The paper concerns the problem of the occurrence of failures of the high-pressure ammonia water pipeline of the coke oven battery complex, which is affected by chemical and thermal factors as well as the operating pressure occurring during its use. Pipeline failures manifested themselves as leaks (leakage of the medium) due to cracks in the area of the pipeline thermal elongation compensators. The conducted tests included, among others: visual inspection, penetration tests, macroscopic and microscopic tests as well as chemical analysis of the material. The study includes microscopic photographs of the material structure and cracks. The results of the pipeline strength and reliability analysis were also presented. On the basis of the conducted research and analyses conclusions were formulated. The assumed cause of the damage was the incorrectly made welded joints. Formulated recommendations and proposals for actions aimed at avoiding further failures of this and similar pipelines were related to the inspection time and preventive renewal.