Factors to Consider When Choosing Flanges for Your Project

Gas and oil plants are complex, large environments with thousands of miles of interconnected piping. For any flange or product to perform correctly, choosing the right type of flange for the job is fundamental. The flange must fit perfectly into the pipe joint to conduct its functions properly. A minor mistake during the flange selection may affect an application resulting in an expensive error.


This blog will discuss the factors associated with selecting the correct flange for the proper application to ensure maximum usability.


It is often easy to spot the flange type by the way it looks. First, you must classify the top of the flange by deciding whether the flange has a socket weld, flat flange, lap joint, threaded bore, welded neck, groove, and tongue flange. Next, the bottoms are identified with the evaluation of whether they have a flat face, which is entirely flat, or a raised face which is a slightly raised section on the face of the flange.

All of this information is usually defined by the stamping on the outside diameter of the flange, provided this has not been completely painted over. It is important to keep an archive of your assembly components for future reference and maintenance.


The flange size consists of factors that include the standard used (: JIS – Japanese International Standard, ANSI – American National Standards Institute, and DIN – Deutsches Institut für Normung / European), the pressure level needed, and the actual overall outside diameter and thickness of the flange. Other factors in determining the full call-out include the number of bolt holes, outer diameter, inner diameter, bolt circle, and bolt hole diameter, but the nominal pipe size is typically universal.


Depending on the flange thickness, it can be determined how high a pressure flange can handle, in any application thicker flanges can resist high pressures.

Bolt holes

Bolt holes help to measure the flange size and pressure class. The actual size of the bolt holes, the pitch circle diameter, and the number of bolt holes on the flange are three factors that need to be addressed. If the bolt is stronger and thicker, it can often correlate with higher pressure capabilities.


There are a lot of industry-defined standards from which you can choose the flanges. So the flanges help to choose based on the standard and application of the product. You can connect it to the three primary standards previously mentioned, including DIN, ANSI, and JIS.

Pressure class

Pressure class signifies the marginal pressure level under which the flange can safely function and sustain. Each standard comes with several pressure levels available, from high-pressure to low-pressure tolerance. The pressure levels of products connected to the flanges must be the same as those of valves and pipes in service. The most common industry pressure class is the modern ASME 150# per B16 spec.


It is crucial to choose a suitable material for a flange depending on the understanding and application the elements will encounter in an application that the piping system is using. The most common materials include chrome, nickel, carbon steel, duplex steel, stainless steel, etc.

Here are a few common ways to choose the flanges:

Define your specification and standard

Pipe flanges come in with standard blind, threaded, weld neck configurations. As fittings come into standard, oilfield dimensions become necessary for functional interchangeability.

Standard dimensions are the same for all materials used. However, the specifications are regularly updated, broadened, and revised.

Figure out the flange facing

Defining the facing of your flange is one of the first steps to order the industrial pipe fittings. The flange face is the sealing surface. The most common types of flange faces include:

. Full face
. Flat face
. Ring-type face
. Large female and male
. Lap joint
. Raised face

Pick put the correct pressure class

The pressure class of the flange standard determines its dimensions. The pressure class ratings may fall within 125 to 900 psi. The four factors which influence the pressure limits of the flange within the oil and gas industry include:

. Flange sizes
. Materials used
. External and internal temperatures
. Size of bolts, number, thickness, and dimensions


You may need to consult the fitting distributor to determine your project’s right flange pressure class. For more information on sourcing suitable flanges for your project, you can reach out to Texas Flange.

How to Choose the Right Flange Type for Your Pipeline Industry Project?

A flange is a ridged fitting that increases a pipe or tube’s connection strength. Generally, it is used in pipeline works to make the system more rigid and stable. A flange plays a significant role in a variety of industries. Using different kinds of flanges can help you prevent the escape of gas, air or water, and any other fluids that are readily available in an industrial and commercial situation. Flanges are of different types and material grades and are used for various conditions and purposes. Here are the most common types of flanges used in pipeline projects:

Flat Face Flanges: The Flat-Face flanges have gasket surfaces in a similar plane as the flanges for the bolting circle face. Flat face flanges are almost never to be bolted to a raised face flange but should be connected to other flat face flanges, usually with flat face gaskets. Some old flanged fittings are made from cast iron, although this is a less common material for pressurized applications these days.

Raised Face Flanges: The most common type of flange used in process plant applications is the Raised Face Flange. You can also identify it quickly at the connection point. The reason behind the name “Raised Face” is that the gasket surfaces are raised above the bolting circle face. This face type allows using a comprehensive combination of gasket designs, including flat ring sheet types and metallic composites such as spiral wound and double jacketed types.


How to Choose the Right Flange Type for Your Pipeline Industry Project

Ring Type Joint Flanges: The Ring Type Joint Flanges are commonly used in high pressure and high-temperature services above 800°F (427°C). They have grooves cut into their faces with steel ring gaskets. The flanges seal when tightened bolts compress the gasket between the flanges into the grooves, deforming (or Coining) the gasket to make intimate contact inside the grooves, creating a metal to metal seal. Gasket materials are almost always steel or alloy. API specifications require these seal types for all flanges (B and BX ring grooves.)

Tongue & Groove Face Flanges: The Tongue and Groove faces of alternate flanges must be correlated. One flange face has a raised ring (Tongue) machined onto the flange face, while the mating flange has a matching depression (Groove) machined into its face. Tongue-and-groove facings are standardized in both large and small types.

Male & Female Face Flanges: With the male and female types, the flanges also must be matched. One flange face has an area extending beyond the regular flange face (Male). On the other side, the female flange or mating flange has a matching depression similar to its face. The female face’s depth is 3/16 inches, and the male face’s height is 1/4 inches, and both are smooth finished. The outer diameter of the female face acts to locate and retain the gasket. There are two versions available – the Small Male & Female Flanges and the Large Male & Female Flanges. Custom male and female facings are commonly found on the Heat Exchanger shell to channel and cover flanges.

So if you are confused about how to choose the perfect flanges type for your particular projects, here are some tips for you:

1. First, you need to learn the configuration of your flange and its process of application. The main issue here is to choose the right flange instead of just defaulting to a simple flat face or raised face configuration slip-on. It will guarantee you that you will be able to prevent some stressful reworking of your pipeline assembly.

2. You need to study and identify the proper detail regarding your flange to secure your connections. This way, you can locate and select the right shape and flange material for your project. You will find it once you are well aware of the media flowing through your pipeline or vessel.

3. Now you have to choose the best alloy type for your project. Since most of these products are often made from different materials, you need to select which material grades you want. Your choices include flange types made from non-metallic, metallic, elastomeric materials, and fibrous.

4. In the next step, you need to evaluate the chemical resistance and corrosion requirements of the flanges to be installed. After you consider the materials, you also need to understand their chemical resistance levels by alloy. It ensures that you will adhere to the specific requirements of your application to suit your project demands.

5. Be sure to find a professional who can guide you properly. Often this is a member of your own staff. This helps to ensure the safety and practicality of your flanged assembly. A well-trained engineer will provide you with the correct information you need and work with you properly to apply the best fitting in the right service. By performing accurate testing and review of your design calculations, you will reliably test the performance of your entire assembly.

6. The next step is to choose the proper manufacturer. To provide you with the best flange that you are looking for, you should find the most reliable, reputable, and qualified manufacturer.

By following all these tips, you will find the perfect match of the flange for your project and have a better decision regarding your many options.

Understand the situation in its entirety and choose the right flange type for your pipeline project.