Anti-seize compound

When molybdenum disulphide is added to a grease, the effect on the flow properties depends critically on the concentration of molybdenum disulphide. Where the quantity added is high enough to cause a major change in the flow properties, the result is a product which no longer behaves as a grease, but behaves like a paste. Such materials are generally used as anti-seize compounds rather than lubricants, and they will be described in Section 13.4. 

There are three main types of application for which molybdenum disulphide pastes and concentrated dispersions are used. They are used as anti-seize compounds for threaded fittings, pipes, flanges, and so on. They are also used to assist assembly, and to a lesser extent running-in, of many different types of mechanical euqipment. Finally, they are used in high-load metalforming processes. 

Rocketdyne, Division of North American Aviation, "Lubricants, Anti-Seize Compounds, and Gasketing Type Sealing Compounds for Rocket Engines," Process Specification No. RA 0112-002, Canoga Park. California (November 12, 1958). 

Add to maintenance procedures to inspect and clean regularly. Add use of anti-seize compound to operating procedures. Add to quarterly inspection to verify all gaskets, 0-rings, and proper seals are in correct position. Verify that each gasket fits over shoulder and end caps. Avoid hammering seal palate into valve assembly. 

The noble metals, i.e. gold, platinum, palladium, and rhodium, and the corrosion-resistant metals, i.e. chromium, nickel, tin, tin-lead solder, and titanium, require no finish other than cleaning. Soldered joints should be protected with a moisture-proofing compound or coating. Corrosion-resistant (or treated to resist corrosion) minor devices (fasteners, etc.) should be used. Fasteners should be treated with zinc chromate, zinc chromate paste, or graphite-free dry-film anti-seize compound. 

Pastes can be made with the same carrier liquids by simply increasing the concentration of powder to achieve a paste-like semi-solid consistency. More stable pastes are obtained by using a carrier which is inherently semi-solid, such as a grease, petrolatum (soft petroleum wax) or a semi-fluid polymer. The concentration of powder in a paste or a dispersion may be anything between 35 and 75%, depending on the application. The British military specification Def Stan 80-81/1 requires not less than 50% of molybdenum disulphide in a mineral oil grease for an anti-seize and anti-scuffing compound for use up to 250 C. This is probably a fairly typical level for anti-seize use. 

In other words, this one material was intended to meet the requirements of anti-seize and anti-scuffing compounds, pre-assembly, and metalforming. A primary objective of the standard was obviously to simplify supply in a relatively tightly-controlled economy. In more competitive economies a very large number of... 

One other area in which the use of molybdenum disulphide may be undesirable for pre-assembly or anti-seize use is when nickel alloys are used in critical applications, especially at high temperatures. Such alloys are extensively used in aviation gas turbine engines, and there have been cases in which serious failures of gas turbines have been attributed to the effect of molybdenum disulphide-based lubricants on high-temperature components Provided these two hazards are kept in mind, molybdenum disulphide dispersions and pastes are of great value as antiseize compounds and as assembly aids. 

Table I. Summary of Qualification Requirements for One Type of Anti-Seize and Sealing Thread Compound for Use in Aircraft Oxygen Systems, Mil-T-5542B [3]...

Military Procurement Specification, QPL 5542-6, "Thread Compound. Anti-Seize and Sealing, Oxygen Systems," U. S. Government Printing Office (July 12, 1954). 

Convair-Astronautics, "Thread Compounds Anti-Seize and Sealing, Gaseous and Liquid Oxygen Systems," Report No. 0.73.001, San Diego, California (January 12, 1957). 

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