Regarding post-weld heat treatment of end caps

The butt welds of the head with a thickness of 26 mm, as well as the welds joined to it, require post-weld heat treatment.

Not only does it itself and the welds to the cylinder require heat treatment, as stated in the general requirements above, but the welds to the non-compressed components welded to it also need heat treatment.

For headers of this thickness, hot forming is generally recommended; after hot forming, the normalized state of the material must not be compromised, otherwise re-normalization is required. The seams of the head have been normalized, so no post-weld stress-relief heat treatment is required. Therefore, hot forming of the head is required, along with heat treatment to restore it to its service condition.

As for whether heat treatment is required after the container is fully formed, it is determined by the design.

This post was last edited by jizhanwei22 on 2017-3-3 at 17:54. Generally speaking, end caps are finished products, and like flanges, they are purchased as well. Even when stamped by the manufacturer itself, it still needs to be manufactured, inspected, and accepted in accordance with GB/T 25198-2010. In other words, the heat treatment of the head no longer needs to be indicated repeatedly on the drawings. Otherwise, it will be difficult for you to fill in the coefficient for Class AB welded joints. For example, if a device requires 20% flaw detection, the coefficient is 0.85 ； So, if the head is welded by joint welding (with 100% flaw detection), the joint welds on the head fall into Category A; in the technical specifications table, should the coefficient be set to 0.85 or 1.0? ? Do the shell and the head need to be labeled separately?? Therefore, I suggest that the head be treated as a finished component just like a flange; the requirements regarding heat treatment and the proportion of weld inspections should all be in accordance with GB/T 25198-2010. No repeated requirements on the pattern. As for whether the owner’s equipment requires overall heat treatment, according to GB150, for the head 26 and the shell 24, the thickness for post-weld heat treatment should be 24 mm for the shell 24; therefore, overall post-weld heat treatment is not necessary. It’s my personal opinion; it has nothing to do with the HaiChuan Forum, nothing to do with the Boiler Capacity Standard Committee, nothing to do with the National Development and Reform Commission, and nothing to do with the State Council.

What was said upstairs is correct; ring-seam annealing is sufficient.

After discussion, we decided to require in the technical data sheet: post-weld heat treatment for the head (including the components welded to it).

It depends on the thickness of the welded joint

According to Clause 8.2.1 of GB150.4, when welding components of different thicknesses, for butt joints with unequal thicknesses, the thickness of the steel material from the thinnest component is taken as the standard. Under this provision, post-weld heat treatment is not required for the ring seams between the head and the cylinder; whereas whether heat treatment is necessary after welding between stressed and unstressed components depends on the thickness of their joints.

The GB/T 25198 standard is a general standard for end caps; however, for the specific requirements of containers, targeted specifications for the end caps should be established based on factors such as the materials used in the equipment and its intended use. In the absence of special requirements, the standards for end caps can be followed. Designers cannot fully follow the head standards without considering the specific requirements of the container.