Some corrosion concerns for girth welds in CRA clad and lined flowlines
It is common practice in the petroleum industry to apply two ASTM standard corrosion tests to corrosion resistant alloys (CRAs) as a means to determine their relative corrosion resistance compared to other alloys and as a quality control method to ensure no manufacturing processes have compromised this corrosion resistance. The ASTM G 48 test for pitting resistance in ferric chloride solution is applied in both cases above and the ASTM A 262 Practice E is used in the latter. The A 262 Practice E is also required by API 5LD. Although the G 48 test has generally been successfully applied for ranking the pitting resistance of stainless steel and some nickel base alloys the application of the G 48 and A 262 tests for manufacturing control and for the evaluation of welding procedures has been less than satisfactory, often leading to conflicting results. This paper will not attempt to explore all of the myriad problems that have been encountered in applying these two tests but instead will focus on two specific problems that are consistently encountered in evaluating the welding of CRA lined and clad linepipe. These two problems are the testing of the inside surface of the liner and root pass of a girth weld to determine the effect of discoloration (heat tint) on the corrosion resistance of the weldment and selective corrosion of the test coupon from the backside (i.e., the side of the cladding or liner on the side nearest the steel) of the test coupon in preference to the root bead side. In both cases the tests are carried out using the G 48 Method A, generally at 22--25 C for 72 hours.
- OSTI ID:
- 423164
- Report Number(s):
- CONF-960525-; TRN: IM9707%%471
- Resource Relation:
- Conference: 28. offshore technology conference, Houston, TX (United States), 6-9 May 1996; Other Information: PBD: 1996; Related Information: Is Part Of 28. annual offshore technology conference: Proceedings. Volume 3: Construction and installation; PB: 373 p.
- Country of Publication:
- United States
- Language:
- English
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