scope:

I. INTRODUCTION

The API Bulletin on Thread Compounds Composition (API Bul. 5A2) specifies a thread compound for casing, tubing and line pipe. This compound was developed by Mellon Institute, and was designed to provide lubrication during make-up (that is to prevent galling), prevent leakage (up to 10,000 psi), and remain stable (up to 300°F). Subsequently the API Task Group on had a considerable number of tests conducted on commercially available API Modified thread compounds by Arco Oil and Gas, Drilco, Jet Lube, and Vallourec Steel. The tests performed by Arco and Jet Lube measured the leak resistance capability of the compounds. The Drilco and Vallourec tests measured relative frictional characteristics. These tests showed that there was a significant difference between compounds, even when they were produced in accordance with API standards. As a result, a need was apparent to evaluate the sealing characteristics of API and non API compounds. Due to environmental concerns interest was also expressed in finding alternatives for lead and zinc in the API Compound.

The Task Group proposed that additional work on the sealing ability of thread compounds was needed, and a research proposal requiring $30,000 was submitted to API and approved (PRAC 84-51) in 1984.

PRAC appointed a Technical Advisory Committee (TAC) to select a test facility and supervise the test program. The TAC was composed of:

TAC designed a test fixture and developed a test program. Bruce Urband of API staff requested bids. Weiner International, Inc. was selected to perform required tests, and a contract was signed in June 1984.

The TAC fixtures were made by Pipe Machinery Company. The test fixtures were hardened and ground and are patterned after an API 4½ inch buttress thread with fixed flank gaps of .001 inches, .005 inches and .009 inches. The clearances model the allowable API thread flank tolerances.

Sample thread compounds were requested from the various manufacturers and sent to Weiner International, Inc. in Houston for identification and storage. Compounds were coded so as not to disclose their original source. Compounds were classified as shown in Section III-B. CAT I is API modified compound, CAT II is lead and zinc free compound, and CAT III is a compound not fitting the other two categories.

Reported herein are the results of 170 tests conducted with 73 different compounds.