Welding process for hydrogen sulfide-resistant pressure pipelines

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Welding techniques for hydrogen sulfide-resistant pressure pipelines – Tian Shuzi 👍 Liu Mingqiang. In China’s petrochemical industry, high-sulfur natural gases such as those containing hydrogen sulfide are often encountered. Due to the strong corrosiveness of hydrogen sulfide gas, electrochemical reactions can occur when it comes into contact with equipment; hydrogen atoms are released at the cathode. However, the presence of hydrogen sulfide itself often prevents these hydrogen atoms from forming hydrogen molecules. As a result, the hydrogen atoms cannot be released and instead end up in the equipment’s pipelines, leading to phenomena such as sulfide stress cracking and hydrogen-induced cracking. Therefore, certain measures to resist hydrogen sulfide must be taken in petrochemical production, with the main approach being the installation of appropriate anti-sulfur pipelines. However, during the actual installation process, if welding is not done properly, the sulfur resistance will not meet the desired standards; therefore, attention must be paid to the welding of sulfur-resistant pipes. Based on this, this paper explores the welding processes for hydrogen sulfide-containing natural gas pipelines—sulfur-resistant pipelines. China’s Puguang gas field is a super-large gas field that primarily produces highly acidic gases. The on-ground production infrastructure includes fuel gas return pipelines and off-site gathering pipelines; the off-site pipelines are used for producing and transporting the acidic gas, that is, natural gas rich in hydrogen sulfide. The total length of these pipelines designed for this purpose is 36.88 km. The pressure is 11 MPa and the temperature is 60 degrees. Hydrogen sulfide is not only a polar molecule; it also has a significant impact on the safety of equipment and the proper operation of underground pipelines. Furthermore, it poses a serious threat to the health of workers carrying out construction work in the vicinity, as well as to the environmental safety of that area. These days, in order to reduce unnecessary maintenance work on the equipment used in petrochemical production, the materials chosen should be determined based on the pressure, the type of medium, and the thickness of the pipeline. For example, in the case of hydrogen pipelines with a design pressure of 30 MPa, the wall thickness of pipes with a diameter of 600 mm is 60 mm, while those with a diameter of 400 mm have a wall thickness of 40 mm.