Long weld neck flange

Arc Alloys Ltd are one of the UK’s leading manufacturers and suppliers of long weld neck flanges for a number of industries including oil and gas, refrigeration, refining, filtration, petrochemical and the offshore industry.

Dimensional standards:

  • ANSI B16.5
  • 47 Series A and B16.47 Series B
  • API 6A
  • API 17D
  • BS EN 1092-1
  • BS 4504
  • BS 10
  • Din
  • JIS
  • Norsok L-005
  • Bespoke to customer drawings / design.

Standard grades:

  • ASTM / ASME A182 / SA182 F51 / F60 / 31803/ 1.4462
  • ASTM / ASME  A182 / SA182 F53/F55 / 32750 / 32760
  • ASTM  / ASME A182 / SA182  F44 / 31254
  • ASTM / ASME / B564 / SB564 UNS NO6625 / Alloy 625 / Inconel® 625
  • ASTM / ASME / B564 / SB564 UNS NO8800 / Alloy 800 / Incoloy® 800
  • ASTM / ASME / B564 / SB564 UNS NO8810 / Alloy 800H / Incoloy® 800H
  • ASTM / ASME / B564 / SB564 UNS NO8811 / Alloy 800HT / Incoloy® 800HT
  • ASTM / ASME / B564 / SB564 UNS NO6600 / Alloy 600 / Inconel® 600
  • ASTM / ASME / B564 / SB564 UNS NO6601 / Alloy 601 / Inconel® 601
  • ASTM / ASME / B564 / SB564 UNS NO8020 / Alloy 20 / Carpenter® 20
  • ASTM / ASME / B564 / SB564 UNS NO2200 / Alloy 200
  • ASTM / ASME / B564 / SB564 UNS NO2201 / Alloy 201
  • ASTM / ASME / B564 / SB564 UNS NO6625 / Alloy 400 / Monel® 400
  • ASTM / ASME / B564 / SB564 UNS NO7718 / Alloy 718
  • ASTM / ASME / B564 / SB564 UNS NO8825 / Alloy 825 / Incoloy® 825
  • ASTM / ASME / B564 / SB564 UNS NO10276 / Alloy C276 / Hastelloy®C276
  • ASTM / ASME / B564 / SB564 UNS NO6022 / Alloy 22 / Hastelloy® 22
  • ASTM / ASME / B564 / SB564 UNS NO10675 / Alloy B3 / Hastelloy® B3
  • ASTM / ASME / A182 / SA182 UNS NO8028 / Alloy 28 / Sanicro®28
  • ASTM / ASME / B564 / SB564 UNS NO5500 / Alloy K500 / Monel® K500
  • ASTM / ASME / A182 / SA182 F304 / F304L / F304H
  • ASTM / ASME / A182 / SA182 F316 / F316L / F316H
  • ASTM / ASME / A182 / SA182 F321 / F321H

Standard facings:

  • Raised face
  • Ring-type joint
  • Flat face
  • Male/female
  • Tongue/groove

Long weld neck flanges are commonly used in high pressure systems and they can cope with both hot and cold temperatures which makes them ideal for the industries mentioned above.

Long weld neck pipe flanges are attached to a pipe by welding the pipe to the neck of the pipe flange. This transfers the stress from the long weld neck flange to the pipe and helps to reduce the high levels of stress which are concentrated at the base of the long weld neck flange.

Long weld neck flanges are ideal for high pressure applications and a key benefit of using them is that they do not interfere with the flow of fluid through the flange. If you place the weld joint at the neck of the flange, the pipe is much easier to align and you can achieve a stronger weld.

Long weld neck flanges are similar to a standard weld neck flange but the “Neck” is significantly longer.

Long weld neck flanges are often used as a nozzle for a barrel or column.

Features of Long Weld Neck Flanges

  • Long weld neck flanges feature a long tapered hub that goes gradually over to the wall thickness from a pipe. This gives strong reinforcement for high pressure, high temperature and sub-zero applications.
  • The tapered hub is created by a gradual increase in thickness of the metal from the weld joint to the flange face. This makes it ideal for conditions of repeated bending caused by line expansion, contraction, or other external forces.
  • Long weld neck flanges are carefully bored to match the inside diameter of the adjoining pipe so there is no restriction in flow. This helps to prevent turbulence at the joint and reduces erosion considerably.

Benefits of Long Weld Neck Flanges

This is a summary of the main benefits:

  • Perfect for high pressure systems and can deal with high and low temperatures.
  • No interference with flow of the liquid and reduces turbulence.
  • Easy to align between the pipe and flange.
  • Easy access for radiography testing to check the integrity of welding.
  • The internal stress is transferred to the pipe through the neck making the connection stronger and more durable.
  • The flange face is kept away from heat affected area

Arc Alloys Ltd can supply long weld neck flanges in a wide variety of material grades, specifications and sizes. Usually they are supplied with a flat face, raised face or RTJ facing so if you need high quality long weld neck flanges then please get in touch.

Long weld neck flanges can be supplied with grooves, back faces, bevels and bores inlaid with a variety of alloys. This is carried out to the appropriate industry standards by highly experienced welders and full certification is available.