Full Description

This specification covers the basic requirements for corrosionresistant finishes for iron andsteel substrates whose basic characteristic is zinc phosphatetreatment and subsequent protectivecompound. Parts coated with this coating are typically used internallyfor engines andtransmissions or in areas where minimum corrosion protection isrequired.

Finishes with oil coatings are not recommended to be used againstplastic surfaces.

Material Description. The material approved to this specificationcovers zinc phosphate treatmentsplus subsequent protective compounds. This coating system must be freeof hexavalent chromium withno hexavalent chromium in final product per the requirements ofGMW3059. GMW3034 shall be used as areferee test. This coating process does not generate hydrogen,however, pretreatment processes i.e.acid pickling could cause hydrogen absorption. This coating has highpermeability, which allowseffusion of hydrogen during curing which might have been absorbedduring acid pickling.

A grade with zinc phosphate only may be designated or may be followedby a supplemental coating. Acode system is provided in the Table in Appendix A for designatingcertain limitations oncompounds.

Cross-Reference of Replaced Specifications

GMW

Delta Motors

GM do Brazil

GM Holdens

GMNA

ISUZU

ITDC

SAAB

GMW3179

HN1277, HN1278 HN1279

GM4435M

GME00253

Typical Application This coating is suitable for internally threadedparts, parts with internaldrive recess, externally threaded and non-threaded ferrous parts whereminimum corrosion protectionand freedom from hydrogen embrittlement are required.

Remarks Use of this coating on threaded surfaces and/or bearingsurfaces of joints could affect thetorque-tension relationship. It is recommended that a torque-tensionstudy of the fastener joint beperformed before releasing this finish on any new application.