INTERN MPAPS G-20 PDF

This specification covers Navistar’s requirements for electrodeposited zinc coatings on iron and steel substrates. Provision is also made to specify mechanical plated zinc coatings by the addition of a suffix “M” to the class designation.

Classification Zinc plating is classified by coating thickness and level of corrosion resistance.

Significant Surfaces

Significant surfaces for evaluation are defined as follows:

Fastener significant surfaces are all exposed surfaces of the fastener(s) when installed, including but not limited to fastener heads, socket recesses, SEMS washers, and external surfaces of nuts. Threads and points are excluded unless otherwise specified on drawing.

Non-fastener significant surfaces are all plated surfaces; deep recesses, blind holes, edges. Tubing interiors are excluded unless otherwise specified on the drawing.

APPLICATION

Zinc plating is used primarily for corrosion resistance. This specification provides for several classes of zinc plating for use on both Engineering designed parts and Engineering Standard Parts. Typical parts include clips, clamps, brackets, small stampings, tubes, rivets, rivnuts, lock bolt collars, screws, bolts and nuts, washers, and fittings. Caution should be exercised when specifying zinc plating for use on components that may be in contact with stressed nylon components. To avoid embrittlement of the nylon, use of a different coating such as MPAPS G-4518, is advised. When zinc plating is unavoidable, consider the use of GF reinforced nylon, or higher strength varieties such as Nylon 612.