How to select flanges for valves
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I work in flange sales. At the workplace, I came across a valve manufacturer who asked us for quotes; however, they only sent us the specifications of the valves and asked us to design the flanges accordingly. But we don’t have much knowledge about valves, so we’re not sure how to go about it. I would like to ask everyone what each part of the valve specifications represents. I mainly want to know what those are the standard numbers for valves, and what should be the corresponding standard numbers for the flanges. Also, it would be helpful to know how the sealing surfaces are arranged; it would be even better if examples could be given of how flanges are attached to each standard valve! I’d like to thank everyone here first!
Firstly, the pressure rating must be matched properly; for example, a valve with a pressure rating of 1.0 MPa should be paired with a flange of the same 1.0 MPa rating. Additionally, the engineering diameter also plays a role in this decision
Valves are standard components, and flanges are used in conjunction with them. The flange connection for a valve must comply with the corresponding flange standards; for example, a valve with the specifications DN50PN25 should be paired with a flange that meets the DN50PN25 standard. In the valve designation, DN denotes the nominal diameter of the valve – 50 in this case indicates that the nominal diameter is 50 mm. PN refers to the nominal pressure of the valve, with 25 meaning that the nominal pressure is 2.5 MPa
The pressure rating of the flange that pairs with the valve must be greater than or equal to the valve’s pressure rating. Additionally, the diameter of the bolt holes in the flange must match those of the valve; otherwise, it may not be possible to tighten the bolts. Pay attention to the length of the bolts – they should neither be too short nor too long. The bolt length should equal the thickness of the valve with its flange plus the thickness of the matching flange, plus the thickness of the nut, plus the thickness of the sealing ring, plus the thickness of the nut washer, plus a margin of 5–10 mm.
Thank you all for your attention. But what the two friends above said is also known. What is wanted to be clarified is how, from the specifications of a valve, it can be determined whether it is a valve based on American standards, German standards, Chinese standards, or some other standard. Do they all have some codes? If so, what is the code name and what standard does it represent? Also, what type of flange is compatible with the valve – WN? PL? or something else? I thought there were also many types of standard flanges?
Standards should be prepared such as the HG20592 series and sh3406-96 standards, and then selected accordingly based on the standards applicable to valves
Simply put, you can directly ask the valve manufacturer for the flange standards and material. Only valve models cannot be paired with flanges.
Common industrial valves include gate valves, globe valves, throttle valves, ball valves, butterfly valves, diaphragm valves, plug valves, check valves, safety valves, pressure relief valves, and steam traps. However, the flanges that match the valves are also selected based on the valve’s nominal diameter, nominal pressure, and material requirements
The specifications and models of the flange should be the same as those of the valve, including parameters such as diameter, pressure rating, and flange standard.
The valve model is used to indicate elements such as the type of valve, drive and connection method, seal material, and nominal pressure. Due to the wide variety of valve types, and for the sake of ease in manufacturing and use, **standardized rules have been established for naming valve product models. The model of a valve product consists of seven elements, which are used to indicate the valve category, type of actuation, connection and structural format, sealing surface or lining material, nominal pressure, and valve body material. The composition of the valve model consists of seven units in sequence: 1 – represents the valve type code in Pinyin, as shown in the table below. Valve Type Code Valve Type Code Valve Type Code Gate Valve Z Ball Valve Q Check Valve S Stop Valve J Plug Valve X Safety Valve A Flow Control Valve L Level Indicator M Pressure Reducing Valve Y Diaphragm Valve G Check Valve H Plug Valve U Disk Valve D Note: For valves designed for low temperatures, those with insulation (equipped with heating jackets), and those with bellows, the Pinyin letters “D”, “B”, “W”, etc., are added in front of the valve type code respectively. 2 – The drive method code is represented by Arabic numerals, as shown in the table below. Drive Method Code: Electromagnetic 0; Bevel gear 5; Electromagnetic-hydraulic 1; Pneumatic 6; Electro-hydraulic 2; Hydraulic 7; Worm gear 3; Pneumatic-hydraulic 8; Spur cylindrical gear 4; Electric 9. Note: 1. Codes for drive methods using handwheels, handles, wrenches, as well as for automatic valves such as safety valves, pressure relief valves, and steam traps are not included. 2. For pneumatic or hydraulic valves, the normally open type is denoted by 6K and 7K, while the normally closed type is denoted by 6B and 7B ； Pneumatic type with manual valve, denoted by 6S ； The Fangbao electric version is denoted by 9B. 3 – The connection type is indicated by Arabic numerals, as shown in the table below: Connection type code; Internal thread: 1; Clamp-type connection: 7; External thread: 2; Clamp: 8; Flange: 4; Sleeve: 9; Welding: 6. Note: Welding includes butt welding and socket welding. 4 – The structural type is also indicated by Arabic numerals, as shown in the table below: Structure type of gate valve: Rod-mounted wedge type, Rod-mounted parallel type, Hidden rod wedge type, Elastic valve plate, Rigid valve plate, Rigid double valve plate, Rigid single valve plate, Rigid double valve plate, Rigid single valve plate. Codes: 0, 1, 2, 3, 4, 5, 6. Structure types of stop valves and throttle valves: Straight-through type, Angle type, Flow-through type, Balanced straight-through type, Balanced angle type. Codes: 1, 4, 5, 6, 7. Structure types of ball valves: Floating type, Fixed type, Straight-through type, L-type tee, T-type tee, Straight-through type. Codes: 1, 4, 5, 7. Structure types of safety valves: Spring type, Closed type, With radiators; Full open type: 0; Slightly open type: 1; Full open type: 2; Lever-operated full open type: 4; Not closed, double spring, slightly open type: 3; Slightly open type: 7, 8, 5; Full open type, Full open type: 6; Pulse type, Slightly open type. Note: For lever-type safety valves, the letter “G” from Pinyin is added before the type code. Structure types of check valves: lift, swing, pivot, straight-through; vertical, single-disc, multi-disc. Code numbers: 1, 2, 4, 5, 6. The code for the valve seat sealing surface or lining material is represented by Pinyin letters in accordance with the rules in the table below. Code for valve seat sealing surface or lining material: Copper alloy – T; Hard alloy – Y; Rubber – X; Lining rubber – J; Nitrile plastic – N; Lead lining – Q; Fluoroplastic – F; Enamel – C; Tin-based bearing alloy (Babbitt) – B; Graphite – S; Alloy steel – H; Boronized steel – P; Nitrided steel – D. Note: The code for the valve seat sealing surface material that is directly machined from the valve body is represented by “W” ； When the materials of the valve seat and valve disc sealing surfaces are different, the lower hardness material is indicated (except for diaphragm valves). 7 – The code for the valve body material is specified in the table below. Valve body material code: Carbon steel – CCr18Ni12Mo2TiR; Malleable cast iron – K; Chromium-molybdenum-vanadium alloy steel – V; Ductile cast iron – QCr5Mo1; Gray cast iron – Z1Cr18Ni9TiP. Note: For carbon steel with a nominal pressure PN ≥ 2.5 MPa, the material code is omitted. If the valve model is Z41H-25 DN50, then a flange with DN50 and PN2.5MPa specifications should be used. Last edited by redboy219 on 2009-3-28 15:51]
Be sure to ask clearly about the medium being used, as well as the temperature and pressure. There are also connectors of Series A and Series B, with flanges selected according to the standards.
Be sure to ask clearly about the medium being used, as well as the temperature and pressure. There are also connectors of Series A and Series B, with flanges selected according to the standards.
Buy a valve design manual and take a look; you’ll know then
The main requirement is that the nominal diameter of the flange and the valve, the pressure rating, the flange standard, and the type of sealing surface be the same
Read more books on the subject; over time, you will understand
First, you need to determine whether the standards for selecting flanges for valves are those from the petrochemical industry, chemical industry, or mechanical industry standards, or if there are special requirements for the valves in question; once that is known, you can look up the appropriate flange specifications according to those standards! Basically, there are more petrochemical standards, and some are chemical industry standards; moreover, the A series of chemical industry standards is identical to the petrochemical standards!
I study welding and lathe operations; it’s very important that the flange material matches the appropriate specifications, as well as factors such as strength and hardness. You should read some books on the subject
Find a valve manual and a flange manual, study them a bit and you’ll know
You are working in flange sales; the company has flange standards, so learn them.
Hurry up and buy a flange standard; follow that standard to select the appropriate flanges (flanges with the same nominal pressure and diameter that match each other), with the material usually being specified by the purchasing party.