HydroFlange is most trusted and famous manufacturer and supplier of Weld Neck Flange with an ISO 9001:2008 and PED Certifications.
A Weld Neck Flange, also called as High Hub Flange or Tapered Hub Flange, is available in two designs namely regular type and long type. The regular type is useful with pipes while on the other hand, the long type is useful in processing plant systems. There is a circular fitting in a weld neck which has a protruding rim at its boundary. Actually, these Weld Neck Flange go through typical butt weld processing into a pipe and are machined from a forging. The rim here has number of drill holes which allow the flange get affixed to another flange using bolts. Weld Neck Flange are brought into use in hostile areas where there is severe pressure, temperature and other stressful forces. This type of flange gets its resilience when you share its stress with the pipe with which it is welded. They are more likely to be useful at pressures up to 5,000 psi.

Weld Neck Flange

Weld Neck Flange

Weld Neck Flange
Weld Neck Flange
Material specifications of Weld Neck Flange
  1. Materials- Carbon Steel (ASTM A 105 and A 181), Stainless Steel (ASTM A 182 and A 240), Alloy Steel (ASTM A 182 and GR F1, F11, F22, F5, F9, F91).
  2. Grade- Super Duplex stainless steel UNS S32750, F 304, 304L, 304H, 317, 347, 347H, , 316, 316L, 316Ti, 904L, Duplex stainless steel UNS S31803.
  3. Nickel Alloys- Monel 400 & 500, Inconel 600 & 625, Incolloy 800, 825, Hastelloy C22, C276.
  4. Copper Alloys- Copper, Brass & Gunmetal.
  5. Size- 1/8″ NB TO 48″NB.
  6. Class- 900#, 1500# & 2500#, ANSI B16.5 Class 150, ANSI B16.5 Class 300, ANSI B16.5 Class 600, ANSI B16.5 Class 900, ANSI B16.5 Class 1500, ANSI B16.5 Class 2500.
  7. Standard- ANSI, ANSI B16.5, ANSI B16.47, DIN2566, DIN2573, DIN2642, DIN2655, DIN2576, DIN2641, DIN2632, DIN2633, DIN2634, DIN2635, DIN2628, DIN2629, DIN2638, DIN2673


Normally, manufacturing of weld neck flanges is in various pressure ratings. As a matter of fact, each class of weld neck flange handles more pressure than previous class of its construction. Strangely enough, higher the class is, thicker the metal which leads to a good handling of huge pressures. The pressure capacity of flanges alters when various factors such as the type of metal used and others. Ironically, as the pressure reduces, the temperature increases and is thus vice-versa. To identify flanges, a tough stamp of flange specification is imprint on the outer diameter of the base flange. However, the standard and arithmetical average roughness height (AARH) determines the flange face finish. Above all, there are five types of flange finishes which are as below.

  1. Cold water – this is done with a wide tool at faster speed which gives mirror like finishing surface or ground surface. It has a mirror like finish. The flange surfaces which have such type of finish are useful in metal to metal applications and not in gasket. They are also useful in oil, chemical and other industries.
  2. Concentric serrated –to make the grove; a 90 degree align angle tool makes a grove of 0.4 mm deep and 0.2 mm apart in concentric circle.
  3. Smooth – This is made in various types of tool shapes and has roughness of finish from 5 to 10 micro millimeters.
  4. Spiral serrated – much similar like stock finish, the only difference is the method of making grove. The same 90 degree incline angle tool is useful to make a grove 0.4 mm deep and 0.2 mm distance.
  5. Stock – This kind of surface is made using a continuous spiral groove which has a roughness of the finish range from 5 to 20 micro millimeters. This is further cut with a tool having approximately 1.5 mm or larger radius.

Flanges which are often bought into use, have a soft gasket squeeze in between the harder flange surfaces which forms a leak-free seal. Materials used for gasket can be rubbers, elastomers (springy polymers), soft metal (copper or aluminum) and soft polymers covering a springy metal (e.g., PTFE covered stainless steel).

Hydro works with an aim to produce the best ever Weld Neck Flange. We aim at manufacturing more amount of output and shipping them worldwide, thus not only satisfying our local customers but also our foreign friends.
When the pipe is weld till the neck of the flange, these pipe flanges get akin. Further, this leads to transmission of stress from the flange to pipe. In addition to that, it also reduces the gathering of stress at the base of the hub. Widely used in areas of high pressure, weld neck flanges have a unique inner diameter which is designed with an intention to match the pipes inner diameter. Hydro flange manufactures weld neck flanges with a hub having size range from 1/2″ through 96″ and also in other material grades, sizes and specifications which include Stainless Steel Weld Neck Flange, Carbon Weld Neck Flange and Alloy Weld Neck Flange.  As a matter of fact, Weld Neck Flange are provided with a raised face where the standard height is 1/16: fewer than 400#, flat face and RTJ facing. With the best warehouse and storage facilities, HydroFlange has various Weld Neck Flange stored as outputs and ready to ship anytime. Our company manufactures ANSI B16.5 Weld Neck Flange, ASME B16.47 Series “A” and B of Weld Neck Flange respectively, pressure Vessel Weld Neck Flange and also custom Weld Neck Flange with clients demands.
  1. Most common type of high pressure flange
  2. Long tapered butt weld hub
  3. The inside diameter of flange matches the inside diameter of the pipe used
  4. Preferred in an environment with extreme temperature conditions
In general, there are two types of Weld Neck Flange namely standard and long. Standard Weld Neck Flange are useful in Butt Weld Fittings whereas Long Weld Neck Flange are useful with vessel nozzles for columns or barrels and equipment. The Flange are in such manner as they match the pipe’s inner diameter. The reason behind boring a flange to match the pipes inner diameter is just to ensure smooth flow and reduce corrosion inside the pipe.  As the name says, long weld neck flanges actually have longer necks than the Standard Flange.
HydroFlange’s Weld Neck Flange are useful in applications at severe and critical applications like high pressure, high temperature, volatile and hazardous fluids and temperatures in the sub-zero range. At HydroFlange, we provide standard connections in wide range of pressure rating sizes and classes which are according to ASME standards of ASME Section VIII Div. 1 and ASME B16.5. Moreover we also manufacture connections which match up to ASME Section VIII Div. 2 and also other specifications when specifications are available. The other types of Weld Neck Flange which HydroFlange manufactures are Weld Neck Flat Face Flange and Raise Face Weld Neck Flange.