A few questions regarding the heat-treated test plates?

1. It is difficult to accurately describe the difference between stress-relief heat treatment and heat treatment aimed at restoring/improving mechanical properties, as some heat treatments that restore a material’s mechanical properties can also serve to relieve stress. In simple terms, the purpose of stress-relief heat treatment is to eliminate the internal stresses generated during the manufacturing process (including cold deformation and welding). On the other hand, the main goal of performance-restoration heat treatment is to restore the material’s heat-treated state or its performance parameters, as these are altered during manufacturing or as a result of reduced performance levels in the material. As for heat treatment aimed at improving the mechanical properties of materials, it is generally applied to individual components in order to enhance parameters such as hardness, impact toughness, and tensile strength. Common heat treatment methods for improving material mechanical properties include quenching and tempering. What we generally refer to as overall heat treatment for pressure vessels and heat treatment for tube boxes both fall under the category of post-weld stress-relief heat treatment. 2. GB150.4 provides clear guidelines regarding whether heat treatment test plates are necessary. Generally, no separate heat treatment test plate is required for stress-relief heat treatment; if a test plate is needed for the equipment itself, it should undergo stress-relief heat treatment in the same furnace as the actual product. Heat treatment aimed at restoring or improving the mechanical properties of materials requires the use of heat treatment test plates. These test plates can be prepared separately or in conjunction with the product test plates; however, those prepared together must have the ability to represent both the product test plates and the heat treatment test plates. 3. If heat-treated test plates are to be prepared, these plates also fall within the scope of inspection required by the boiler inspection agency. The preparation and processing of heat-treated test pieces are governed by the relevant requirements specified in GB150.4, which are quite clear.

I’ve learned from it; I roughly understand now. Thank you

Third question: If your equipment is subject to inspection by the Pressure Vessel Inspection Agency (Special Inspection Institute), then the heat treatment test plates should also be inspected by that agency. If the equipment is not classified as such and therefore not under the supervision of the Pressure Vessel Inspection Agency (Special Inspection Institute), is it still necessary to inspect the test plates?

The fact that it is not under the supervision of a boiler inspection agency does not mean that quality control is not necessary for the test plates

Looking at the factory’s quality plan, it’s very detailed.