Fracture Cause Analysis on 5-1/2FH Double Shoulder Drill Pipe Box
摘 要
采用宏观检验、化学成分分析、力学性能测试、金相检验和断口分析等方法对某5-1/2 FH双台肩钻杆内螺纹接头的断裂原因进行了分析。结果表明: 此双台肩钻杆内螺纹接头在副台肩第一完整螺纹根部发生了疲劳断裂失效。断裂具有多源特征, 起源于内螺纹根部并向外壁扩展, 当穿透壁厚形成通道时发生了刺漏, 从而使断口表面形成了冲刷痕迹。上扣扭矩不足, 同时接头承受的弯曲应力较大是造成接头疲劳断裂失效的主要原因, 另外FH型螺纹固有的螺纹根部半径较小、应力集中较大, 使接头失效的风险增大。
Abstract
The fracture causes of a 5-1/2FH double shoulder drill pipe box were analyzed by means of macroscopic examination, chemical composition analysis, mechanical property testing, metallographic examination, fracture analysis and so on. The results showed that fatigue fracture failure was happened to the first whole thread of the second shoulder on the double shoulder drill pipe box. The cracks initiated from the root of thread and developed to the outer surface to form the flowing outlets that led to the flushing of the fracture. Insufficient of make-up torque and bending stress on the box were the main reasons of the fatigue. In addition, the root radius of FH thread is small while stress concentration is large, which increased the risk of box fatigue.
中图分类号 TE921+.2
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收稿日期 2010/11/18
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备注谷振乾(1960-), 男, 高级工程师。
引用该论文: GU Zhen-qian,ZHANG Xin-sheng,WANG Yong-jiang,ZHANG Guo-zheng,ZHANG Chun-wan. Fracture Cause Analysis on 5-1/2FH Double Shoulder Drill Pipe Box[J]. Physical Testing and Chemical Analysis part A:Physical Testing, 2011, 47(9): 575~578
谷振乾,张新胜,王永江,张国正,张春婉. 5-1/2FH双台肩钻杆内螺纹接头断裂原因分析[J]. 理化检验-物理分册, 2011, 47(9): 575~578
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参考文献
【1】KESSLER F, SMITH J.Double-shouldered tool joints increase tortional strength [J].Journal of Petroleum Technology, 1996,48(6):514-517.
【2】API Specification 7-2Specification for Threading and Gauging of Rotary Shouldered Thread Connections[S].2008.
【2】API Specification 7-2Specification for Threading and Gauging of Rotary Shouldered Thread Connections[S].2008.
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