1 Scope
This Part of BS 7371 specifies requirements for phosphate or phosphate and oil coatings on metal fasteners
and accessories, applied by immersion or spraying.
NOTE 1 Phosphate coatings are primarily intended for application to ferrous, zinc or zinc
alloy fasteners.
NOTE 2 Phosphate coatings can be used as an undercoat to improve the corrosion resistance
and adhesion of a subsequently applied top coat (e.g. organic coating).
NOTE 3 Phosphate coatings can be used to impart a controlled torque/clamping force relationship
to a threaded fastener (see BS 7371: Part 2: 1993).
This Part of BS 7371 should be read in conjuction with the requirements for phosphate and phosphate and
oil coatings of BS 7371: Part 1General requirements and selection guidelines.
This Part of BS 7371 also specifies requirements for the following:
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a) athe minimum coating mass per unit area;
-
b) assessment of the corrosion resistance of unused coated parts when subjected to neutral
salt spray testing (see for example BS 7479:1991).