American Petroleum Institute

Investigation of Pipe Thread Compounds - PN4875
 N REPORT 88-51

Annotation

API Bulletin 5A2 ("Bulletin on Thread Compounds for Casing, Tubing and Line Pipe"), presents a thread compound formulation for use on API round-thread connections that will meet certain listed performance objectives. These objectives include: prevention of galling and thread damage during make-up, ability to seal the leak path at pressures to 10,000 psi and temperatures to 300°F, and material stability in a range of conditions. The original composition was developed in 1951 by the Mellon Institute and subsequently modified in 1955 to the present formulation. This compound formulation came to be known as "API Modified Thread Compound".

API Modified has been the primary compound used for LP-C&T (line pipe, casing and tubing) connections for over forty years and by and large has proven satisfactory in a wide range of conditions on API threadforms. Over the years, however, concern was raised over the apparent difference in performance properties of API compounds made by different thread compound manufacturers and even in different lots from the same manufacturer. Various controlled laboratory tests by several oil field companies, seemed to validate this concern and led to an evaluation of existing commercially available API compounds by the API Committee 5 Task Group on Thread Compounds and Leak Resistance. The results of this study were presented in January 1982. Particle size and component analysis showed several compounds that did not conform to the compositional requirements of Bulletin 5A2. Even those compounds that did conform showed significant differences in both sealing and frictional performance.

At that time, it was realized that there was a need to reevaluate Bulletin 5A2. There were several shortcomings that were apparent:

1. Thread compound manufacturers were not required to demonstrate compliance to the compound composition specifications or to the control and performance test requirements.