Assessment of internal corrosion defect
Assessment of internal corrosion defect
(OP)
Hi All,
Based on the ILI data, we are planning to excavate internal corrosion defect in our pipe line. Once excavated what sort of NDT methods can be used to find out the length, bredth and wall loss of this internal corrosion defect?
Based on the ILI data, we are planning to excavate internal corrosion defect in our pipe line. Once excavated what sort of NDT methods can be used to find out the length, bredth and wall loss of this internal corrosion defect?





RE: Assessment of internal corrosion defect
- Hand Held Low Resolution Yoke: looks for cracks, surface breaking indications, etc.
- A variety of hand held UT probes and tools are available that are good for evaluating either metal loss (general or pits) or cracks.
- Automated UT is available and consists of a motorized arm that travels vertically and horizontally on rails to map out the anomalies.
- Laser mapping can be used for external corrosion and is more accurate than traditional methods such as pit gauges and depth micrometers.
- Eddy current lift off measurement arrays can be used.
and of course, you could always cut out the section of pipe and then open it up to visually examine and evaluate internal corrosion defects.
RE: Assessment of internal corrosion defect
Does the report say anything about the wall loss?
RE: Assessment of internal corrosion defect
with a wall loss of 19%.
are planning to have SLOFEC inspection method.Have any one with passed experiance with this system? How accurate for the size of the defect which I'm face with?
RE: Assessment of internal corrosion defect
If you know exactly where the corrosion is, x-ray is also a good way of determining length & breadth........
To be honest though, this is quite a sizeable area of 6" pipe, and I would be just as concerned with what is causing the corrosion, rather than sizing it!
RE: Assessment of internal corrosion defect
Good luck
RE: Assessment of internal corrosion defect
I'd consider taking accurate river bottom profile measurements of the anomaly and evaluating using the RSTRENG EFFECTIVE method which takes into account this profile rather than just applying the deepest spot to the entire length.
More info on RSTRENG EFFECTIVE can be found in the paper "Continued Validation of RSTRENG", PR 218-9304, Pipeline Research Committee, AGA (authors, Kiefner, Vieth, and Roytman)
RE: Assessment of internal corrosion defect
From the sample we got it from the internal surface of the pipe (black powder) mineralogy of scale deposit shows
Sulpher - Dominant
Magnetite (Fe3O4) - Sub dominant
Siderite (FeCO3) - Accessory
Mackinwaite (FeS.9) - Trace
will these composition aid the corrosion process?
RE: Assessment of internal corrosion defect
MAOP- 7.322 MPa
Dia meter - 8"
Wall thickness = 4.78 mm
Material - API5LX42
Design factor- 0.72
RE: Assessment of internal corrosion defect
RE: Assessment of internal corrosion defect
RE: Assessment of internal corrosion defect
Also my experience with metal loss corrosion is that automated UT scans are the way to go. does hovever requirer an experienced NDE "guy".
Best of luck.