Flanges are among the most important parts of any piping system. They connect pipes, valves, pumps, and other equipment into one secure assembly, and they hold that connection under pressure while still letting the line open up for service. Industries such as oil and gas, chemical plants, water treatment, food processing, and power generation use them extensively. The right flange depends on the pressure, temperature, and type of fluid in the line, so the one picked for a high-pressure header is not the same as the one used for a simple water line. A good choice gives a strong, leak-free joint that lasts. This blog covers the flange types used most often in piping, what each one does, where it fits, and the materials used to make them.
What are Flanges?
A flange is a mechanical part that joins pipes, valves, pumps, and fittings in a piping system. It creates a strong and removable joint, which makes maintenance, inspection, and cleaning far easier. Bolts hold two flanges together, and a gasket between the faces seals the joint and stops leaks.
The main job of a flange is to give a secure connection that still comes apart when needed. Engineers use flanges across high-pressure and high-temperature systems, where a fully welded joint would not be suitable.
10 Popular Flange Types Used in Piping Systems
The flange that fits a given line depends on the pressure it carries, the temperature it runs at, and the job it has to do. Seeing the different types of flanges with pictures, along with their shapes and structures, makes it easier to identify each one and match it to the right application. A sound choice strengthens the connection, keeps the system safe, and improves overall performance.
The flange types below are the ones you will meet most often in industrial piping.
1 Weld Neck Flange
A long tapered hub is the key feature of the weld neck flange. The hub spreads stress smoothly from the flange into the pipe, which lowers the strain at the joint. A welder joins it straight onto the pipe, and it performs well in high-pressure and high-temperature lines. Its strength makes it a common choice for critical piping.
2 Slip On Flange
The slip on flange slides over the pipe end before welding, which makes it simple to fit. It costs less than many other types, so low-pressure systems often use it. Two welds, one inside and one outside, hold the joint firmly in place.
3 Blind Flange
A blind flange closes off the end of a pipe run or a vessel opening. It has no bore, so it stops the flow completely. That makes it useful for maintenance work and pressure testing, and its solid face holds full line pressure.
4 Socket Weld Flange
The socket weld flange suits small, high-pressure lines. The pipe fits into a recessed socket, and a single weld around the outside finishes the joint. The result is a smooth bore and a strong, leak-resistant connection.
5 Threaded Flange (Screwed Flange)
The threaded flange has internal threads that screw onto a matching pipe, with no welding needed. Low-pressure systems use it, along with areas where welding would be unsafe, such as gas lines. It goes on and comes off with simple hand tools.
6 Lap Joint Flange
The lap joint flange works with a stub end and suits lines that are taken apart often. It turns freely around the stub end, so the bolt holes line up quickly during reassembly. Low-pressure applications favour it, and it helps keep installation costs down.
7 Long Weld Neck Flange
An extended neck gives the long weld neck flange extra support where the pipe meets the flange. Pressure vessels and heavy high-pressure systems rely on that support. The design offers solid strength and a long working life.
8 Orifice Flange
The orifice flange is made for measuring flow in liquid and gas lines. Small pressure tappings on each side connect to instruments that read the flow rate. Petrochemical plants and process industries use it wherever flow needs to be monitored.
9 Spectacle Blind Flange
The spectacle blind flange isolates a section of pipework for safe maintenance. It has one solid disc and one open ring joined by a short bar, and the shape looks like a pair of spectacles. Operators turn the plate between the open and closed positions before inspection or shutdown.
10 Ring Type Joint Flange (RTJ Flange)
The RTJ flange is used in high-pressure, high-temperature lines where leaks cannot be allowed. A machined groove holds a metal ring gasket, and tightening the bolts presses that ring into a tight metal-to-metal seal. Oil refineries and offshore platforms depend on it for the toughest sealing applications.
Materials Used in Flange Manufacturing Process
The material of a flange is chosen to match the pressure, temperature, and corrosion it will face in service. Manufacturers shape flanges by forging, machining, cutting, and heat treatment to make parts that stay strong and reliable.
Carbon Steel
Carbon steel flanges are strong, durable, and reasonably priced. They handle moderate to high-pressure work and appear widely in oil and gas pipelines and water lines.
Stainless Steel
Stainless steel flanges resist corrosion and last a long time. Chemical, marine, food processing, and pharmaceutical plants choose them where hygiene and corrosion protection matter.
Alloy Steel
Alloy steel flanges are built for high-temperature and high-pressure use. Extra alloying elements add strength, hardness, and wear resistance for demanding conditions.
Super Duplex Steel
Super duplex steel flanges offer exceptional mechanical strength and outstanding resistance to pitting, crevice corrosion, and chloride stress corrosion cracking. They are widely used in seawater systems, offshore platforms, desalination plants, and aggressive chemical processing environments.
FAQ
How Many Types of Flange Exist?
Piping systems use many flange types, and each one is made for a certain purpose. There are mainly 10 different types of flanges. Some are meant for high-pressure duty, while others help with easy installation, maintenance, or flow control. The most common types are the weld neck, slip on, blind, socket weld, threaded, lap joint, orifice, spectacle blind, RTJ, and long weld neck flange. The choice comes down to pressure rating, temperature, pipe size, and the application.
What are the Different Types of Pipe Flanges?
The main pipe flange types are:
- Weld Neck Flange
- Slip On Flange
- Blind Flange
- Socket Weld Flange
- Threaded Flange
- Lap Joint Flange
- RTJ Flange
- Orifice Flange
- Spectacle Blind Flange
- Long Weld Neck Flange
The choice depends on pipe size, pressure level, temperature, and application. Some types are built for high-pressure systems, while others are preferred for easy maintenance and lower installation cost.
What are Flanges Used For?
Flanges connect pipes, valves, pumps, and equipment in a piping system. They form secure, leak-proof joints while still allowing easy inspection, cleaning, and replacement. Industries such as oil and gas, power plants, chemical processing, and water treatment rely on them.
How do Pipe Flanges Work?
Pipe flanges join two pipe sections with bolts, nuts, and a gasket. The gasket sits between the two faces and stops fluid from leaking out. Once you tighten the bolts evenly, the joint becomes strong enough to handle the line’s pressure and temperature.
What does a Flange do?
A flange creates a safe connection that can be removed when needed. It makes maintenance, equipment installation, and system changes much simpler. A flange also improves pipe alignment and helps keep the flow steady through the system.
What are the Industrial Types of Flanges?
Industrial flanges are available in weld neck, blind, slip on, socket weld, threaded, RTJ, orifice and lap joint flanges. They are a daily requirement in petrochemical plants, refineries, power stations, marine operations and water treatment facilities.