Finished (Plating)

Self Colour / Black Finish

• products are supplied in a black finish with a light covering of oil

Hot Dip Galvanised (HDG)

• heavy coating deposits of molten zinc (40-180 microns) suitable for long term corrosion protection;
• a thicker coating deposit gives a longer life expectancy;
• it is most suitable for structural steelwork;
• the coating will affect the thread fit and assembly of fasteners due to the non-uniformity of the coating and the average coating thickness of 50-80 microns; in general the fullnuts are tapped oversize after the plating to allow for this but in some cases the bolt threads are undersize prior to coating;
• high temperature may affect the metallurgical properties of high tensile metals, i.e. grade 12.9 and above;
• hydrogen embrittlement can be avoided by specifying a non-acid cleaning treatment;
• bright, shiny finishes until weathered;
• requires primer treatment before painting;
• high temperature galvanizing results in a high quality surface finish which is smoother;

Sherardized (SHER / SHERA)

• uniform diffused zinc/iron alloy coating, useful for protecting irregular shaped components;
• matt textured grey coating, unless an additional oil protection is added to give it a darker colour;
• eliminates the possibility of hydrogen embrittlement;
• coating deposit range of 15-80 microns offering long term corrosion protection;
• relatively low process temperature, does not affect high tensile metal properties, i.e. 12.9, 10.9 and 8.8 fasteners can be processed;
• the process is normally carried out in a slowly rotating closed container at temperatures ranging from 320-350 degrees centigrade;
• assembly problems are eliminated due to the uniformity of the coating deposit but fullnuts are tapped oversize before coating or the bolt threads are undersize before coating to allow for the plating finish.

Bright Zinc Plated (BZP)

• relatively thin coating deposits (5-10 microns) gives relatively short term protection;
• electrodeposited zinc gives sacrificial protection to the underlying iron or steel;
• no thread clearance necessary;
• does cause hydrogen embrittlement on high tensile (above grade 8.8 products) or hardened components due to the method of application. hydrogen embrittlement treatment can be conducted on grade 10.9 and above products but this treatment cannot guarantee the complete removal of the risk of failure;
• requires primer etch treatment before painting.

Mechanically Applied Coating (MZP) / Mechanical Galvanizing (MG)

• depending on the coating thickness thread clearance may be required;
• avoids hydrogen embrittlement;
• medium term corrosion protection;
• the process is carried out at ambient temperatures in rotating barrels containing glass beads, surface conditioners and zinc powder;
• the energy expended from the rotation of the barrel causes the glass impact media to cold weld the zinc powder to the surface area.

Stainless Steel (ST ST)

• stainless steel covers a wide range of steel types and grades for corrosion or oxidation resistant applications;
• stainless steels are iron alloys with a minimum of 10.5% chromium. other alloying elements are added to enhance their structure and properties such as formability, strength and cryogenic toughness. non-metal additions are also made;
• the main requirement for stainless steels is that they should be corrosion resistant for a specified application or environment. the selection of a particular “type” and “grade” of stainless steel must initially meet the corrosion resistance requirements. additional mechanical or physical properties may also need to be considered to achieve the overall service performance requirements.

Other finishes available on special request