摘要
某油田在检验一批244.5mm偏梯形螺纹接头套管时发现,管端至螺纹消失点的长度L4比公称值小25.22mm。虽然API SPEC 5B对套管偏梯形外螺纹接头L4没有规定公差,但依据APISPEC 5CT和油田规定的外径公差可以推算结果,L4的上偏差为39.11mm(7.7扣),下偏差为-17.39mm(3.42扣)。分析结果表明:该批套管L4实际公差已经超过推算出的L4负公差,使套管接头密封性能降低22.0%,并降低了螺纹连接强度。
It was found that the total length end of pipe to vanish point L4 is less 25.22 mm of cas- ing connection than that of the normal dimension specified in API SPEC 5B for 244.5mm buttress thread casing during inspection in one oil field. Though L4 tolerance is not specified in API SPEC 5B,but it is considered that L4 tolerance can be deduced per outside diameter tolerance in accord- ance with API SPEC 5CT and the oil field specification,the calculation result is that the upper de- viation and lower deviation of L4 is ＋39.11mm （7.7 thread） and --17.39mm （3.42 thread） ,re- spectively. The actual L4 is shorter than the lower deviation that will decrease 22% of seal per- formance of casing connection, and reduce the tension strength of casing connection.
出处
《石油矿场机械》
2012年第6期63-66,共4页
Oil Field Equipment
关键词
套管
偏梯形螺纹
长度
公差
casing
buttress thread
length
tolerance
