In this paper the risk management is brief introduced and the discussion on acceptable risk is a focus. for example as expression of acceptable risk ( individual risk, societal risk, economical risk, environment risk and total risk ), the determination of acceptable risk level at home and abroad, The level of acceptable risk and ALARP criteria, the effect factors for acceptable risk level. The recommendation of determination for the level of acceptable risk are proposed.

This paper discusses the plastic limit load of elbows under combined internal pressure and in-plane closing bending moment. Finite element analysis (FEA) and experiments have been carried out. The results of FEA show that when the ratio of pressure to the limit pressure (P/PL) is smaller than 0.469, the limit moment of elbows increases with the increasing of the pressure; when the ratio (P/PL) is bigger than 0.469, the limit moment of elbow decreases with the increasing of the pressure. The results of FEA are verified by experiments. By fitting the results of FEA, the safety assessment figure for elbow under combined internal pressure and in-plane closing bending moment is drawn. The safety assessment method using the figure is simple and is applicable for the engineering.

This paper discusses the plastic limit pressure of elbows without defects and with local thinned area in the extrados. Finite element analysis (FEA) and experiments have been used. The results of FEA show that the limit load of elbows under internal pressure increases with increasing wall thickness and bend radius of the elbow. The results are consistent with the calculated results by the Goodall formula, the maximum error is 6.58%. By data fitting of FEA, an empirical formula for the limit load of elbows with local thinned area in the extrados has been proposed, which is validated by experiments.

近些年来，国内外对高温炉管常用的HK40、HP-Nh和Cr5Mo等材料已有颇多研究，但对Cr9Mo炉管材料，还依然集中在其焊接性能方面，而对该材料制成的炉管寿命预测方面的研究开展得较少。本文针对长期服役后的Cr9Mo材料进行了研究，并在此基础上，确定炉管材料的老化程度，根据炉管的载荷，预测炉管的剩余寿命。这些研究对Cr9Mo炉管的全周期寿命设计及高温性能预测具有指导意义。

W. Kent Muhlbauer的指数评分法是一种比较成熟的管道风险评价方法，但该方法还存在不完善之处。通过对此方法加以改进，并将改进后的方法用于南京市城市天然气利用工程高压输气管道的风险评价中，实际应用结果表明，此改进方法的评价结果与相关文献的结果相一致，其表达更明确更直观。