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.

采用有限元分析法对内压作用下外拱内壁局部减薄弯管的极限载荷进行研究。计算结果与外拱外壁弯管试验及有限元计算结果进行比较表明，外拱内壁局部减薄弯管极限内压较外拱外壁局部减薄弯管极限内压偏低。由有限元计算结果数据拟合出了外拱内壁局部减薄弯管塑性极限内压的计算公式。

For the leakage of high pressure air coler tubes caused by corrosion, the effect of hydrodynamic erosion on corrosion process is analyzed by. CFD simulation. Simulated is the actual flow of high pressure air cooler tubes in the hydrocracking unit of a petrochemical and SIMPLEC method are adopted. The numerical simulation results are in good agreement with the К-εturbulence model and SIMPLEC method are adopted. The numerical simulation results are in good agreement with the inspection results of tubes. Furthermore, the flow characteristic in air cooler tubes with different lining tube structure is studied, which would provide helpful information for the improvement of air cooler tubes.

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。

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.