BS EN ISO 17668 Sherardized Fasteners

Stud Bolts, Nuts, Screws, Threaded Rod & Washers

Corrosion control begins at the design stage and requires the awareness and co-operation of the entire engineering design team. In order to ensure the correct specification, the many factors influencing corrosion, including environment, stress, shape and desired design life must be taken in to account The service life of any zinc coating in a given environment is proportional to the thickness of the coating itself and is an important consideration when specifying. When specifying Sherardized components, it is vital to consider the factors specific to the process itself.

Components should be able to withstand process temperatures of 380-500 ˚C
Components must fit into process containers, maximum [2000x500x400mm]
Threaded components must have allowances for thread clearance.
Components should not have any airtight voids as distortion may occur
Salt Spray Test requirements, standard Sherardizing 96 hours, Sherardize P1000® in excess of 1000 hours to ASTM B117.

Standards Used In Sherardized Coatings

BS EN ISO 17668:2016

Sherardizing - Zinc diffusion coatings on ferrous products

BS EN ISO 17668:2016 replaces BS4921

CLASS OF COATING	LOCAL COATING THICKNESS (MINIMUM VALUE)
CLASS 15	15 µm
CLASS 30	30 µm
CLASS 45	45 µm
BS EN ISO 17668:2016 COATING MINIMUM THICKNESS IN MICRONS

BS 7371-8:1998

Coatings on Metal Fasteners

CLASS OF COATING	LOCAL COATING THICKNESS (MINIMUM AVERAGE VALUE)	ADDITIONAL THREAD CLEARANCE for ISOMETRIC COURSE THREADS
S1	30 MICRONS	360 µm
S2	15 MICRONS	180 µm
S3	30 MICRONS PLUS SEALANT	360 µm
BS EN 13811:2003 COATING MINIMUM THICKNESS IN MICRONS

DEF STAN 21-005/ISSUE 2

Ministry of Defence Code of practice for protective finishes