Tuz Lechosław
Faculty of Materials Engineering and Industrial Computer Science, AGH University, 30-059 Kraków, Poland.
Materials (Basel). 2023 Oct 5;16(19):6557. doi: 10.3390/ma16196557.
The expansion of the gas pipeline network makes it necessary, on the one hand, to meet the requirements of standards regarding the materials used, but on the other hand, it is necessary to weld them. In the case of natural gas as a fuel, the welding process is widely used, but in the case of replacing natural gas with a mixture of this gas and hydrogen, the requirements regarding the quality of the process must be significantly increased or the process must be completely changed. This article presents the results of testing welded joints for a newly developed welding technology for the transmission of a hydrogen mixture. Material tests were carried out on a butt-circumferential-welded joint made between two spiral pipes with an outer diameter of 711 mm and wall thickness of 11 mm in the X70 grade. The developed welding technology is distinguished by a change in the beveling method of the edges, which allows the heat input to the material to be limited. The technology was developed for use in natural on-shore and off-shore gas pipelines with the addition of hydrogen. As a result, additional requirements in terms of joint plasticity had to be met during welding. The test results obtained indicate that the joints are characterized by high strength (more than 581 MPa), higher than that of the base material (fracture in the base material) and good impact strength at reduced temperature (more than 129 J). In transverse corrosion, a hardness below 250 HV and a favorable structure of ferrite with different morphologies were obtained.
天然气管道网络的扩展一方面使得有必要满足关于所用材料的标准要求，另一方面也需要对管道进行焊接。对于以天然气作为燃料的情况，焊接工艺被广泛应用，但在用这种气体与氢气的混合物替代天然气的情况下，对焊接工艺质量的要求必须显著提高，或者必须完全改变该工艺。本文介绍了一种新开发的用于传输氢气混合物的焊接技术的焊接接头测试结果。对两根外径为711毫米、壁厚为11毫米的X70级螺旋管之间的对接环向焊接接头进行了材料测试。所开发的焊接技术的特点是边缘坡口加工方法有所改变，这使得输入到材料的热量受到限制。该技术是为添加了氢气的陆上和海上天然气管道而开发的。因此，焊接过程中必须满足关于接头塑性的额外要求。所获得的测试结果表明，接头具有高强度（超过581兆帕），高于母材强度（母材断裂），并且在低温下具有良好的冲击强度（超过129焦）。在横向腐蚀方面，获得了低于250维氏硬度以及具有不同形态的有利铁素体组织。
