钻杆接头螺纹退刀尺寸对接头寿命的影响

钻杆接头螺纹退刀尺寸是指外螺纹接头的台肩面到螺纹消失前第一个完整螺纹之间的距离。GB9253．1－88规定退刀尺寸应小于或等于12．7mm内螺纹，钻杆接头内螺纹的锤孔尺寸为16±2mm，以保证内、外螺纹啮合良好。经检测发现，从日本NKK公司进口的所有φ127mm钻杆接头外螺纹退刀尺寸都大于12．7mm，镗孔尺寸为16～18mm。而APISpec7K规定钻杆接头内螺纹最小镗孔尺寸为15．9mm。鉴于此，建议对我国的有关标准作相应修改，与API标准保持一致。

Influence of shoulder-runout distance of tool joint on life of joint

Accowhng to CB9253. 1 - 88, the should-runout distance of tool joints should be 12. 7mm or less, and the diameterof counterbore of tool joint box should he 16 ± 2mm to ensure good engagement. Detection shows that the should-runoutdistance of tool joint pin of all φ127mm drill pipes imported from NKK Company is more than 12 .7mm, and the diameterof counterbore is 16 ~ 18mm. While according to the stipulations of API Spec 7K, the minimum counterbore of tool jointbox should be 15.9mm. the view of this situation, relevant Chinesc Standards should be revised to keep them identicalwith cmponding API Standards.