Regarding the material requirements for new forgings in GB/T150.2

The new requirements introduced in GB/T150.2-2024 have indeed raised similar questions among many organizations. Articles 7.1.3 and 7.2.3 of the current GB/T150.2-2024 explicitly state that: \"Cylindrical, annular, and bowl-shaped forgings intended to be used as vessel shells or heads shall be of grade three forgings.\" ” Compared to the 2011 version of the standards, this requirement is indeed new. The current general understanding within the industry is as follows: 1. The standards specify that it refers to \"cylindrical, annular, or bowl-shaped forgings used as container shells or heads\", that is, they are the main pressure-bearing components within the pressure vessel’s pressure-bearing shell structure, and therefore grade 3 forgings must be used. 2. If standard flanges (such as HG/T47021~47023, etc.) are used as connection flanges for equipment or as accessory flanges on pipe ends, their function is primarily to facilitate sealing, rather than to form part of the cylinder or head that constitutes the main body of the container; therefore, they do not fall under the category described in the standards as those \"used for container cylinders or heads\". In such cases, it is generally not necessary to mandate the use of three-stage forgings. In other words, the fundamental purpose of adding this requirement in GB/T 150.2-2024 is to ensure that the forgings, which serve as the main load-bearing elements of the overall cylinder (or head), possess higher metallurgical quality, better overall mechanical properties, and stricter requirements for non-destructive testing. Generally, connection flanges are not considered to be main cylinder sections or head components, and therefore these provisions do not apply directly to them; they can still meet the requirements of their respective original grades. Of course, to eliminate any ambiguity, it is recommended that during the actual implementation of the project, further confirmation be sought from the relevant design review departments or standard-setting bodies, or that clarity be provided in the manufacturing design specifications, in order to avoid disputes. However, according to the current mainstream practices and usual procedures in the industry, the connection flange does not need to be treated as a grade-3 forgery. .

These two clauses were already present in the 2011 version, namely clauses 6.1.3 and 7.2.4 of GB/T150.2-2011. Apart from design requirements such as load, size, and medium, the flanges used to connect the two sections of the cylinder or the cylinder to the head do not require grade III or forgings.

1. This clause was already present in the older version of the standard. 2. The clause is clearly intended for use in manufacturing cylinder or head forgings; so why would one think of flanges that connect to cylinders and heads?

7.1.3 specifies that they are forgings to be used as the cylinder and head, without mentioning the flanges that connect the cylinder and head. Do not overinterpret the term “ring-shaped”; ring forgings can be made into heads with a hole in the center. The standards may not have taken into account that a cylindrical forging can also be processed into a cylinder.