How to get high quality Welding Neck Flanges?

What is a weld neck flange?

weld neck flange (also known as a high-hub flange and tapered hub flange) is a type of flange. There are two designs. The regular type is used with pipes. The long type is unsuitable for pipes and is used in process plant. A weld neck flange consists of a circular fitting with a protruding rim around the circumference. Generally machined from a forging, these flanges are typically butt welded to a pipe. The rim has a series of drilled holes that permit the flange to be affixed to another flange with bolts.
Such flanges are suitable for use in hostile environments that have extremes of temperature, pressure or other sources of stress. The resilience of this type of flange is achieved by sharing the environmental stress with the pipe with which it is welded. This type of flange has been used successfully at pressures up to 5,000 psi.

A weld neck flange is a type of steel flange designed to transfer stresses to the pipe to reduce high stress concentrations at the base of the flange. Compared with other types,weld neck flanges are know for their tapered hub and gentle transition from flange thickness to pipe wall thickness. They are deformation-resistant, and are normally used for high pressure piping system, high or low temperature conditions.
A weld neck flange (WN flange) means a flange has a neck for weld with the pipe, it is easily to recognized by their long tapered neck on the flange (The neck is also called hub in the weld neck flange). The tapered neck can supply a high strength reinforcement to support flange and pipe. It means the weld neck flange is suitable to used in high pressure and extremely temperature situation. 
Connection of Weld Neck Flange:
The weld neck flange is connected with the pipe from the neck in butt welding method, that means the neck should be have same material and same outer diameter and wall thickness with the pipe. The butt welding joint could provide a strong connection between the pipes and flanges which is better for high pressure application.
Sealing Face of Welding Neck Flange: 
With a neck on one side of the flange, the other side of the flange is sealing face, which are between the two flanges joint. WN flange usually supplied with flat face (FF), raised face(RF) and ring type joint (RTJ). The raised face has a height on the flange rather than the flat face, the RTJ face is used to contain the gasket ring which are specially for high pressure application. 
Dimensions of Weld Neck Flange:
In different standard for weld neck flange, the dimensions of the flange and sealing face have a different technical data, it is necessary to confirm all the details to make sure the flange can match the joint with the pipe and another flange. Except the standard and specification information, the neck data is also important, it means the thickness of the neck also should be provide to confirm a weld neck flange.
Advantages of Weld Neck Flanges:
Yaang’s weld neck flanges have following advantages:

  • The weld neck flange is suitable to used for high pressure, high temperature, low temperature situation because of the butt welding connection method.
  • The weld neck flange has a good excellent stress distribution by its tapered neck .
  • The butt welding joint can be inspected easily ,for example the radiography testing. 

Those advantages make the weld neck flange of Yaang.com widely used in industry application. 

Welding Neck Flanges

A weld neck flange (also known as a high-hub flange and tapered hub flange) is a type of flange.
welding neck flanges banner 3 - How to get high quality Welding Neck Flanges?

The Welding neck flanges is normally referred to as the high hub flange. It is designed to transfer stresses to the pipe, thereby reducing high stress concentrations at the base of the flange.

WELDING NECK FLANGE NPS 6, CLASS 150, SCHEDULE 40, ASME B16.5

WELDING NECK FLANGE NPS 6 3 - How to get high quality Welding Neck Flanges?

The flange above has 8 bolt holes, and a welding bevel of 37.5 degrees (red circle). All given dimensions are in millimeters. The raised face (RF) does not need to be specified, because according to ASME B16.5, each flange is standard delivered with a raised face. Only a different design (Ring Type Joint (RTJ), Flat Face (FF) etc.), should be specified.

The welding neck flange is the best designed butt-welded flange of those currently available becuase of its inherent structural value.

Expander Flange

Expander Flange 3 - How to get high quality Welding Neck Flanges?

Expander Flange is a Welding Neck pipe flange where the nominal size of the non-flanged end is larger than the nominal size of the flanged end. They can be used to change the size of a pipe run. These are usually used to increase the line size to the first or second larger size. This is an alternative to using a separate reducer and weld neck flange combination. The expander flange can be used to connect pipe to pumps, compressors and Valves.

An Expander Flange is a type of welding neck pipe flange used to increase pipe size at the flange connection (see sketch).

The Expander Flange is normally referred to as the high hub flange. It is designed to transfer stresses to the pipe, thereby reducing high stress concentrations at the base of the flange.

An Expander Flange is a type of welding neck pipe flange used to increase pipe size at the flange connection (see sketch). Expander flanges are also known as a cost effective alternative to using a separate reducer-welding neck flange combination.

Expander Flange

Expander flanges are also known as a cost effective alternative to using a separate reducer-welding neck flange combination. The expander flange is available in a range of sizes and materials.

An expander flange is similar to a weld neck flange but with the hub expanding to a larger size (one or two sizes). If you have limited space or just need to connect to a larger pipe size, it provides a convenient way for equipment, pumps and valves. It can replace the use of a flange and reducer. Pressure ratings and dimensions are in accordance with ANSI/ASME B16.5.

Dimensions of Expander Flanges

Dimensions of Expander Flanges 3 - How to get high quality Welding Neck Flanges?

It’s compact size saves space when compared to a reducer-welding neck flange. This flange has a raised face.

Only one butt-weld is needed to install the Expander Flange Very cost effective and competitively priced.

Applications Of Expander Flanges

The expander flange can be used to connect pipe to pumps, compressors and Valves.

  • Expander Flanges are used in Chemical and petrochemical processing.
  • Expander Flanges are used in electronics. Expander Flanges are used in processing equipment for maintaining product purity in handling foods, synthetic fibers.
  • Expander Flanges are used in marine and offshore engineering.
  • The expander flange is available in a range of sizes and materials.

Packing: 
At Yaang will be special Expander flanges with plastic cover to ensure the integrity of sealing surface. Bubble bag, then put in to export wooden neatly in to products during transportation to prevent bumps , scratches and other situations encountered or as per customer requirement.

Surface Treatment: 
Anti-rust Oil, Transparent/Yellow/Black Anti-rust Paint,Zinc,Hot dipped Galvanized.

Long Weld Neck Flanges

Long Weld Neck Flanges 3 - How to get high quality Welding Neck Flanges?

Long Neck Welding (abbreviated LWN) flanges are similar to a standard Welding Neck flange, but the “Neck” is considerably longer. This type is often used as a nozzle for a barrel or column. In addition, there are the type LWN Heavy Barrel (HB) and the Equal LWN Barrel (E); they have a different shape and a thicker “Wall”.

The Long Weld Neck Flange is normally referred to as the high hub flange. It is designed to transfer stresses to the pipe, thereby reducing high stress concentrations at the base of the flange.

The Long Weld Neck Flanges are the best designed butt-welded flange of those currently available becuase of its inherent structural value. It is expensive because of the design.

Details of Socket Weld Flange

flg sw det 3 - How to get high quality Welding Neck Flanges?
1. Socket Weld flange 2. Filled weld 3. Pipe X = Expansion gap

Their static strength is equal to Slip On flanges, but their fatigue strength 50% greater than double-welded Slip On flanges.

Long Weld Neck Flanges

Long welding neck flange, lwn flanges are similar to a standard Welding Neck flanges, but the “Neck” is considerably longer than other flanges. LWN flange is often used as a nozzle for a barrel or column. In addition, there are the type LWN Heavy Barrel (HB) and the Equal LWN Barrel (E); they have a different shape and a thicker “Wall”.

Tube OD sizes: 3/8 to 2 inches

Materials:
Carbon steel: A105,SS400,SF440 RST37.2,S235JRG2,P250GH,C22.8
Stainless Steel: F304 F304L F316 F316L 316Ti, Copper etc.

Vacuum range
Elastomer seal: >=1 x 10^-8 Torr – High vacuum
EVAC metal seal: >=1 x 10^-11 Torr – UHV

Temperature range
Viton: -20°C to 200°C
Silicone: -50°C to 230°C
Buna: -30°C to 110°C
EVAC metal seal: -270°C to 150°C

Packing: No Fumigate or Fumigate Plywood/Wood Pallet or Case

Surface Treatment: Anti-rust Oil, Transparent/Yellow/Black Anti-rust Paint,Zinc,Hot dipped Galvanized.

NW Long Weld Neck Flanges

NW Long Weld Neck Flanges 3 - How to get high quality Welding Neck Flanges?

The NW Long Weld Neck Flanges is normally referred to as the high hub flange. It is designed to transfer stresses to the pipe, thereby reducing high stress concentrations at the base of the flange.

Long weld neck flange(LWN flange) is also call integral flange, it means a welding neck flange has a very long neck. Commonly, the welding neck flange has a tapered neck and a bevel end which is going to butt welding with the matching pipe. But the long weld neck flange, has a straight short pipe as the neck of a long weld neck flange.

The NW Long Weld Neck Flanges are the best designed butt-welded flange of those currently available becuase of its inherent structural value. It is expensive because of the design.

NW Long Weld Neck Flanges

three pcs NW long weld neck flanges 3 - How to get high quality Welding Neck Flanges?

Long welding neck flange, lwn flanges are similar to a standard Welding Neck flanges, but the “Neck” is considerably longer than other flanges. LWN flange is often used as a nozzle for a barrel or column. In addition, there are the type LWN Heavy Barrel (HB) and the Equal LWN Barrel (E); they have a different shape and a thicker “Wall”.

The long weld neck flange should be butt welded with the pipes, it means the neck dimensions is same with the matching pipe, same diameter and wall thickness , commonly the long weld has a plain end, not a bevel end for welding . Except the neck, the LWN flange has a same dimensions with the welding neck flange. In addition, there are also the type LWN Heavy Barrel (HB) and the Equal LWN Barrel (E); they have a different shape and a thicker “Wall” which name is Nozzle .

NW Long Weld Neck Flange draw 3 - How to get high quality Welding Neck Flanges?

Tube OD sizes: 3/8 to 2 inches

The NW Long Weld Neck Flange is normally referred to as the high hub flange. It is designed to transfer stresses to the pipe, thereby reducing high stress concentrations at the base of the flange.

The NW Long Weld Neck Flange is the best designed butt-welded flange of those currently available becuase of its inherent structural value. It is expensive because of the design.

Materials:
Carbon steel: A105,SS400,SF440 RST37.2,S235JRG2,P250GH,C22.8
Stainless Steel: F304 F304L F316 F316L 316Ti, Copper etc.

Vacuum range
Elastomer seal: >=1 x 10^-8 Torr – High vacuum
EVAC metal seal: >=1 x 10^-11 Torr – UHV

Temperature range
Viton: -20°C to 200°C
Silicone: -50°C to 230°C
Buna: -30°C to 110°C
EVAC metal seal: -270°C to 150°C

Packing: No Fumigate or Fumigate Plywood/Wood Pallet or Case

Surface Treatment: Anti-rust Oil, Transparent/Yellow/Black Anti-rust Paint,Zinc,Hot dipped Galvanized.

Weldoflange, Nipoflange

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The Weldoflange and Nipoflange is a combination of a Welding Neck flange and a supposedly Weldolet or Nipolet.

Two different pipe branch connections

On the run pipe side a nipoflange is designed like a weldolet. That means the branch connection on the run pipe side is a welding connection. On the other side there it has a flange connection. The flange connection can be designed according to customers requirements (acc. To DIN or ANSI).

Forged material
A nipoflange similar to ANSI B 16.9 or MSS-SP 97 is manufactured from forged material. That means a nipoflange is a forged fitting without welding seam.

Standard and special materials
Anthermo is able to deliver nipoflanges in standard materials. Upon request special materials are also deliverable.

The Weldoflange and Nipoflange is a combination of a Welding Neck flange and a supposedly Weldolet or Nipolet. The 2 components are manufactured in one piece, and not welded. These flanges are primarily in Branch connections. Furthermore, they have an expanded range of special flanges, fittings and branch connections.

nipo flanges draw 3 - How to get high quality Welding Neck Flanges?

Size: 1/2″ NB TO 24″ NB.
Class : 150#, 300#, 400 #, 600#, 900#, 1500# & 2500#
Flanges available with NACE MR 01-75

ansi nipoflange 3 - How to get high quality Welding Neck Flanges?

Packing: No Fumigate or Fumigate Plywood/Wood Pallet or Case

Surface Treatment: Anti-rust Oil, Transparent/Yellow/Black Anti-rust Paint,Zinc,Hot dipped Galvanized.

Standards, Dimensions & Weight of Welding Neck Flanges

It is expensive because of the design.

Specifications of Welding Neck Flanges:

Size: 1/2” to 60”, DN 12mm to DN 1500mm
Pressure class: Class 150 to Class 2,500, PN 2.5 to PN 250
Facing: RF / RTJ

Material of Welding Neck Flanges:

Cabon steel: A105, A350 LF2, C22.8, S355JR
Stainless steel: A182 F304/F304L/F316/F316L/F321
Alloy steel: F11, F12
Packing: plywood case and plywood pallet

Temperature range
Viton: -20°C to 200°C
Silicone: -50°C to 230°C
Buna: -30°C to 110°C
EVAC metal seal: -270°C to 150°C
Tube OD sizes: 3/8 to 2 inches
Materials:
Flange: 304 or 316L stainless steel
O-rings: Viton, Buna, & silicone
Fasteners: Wingnut, SureSeal, bulkhead & EVAC clamps
Vacuum range
Elastomer seal: >=1 x 10^-8 Torr – High vacuum
EVAC metal seal: >=1 x 10^-11 Torr – UHV

20180201105758 91939 - How to get high quality Welding Neck Flanges?

NPS 1/2 – O.D. 21.3
CL 150 300 600 900 1500 2500
DIA
A
30 38 38 38 38 43
DIA
D
90 95 95 120 120 135
THK
B
9.6 12.7 14.3 22.3 22.3 30.2
11.2 14.3 20.7 28.7 28.7 36.6
DIA
G
35.1 35.1 35.1 35.1 35.1 35.1
DIA
K
60.3 66.7 66.7 82.6 82.6 88.9
H 46 51 52 60 60 73
47.6 52.6 58.4 66.4 66.4 79.4
NO.
L
4 4 4 4 4 4
DIA
L
15.9 15.9 15.9 22.2 22.2 22.2
Stud Bolts Diameter x Length
DIA
(IN)
1/2 1/2 1/2 3/4 3/4 3/4
Len
mm
55 65 75 110 110 120
Other Diameters
NPS 3/4 1 2
3 4 5 6 8 10
12 14 16 18 20 24  
 

Notes:

  • Dimensions are in millimeters unless otherwise indicated.
  • The length of the Stud Bolt does not include the height of the chamfers (points).
  • ID = Depending on the wall thickness of the pipe, must be specified by the purchaser.
20180201105715 99275 - How to get high quality Welding Neck Flanges?

Dimensional Tolerances of Weld Neck Flanges ASME B16.5

Dimensions are in millimeters unless otherwise indicated.

OUTSIDE DIAMETER

≤ 24 = 1.6 mm
> 24 = ± 3.2 mm

INSIDE DIAMETER

≤ 10 = ± 0.8 mm
≥ 12 = + 1.6 mm / – 0 mm

DIAMETER OF CONTACT FACE

1.6 mm Raised Face = ± 0.8 mm
6.35 mm Raised Face
Tongue & Groove / Male-Female = ± 0.4 mm

DRILLING

Bolt Circle = 1.6 mm
Bolt Hole Spacing = ± 0.8 mm
Eccentricity of Bolt Circle with Respect to Facing
≤ 2½ = 0.8 mm max.
≥ 3 = 1.6 mm max.

DIAMETER OF COUNTERBORE

Same as for Inside Diameter

OUTSIDE DIAMETER OF HUB

≤ 12 = + 2.4 mm / – 1.6 mm
≥ 14 = ± 3.2 mm

THICKNESS

≤ 18 = + 3.2 mm / – 0
≥ 20 = + 4.8 mm / – 0

LENGTH THRU HUB

≤ 18 = + 3.2 mm / – 0.8 mm
≥ 20 = + 4.8 mm / – 1.6 mm

Source: China Welding Neck Flanges Manufacturer – Yaang Pipe Industry (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@steeljrv.com

Please notice that you might be interested in the other technical articles we’ve published:

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  • Development trend of high pressure pipe fittings
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  • What are Specialty Flanges
  • How to get high quality alloy steel pipes
  • HOW TO GET HIGH QUALITY STEEL PIPES
  • What are socket weld flanges
  • When to use slip on flanges
  • What are slip on flanges
  • WHEN TO USE A SPECTACLE BLIND FLANGE
  • HOW TO GET HIGH QUALITY BOILER TUBES
  • When to use lap joint flange
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References:

  • https://en.wikipedia.org/wiki/Weld_neck_flange
  • https://www.yaang.com
  • http://www.wermac.org/flanges/dimensions_welding-neck-flanges_asme-b16-5.html

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