The existing American Petroleum Institute (API) equation for internal leak predicts the internal pressure to overcome the pin-box contact pressure generated from the makeup interference plus the energizing effect of internal pressure, which enhances the seal. For threaded connections, internal and external pressures close the connection and increase the leak resistance, whereas axial loads open the connection and decrease the leak resistance. These competing effects must be included to accurately assess the connection leak resistance under any combination of loads at any point in any string. Following the same approach used by the API for internal leak, this paper obtains similar results for external leak. For API connections, the effects of combined axial force and backup pressure are then incorporated into the internal/external leak equations using results from a “toy connector” elastic model. Sensitivities of leak ratings to combined loads for API connections are presented for both tubing and casing sizes. An example design case shows the importance of considering combined loads.

现有的美国石油协会（API）内部泄漏方程式可预测内部压力，以克服由补给干扰产生的针盒接触压力以及内部压力的激励作用，从而增强密封性。对于螺纹连接，内部和外部压力会关闭连接并增加耐泄漏性，而轴向载荷会打开连接并降低耐泄漏性。必须包括这些竞争效应，以准确评估在任何串中任何点的任何载荷组合下的连接泄漏抵抗力。遵循API用于内部泄漏的相同方法，本文对于外部泄漏也获得了相似的结果。对于API连接，然后，使用“玩具连接器”弹性模型的结果将组合的轴向力和备用压力的影响合并到内部/外部泄漏方程中。针对管道和套管尺寸，提出了泄漏额定值对API连接的组合载荷的敏感性。一个示例设计案例说明了考虑组合载荷的重要性。