Flanges Used In The Oil and Gas Industry

Connections through pipes are a crucial channel for transporting steam and fluids along with gas from refineries to factories or across continents as well. Flanges are one of the efficient components in a method to connect pipes. Along with forging connections in a piping system,

flanges regularly permit the worker with inspection points which are easy to modify and clean these systems. Different alloy grades are useful to produce various flanges that are a part of piping systems in the gas and oil industry.

Therefore, these flanges are required to not only be durable, but they must also be easy to install and maintain.


Below are a few of the commonly sighted flange types used in the gas and oil industry:

Weld Neck Flange

Useful in high-pressure environments, it is easy to recognize the weld neck flanges because of the beveled hub. Moreover, weld neck flanges are particularly well suited to be used in repeat bending conditions. These flanges are attached to a piping system by means of welding the pipe to the flange neck.

Therefore, stainless steel grades have good weldable properties preferred for its manufacture. Weld neck types not only reduce the stress concentration from the base of the hub but also aid the transference of stress from the flange to the pipe.

Slip-on Flange

Slip-on flanges are designed to be used in lower-pressure, low-temperature processes. These are favored by the engineers in the gas and oil industry due to their economical value in comparison to the weld neck flanges.

This kind of flange is slipped over the pipe, following which they are welded both on the outside and inside to increase its strength and prevent leakage.

Lap joint

A lap joint flange is a two-part attachment preferred to be used in processes where space constraints and frequent dismantling are primary requirements. In this type of attachment, the lap joint stub end is welded to the pipe, and the loose backing flange is used in conjunction to slip over the pipe or stub end.

As the backing flange is not in contact with the product in the piping systems, moderate corrosion resistance and less expensive material with high hardness like carbon steel is good to use. Also, the stub ends need to be highly corrosion-resistant material with good mechanical properties.

Threaded Flange

It is useful in circumstances where there’s a need for quick fixes. Threaded flanges or as referred to as screwed flanges are produced with threaded bores that aid in a fast and simple attachment.

A threaded flange is usually attached to the pipe without a need to carry out a welding operation due to the pre-existing threads. Typically, threaded flanges are seen in the processes where the pipes in the systems are used to transport water or air. Threaded flanges are best used in low-pressure environments and temperatures.

Blind Flange

The production of blind flange is done without a bore at the center and the main purpose of using it is to blank off the end of valves or piping systems or even pressure vessel openings.

Blind flanges could also be used in conjunction with any other flange to isolate a piping system in the gas and oil industry. Furthermore, they make an excellent manhole, especially if they perform the tasks of terminating the flow in the vessel or a piping system.

Socket Weld Flange

It is recommended to be used for low-temperature and low-pressure settings, the socket weld has a static strength that is equal to a slip-on flange. A socket-weld connection is made with the pipe by using a filler weld performed on the outside of the flange.

Socket weld flanges are designed to be used in processes where small bore piping is needed. However, due to some corrosion issues, it is best to avoid these in a few processes.

If you still have any doubts about how to select flanges for the oil and gas industry and what to look for, do let us know in the comment section or call us today!

Difference Between Alloy Steel Flanges v/s Carbon Steel Flanges

Carbon steel and alloy steel are different kinds of material grades for flanges, although both are extremely common. Alloy steel comes with a variety of elements depending upon future applications.

Carbon steel is also known as iron-carbon alloy contains less than 2% carbon WC. It usually contains small amounts of carbon, phosphorus, sulfur, manganese, and silicon in the mix.

In the case of alloy steel, elements like molybdenum, manganese, chromium, nickel, vanadium, silicon, and boron are used to form a different chemical composition. Generally, alloy steels are of the higher nickel variety and the term is used to distinguish them from regular stainless or low chrome materials.

Alloy steel

Alloying improves the mechanical properties of steel. The variety of elements used helps to improve future applications. Every steel is an alloy but not all steel is referred to alloy steel.

However, the term alloy steel is the standard term that refers to steel with other elements added deliberately in addition to vanadium, silicon, boron, molybdenum, manganese, chromium, nickel, and other elements.

The less common alloy elements include aluminum, cobalt, copper, cerium, niobium, titanium, tungsten, tin, zinc, lead, and zirconium, etc. The alloyed steels have improved properties, like strength, hardness, toughness, wear resistance, corrosion resistance, hot hardness, and hardenability.

Uses and application of Alloy steel

Alloy steels flanges come in a broad range of applications.  Low alloy steel has applications in a wide range of industries due to its cost-effectiveness. It has applications in military vehicles, construction equipment, ships, pipelines, pressure vessels, and oil drilling platforms.

High alloy steels are widely applied in various applications due to their structural components, automotive applications, chemical processing equipment, corrosion resistance, and superior hardness.

Advantages of Alloy steel

Here are some advantages of alloy steel

1. Corrosion resistance

2. Powerful parts

3. Efficient at high temperature

4. Heat dissipation properties

5. Durable

6. Tough

7. Lightweight

8. High tensile strength

Carbon steel

Carbon steel is a special type of steel with a higher concentration of carbon compared to regular iron. Carbon steel with carbon components less than 0.30% is categorized as low or mild carbon steel, carbon steel with carbon components between 0.30% to 0.60% is considered medium carbon steel, and carbon steel with high carbon components more than 0.60% is known as high carbon steel.

The use of high-carbon steel is usually for tools and knives. Though low carbon steel is more common compared to high-carbon steel because of its greater ductility, easy use, and low production cost.

Uses and application of Carbon steel

Carbon steel flanges are one of the most preferable materials used in fields where higher strength is required. Many types of carbon steel pipes come with a wide range of applications in various industries. Low-carbon steel has applications like automobile components, pipes, construction components, bridge components, containers/cans, etc.

Medium carbon steel is usually useful in machinery parts, gears, railway tracks, train wheels, and crankshafts that require higher strength and toughness. High carbon steel has applications in shear blades, cold setts, punches, rock drills, hand tools, cold chisels, band saws, anvil faces, hammers, wrenches, car bumpers, small forgings, cable wire, large dies for cold presses, cutting tools, high strength wires, and springs.

Advantages of carbon steel

Here are some advantages of carbon steel

1. Good strength

2. Good ductility

3. Durable

4. Safe to process

5. Economical / Budget friendly

6. Healthy and long-lasting for cookware

7. Environment friendly


There are many types of steel within the groups of alloy steel and carbon steel. As the name shows, alloy steel is the category of steel formed by adding various other elements to the steel through metallurgy and heat treatment. On the other hand, carbon steel is steel with carbon as the accompanying component. It also usually does not require any minimum percentage of other elements.

Carbon steel is the type of steel predominantly used in the US for most basic applications when compared to alloy steel, which is found in more chemically sensitive and temperature-elevated services.

In the above comparison, we hope you’ve understood the difference between carbon steel and alloy steel and their uses. This guide will help you identify the key things if you are stuck between selecting the two flanges. To learn more about flange basics, visit https://www.texasflange.com/flange-basics/