Types of Flange Used in the Oil and Gas Industry
The oil & gas industry is complex, and numerous components work together for smooth operations in various processes. Among these, flanges play a crucial yet often overlooked role. A flange is a seemingly simple yet indispensable piece that connects pipes, valves, and other equipment. They prevent leakage and maintain operation safely.
Using different flange types in the oil and gas industry is a core requirement. To ensure familiarity with these, here are the most common flange types and their applications.
Let’s dive in!
Blind Flange
If a piping line extension or a piping inspection is necessary (remove the blind flange to access the pipe interior), a blind flange can replace a butt weld cap due to its lack of a weld seal and reliance on bolting instead. This flange can also serve as the rod access point on drain systems. A blind flange may be tapped and used as a threaded flange, or it may be drilled and used as a slip-on flange, depending on the application.
Despite having a simple design, this kind of flange is relatively pricey in larger diameters. Many routine non-destructive inspection (NDI) programs do not include blind flanges. It is crucial to measure the blind flange’s thickness as a preventative measure depending on your operating pressure.
Lap Joint Flange
Lap joint flanges are quite popular in piping and duct systems. They are well-known by various names, including backup flanges, loose ring flanges, loose hubbed flanges, and van stone flanges. This flange type consists of a lap joint stub end and a backing lap joint flange. Lap Joint Stub End is a butt welded to the pipe, and a backing lap joint flange slid onto the pipe before welding the stub end.
Lap Joint flanges and Slip-on flanges are similar, however Lap Joint flanges have a radius where the flange face and bore intersect to accommodate the flanged portion of the lap joint stub end. As a result, they are usually only compatible with lap joint stub ends.
The Lap Joint Stub Ends, and Lap Joint flange material vary and even differ within a single application to enable greater cost flexibility. Sometimes, a stainless stub end will weld to stainless pipe, whereas the lap joint will just need to be carbon steel.
Socket Weld Flanges
Socket weld flanges very much resemble slip-on flanges on the outside, but with a twist. They have a socket fit for the pipe to slip into, followed by a fillet weld around the outer circumference for installation. These flanges are famous for their compact size and exceptional resistance to leakage. They find their applications in smaller pipes and mid-pressure systems, making them a reliable choice where space concerns them.
Slip-on Flanges
Another popular name for Slip-on flanges is hubbed flanges, a hub with a shallow profile. Slip-on flanges connect with a pipe by one or two fillet welds, one outside, and the other inside. However, it is possible to use only a single weld. Slip-on flanges come in numerous sizes and are suitable for lower-pressure applications.
A slip-on flange’s internal diameter is bigger than the connecting pipe’s. Due to this, it slips onto the pipe quickly. There are restrictions on its use because there isn’t a full penetration weld between the pipe and the flange and inferior weld integrity. They may not be the best option for high-pressure scenarios, as their lack of neck can compromise the joint’s strength.
Threaded Flanges
Threaded flanges are unique in that they feature internal threads, enabling them to screw onto the pipe. It eliminates the need for welding, making them suitable for small-diameter pipes or areas where welding might be challenging.
However, threaded connections might not be as robust as welded ones, so these flanges are best for lower-pressure environments. The main disadvantage of this flange type is that they are prone to leaks compared to weld flanges. Therefore, a threaded flange is applicable on smaller pipes.
Weld Neck Flange
A weld neck flange is a tapered hub flange or high-hub flange. This flange transfers stresses to the pipes, reducing the high-stress concentration at the bottom of the flange. They are available in two designs: the first is used with pipes, while the second, a longer kind, is only suitable for process plants and cannot be used with pipes but rather are used in place of them as nozzles to tanks.
A weld neck flange requires a butt weld to install. It is renowned for pipe processing as it can bear high pressure and temperatures, reducing erosion and turbulence. This is the required flange type for the highest pressure applications.
Conclusion
Flanges might not be the first thing that comes to mind when envisioning the complex oil and gas industry, but they are undeniably the unsung heroes that hold everything together in an assembly.
From the rugged strength of weld neck flanges to the simplicity of slip-on flanges, each flange types in the oil and gas industry has a role. Next time you see a pipeline in action, take a moment to appreciate the unassuming flange working tirelessly behind the scenes.
FAQ
Q.1 Explain the role of Slip-On Flange in the oil and gas industry.
The design of the Slip-On Flange allows it to slide over the pipe’s end and then be welded in place. Its ease of installation and lower cost than other flange types make it a suitable option. In the oil and gas sector, maintenance and repairs may be necessary in remote locations; the simplicity of installing Slip-On Flanges can help reduce downtime and associated costs.
Q.2 What makes the Blind Flange necessary in oil and gas operations?
Blind Flanges are useful for sealing the end of a piping system, effectively blocking the flow of fluids. They are indispensable during testing, maintenance, or when a pipeline needs to be temporarily closed off. In the oil and gas industry, where safety is a priority, Blind Flanges effectively contain hazardous materials during maintenance procedures.
Originally published at https://www.texasflange.com on June 26, 2024.
