GMNA 9985490 PDF

This specification describes the qualification requirements of preapplied thread sealers with no chemical locking. These sealers are used to prevent leakage of gases and/or fluids through threaded joints caused by vibration, thermal cycling, pressure cycling, thread damage, etc. Sealants approved to this specification have a wider temperature usage range than 9985473 approved sealants (−29 to 150°C).

Material Description. Polymeric, water based dispersion containing additives and fillers that act as a sealer (no chemical locking) when applied wet to threaded parts and dried to form a non-tacky, non-hardening coating.

Types. When specific characteristics of an adhesive are needed for an application, adhesives can be described by "type" instead of listing the brand name on the part drawing. Part drawings must specify Type I or II, etc. to designate the use of a particular type of adhesive. MATSPC identifies which materials are approved to each type. If a certain type of adhesive is not necessary for the application, simply call out "9985490" on the print.

Symbol. Not applicable.

Typical Application. Preapplied thread sealers have a range of applications including bolts, plugs, nuts, and fittings that require thread sealing, but not thread locking, ability.

Applications of sealants approved to this specification include engine head bolts. Type I and Type II adhesives are specifically for head bolt applications.

Remarks.

This specification may involve hazardous materials, operations, and equipment. The specification does not address the safety problems associated with its use. It is the responsibility of the user of this spec to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

These materials are designed for limited reuse using current GM practice of standard fuel internal straight pipe thread (NPSF) with external Dryseal American Standard Pipe Thread Fuel (NPTF) or PTF/NPT with standard intermediate internal straight pipe thread (NPSI). For more information see SAE J476 or ANSI B1.20.3.

Each sealant has its own lubricity (k) factor reducing torque coefficient of threaded assemblies resulting in lower applied on-torques to achieve sealing or clamp load. Changes in part finish, treatments (oil), and thread size must be evaluated in the end-use application (see 5.4). Failure to determine these effects could lead to damaged parts and/or leakage.

This specification is expressed in SI units.