BS 7371-8:2011

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Process
5 Classification
6 Properties
7 Thread clearance
8 Information to be documented and supplied to
  the coater
9 Identification
Annexes
Annex A (informative) - Selection of coating
Annex B (normative) - Measurement of coating
        thickness
Bibliography

Describes requirements for sherardized coatings on iron and steel fasteners and accessories applied by thermal diffusion of zinc powder onto a component's surface.

This part of BS7371 specifies requirements for sherardized coatings on iron and steel fasteners and accessories applied by thermal diffusion of zinc powder onto a component’s surface. NOTE Hydrogen embrittlement is not induced as a result of this coating process. The coating consists of zinc/iron alloys, which are subsequently treated using either a zinc phosphate treatment (see BS7371-9:1996, Type2) or a suitable substitute treatment similar to those used in electroplating zinc (see BS7371-3:2009) and mechanical plating (see BS7371-7:2010). This results in a dust free surface, which, when required, can be lubricated to give controlled torque/clamping force properties (see BS7371-2:1993). In addition to the requirements in this part of BS7371, the requirements in BS7371-1:2009 that are applicable to sherardized coatings apply. This part of BS7371 also specifies requirements for: the local coating thickness for six grades of coating; possible types of post treatment; the assessment of corrosion resistance of unused coated parts when subjected to neutral salt spray testing (see BSENISO9227:2006).