Abstract: The main cause for affects the uncertainty of pipeline leakage risk assessment is the analysis for uncertain factors of gas pipeline leakage model. For this purpose, on the one hand, four factors which were inlet pressure, leakage hole area, gas temperature and distance from the leakage hole to the pipe inlet were determined as the main uncertain factors affecting the calculation of gas pipeline leakage rate; on other hand, the multi-factor sensitivity analysis method was used to study the effects of uncertainty factors on the leakage rate by extracting twelve groups of samples with 500, 1 000, 2 000 and 3 000 samples. The results showed that:the rank of Spearman rank correlation coefficient of uncertain factors calculated under different sample sizes is basically consistent, that is, the leakage hole area has the greatest influence on the leakage rate; the gas temperature the second, the inlet pressure and the distance from the leakage hole to the pipe inlet has the third influence; within the existing value range of uncertain factors, the calculated results of the gas pipeline leakage model could meet the accuracy requirements of subsequent pipeline leakage risk analysis when the number of samples is greater than 500, because of the same rank trend of Spearman rank correlation coefficient among different samples.

Key words: gas pipeline, leakage model, uncertainty factors, multi-factor sensitivity analysis, risk assessment