What Are Large Diameter Flanges and What Are They Used For?

The large diameter weld neck, slip-on, and blind are two types of the commonly used flange in large assemblies. Butt welding flange and slip-on flange styles are known common large diameter flange options, although the application and structure range of the flat welding large diameter flange and the butt welding large diameter is different.

About large diameter flange

Large diameter flat welding flange has less high-pressure suitability compared to its weld neck counterpart. The basic ring style is suitable for the occasion of low pressure. The butt weld category of the flange is known as a weld neck flange. It suits the occasion of high temperature and pressure as defined in the ASME B16.47 code. Large diameter flanges are widely popularized and used in the sewage treatment industry, wind power industry, chemical industry, and machinery industry.

The material used to manufacture large flanges

The most common material used to manufacture large diameter flange is carbon steel that is forged carefully and of which surfaces have been machined. These flanges are made in multiple ways. Some come with raised faces, while some do not. Almost every type of flange has a seal attached to it to preclude any leaks from the pipeline.

The ASME/ANSI B16.47 Large Diameter Steel flanges include NPS 26 through NPS 60. The standards cover testing, marking, tolerances, dimensions, materials, temperature ratings, and pressure ratings for flanges of this size with rating class designations 2500, 1500, 900, 600, 300, 150, and even 75# for Series B compact style flanges.

Uses of large diameter flanges

The versatility of large diameter flanges, alongside using it with larger pipes, has enabled their installation with applications including engineering units, food industries, gas and oil processing, power plants, construction, cement manufacturing, etc.

Benefits of large diameter flanges

The following are benefits of large diameter flanges:

Properly installed large diameter flanges are corrosion resistant and come with a wide variety of media uses.

They are easy to fit in any climate, and the reason is their simple installation. They can be installed easily, even underwater, given the large sealing surface areas.

Elastomeric sealing gaskets expand the life expectancy of these flanges to at least 50 years.

They come with long-term protection against corrosion, abrasion, and impact to ensure continued reliable performance when properly manufactured.

The welding process of large diameter flanges

Manufacturing of large diameter flanges is usually used in some tank equipment and large-scale furnace to strengthen and connect. The kind of equipment is not typically made as a commodity production run, but rather belongs to the small-batch or single-piece production. The conventional process is to cut the circular plate as per the size of the whole steel plate for plate flanges. After, it needs to be cut off the inner circle on the circular plate. The process method is simple but requires operation space, and large black size, so it is helpful to add a large diameter flange that will cause low economic benefit and low material utilization. Forgings are required for large diameter slip ons with hubs and weld necks.

The flange must be drilled with bolt holes needed to match with a rubber sealing ring and another flange that is added in the middle. To make sure about the sealing effect, the flatness tolerance of the flange is usually required to be higher by end-user applications, and the overall thickness of the flange plays a supporting role. Therefore, dimensional tolerance and roundness of the outer and inner holes of the flange are not as high as smaller flanges.


Texas Flange creates a significant volume of different diameter flanges for the biggest jobs in the industrial and energy fields. We can create a variety of different flange dimensions for custom flange types, configurations, and sizes using numerous suitable materials of construction for every application.

If you need assistance and want to learn more about the different flange sizes, contact Texas Flange today!