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Title: Assessment of the effects of surface preparation and coatings on the susceptibility of line pipe to stress-corrosion cracking

Objectives were to evaluate susceptibility of pipeline steel to SCC when coated with coal-tar enamel, fusion-bonded epoxy (FBE), and polyethylene tape coatings. The tests included standard cathodic disbondment tests, potential gradients beneath disbonded coatings, electrochemical measurements, and SCC tests. It was concluded that factors affecting relative SCC susceptibility of pipelines with different coatings are the disbonding resistance of the coating and the ability of the coating to pass cathodic protection (CP) current. FBE coated pipelines would be expected to exhibit good SCC resistance, since the FBE coating had high cathodic disbonding resistance and could pass CP current. Grit blasting at levels used at coating mills may be beneficial or detrimental to SCC susceptibility. Excellent correlation was found between th Almen strip deflection and change in SCC threshold stress. It appears to be beneficial to remove as much mill scale as possible, and a white surface finish probably should also be specified. 50 figs, 10 tabs.
Authors:
 [1]
  1. (Cortest Columbus Technologies, Inc., OH (United States))
Publication Date:
OSTI Identifier:
6799002
Report Number(s):
AGA-93007094
CNN: Project 186-917; TRN: 93-005037
Resource Type:
Technical Report
Research Org:
American Gas Association, Inc., Arlington, VA (United States). Pipeline Research Committee; Cortest Columbus Technologies, Inc., OH (United States)
Sponsoring Org:
AGA; American Gas Association, Inc., Arlington, VA (United States)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 03 NATURAL GAS; PIPELINES; CATHODIC PROTECTION; PROTECTIVE COATINGS; CRACKS; DESCALING; ENAMELS; EPOXIDES; NATURAL GAS DISTRIBUTION SYSTEMS; POLYETHYLENES; PROGRESS REPORT; STEELS; SURFACE TREATMENTS; ALLOYS; COATINGS; CORROSION PROTECTION; DOCUMENT TYPES; IRON ALLOYS; IRON BASE ALLOYS; ORGANIC COMPOUNDS; ORGANIC OXYGEN COMPOUNDS; ORGANIC POLYMERS; POLYMERS; POLYOLEFINS; SURFACE FINISHING 360105* -- Metals & Alloys-- Corrosion & Erosion; 032000 -- Natural Gas-- Transport, Handling, & Storage