Shop primer as part of the corrosion protective coating for submerged steel structures

Conference · Thu Dec 31 04:00:00 EST 1998

OSTI ID:351812

Bjordal, M; Steinsmo, U ^[1]

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1. SINTEF Materials Technology, Trondheim (Norway)

In Norwegian workshops the standard pre-treatment procedures for steel structures intended for sub-sea use, normally include removal of shop primer by blast cleaning to Sa 2 1/2 before application of corrosion protective coatings. This is also stated in the Norwegian offshore standard NORSOK. Omitting this stage in fabrication will represent large reductions in both time consumption and costs, and reduce the volume of waste from the blast cleaning. This report presents results from investigations of how a shop primer will influence on the coating properties. The aim of the investigation was to test whether the systems are good enough if the shop primer is left on the surface. Two different zinc silicate shop primers have been included in the investigation. As protective coatings the authors have used three different epoxy mastic systems with Al pigments. In addition to panels with original shop primer, they have also tested shop primed panels pre-treated in various ways, such as heated, corroded and blast cleaned to various degrees before coating. The coatings have been tested in the ASTM-G8 121 test and in a long term test in sea water polarized with a Zn anode. They have found that coatings including the zinc silicate shop primer are more susceptible to cathodic disbonding than the coating applied directly on blast cleaned steel. It is however possible to meet the NORSOK criteria with a zinc silicate shop primer as first coat.

• OSTI ID: 351812
• Report Number(s): CONF-980316--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
CORROSION PROTECTION
OFFSHORE OPERATIONS
PERFORMANCE
PROTECTIVE COATINGS
STEELS
SURFACE TREATMENTS