石化厂硫酸输送管道开裂失效分析

Failure Analysis on Cracking of Sulfuric Acid Pipeline in a Petrochemical Plant

由于硫酸具有强腐蚀性,该类输送管道一旦发生泄漏失效,将给企业生产和周围环境带来严重的危害。以某石化厂的硫酸输送主管道为分析对象,采用化学成分分析、金相检验、拉伸试验及硬度试验等方法,对管道开裂原因进行了分析和讨论。结果表明:管道铸造模线附近靠近内壁处存在大量孔洞及微裂纹等铸造缺陷,材料中的片状石墨长度达到2级,且存在少量磷共晶,这些铸造缺陷以及细长片状石墨和非金属共晶体的存在显著降低了材料的拉伸性能,使其不能满足相关标准要求,最终导致管道在运行过程中发生了开裂泄漏。

The leakage failure of sulfuric acid pipelines will cause serious damage to the production and surrounding environment due to the strong corrosive nature of sulfuric acid. Taking the main pipeline of sulfuric acid transportation in a petrochemical plant as the analysis object, the cracking causes of the pipeline were analyzed and discussed by using chemical composition analysis, metallographic examination, tensile test and hardness test. The results show that there were a lot of casting defects such as holes and microcracks near the inner wall of the pipeline casting mold line. The length of flake graphite in the material reached grade 2, and there was a small amount of phosphorus eutectic. The presence of these casting defects, slender flake graphite and non-metal eutectic led to an abvious decrease in the tensile properties of the material, which made the tensile properties could not meet the requirements of relevant standards and eventually led to the cracking leakage during the operation of the pipeline.