The welding neck flange

Among the most used flanges are those known as Weld Neck or Welding Neck (WN). As with the others, the characteristics of this flange are very specific, differentiating it from the rest by its use and application. The WN flange is very durable and forms a good seal. It is often used on high-pressure pipes and pipelines.

What is a welding neck flange and what is it used for?

The welding neck is just one among all the different types of flanges. We frequently see it in use sealing pipelines in the petrochemical industry.

Characteristics of welding neck flanges

These flanges are distinguished by having a long conical neck, the end of which is welded to the connecting pipe. The inside diameter of the pipe is equal to that of the flange, providing a conduit of generally constant cross-section and no interruptions or turbulence in the gases/liquids flowing through the pipe. Welding neck flanges provide high load strength along with even stress distribution.

Attention must be paid to the junction between the flange and the pipe to be welded on in order to avoid possible interruptions in high speed flows.

Why use a welding neck flange?

WN flanges are intended for activities involving high pressure and extreme conditions (cold or heat), flammable or corrosive contents, etc., and, above all, environments where leakage must be minimal or almost non-existent. They are used in order to minimize the number of welds on small parts while helping to reduce corrosion of the junction itself.

They are used in steam lines; oil, natural gas and refined hydrocarbon lines; fire networks; petrochemical facilities, etc.

What type of materials are used to manufacture them?

The materials used for this type of flanges are quite diverse, but always depend on the environmental conditions and stress they will need to withstand.

For moderate temperatures, carbon steel flanges are usually used. If they need to withstand much more extreme temperature or pressure conditions, alloy steel is used. Finally, for flanges that will be exposed to corrosive gases or liquids, alloys with metals such as nickel, chromium or molybdenum are the most suitable.

Types of flange gasket face

When talking about flanges for piping systems, we must also discuss the different flange gasket faces that exist and that are manufactured as standard. Most common in the sector are:

  • Flat Face (FF)
  • Raised face (RF)
  • Male/Female Face (MFF)
  • Tongue and Groove Face (TGF)
  • Ring-Joint Face (RJF)
  • Lap-Joint Face (LJF)

*Dimensions and materials in accordance with ASME B16, ASME B16.47 and MSS SP-44 standards

Selecting the right flange: welding-neck or slip-on?

ULMA Forged Solutions Welding Neck Flanges

At ULMA Forged Solutions, we have a wide variety of forged flanges. In our catalog you will see pieces with a vast range of sizes (from 1/2 to 102 inches), different pressure ranges and multiple alloys.

Nevertheless, we know that each engineering project has very specific characteristics. Therefore, in addition to our wide variety of parts, we also calculate, design, and produce tailor-made flanges based on the needs of each customer.

All ULMA Forged Solutions flanges follow standards set out by and in API (American Petroleum Institute) ASME B16, ASME B16.47 and MSS SP-44, so that their functionality is guaranteed and their replaceability in case of wear is made easier.