Today, stainless steel is one of the most popular metals used. Due to its physical properties, such as corrosion resistance and durability, this metal scores over several other metal Flanges. This metal is used in the production of a wide variety of industrial, commercial, and residential items. 

A popular stainless steel product is pipes. Certain stainless steel accessories support these stainless pipe flanges. A stainless steel flange is one such accessory used to support steel pipe flanges. A wide range of Stainless flanges are available for purchase. There are eight types of Stainless flanges that you should be aware of in this post.

Types of Flanges

Slip On Flanges

Slip-on flanges consist of a ring placed over the end of the types of pipe flanges, with a flange face that extends sufficiently from the end to apply a welded bead to the inner diameter. These flanges slip over a pipe, hence their name, Slip On Flanges. Slip-on flanges are also called SO flanges. It’s a kind of flange that slides over the pipe and is slightly bigger than the pipe. The top and bottom of the SO flange can be welded directly to equipment or pipe because the inner dimension of the flange is slightly larger than the external dimension of the stainless pipe flanges. The pipe is inserted into the inner hole of the flange with this tool. With a raised or flat face, Types of pipe flanges are used. Low-pressure applications benefit from slip-on flanges. Many fluid pipelines use slip-on flanges excessively.

Weld Neck Flanges

A Weld Neck Flange is also known as a tapered hub flange or a high-hub flange. A stainless steel weld neck flange (WN flange) has a neck that can move the pipe tension, thereby reducing the pressure gathered in the Flange bottom. The material is compatible with pipelines that operate at high or low temperatures and withstand high pressure pipe flanges. A welding neck flange is easily identified by its long tapered end, which slowly passes through the wall thickness of a pipe or fitting. The long tapered hub provides significant shielding for use in applications involving high pressure, sub-zero temperatures, and/or high temperatures. A stainless steel weld neck flange consists of a circular fitting with a protruding edge around its circumference. Pressures up to 5,000 psi have been successfully applied to Weld Neck Flanges.

Socket Weld Flanges

There is only one fillet weld connecting socket weld flanges on the outside, so they are not recommended for critical services. Most of the time, they are used for small-bore lines. The static strength is the same as Slip On flanges, but the fatigue strength is 50 percent higher than double-welded Slip On flanges. The bore length of these flanges should be determined by the thickness of the connecting pipe. Before welding, a gap must be formed between the socket weld flange and the pipe. A socket weld’s bottom clearance is designed to minimise residual pressure at the weld root during metal solidification. Making the right space is one drawback of the socket weld flange. In steel pipe flange systems, corrosion can occur between the pipe and the flange due to corrosive products. This flange is not allowed in some processes. This flange must also be welded first by a pipe and then by a fitting.

Blind Flanges

A blind flange is produced without a bore and is used to cover the ends of pipes, valves, and pressure vessels. The most overstressed flange types, especially in bigger sizes, are blind flanges due to internal pressure and bolt loading. In spite of this, most of these pressures are bending types near the centre and, since there is no standardised inner diameter, these flanges are ideal for higher pressure and temperature systems. This flange is used to block a segment of pipe or nozzle on a vessel that is not in use. For pressure checks in plants or just because the consumer doesn’t need all the nozzles provided on the tank, the nozzles are often blanked off with blind flanges.

Spectacle Blind Flanges

In most cases, spectacle blinds are used to permanently split stainless Steel pipe flanges networks or simply to connect them together. Spectacle Blinds are steel plates that have been cut into two discs of a certain thickness.

A piece of steel, similar to that on the nose of a pair of glasses, connects the two discs. The name derives from the fact that the assembly resembles eyeglasses or spectacles. One disc is solid, and the other is a ring with an inner diameter equal to a flange. Spectacle Blinds are used to separate structures from other installations on a regular basis. In order to facilitate flow through the pipe, the Spectacle Blind is usually installed in the “open” position. In the “closed” position, the Spectacle Blind blanks off the pipe and no flow is possible.

Lap Joint Flanges

When the pipe is made of expensive material, lap joint Steel flanges are used. For e.g., a carbon steel flange can be added to the steel pipe flanges system because the flange will not come into contact with the substance in the pipe. The stub ends will be butt-welded to the pipe and the flanges will remain loose. The inner radius of these Steel flanges is bevelled to clear the stub end radius. Lap joint Steel flanges are almost similar to the Slip On flange, except for the radius at the intersection of the flange face and the bore to accommodate the flanged portion of the Stub End. Their ability to hold pressure is little, if any, stronger than that of Slip On flanges, and the fatigue life of the assembly is only one-tenth that of the stainless steel weld neck flange. Lap joint flange is therefore used in low-pressure and non-critical applications.

Reducing Flanges

When the size of the pipe changes, reducing Steel flanges are used. A flange (dimensions) primarily matching the larger pipe size (NPT), but with a smaller bore matching the smaller pipe size (NPT). There are four types of neck flanges: blind, slip-on, threaded, and weld. They are available in all pressure classes and are a great alternative to connecting two different pipe sizes. If an unexpected change, such as at a pump, would cause unnecessary turbulence, this type of flange should not be used.

Designed for use in piping systems with changing diameters. Reduction flanges consist of a flange with a specified diameter and a smaller diameter bore. Except for the bore and hub dimensions, the flange will have measurements of the greater pipe size. Reducer flanges are attached by welding, glueing or clamping flanges of the same size with different connecting pieces.

Threaded Flanges

Despite looking similar to Slip-On flanges, threaded flanges have been bored out to match the inside diameter of a particular pipe. An ASME B1.20.1 threaded flange has taper pipe threads in the bore and can be used in piping systems where welding to the pipe is not possible, such as highly explosive areas. Galvanised and cast-iron piping is commonly used with threaded flanges since they have additional threads. The main advantage of threaded  Steel flanges is that they can be installed without welding in systems with high pressures and small diameters.

Square Flanges

Square flanges are made in accordance with JIS B2291/JIS F7806. Pipe-to-pipe and pipe-to-component connections often use square flanges. Steel and stainless steel are most commonly used in hydraulic systems where fluid passes through. Square flanges are composed of an o’ring, bolts, female flange (o’ring side), and male flange (flat side). Part A is the female flange. Male flanges are identified in Part B. The full set is AB.

SHAB – Used with hexagon hex bolts, larger flange body size, SSAB – Used with socket cap screws, smaller body size than SHAB, LSA – O’Ring side only, L shaped internal flow.

Long Neck Weld Flanges

In high pressure and high temperature situations, primarily in the oil and gas industry, long stainless steel weld neck flange (often abbreviated to LWN) are used. Unlike a standard welded neck flange, the long neck guides the pipe into the flange itself and provides reinforcement. High pressure systems, whether industrial, commercial or residential, need this reinforcement to be safe. Long Weld Necks do not have scheduled bores like many other types of flanges. Flanges with long weld necks are typically made with square cuts to replace pipes rather than to be welded to them.

A long weld-neck flange is generally an anchor for water-mains or gas sources being pumped into a larger network of pipes, like those in a factory or apartment building.

Expander Flange

EXPFs are welded neck flanges with hubs that extend to a larger size (one or two sizes). If you have limited space or just need to connect to a wider pipe diameter, it provides a convenient place for equipment, pumps, and vents. The compact size saves space compared with a reducer-welding neck flange which can eliminate the use of flange and reducer. Reducer-welding neck flanges are also considered a cost-effective alternative to expander flanges. Pressure ratings and dimensions comply with ANSI / ASME B16.5. The Expander flange has a raised face. Installing the Expander Flange requires a single butt-weld.

Spade and Ring Spacer Flange

Spectacle Blinds and Spade and Ring Spacer Flanges are similar, except they are not connected. Spades and spacers are used in systems where maintenance is not frequently required or when large stainless Steel pipe flanges are used. It is possible for spades to weigh hundreds of pounds, depending on the size of the flanges and the stress level. Flange connections are not selected for the Spectacle Blind, but for two separate parts instead, to avoid additional weight. It may be necessary to temporarily replace the Ring Spacer with a spade due to high maintenance of the pipe system.

Weldo Flange / Nipo Flange

A Nipoflange is a combination of a weldolet, nipolet, and welding neck flange used for 90° branch connections. Weld Flanges have weldolets on the run pipe side and flange connections on the other side. The branch connection on the run pipe side is welded. In a Nipo Flange the branch connection on the run pipe side is a welding connection and on the other side, it has a flange connection.

Orifice Flanges

For measuring the flow rate of liquids or gases in pipelines, orifice flanges are used with orifice metres. On the orifice flange, pressure “Tappings”, usually on two sides, are machined. American Gas Association (AGA), ASME, and International Society of Automation (ISA) recommendations are followed when designing and manufacturing orifice flange unions. There are many different types of flanges available, including raised face weld neck orifice flanges, raised face slip-on orifice flanges, and ring-type joint orifice flanges.

Loose Flanges

To make a flanged coupling, a loose flange is welded to the end of a piece of pipe. It is made of carbon steel or stainless steel according to the intended specification, and consists of a flat steel forging with bolt holes around the perimeter and an opening at the centre for welding the pipe to the loose flange. The loose flange type can be used with elbows, valves, and almost any pipeline component.

High Hub Blind Flanges

High Hub Blind Flanges are used to seal the ends of pipe structures. It’s a circular plate without a centre hold, but with all the right bolt holes. High hub blind flanges are available in a variety of sizes and materials. constructive closure at the ends of pipes, valves or nozzles. When sealed, this flange allows you to easily access the line. Sometimes the high hub blind flange can be specially built or machined to match the nominal size of the pipe to which the reduction is made. This reduction could be a reduction in threads or a reduction in welds. Often high hub blind flanges are supplied with NPT fittings which allow the installation of pressure test connections. Considering factors such as internal pressure and bolt loading, high hub blind flanges are the most stressed of all different types of flanges, particularly in the larger sizes.

Screwed Flanges

Screwed flanges are also known as Threaded Flanges. They have a thread inside the bore of the flange that fits on the pipe. They are mostly used in utility services, such as air and water. For small diameter, high pressure requirements, screwed flanges are often used. Flanges with hubs have issued requirements ranging from 1/2′′ to 24′′. Pressure class: Class 150 to Class 2,500, PN 2.5 to PN 250 and Facing: RF / RTJ

A screwed flange is threaded in a bore that matches the pipe’s external thread. Screwed flanges are used with externally threaded pipes. These flanges can be mounted without welding, which is an advantage.

Plate Flanges

Plate Flanges have a gasket surface on the same plane as the bolting circle. A flat-faced flange is also known as a flat-faced flange. Often flat face flanges are used in applications where a casting is made of the mating flange or flanged fitting. If your counter-flange has a flat face, you should use flat face flanges. Cast iron equipment, valves, and specialties are commonly associated with this condition. ASME B31.1 states that when connecting flat face cast iron flanges to carbon steel flanges, the raised face of the carbon steel flange must be removed and a full face gasket is needed.

Flat Face

In the same plane as the bolting circle, the Flat Face flange has a gasket surface. Flat facial flanges are typically used in applications where the mating flange or flanged fitting is cast. Flat steel flanges are flanges that are machined flat and do not have an elevated surface or ring type joint. A loose flat flange allows full contact between the gasket and the mating surface.

An elevated face flange should never be bolted to a flat face flange. A full face gasket is required when connecting flat face cast iron flanges to carbon steel flanges in accordance with ASME B31.1. The flange face form refers to all applications in which cast iron and other brittle materials are used to produce equipment and valves. For “Flat Face” flanges only Full Face Gaskets are to be used. This ensures that the two mating flanges are in full and equal contact.

Raised Face Flanges

Raised Face flanges are the most common type of flange used in process plants because the surfaces of the gasket are raised above the face of the bolting circle. For all forged steel flanges like machinery and valves, this form of flange mask is commonly used. A wide combination of gasket designs can be used in the Raised face flanges. These combinations can also include Flat ring sheets and spiral wound and double jacketed type’s metallic components.

Raised Face Flanges concentrate pressure on a smaller area of the gasket, thereby increasing the joint’s pressure containment capacity. Bolt holes are found in the outer ring region of those flanges. The “Move” adjustment between the heights of the two rings creates a stronger seal when a gasket is attached and the bolts are tightened. Based on the pressure class, the flange face is either 1/16″ or 1/4″ ANSI 300 and under have a 1/16″ face raised, and ANSI 400 and higher have a 1/4″ face raised.

Ring joint flanges (RTJ)

Steel ring gaskets are cut into the faces of ring joint flanges (RTJ). By pushing bent bolts into the grooves, the gasket between the flanges closes (or coins) and creates intimate contact within the grooves, creating a metal-to-metal bond. In systems over 427 °C with extreme pressure and high temperature, Ring Style Joint flanges are usually used. An RTJ flange with a ring groove machined into it may have an elevated face. The face raised does not act as any component of the means of sealing. The elevated faces of the attached and tightened flanges may touch one another for RTJ flanges which seal with ring gaskets.

To achieve this, the ring joint gasket material must be weaker (more ductile) than the flange material. In this case, the strained gasket cannot withstand additional load beyond the tension of the screw; vibrations and motion cannot damage the gasket further and reduce the connection voltage. RTJ gaskets with an octagonal portion are the most common, as they provide an extremely strong seal. Nonetheless, a “simple groove” style recognizes that both RTJ gaskets have an octagonal or oval portion.

Groove & Tongue Flanges

Tongue and Groove flanges must fit the Tongue and Groove ears. One side of a flange has a raised ring (Tongue) machined onto the face of the flange while the mating flange has a corresponding depression (Groove) machined in its nose. Both large and small types of tongue-and-groove facings are standardised. These vary from male-and-female in that the tongue-and-groove internal diameters do not reach into the base of the flange, thereby holding the gasket on its inner and outer diameter. These are commonly found on Valve Bonnets and on pump coverings.

Additionally, tongue-and-groove joints serve as elastic buffers and are self-aligning and the loading point in line with the joint and does not require an intensive machining process. Specific flange faces like the RTJ, T and G, and F and M are not to be bolted. This is because the touch surfaces do not overlap and there is no gasket which has one type on one hand and another type on the other. Groove & Tongue flanges are used in low pressure, non-critical applications, to attach other Groove & Tongue components.

Male & Female Flanges

Male & Female Flanges are flanges that want to fit together. In these variations, one flange face extends beyond the usual flange face. The Man is the name of this flange. On the other side, the mating flange will have a similar depression machined into its nose. Woman flange refers to this mating flange

This form must also be aligned with the flanges. Each facial flange has a region that extends beyond the normal face (Male). The other flange or mating flange has a corresponding depression (Female) machined into the face of it.

Female faces should be 3/16-inch long, male faces should be 1/4-inch wide, and each end should be flat. The female face’s exterior diameter is responsible for finding and maintaining gauze. Medium M&F Flanges and Wide M&F Flanges are available in two versions.

Male and female flanges have improved sealing capabilities, more reliable positioning and compression of sealing material, and advanced sealing materials (O-rings).

8 Types of Stainless Steel Flanges 

  • Weld Neck Flanges. Their distinct feature is their protruding neck.
  • Threaded Flanges. They are only used for special applications.
  • Slip-on Flanges.
  • Lap Joint Flanges.
  • Socket Weld Flanges.
  • Ring-Type Joint Flanges.
  • Orifice Flanges.
  • Blind Pipe Flanges.


  1. Weld Neck Flanges: Protruding necks distinguish these flanges. The stainless steel weld neck flange has the same bevel and thickness as pipe. For severe service conditions such as sub zero or high temperatures and high pressures, this flange is recommended.
  2. Slip-On Flanges: Flanges of this type are the most affordable on the market. Slip-on flanges have a slightly larger diameter than pipe, so it makes it easier to slip them over the pipe. Fillet welded to a position, these stainless steel flanges are ideal for low-pressure applications.
  3. Blind Flanges: The flanges are used to seal vessel openings and piping systems without a bore. Flanges like these are ideal for piping systems or vessels that require regular inspection. Blind flanges can be supplied with or without hubs. Internal pressure can easily cause high stress on this flange.
  4. Threaded Flanges: These different types of flanges are used in special applications and can easily be assembled without welding. Pipes with external threads are compatible with stainless steel threaded flanges. It is not recommended to use the flanges in applications involving bending stresses, high pressures, or high temperatures.
  5. Lap Joint Flanges :Flanges with lap joints are slip-on flanges that have a stub end fitting attached. Pipes made of low alloy steel or carbon steel require regular inspection and maintenance, so these flanges are ideal.
  6. Socket Weld Flanges:Flanges are designed for use with small diameter and high-pressure piping. Socket weld flanges have internal welds that enhance their durability as well as fatigue resistance. Chemical processing industries use these flanges.
  7. Orifice Flanges: Steel flanges provide access to a line for metering liquids or gases. Orifice flanges are installed with orifice plates or flow nozzles.
  8. RingType Joint Flanges: High pressure and temperature applications require these flanges. On blind, slip-on or weld neck flanges, ring-type joint flanges have a groove that can be compressed easily. Flanges prevent leaks in pipelines where high-pressure and high-temperature media are transferred.

Application of Stainless Steel Flanges

In plumbing, you can connect two sections of metal piping by soldering or welding them together. However, pipes connected in this way are very susceptible to bursting under high pressure. The pipe will often hold even if high pressure pipe flanges build inside it, even if gases or liquids build up inside.

When connecting two sections of a large, enclosed area, stainless steel flanges are usually the best choice. Foreign exchange. In an automobile, one of these connections is between the engine and the transmission. The situation here is that the engine and transmission contain various moving parts which can easily be damaged if dust or other small objects get inside. 

Electronics – Stainless Steel Flanges are used in cameras and other electronic devices. While stainless steel flanges on these items do not have to withstand high pressures, they must be kept tight to keep harmful particles out. In most cases, stainless steel flanges connect two different materials, such as the glass of a lens and the rest of the camera body.

Which Standards Apply to Stainless Steel Flanges and Fittings?

Standards establish the chemical composition, dimensions, pressure ratings, and other requirements of flanges and fittings. Stainless steel is usually subjected to the following standards:

  • The AWWA C228 specifies the minimum material requirements and dimensions for stainless steel flanges used in stainless steel piping systems
  • High-temperature forged or rolled piping system components are covered by ASTM A182
  • A dimensional standard for pipe flanges and flange fittings, including stainless steel flanges, is ASME B16.5
  • ANSI B16.34 is a pressure/temperature rating for threaded and welded valves used to connect flanges
  • Large-diameter steel and stainless steel flanges are covered by ASME B16.47

Flange Grade Selection

When choosing stainless steel flanges, fittings, and accessories, you should choose the appropriate grade. 304 and 316 stainless steel are the most common choices, because they are strong even under heavy stress. For stainless steel to be able to withstand the intended use, it must be of the correct grade. Using an incorrect grade at high temperatures can result in warping or other problems. It is important to choose the appropriate grade for the intended application to prevent damage to the piping system or early failure of the system.

Benefits of Stainless Steel Flanges flanges:

There is no doubt that stainless steel flanges are the best choice for your plumbing system. They are lightweight, durable, and easy to clean. Stainless steel flanges are also corrosion resistant, making them an excellent choice for your home or business’s wastewater system.

Because stainless steel does not rust, it is an excellent metal Flanges for your plumbing system. If you want to fix a broken joint in your drain line, you don’t want it to become damaged or unusable after years of use.

Even though stainless steel flanges are lightweight, they are still durable enough to withstand heavy use by your home’s plumbing system. Consider stainless steel flanges for your home or office if you’re in the market for new flanges.

Flange Standards And Markings

Flanges are governed by ASME B16.5 and B16.47, global standards established by the American Society of Mechanical Engineers (ASME).

If you’re attempting to replace or verify existing parts, all flanges must include markers — typically on their outer perimeter — to aid in the process.

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