Re: UT Thickness Verification Old Piping

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Re: UT Thickness Verification Old Piping - Equipment Needs
Posted by: Jim Johnson KM943 , E-mail: jjohnfly@mindspring.com, on May 29, 1999 at 17:00:28 :
In Reply to: UT Thickness Verification Old Piping - Equipment Needs posted by : Michael Crapps on May 19, 1999 at 21:58:04:
: Looking for an inexpensive gage, don't need all the bells
: and whistles, just good performance at a reasonable cost.
: Will need to verify remaining wall thickness of piping
: that has been in service for a number of years - have no way
: to know the as-is condition until we go into a shutdown.
I agree with Jan Verkooijen, you have not presented enough data to make
any determination. A simple thickness gage can lead to misinterpretations.
For determinations of hoop stress you need length, width and depth. What kind of sampling
are you proposing? What materials are being transported? With a simple hand held instrument
using a good sampling technique, what are the odds of finding a critical flaw on your surface area?
You may want to go to an instrumented pig for 100% coverage or computer controled
external scanning (if the surface is good).
I have about 15 years in piping and e/c and there is not a simple answer, nor, typically, a
single piece of equipment which will resolve your problem. I have had pipe rupture between sampling
points (egg in the face). You need to resolve your risk tolerance, not just the inspection equipment issue.
JJ NDT III KM 943
:
: Any leads would be appreciated.

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: : Looking for an inexpensive gage, don't need all the bells : : and whistles, just good performance at a reasonable cost. : : Will need to verify remaining wall thickness of piping : : that has been in service for a number of years - have no way : : to know the as-is condition until we go into a shutdown. : I agree with Jan Verkooijen, you have not presented enough data to make : any determination. A simple thickness gage can lead to misinterpretations. : For determinations of hoop stress you need length, width and depth. What kind of sampling : are you proposing? What materials are being transported? With a simple hand held instrument : using a good sampling technique, what are the odds of finding a critical flaw on your surface area? : You may want to go to an instrumented pig for 100% coverage or computer controled : external scanning (if the surface is good). : I have about 15 years in piping and e/c and there is not a simple answer, nor, typically, a : single piece of equipment which will resolve your problem. I have had pipe rupture between sampling : points (egg in the face). You need to resolve your risk tolerance, not just the inspection equipment issue. : JJ NDT III KM 943 : : : : Any leads would be appreciated.

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