld]

mishigander,
Yes you will no doubt have significant mechanical property variences because of grain structure orientation. A better approach would be to use pvrerate's recommendation or to machine round bar stock.

 

[MJCronin]

What is the design pressure for this so-called pipe ?

Why do you need 1" wall thickness at this diameter ?

 

[michigander]

Thanks for the responses. You have all confirmed my concerns and fears. This was the case of client pushing due to time constraints. A forging had been ordered but rejected on receipt. Time became an issue and the client suggested using plate as piece was available. I didn't think this was appropriate to machine due to the grain issues.

Thanks again everyone.

 

[EdStainless]

Good call MI.
I would even feel better about trepanning a 7" out of a much larger OD round forging than trying to use plate.
With plate the load directions are just wrong, and any directionality of properties would hurt you.

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Plymouth Tube

 

[racookpe1978]

As above, Get a round forging slightly over 7.0 inch dia x 12 long. Machine the OD to your 7 inch, and bore out the center to 5 inch ID.