Based on the statistics, 86%of tubing failure occurs in the place of thread joint, the failures of thread joint have two aspects, seal failure and slippage failure.
据统计，油管失效86%发生在螺纹联接处，而螺纹联接失效表现在两个方面：密封失效和滑脱失效。
2
The reasons caused seal and slippage failure are complicated, the most important factor was the thread gluing reduced the intensity and the sealing property of the thread joint.