Reject/Accept of punch marks on SS line
Reject/Accept of punch marks on SS line
(OP)
A visual inspection was done on a 12" SCH 40 (10.31mm thick) stainless steel pipe for possible damage. I was asked to investigate if punch marks(+/- 1mm deep) measured on pipe will be detrimental. No fatigue stresses are predicted for this line. Punch marks were introduced to start welding of smaller line to the 12"line. Location of this tie in has now been changed.
API 5L states that a discontinuity should not be more than 12.5% of the pipe wall thickness. Hence any discontinuity more than 1.29mm is not allowed and line should be scrapped.
My concern is the measured thickness is VERY close to the max allowable thickness of this discontinouity. At what point can i say we should reject/accept this pipe?
Thanks in advance
API 5L states that a discontinuity should not be more than 12.5% of the pipe wall thickness. Hence any discontinuity more than 1.29mm is not allowed and line should be scrapped.
My concern is the measured thickness is VERY close to the max allowable thickness of this discontinouity. At what point can i say we should reject/accept this pipe?
Thanks in advance





RE: Reject/Accept of punch marks on SS line
http://www.welding-advisers.com/
RE: Reject/Accept of punch marks on SS line
What code governs your facility and what is the service, MAOP, Op temp, etc?
Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website: www.oil-gas-consulting.com
RE: Reject/Accept of punch marks on SS line
RE: Reject/Accept of punch marks on SS line
In either case I wouldn't be too concerned about punch marks unless they are deep and very sharp. There are probably tooling and handling marks in the surface deeper than these.
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