Introduction to Valve Pressure Ratings

At present, the new construction petrochemical and fertilizer and chemical projects, including the previously introduced technology devices, basically use CL150LB~2500LB "pound-level valves". Such as BW 900LB gate valve "Pound valve" is called "API valve" or "American standard valve". It is inaccurate to refer to a "pound valve" as an "API valve". Because the "pound-level globe valve" and "pound-level butterfly valve" in "pound-level valve", they do not belong to "API-6D valve". April 2008, 23rd Edition [ISO 14313:2007] "API-6D Valves" only includes: gate valves, check valves, ball valves and plug valves.

Butterfly valve in the United States AWWA (American Waterways Association Valve Standard): AWWA A504 "Rubber Seat Butterfly Valve" standard; in MSS (American Valve and Fitting Manufacturers Standardization Association Valve Standard): MSS SP-67 "Butterfly Valve"; In the API standard, there is only one standard of "Lug and Wafer Butterfly Valves" API 609 (4th Edition); Welded End Steel Globe Valves and Globe Check Valves" Standard. Therefore, it is also inaccurate to refer to the "pound valve" as "American standard valve".

1. Materials and design and manufacturing standards used in "pound-level valves"

The so-called "pound-level valve" must meet the following conditions, that is, the standard adopted by "pound-level valve", which can be divided into the following categories:

1.1.Material:

The material standards used in "pound-level valves" are ASTM standards (American Society for Testing and Materials standards) and United States UNS system materials. Such as ASTMA216 WCB; WCC; ASTM A105; ASTM A217 WC6; WC9; C5; ASTMA351 CF3; CF8; CF3M; CF8M; CF8C; CG8M; ASTM A182 F11; F22; F5; .

⑴. A note about the standard materials of the ASTM system in the United States:

     American ASTM system standard materials, usually composed of three units, with ASTM A216WCA; WCB; WCC and ASTM A351 CF3; CF8; CF3M; CF8M; CF8C...; ASTM A182 F304; F304L; F316; F316L; Etc., for example, where: the first unit ASTM is the code name of the "standard issuing organization", ASTM is the "code name of the American Society for Testing and Materials"; the second unit A216 or A351 or A182 is the "standard number" ;The third unit is the specific "material number", such as WCA in A216; WCB; WCC respectively represent three steel grades of carbon cast steel WCA; WCB; WCC, of ​​which A; B; C represent the strength of carbon cast steel , A is low; B is medium; C is high. A351 CF3; CF8; CF3M; CF8M; CF8C…; A182 F304; F304L; F316; F316L; F321; F347…etc. ... etc. represent various steel grades, respectively. There is only ASTM A105 in the ASTM system standard. The second and third of this standard are combined, that is, A105 represents both "standard number" and "steel grade", which is like a Chinese name with two characters.

⑵. About the "Uniform Digital System" material code in the United States:

There are different representation methods in different American standard systems. In order to facilitate the use and unified management of computers, SAE (Society of Automotive Engineers) and ASTM (American Society for Testing and Materials) jointly developed the ASTM-SAE "Unified Digital System" (Unified Digital System). Numbstring System—UNS). "Unified Digital System UNS" is another commonly used material standard system code in addition to the ASTM system standard system.

The UNS material number is sometimes an important basis for distinguishing between the same ASTM alloy number and two rolling materials. Such as Hastelloy C-276 alloy in Hastelloy C (see Table 2).

Table 2. The material number of UNS system for rolling products of Hastelloy C-276 alloy and the comparison of Chinese, German and English material numbers

China (GBn) USA (ASTM) Germany (DIN) UK (BS)

NS333 (HastelloyC-276)

N10276(Inconel625) NiMo16Cr15WZ.4819 /

NS336 (HastelloyC-276)

N06625(Inconel625) NiCr22Mo9NbZ.4856 NA21Ni-Cr-Mo-Nb

※ Note 1: For this information, see: Deng Zhaoyi, Yao Zhenfu, Editor-in-Chief of "New World Steel Grades Handbook", "Machinery Industry Press", Beijing First Edition, May 1995, "5.3 Corrosion Resistant Alloys" on page P1587.

※ Note 2: There are two grades of Inconel625 alloy. If it is used for anti-oxidation of high pressure valves, UNS N06625 (Inconel625) is generally selected; if it is used for strong corrosion resistance, UNS N10276 (Inconel625) is usually selected.

【Attachment】: Some commonly used stainless steel grades compared with ASTM (American Society for Testing and Materials) and UNS (Unified Numbering System) (see Table 3).

Table 3. Some commonly used stainless steel grades compared with ASTM and UNS: 1). Austenitic type (including high nitrogen austenitic type)

2). Martensitic stainless steel