基于Gumbel极值分布的大型原油储罐剩余寿命预测

储罐的剩余寿命是预测储罐的未来工作能力,预测储罐未来腐蚀发展趋势和壁厚减薄趋势。预测其在满足剩余强度及其安全性要求前提下储罐的剩余寿命。根据储罐的腐蚀特点,储罐的最大腐蚀坑深服从Gumbel I型最大极值分布。基于最大极值分布和概率统计,推导出储罐剩余寿命计算公式。储罐的剩余寿命由储罐中幅板的剩余寿命决定。分别采用API653和API 650的规定确定罐底板和罐壁板的最小允许厚度。在0.99、0.999和0.999 9的可靠度下储罐A的剩余寿命分别为25年、20年和17年。与国外标准进行对比,国内标准对储罐检修周期的规定相对保守。提出的剩余寿命预测方法对于确定储罐检修周期具有参考价值。

The Remaining Life Prediction of Large-Scale Oil Tank Based on the Gumbel Extreme Value Distribution

The remaining life prediction of storage tank is to forecast the thinning trend of plate thickness,and forecast remaining life on the premise that remaining strength of storage tank meets the tank operation and safety requirements.According to characteristics of tank corrosion,maximum corrosion depths of tank bottom plate obey the extreme value distribution of Gumbel type Ⅰ(the maximum extreme value distribution).Based on maximum extreme value distribution and statistics of corrosion data,the calculation formula of the remaining life prediction for large-scale crude oil storage tank was obtained by formula derivation.The remaining life prediction of crude oil storage tank is determined by that of tank bottom plate.The provisions of API 653 and API 650 are used to determine minimum allowable thickness of tank bottom and tank shell.The remaining life of tank A at the reliability of 0.99,0.999 and 0.999 9 are 25 years,20 years and 17 years,respectively.Compared with foreign standards,standards provisions for inspection period in china is relatively conservative.It shows that remaining life prediction of crude oil storage tank has a reference value for maintenance and the determination of repair period of the storage tank.