American Petroleum Institute

Bulletin on Thread Compounds for Casing, Tubing, and Line Pipe - Sixth Edition
 N BULL 5A2

Annotation

a. The purpose of this bulletin is to provide information on two types of thread compounds recommended for casing and tubing connections in high-pressure well service. This bulletin is for the convenience of purchasers and manufacturers in ordering and producing thread compounds and is not intended to inhibit purchasers and producers from purchasing and producing thread compounds meeting specifications other than those contained herein.

b. These compounds were originally developed by the Mellon Institute of Industrial Research, under an API-sponsored research project, to meet the following objectives:

1. Adequate lubricating qualities to prevent galling in threaded connections during make-up.

2. No tendency to disintegrate nor undergo radical change in volume at temperatures up to 300 F.

3. No tendency to become excessively fluid at temperatures as high as 300 F.

4. Sealing properties sufficient to prevent leakage at temperatures as high as 300 F.

5. Absence of any deleterious instability and of any drier or hardener that will evaporate or oxidize, thereby changing the thread-compound properties.

6. Resistance to water absorption.

7. Sufficient inert filler to prevent leakage of API round-thread casing and tubing joints under pressure as high as 10,000 psi.

8. Readily applicable by brush to pipe joints in cold weather.

These objectives are broadly stated and it is recognized that the ability of a thread compound to meet some of these objectives can be measured only by service experience. Both modified and silicone thread compounds have demonstrated over a period of years that, in general, the objectives have been satisfactorily achieved under service conditions.