特殊螺纹油管接头现场端接箍胀大原因分析

Cause Analysis of Field End Coupling Expansion of Tubing Premium Connection

针对某西部油田商检时发现的特殊螺纹油管接头现场端接箍胀大问题,进行调查研究、有限元分析、上扣验证试验和密封验证试验。结果表明:特殊螺纹油管接头工厂端上扣后,现场端接箍的螺纹中径胀大很小,但密封面直径胀大较大;接头的壁厚越厚、上扣转矩越大、拐点转矩越低和台肩宽度越窄,密封面直径胀大就越明显。研究还发现接箍过大的胀大量会导致接头密封失效。为防止接箍胀大而影响密封性能,建议生产厂严格控制拐点转矩、适当延长转矩台肩宽度,并将这两项指标列入检验标准;同时,建议油田制订验收标准时限定接箍密封面直径胀大量,并据此调整验收标准的公差范围。

The field end coupling expanded significantly was founded during the tubing premium connections at a western oilfield.Investigation and research,finite element analysis,deduction verification test,and seal verification test were conducted.The results show that after the factory end of the tubing premium connection is made up,the pitch diameter expansion on coupling field end is very small,but the seal diameter expansion is quite large,and the thicker the pipe wall thickness,the greater the makeup torque,the lower the shoulder torque,and the narrower the torque shoulder width,the expansion is more obvious.The research also found that the expansion of the coupling has a notable impact on its seal performance,and excessive expansion will lead to joint seal failure.In order to prevent the coupling expansion from damaging its seal performance,it is recommended that the manufacturers should strictly control the makeup torque,extend the width of the torque shoulder,and take these two parameters under control.It is recommended that the oilfield formulates the inspection and acceptance of the coupling seal surface diameter expansion to limit the cover diameter accordingly.