JB308-75 Mechanical Industry Ministry Standard Valve Modeling Method
In order to unify the management and control of valves, the Ministry of Industry and Information Technology of the Peoples Republic of China (MIIT) issued JB/T 308-75 valve model coding standard. This paper is aimed to describe the general rules for the coding of valve models according to this standard.
1. Structure of Model Code
The valve model code is composed of three parts. The first part is JB/T308-75, which indicates the standard for code number that mandated by the Ministry of Industry and Information Technology. The second part consists of a letter, which indicates the type of valve. The third part is a number, which consists of numbers or letters, used to express the model parameters.
2. Coding Method of Valve Type
The letter in the model code indicates the type of valve, including gate valve (T), globe valve (F), ball valve (K) and plug valve (H).
3. Coding Method of Model Parameters
The numerical parameters in the code can be divided into three categories, namely valve body size, flange dimension and others.
(A) Coding of Valve Body Size
The numerical parameters specifying the valve body size includes the nominal size of the valve body, the understanding of the valve body structure and the connection type. The various parameters in this category can be divided into five parts.
i. Nominal size: The number of the size of the body is composed of units, followed by double decimal number. The number of the unit is generally expressed by a capital letter, with A for 10mm, B for 20mm, C for 40mm and D for 80mm. For example, the code for a valve body size of DN50 will be B05;
ii. Bypass valve body structure: This section is composed of a number of Chinese characters and corresponding numbers. The characters stand for the valve body structure, while the numbers are used to express the structure type. For example, the code for an easy dismantling seal structure is BD;
iii. Valve body connection type: This section is composed of two English letters, one of which is slightly uppercase, stands for material and is expressed in two English letters. The other one stands for the connection type and is expressed in two English letters. For example, the code for a flanged connection is MJ;
iv. End connection size: This section is composed of two English letters and two Arabic numerals, which is used to express the size of the end connection;
v. Whole size: This section is also composed of two English letters and two Arabic numerals, which is used to express the actual size (whole size) of the valve body.
(B) Coding of Flange Dimension
The number parameter of the flange dimension is composed of two English letters, one of which stands for the nominal diameter of the flange and is expressed in two English letters. The other one stands for the flange type of the valve and is expressed in two English letters.
(C) Other Parameters
In addition, other parameters of the code mainly refer to the valve structure material, pressure level, type of valve stem, seal medium and valve cover position.
The coding method of other parameters is specified in the same way as the above. The coding of the valve model shall conform to the structure of JB/T308-75.
In conclusion, the JB/T308-75 valve model coding standard issued by the Ministry of Industry and Information Technology follows a certain structure and composition, often including three parts. The first part is JB/T308-75, which is the standard for code number that mandated by the Ministry of Industry and Information Technology. The second part, a letter, indicates the type of valve. The last part, numbers or letters, expresses the model parameters, including the valve body size, flange dimension and other parameters.
