管线钢在含氢气的煤制天然气中服役安全性评估

煤制天然气是我国煤炭清洁利用的重要发展方向.现有管道用于输送煤制天然气(最高氢分压为0.72 MPa)时需要考虑其中低压氢气的影响,因而需先进行氢致开裂安全性评估.本文利用高压釜环境下恒载荷实验和电化学充氢,模拟研究X-70管线钢和20^#钢在不同氢含量下的氢损伤和氢致延迟开裂,并对其在煤制天然气中服役安全性进行评估.在总压12MPa(10 MPa N₂+2 MPa H₂)的高压釜中放置一个月,两种钢的金相试样均不出现氢损伤,U弯试样不开裂,加屈服强度σ_s的恒载荷试样不发生断裂.在含0.72 MPa的煤制天然气中长期服役时,进入两种钢的氢含量均远低于σ_s下发生氢致延迟开裂的门槛氢含量和出现氢损伤的门槛氢含量,因而X-70钢和20^#钢在煤制天然气中长期服役均具有高的氢损伤和氢致开裂安全系数.

Safety evaluation of pipeline steels under SNG containing H2

Synthetic natural gas(SNG) is an important developing direction of the clean utilization of coal. The present pipeline steel may cause hydrogen-induced delayed cracking when used to transit SNG due to the hydrogen partial pressure in SNG perhaps up to 0.72 MPa. Therefore,the safety assessment of pipeline steel for long-term service is very important and necessary. In this work,hydrogen damage and hydrogen-induced delayed cracking in X-70 pipeline steel and 20#steel at different hydrogen contents were studied by using autoclave constant load test and electrochemical hydrogen charging methods. The service safety of the steels in SNG was evaluated. There is no hydrogen damage in the two kinds of steel after being placed in the autoclave in which the total pressure 12 MPa(10 MPa N₂+ 2 MPa H₂) is kept for one month. Hydrogen-induced delayed cracking does not occur in the U-bending specimen. And the constant load samples do not fail after they are kept at the yield stress for one month. The hydrogen content entering into X-70 and 20# samples is much lower than the threshold hydrogen content for hydrogen-induced delayed cracking and that for hydrogen damage.Therefore,both X-70 steel and 20# steel have high safety factors during the long-term service of transiting SNG.