BS 7371-3:2009

This standard BS 7371-3:2009 Coatings on metal fasteners is classified in these ICS categories:

• 21.060.01 Fasteners in general
• 25.220.40 Metallic coatings

This Part of BS 7371 specifies requirements for coatings applied by the electrolysis of solutions of zinc.

NOTE The coatings consist principally of zinc and can be lubricated to give controlled torque/clamping force properties when required (see, for example, BS 7371-2).

In addition to the requirements in this Part of BS 7371, the requirements in BS 7371-1 which are applicable to zinc electroplated coatings apply.

This Part of BS 7371 also specifies requirements for:

1. the coating thickness;

2. the type of conversion treatment or topcoat to be applied;

3. quality assessment of the corrosion resistance of unused coated parts when subjected to neutral salt spray testing (for example BS EN ISO 9227); and

4. an adhesion test.

Zinc electroplated coatings covered by this Part of BS 7371 are for use on fasteners and accessories where the following apply:

1. A coating giving galvanic protection is required for ferrous fasteners.

2. A substrate is required to improve the corrosion resistance of subsequent coatings on ferrous fasteners, e.g. organic.

3. The risk of hydrogen embrittlement of high tensile steel fasteners is acceptable.