对国内某钢厂生产的P91钢管，在试验温度625 ℃、应力80～140 MPa范围内进行了7个应力水平的持久强度试验，对每一应力对应的破断时间进行一元线性回归，并对结果进行相关系数检验，外推得到基于一定置信度和存活概率的100 000 h持久强度。结果表明：试验温度为625 ℃时，在置信度γ为95%、存活概率为99. 9%条件下，外推得到该P91钢管100 000 h的持久强度为71. 38 MPa；随着破断时间的延长，同一应力下不同破断时间的标准差逐渐降低，推测与蠕变机制的变化有关。

The endurance strength test at 625 ℃ and seven stress levels with stress ranging from 80 MPa to 140 MPa were conducted on the P91 steel pipes produced by a steel plant in China. The unary linear regression of the breaking time under each stress was carried out, and the correlation coefficient of the results were checked. Finally, the 100 000 h endurance strength based on a certain confidence and survival probability was extrapolated. The results show that when the test temperature was 625 ℃, and the confidence γ was 95% and the survival probability was 99. 9%, extrapolated the 100 000 h endurance strength of P91 steel pipe was 71. 38 MPa. With the extension of the breaking time, the standard deviation of different fracture times under the same stress decreased gradually, which may be related to the change of creep mechanism.