西南石油大学学报(自然科学版)

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Theoretical Analysis on Makeup Torque in Tubing and Casing
Premium Threaded Connections

Xu Honglin, Shi Taihe, Zhang Zhi   

  1. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation,Southwest Petroleum University,Chengdu,Sichuan 610500,China
  • Online:2014-10-01 Published:2014-10-01

Abstract:

The makeup torque and its composition of premium threaded connections are of great importance for improving
mechanical and sealing integrity of tubing and casing. On the basis of analysis on typical makeup torque vs. turns curve,
the theoretical calculation method of makeup torque for premium threaded connections has been established with the elasticity
mechanics theory of thick-wall cylinder and rotary shoulder torque formula. The influences of different interferences and
thread compound friction coefficient on the total torque and the ratio of torque acting on shoulder to total torque has also
been investigated and the results show that the larger the interferences and thread compound friction coefficient,the higher the
total makeup torque. The smaller the thread tooth radial interference,sealing surface radial interference and thread compound
friction coefficient or the larger of the shoulder axial interference,the higher the ratio of torque acting on shoulder to total
torque. Generally,the ratio is mainly influenced by thread tooth radial interference and shoulder axial interference,while the
thread compound friction coefficient mainly affects the total torque. We suggest that enhancement of tolerance matching be
optimized,processing precision be improved,makeup turns be strictly controlled and attention to thread compound optimized
should be carried out. The study results provide theoretical basis for determining reasonable makeup torque of premium threaded
connections and calculating its strength.

Key words: tubing and casing, premium threaded connection, makeup torque, composition, influence factors, theoretical
analysis