循环接头循环接头是下套管中途或下完套管时循环钻井液用的专用接头，分为套管螺纹循环接头和由壬螺纹循环接头。CirculatingSubThecirculatingsubisaspecializedtoolforcirculatingdrillingfluidwhenrunningincasingonthewayorfinishingrunningcasingcordingtoactualneeds.therearecirculatingsubwithcasingthreadandcirculatingsubwithunionthread.Specificati***andparametersofcirculatingSub:钻杆母螺纹drillingpipeboxthread套管螺纹casingthread水眼borehole长度length(mm)NC385″偏梯扣BTC575005″长圆扣LTC5″短圆扣STCNC385″偏梯扣BTC575805-1/2″长圆扣LTC5-1/2″短圆扣STCNC507″偏梯扣BTC716007″长圆扣LTC7″短圆扣STCNC509-5/8″偏梯扣BTC716209-5/8″长圆扣LTC9-5/8″短圆扣STCNC5010-3/4″偏梯扣BTC7167010-3/4″长圆扣LTC10-3/4″短圆扣STCNC5013-3/8″偏梯扣BTC7167013-3/8″长圆扣LTC13-3/8″短圆扣STC)