The welding requirements of thermal oil boilers are very strict, and the welding joints need to meet different requirements according to different pressure components.
For the longitudinal circumferential welds of thermal oil boilers, the sealing seams are 100% radiographic or 100% ultrasonic plus at least 25% radiographic flaw detection, which is basically consistent with the current requirements for steam boilers and hot water boilers, and only the provisions of 100% ultrasonic plus at least 25% radiographic flaw detection are added, which is the same as the 80 version of steam boilers. This regulation mainly considers 100% ultrasonic plus 25% radiographic flaw detection, which can fully discover defects in welds, meet safety requirements, and reduce production costs. 25% radiographic flaw detection must include cross joints of longitudinal joints and circumferential joints.
For the flaw detection of heating surface pipe butt joints, requirements are put forward according to different heating conditions. Different heating refers to radiant heat and convection heat. In the draft for comments, 25% and 10% flaw detection and spot checks are stipulated respectively. In the feedback, some units believe that the requirements are low and suggest changing to 100% and 50%; some units believe that this requirement can be lower. After analysis and research, we adopted the latter view, that is, the radiation section shall be no less than 10% of the radiographic inspection and spot check; the convection section shall be no less than 5%. The main consideration is that the regulations on the butt weld of the heating surface tube should adopt gas shielded welding, and the quality is guaranteed. In addition, this procedure also stipulates the calculation of the flaw detection method and the spot check rate, making this procedure more operational.
Except for the cylinder of the gas phase furnace, the mechanical property test shall be carried out. The cylinder of the liquid phase furnace, the heating surface tube of all organic heat carrier furnaces and the butt joints of the pipeline do not need to be tested for mechanical properties. Therefore, this regulation is only for the mass production of gas phase furnaces. In other cases, test plates are not required. Mainly considering that the use pressure of the liquid phase furnace is relatively low. At the same time, this regulation not only clearly stipulates the welding method, but also puts forward requirements for the evaluation of the welding process, which can ensure the quality and performance of the weld.
The welding requirements of thermal oil boilers are very strict, and the welding joints need to meet different requirements according to different pressure components.
For the longitudinal circumferential welds of thermal oil boilers, the sealing seams are 100% radiographic or 100% ultrasonic plus at least 25% radiographic flaw detection, which is basically consistent with the current requirements for steam boilers and hot water boilers, and only the provisions of 100% ultrasonic plus at least 25% radiographic flaw detection are added, which is the same as the 80 version of steam boilers. This regulation mainly considers 100% ultrasonic plus 25% radiographic flaw detection, which can fully discover defects in welds, meet safety requirements, and reduce production costs. 25% radiographic flaw detection must include cross joints of longitudinal joints and circumferential joints.
For the flaw detection of heating surface pipe butt joints, requirements are put forward according to different heating conditions. Different heating refers to radiant heat and convection heat. In the draft for comments, 25% and 10% flaw detection and spot checks are stipulated respectively. In the feedback, some units believe that the requirements are low and suggest changing to 100% and 50%; some units believe that this requirement can be lower. After analysis and research, we adopted the latter view, that is, the radiation section shall be no less than 10% of the radiographic inspection and spot check; the convection section shall be no less than 5%. The main consideration is that the regulations on the butt weld of the heating surface tube should adopt gas shielded welding, and the quality is guaranteed. In addition, this procedure also stipulates the calculation of the flaw detection method and the spot check rate, making this procedure more operational.
Except for the cylinder of the gas phase furnace, the mechanical property test shall be carried out. The cylinder of the liquid phase furnace, the heating surface tube of all organic heat carrier furnaces and the butt joints of the pipeline do not need to be tested for mechanical properties. Therefore, this regulation is only for the mass production of gas phase furnaces. In other cases, test plates are not required. Mainly considering that the use pressure of the liquid phase furnace is relatively low. At the same time, this regulation not only clearly stipulates the welding method, but also puts forward requirements for the evaluation of the welding process, which can ensure the quality and performance of the weld.