Welding Repair Scheme of High Pressure Adjustment Valve of Turbine
1 Introduction
Turbines generally consist of basic elements such as rotors, turbines and stators. Its working principle is to convert the pressure energy of steam into kinetic energy and drive the rotor to rotate. High pressure adjustment valves are an important component of the turbine, because without them, the steam flow in the turbine can not be adjusted. The high pressure adjustment valve is mostly welded and deformed, and due to long-term use, cracks may occur. In this paper, a welding repair scheme suitable for high pressure adjustment valves of turbines is proposed, and the welding process and requirements of related welding materials are discussed in detail.
2 welding repair scheme
2.1 Wire Selection
The welding material requirements of the high pressure adjustment valve of the turbine are mainly determined according to the size and material of the original material. Due to the high temperature and pressure in the high pressure adjustment valve pipeline, the welding material should have good oxidation and corrosion resistance, and the welding wire should have a smaller wire diameter and a certain hardness. When the pipeline material is 12Cr1MoV alloy steel, G and Y pipe elbow can be selected for welding, and the wire model should be ER50-6.
2.2 Welding Process
Before welding, the surface of the workpiece should be surface treated to ensure that there is no rust and oil on the surface. After cleaning, it can be vacuum dried to ensure the welding quality. Secondly, it is necessary to check the installation size and alignment accuracy of the weldment, so as to ensure that the welding part is not elastic and miscellaneous. Before welding, the groove width and angle should be determined, and the prepared welding materials should be preheated and post weld inspected.
2.3 Welding Process Requirement
The welding process of the high pressure adjustment valve of the turbine should be strictly controlled. The welding must be completed by qualified personnel, and the welding process should be strictly tested. Before welding, the weldment should be strictly checked to ensure the installation size and alignment accuracy. The width and angle of the groove should be determined according to the process requirements. During welding, manual argon arc welding should be performed. The welding current should be selected correctly, otherwise it will cause excessive fusion, insufficient penetration and welding defects. In order to avoid cold and hot cracks, the cooling rate should be controlled properly. Generally speaking, the cooling rate of large weldment should not exceed 8-10℃/min.
3Conclusion
In this paper, a welding repair scheme suitable for the high pressure adjustment valve of the turbine is proposed. The welding material and wire model are selected according to the size and material of the original material, and the welding process requirements such as preheating, welding, cooling and welding inspection are discussed in detail. Only by ensuring the welding process, can the welding repair of high efficiency adjustment valve of turbine be more perfect and stable.
