Testing thread compounds for rotary-shouldered connections

Journal Article · Wed Sep 01 00:00:00 EDT 1993 · SPE Drilling Engineering (Society of Petroleum Engineers); (United States)

DOI:https://doi.org/10.2118/23844-PA· OSTI ID:5965604

Bailey, E I ^[1]; Smith, J E ^[2]

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1. Stress Engineering Services Inc., Houston, TX (United States)
2. Grant TFW Inc., Houston, TX (United States)

Trouble-free rotary-shouldered-connection performance depends on proper joint makeup. Joints must be tight enough to prevent shoulder separation under bending and tensile loads but not so tight that their tensile capacity decreases or the pin or box is damaged. The preload in a connection from tightening depends on the makeup torque and frictional properties of the thread compound. In 1957, Farr developed and published a simplified torque formula to calculate makeup torque: T[sub mu] = ([sigma]A/12)[(p/2[pi])+(r[sub t]K[sub f]/cos [Theta])+r[sub s]K[sub f]]. This formula, often called the Farr equation, is in the Appendix of API RP 7G. The makeup torque values in API RP 7G were calculated by use of the Farr equation with a thread-compound friction coefficient, K[sub f], of 0.08.K[sub f] is not always equal to 0.08 for all thread compounds, so the values listed in API RP 7G may not be correct for a given compound. To address this problem, API create API RP 7A1, Recommended Practice for Testing of Thread Compound for Rotary Shouldered Connections, which defines the procedure for determining K[sub f] and for recalculating makeup torque when it does not equal 0.08.

• OSTI ID: 5965604
• Journal Information: SPE Drilling Engineering (Society of Petroleum Engineers); (United States), Journal Name: SPE Drilling Engineering (Society of Petroleum Engineers); (United States) Vol. 8:3; ISSN 0885-9744; ISSN SDENEC
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
422000* -- Engineering-- Mining & Underground Engineering-- (1980-)
DRILL PIPES
DRILLING
DRILLING EQUIPMENT
EQUIPMENT
FRICTION
FRICTION FACTOR
JOINTS
LUBRICANTS
LUBRICATING PROPERTIES
LUBRICATION
MATERIALS
PERFORMANCE
PHYSICAL PROPERTIES
PIPES
ROTARY DRILLING
SEALING MATERIALS
SEALS
STRESSES
THREADED JOINTS
TORQUE
WELL DRILLING