For a given valve of material, type, size, pressure class, and connection form, to ensure the interchangeability of its installation, the standardization of the characteristic size valve face-to-face is very necessary. Therefore, each country has clearly stipulated the face-to-face when formulating various valve product standards and has systematically formulated comprehensive standards for valve face-to-face. Such as ANSI B16.10 in the United States, DIN 3202 in Germany, BS 2080 in the United Kingdom, NF E29305 in France, JIS 2002 in Japan, and GB/T 12221 and GB/T15188 in China. The International Organization for Standardization Valve Technical Committee (TC153) takes DIN3202, ANSI B16.10, and BS 2080 as a reference, and proposes a revised draft ISO/DIS 5752 specification for the face-to-face of metal valves (the International Electrotechnical Commission has formulated the face-to-face standard IEC 543-3). The European Committee for Standardization (CEN) takes ISO / DIS 5752 as a reference and takes into account the actual situation of European countries, and formulated EN 558-1996 “Flange piping system with metal valves face-to-face > standard. This paper analyzes and compares the face-to-face standards of general-purpose valves (excluding pressure-reducing valves, safety valves, steam traps, and other special valves).
Valve face-to-face standard types
Based on the determination of the main parameters of the face-to-face of various valves, such as caliber specifications, pressure levels and connection forms, the main content of the valve face-to-face standards in various countries is basically the same. However, judging from the content of the current national standards, there are two systems for nominal pressure levels: one is based on the ANSI nominal pressure series, such as 150 pounds (PN2.0MPa), 300 pounds (PN2.5MPa), 600 pounds (PN10MPa), 900 pounds (PN15MPa), 1500 pounds (PN25MPa) and 2500 pounds (PN42MPa); the other is based on DIN nominal pressure series, such as PN2.5, 6, 10, 16, 25, 40, 50 and 100bar. The expression form and content of the corresponding valve face-to-face standard can also be divided into two systems. German DIN 3203 can be called the European series of standards. It divides the face-to-face of flanged valves into 20 series such as Fl, F2…Fl6, F3l~F33, and the face-to-face of welded valves into S2 S3 ….. S14 S31, etc. 11 series; the face-to-face of the clip-on valve is divided into 5 series such as K1, K2… ～V3 and other 3 series. ANSI B16.10 can be called the American series of standards. It is classified according to the pressure class (class of pounds), and 97 series are standardized for the face-to-face degree of flange connection, butt welding connection, and wafer connection.
In the face-to-face series of the two system standards, some series correspond to each other, and some series cannot correspond. In addition, in the same series, the same caliber specifications range is larger or larger. For example, the S12 series in Table 1 in DIN3202~1982 has a maximum diameter of 800mm, while the 2 series in Table 3 in ANSI B16.10-2000 has a maximum diameter of 900mm (36 inches). The maximum diameter in Table 1 in EN 558-1-1996 The 5th series has a maximum diameter of 600mm.
Valve face-to-face basic series
1. Number of basic series of national standards
DIN 3202 divides face-to-face into 50 series such as F, S, K, M, V, etc. Except that F, F, S, and Sq belong to the same series, it can be regarded as having 48 basic series. The 1974 edition of BS 2080 did not systematically specify the basic series, while the 1989 edition referred to standards such as IS0 5752, ANSI B16.10, MSS SP67, API 609, DIN 3202, and BS 5154, BS 5155, and BS 5353. Thirty-five basic series are specified. JIS 2002-1987 specifies 48 basic series. my country’s GB/T 12221-1989 and GB/T15188-1994 stipulate a total of 98 series, of which 10 belong to the same series (Table 1), which can be regarded as 88 basic series. ANSIB16.10-2000 regulates 97 series, of which 28 belong to the same series, which can be regarded as 69 basic series. ISO 5752-1988 standardizes 21 basic series of face-to-face flanged pipeline valves. EN 558-1-1996 is consistent with ISO/DIS 5752-1993 basic series numbers, dividing face-to-face into 44 basic series. EN 558-2-1996 is divided into 34 basic series (imperial series).
2. Basic series comparison
Based on EN 558-1-1996, compare the similarities and differences of the basic series of valve face-to-face standards in various countries. From the first half of Table 1 (before the 25 series), EN 558-2-1996 (imperial series) supplements the 24 series, which is the same as IsO/DIs 5752-1988, but it does not list the 15 series. BS 2080-1989 face-to-face basic series also has 2 basic series different from EN 558-1-1996. It can be seen from this aspect that EN 558-2-1996 adopts the first 25 series items of BS 2080-1989. DIN 3202 has the same 11 basic series as EN 558-1-1996. JIS 2002-1987 and EN 558-1-1996 have 20 basic series, my country’s GB 12221-1989 has 19 basic series and ANSI B16.10-2000 has 11 basic series. See Table 2 for the ratio of the number of basic series that are the same as those in EN 558-1-1996 to the total number of basic series of each standard.
3. ISO 5752 and EN558 basic series
The 21 basic series of ISO/DIS 5752-1988 are composed of 6 series of DIN 3202, 10 series of ANSI B16.10, 1 series of MSS SP67, 4 series of BS 5155, BS 5156, and BS 5154. BS 2080-1989 used the American standard face-to-face series extensively when formulating the basic series. In addition to the 11 series that ISO adopts in the United States, another 12 series of ANSI B16.10 are also adopted. When the European Community CEN formulated EN558-1-1996. None of the 12 series were adopted. Instead, 9 series of NF E29 305, NFE29 377, and NFE29 311 are considered. 5 series of DIN 3202, DIN 3357, 4 series of IEC 534-3. Listed after the 25 series. The basic series before the 25 series maintains the consistency of ISO/DIS 5752-1988, and supplements the 63 and 64 series of BS 2080-1989 as the basic series face-to of the 22nd and 23rd basic series EN 558-1-1996 See Table 3 for -face values.
4. About the same type series
There are several standards such as ISO/DIS 5752, GB 12221, JIS 2002, EN 558-1 that stipulate the “same type series”. The so-called “same type series” means “same structure series”. Refers to “the general term for a series of low-pressure gate valves with a specified shape” (see Table 2 of GB 12221-1989). It is different from the “isobaric series”. Since this series of gate valves are generally made of gray cast iron, the maximum allowable pressure at 20″C decreases with the increase of the nominal diameter. Therefore, the basic series 14 (Table 3) should comply with the provisions of Table 4 when used in cast iron gate valves.
In addition to ISO 5752 and GB 12221, EN 558-1-1996 also stipulates the standard for “same type series”. The 14 series is “used for the same type series gray cast iron gate valve (see related product standards for details)”. Although JIS 2002-1987 has the provisions in Table 4 for cast iron valves (see the nominal pressure part of JIS 2002-1987). But “same type series” is not explained in the standard. In its Schedule 1-1, the “same type series” applies to all materials, not just cast iron. Several standards such as ANSI B16.10 and BS 2080 do not cover this content.
1. Lining valve
In general, the dimensions in the face-to-face series table include the lining thickness of the lined valve. When the lining (or valve seat) at the pipe connection (generally referred to as a wafer connection) can play a sealing role (eliminating the sealing gasket), the dimensions in the table can be appropriately increased by 2ram (see DIN 3202-3-1979 No. 2 chapter). GB/T 15188.2-1994 “face-to-face and limit deviation” stipulates: “If the valve has an elastic lining and the lining is used as a sealing gasket at the connection end, the valve face-to-face shall be the valve after the valve is installed. The distance between the two ends of the valve.
ISO 5752 ~ 1988 makes relevant provisions for lined valves:
- When the valve has an elastic lining and is assembled with the flange to form a caulked seam. The face-to-face dimension is the distance between the valve ends.
- For valves with hard lining, under normal production conditions, the thickness of the lining on the mating surface is included in the basic dimensions of FTF (face side) or CTF (center side).
- For valves with elastic or hard lining, when used for normal production of valves, the thickness of the lining on the mating surface is added to the basic ruler of FTF or CTF.
JIS 2002-1987 stipulates the face-to-face of lined valves when the rubber valve seat or the valve body lining directly constitutes the valve end face, face-to-face refers to the two end faces composed of rubber or lining material after the valve is installed The distance between or from one of the end faces to the centerline of the valve.
EN 558 specifies that, for elastomeric lined valves with gaskets connected to mating flanges, the FTF and CTF face-to-face shall be the distance between the two ends of the valve in the installed condition. The manufacturer shall provide the overall length of the valve prior to assembly. For elastic-lined or hard-lined valves as a common production feature. The thickness of the liner on the mating surface shall be included in its FTF and CTF face-to-face unless the valve design does not include this part. If the design does not allow the FTF and CTF face-to-face given in the table to include the lining portion, then the length of the lining shall be added to the basic dimensions. For elastomeric-lined or hard-lined valves not normally produced as a feature, the thickness of the lining on the flange face can be added to the FTF and CTF face-to-face given in Table 3.
2. Dimensional adjustment of different flange sealing surfaces
The flange connection sealing surface forms are different, and the valve face-to-face needs to be adjusted on the basis of the basic size. Usually (referring to plane or raised surface connection) the flange sealing surface generally directly selects the corresponding value in the face-to-face series (as shown in Table 3). When the valve adopts a concave-convex surface, tongue-and-groove surface, or ring connection surface flange, its face-to-face adjustment is divided into two situations. One is that EN 558-1-1996, DIN 3202-1-1977, GB12221-1989, and other standards do not require adjustment. Second, the standards such as EN 558-2-1996 GB 2080-1989 ANSI B16.10-2000, JIS 2002-1987, and ISO 5752-1988 all stipulate the adjustment value.
For the connection structure of the concave-convex surface and tongue-and-groove surface, the adjustment dimensions are as follows. In ISO 5752-1988, the valve face-to-face for pressure classes PN2.5, 6, 10, 25, and 40bar is specified to be directly selected from the table without adjustment. For PN20, 50, and 100bar valves face-to-face, there are 2 cases. The sealing surface is processed normally, and the value in the table is directly selected without adjustment. Other standard machined surfaces should be adjusted according to the given values. According to JIS 2002-1987:
- When the valve adopts K nominal pressure flange whose sealing surface is concave-convex and tongue-and-groove type, its face-to-face should be adjusted. is half value).
- When the valve adopts the nominal pressure of PN20, 50, and 100bar series, and the sealing surface is concave-convex and tongue-and-groove flanges, the face-to-face correction method is shown in Table 5.
The face-to-face adjustment values of ANSI B16.10-2000 and BS 2080-1989 concave-convex and tongue-and-groove sealing face flanges are basically the same as EN 558-2-1996 (Table 6).
The adjustment dimensions of the face-to-face flange valve with ring connection face are clearly specified in EN 558-2-1996, ISO 5752-1988, JIS 2002-1987, and ANSI B16.10-2000 and other standards (Table 7 ).
Valve face-to-face tolerances are specified in national standards. The difference is that the dimensional segments for a given tolerance are not the same. One is to give tolerances according to face-to-face size segments, and the other is to give tolerances according to caliber specifications. The third is to not segment the given tolerance.
ISO 5752, EN 558-2, and JIS 2002 give tolerances by valve face-to-face (Table 8). The tolerances specified in GB 12221 in my country are the same as those in ISO 5752, but the dimensions are different. BS 2080 and ANSI B16.10 are given tolerances according to valve size specifications. BS 2080-1989 stipulates that below 10in (DN 250mm) ±2.0mm, above 12in (DN 300mm) ±3.5mm. ANSI B16.10-2000 stipulates, ≤NPS 10 (DN 250mm)±2mm, ≥NPS 12 (DN 300mm)±3mm. For 125 and 250-pound class cast iron valves and 150 to 2 500 pound class wafer-type steel valves, it is also specified, ≥ NPS 30 (DN750mm) ±6mm. Special regulations are made for butterfly valves, ≤ NPS 6 (DN150mm) ± 2.5mm, ≥ NPS 8 (DN 200mm) ± 3mm, ≥ NPS 3 0±6 mm. The eccentric seat wafer-type steel butterfly valve is all ±3mm. The tolerance of face-to-face in China GB/T 15188 is also given according to the caliber specification (Table 9). DIN is not segmented to a given tolerance. As specified in DIN 3202. According to ±0.5% allowable deviation, min=1mm.
Compatibility of face-to-face EN basic series
National standards have many face-to-face series for different valve types. From the first 25 series in Table 1, it can be seen that the basic series of national standards are relatively uniform. Here, the valve face-to-face is analyzed by valve type. The codes of the same EN basic series of gate valves are shown in Table 10 (the following tables can be viewed in conjunction with Table 1 and Table 3, and the connection form is not specified in the subsequent tables, which are all flange connections). See Table 11 for the codes of the EN basic series for the straight-through globe valve. See Table 12 for the code of the EN basic series for the same use of the angle type globe valve and the lift type check valve. See Table 13 for the codes of the same EN basic series of check valves. See Table 14 for the codes of the EN basic series used for both the plug valve and the ball valve. See Table 15 for the codes of the EN basic series of butterfly valves. See Table 16 for the codes of the EN basic series for the same diaphragm valve.
Through comparison and analysis, ISO 5752 and EN 558 are general standards for valve face-to-face, which are widely used. However, due to the different status of valve production in various countries for many years, there are still quite a few face-to-face series that is difficult to achieve unity, and each maintains relative independence. In particular, the existence of two major pressure systems, the American nominal pressure system represented by ANSI and the European pressure system based on DIN (ISO pressure series is based on the European system), makes countries have to carefully consider when formulating and revising standards. In addition, for the determination of the tolerance of the valve face-to-face, it should be said that it is more reasonable to give the tolerance according to the face-to-face dimension. But some people think that the tolerance size is too large (relatively large diameter).