Problems with heat treatment and insulation time of pipe boxes
Thread Content
The pipe box nipple 16MnRδ16 and the flange 16MnRδ46 need to be covered with 2 PQRs lower than the lower transition temperature, but the holding times of the two PQRs are different, (one is 620℃/2h and the other is 620℃/3h). How to fill in the heat treatment time when compiling the product welding process specification in this case? (620℃/? )
What does 620℃/2h mean? It means keeping the temperature at 620 degrees for 2 hours? The thickness should be measured at the welded joint, not the flange thickness.
Article 8.2 of JB4709-2000 has detailed regulations. One hour of heat preservation time is enough.
The thickness of post-weld heat treatment of pressure vessels or pressure components shall be as follows:: The post-weld heat treatment thickness of equal-thickness full-penetration butt joints is the thickness of the weld, which is also the thickness of the steel of the container or its pressure components. The thickness of the weld is the greater of the thickness of the butt weld and the thickness of the fillet weld. The post-weld heat treatment thickness of unequal thickness welded joints is limited to the shell thickness when welding tube plates, flat heads, cover plates, or flanges on the shell. When the nozzle, manhole and shell are assembled and welded, the thickness of the neck of the nozzle, the thickness of the shell, the thickness of the head, the thickness of the reinforcing plate and the thickness of the connecting fillet weld shall be chosen, whichever is greater. The pipe neck thickness is limited when the nozzle is welded to the high-neck flange. When welding the pipe to the tube sheet, the thickness of the weld is taken. The thickness of the weld at the joint between non-pressure components and pressure components. During welding repair, the thickness of the weld metal filled shall be taken. The thickness of the base material on the thinner side of the butt joint is taken.
The holding time is calculated according to the requirements in Table 8.3 of JB/T4709-2000.