Cortest Laboratories, Inc., Cypress, TX
Mobil Exploration and Production U.S., Inc., New Orleans, LA
Pages: 27 Published: Jan 1993
Laboratory corrosion tests consisting of electrochemical cyclic polarization, critical pitting temperature (CPT), and slow strain rate (SSR) tests were performed on a group of candidate nickel base alloys. The objective of the test program was to predict service performance in deep sour gas well applications. Of particular interest were localized corrosion resistance and stress corrosion cracking (SCC).
The test data indicated that localized corrosion can occur at intermediate temperatures (110 to 170°C) and that SCC may also occur in this temperature region. The temperature region of susceptibility coincides with the transition from a stable chromium oxide surface film to a predominantly sulfide surface film. The localized loss of chromium oxide protectiveness at 150 to 180°C is manifested by crevice corrosion, pitting, and ductility loss. Elemental sulfur in the test environment lowers the region of susceptibility to 100 to 150°C.
From the information provided by this experimental program (and others), procedures and criteria were established for purchase specifications for tubular products. SSR test methods were used to predict service performance.
slow strain rate (SSR) testing, stress corrosion cracking (SCC), nickel base alloys, critical pitting temperature (CPT) tests, natural gas production, petroleum, localized corrosion, pitting
Paper ID: STP12768S