Salt spray testing of sacrificial and barrier type coatings for the purpose of finding a corrosion resistant and environmentally acceptable replacement for cadmium plate
Cadmium plate is used to protect various components of offshore oil and gas production equipment from surface marine environments such as salt spray. This research project was performed to find an environmentally acceptable coating which provides equivalent or superior resistance to surface marine corrosion when compared to cadmium plate. In order to find a replacement for cadmium plate, a large number of sacrificial and barrier type coatings were exposed to an accelerated salt spray test in accordance with ASTM B117-94. The only sacrificial coating which resisted 1,000 hours of accelerated salt spray testing without any indication of failure was the 0.0006-in. thick zinc-nickel plate with an olive drab chromate treatment. Based on these test results, zinc-nickel plate is recommended as a corrosion resistant and environmentally acceptable replacement for cadmium plate for use in surface marine environments. Electroless nickel coatings with a minimum applied thickness of 0.002-in. also resisted 1,000 hours of accelerated salt spray testing without indication of failure. Electroless nickel is not recommended for corrosion resistance in salt spray environments for two reasons. Electroless nickel is susceptible to microcracking when heat treated at moderate to high temperatures. Heat treatment improves the hardness and resultant wear resistance of the coating. Microcracking will compromise the integrity of the coating resulting in pitting, cracking or crevice corrosion of the substrate in corrosive environments. Secondly, any significant mechanical damage to the coating or disbonding of the coating substrate interface will also result in corrosive attack of the substrate.
- OSTI ID:
- 423166
- Report Number(s):
- CONF-960525-; TRN: IM9707%%473
- 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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Related Subjects
03 NATURAL GAS
42 ENGINEERING NOT INCLUDED IN OTHER CATEGORIES
36 MATERIALS SCIENCE
FIELD PRODUCTION EQUIPMENT
PROTECTIVE COATINGS
CORROSION PROTECTION
MATERIALS TESTING
NICKEL ALLOYS
CORROSION RESISTANCE
ZINC ALLOYS
CARBON STEELS
LOW ALLOY STEELS
OFFSHORE SITES
BRINES
CORROSIVE EFFECTS
CADMIUM
MATERIAL SUBSTITUTION
EXPERIMENTAL DATA