Flange Types and Sizes

Table of Contents

Flanges are integral components utilized in a assortment of mechanical applications to interface channels, valves, pumps, and other gear. Understanding the distinctive sorts and sizes of spines is vital for selecting the right one for a particular application. This article gives a comprehensive diagram of spine sorts based on different classifications, standard rib sizes, and measurements agreeing to Din and ISO standards. It too highlights a driving rib producer, Hebei Pengrun Pipe Fittings Co, Ltd.


Flanges can be classified based on a few criteria, counting their association strategy, shape, fabric, and application. Each sort has special characteristics that make it reasonable for particular purposes.

1. Based on Association Method:

Weld Neck Flanges: These spines have a long, decreased center that is welded to the pipe. This plan gives a smooth move from rib to pipe, diminishing stretch concentrations and making them perfect for high-pressure applications.

②Slip-On Spines: These are slipped over the pipe and at that point welded. They are less demanding to adjust than weld neck spines but give less quality. They are appropriate for low-pressure applications.

③Socket Weld Flanges: These spines have a attachment into which the pipe is embedded and at that point welded. They are utilized for small-diameter, high-pressure pipes.

④Threaded Flanges: They have threads that match the pipe’s threads, allowing for assembly without welding. They are used in low-pressure applications and where welding is not possible.

⑤Blind Flanges: Used to close off the end of a pipe or valve, they do not have a bore and are used for inspection and maintenance purposes.

⑥Lap Joint Flanges: These are used with a stub end, and it does not contact the fluid. They are useful for systems requiring frequent disassembly.

2. Based on Shape:

①Flat Flanges: These have a flat face and are generally used for less demanding applications where the stress on the flange is low.

②Raised Face Flanges: The most common type, they have a raised area around the bore, which helps in sealing when used with a gasket.

③Ring-Type Joint Flanges: they have a groove cut into their faces and are used with a metal ring gasket. They provide a strong seal for high-pressure applications.

3. Based on Material:

①Carbon Steel Flanges: Widely used due to their strength and durability, they are suitable for high-pressure and high-temperature applications.

②Stainless Steel Flanges: Known for their resistance to corrosion and heat, they are used in environments with aggressive chemicals and extreme temperatures.

③Alloy Steel Flanges: These products offer enhanced mechanical properties and resistance to corrosion. They are used in specialized applications.

④Cast Iron and Ductile Iron Flanges: These are used in water and sewage systems due to their cost-effectiveness and adequate strength.

Standard Flange Sizes

Selecting the appropriate size is essential for ensuring the integrity and efficiency of a piping system. Standard sizes are defined by various standards organizations, ensuring compatibility and interchangeability across different systems and applications.

1. Nominal Pipe Size (NPS) and Nominal Diameter (DN): These are the most common designations for pipe sizes. NPS is used primarily in North America, while DN is used internationally. Both systems provide a standard way to specify pipe diameter.

2. Pressure Ratings: they are also classified by their pressure rating, which indicates the maximum pressure they can withstand. Common pressure ratings include Class 150, 300, 600, 900, 1500, and 2500 in the ASME standard, and PN (Pressure Nominale) ratings such as PN10, PN16, PN25, and PN40 in the DIN standard.

3. Dimensions: its dimensions include its outer diameter, inner diameter, bolt circle diameter, number and size of bolt holes, and thickness. These dimensions are standardized to ensure that products can be used interchangeably.

For example, according to the ASME B16.5 standard:

– A Class 150, NPS 4 has an outer diameter of 9 inches, a bolt circle diameter of 7.5 inches, and eight 0.75-inch bolt holes.

– A Class 300, NPS 4 has an outer diameter of 10.5 inches, a bolt circle diameter of 7.88 inches, and eight 0.88-inch bolt holes.

These standardized dimensions help in its proper selection and installation in various applications.

DIN Flange Dimensions

The Deutsche Institut für Normung (DIN) standards are widely used in Europe and specify dimensions, materials, and pressure ratings. DIN standards ensure that products manufactured by different companies are compatible and can be used interchangeably.

For example, the DIN 2633 standard specifies dimensions for weld neck flanges with a pressure rating of PN16:

– A DN 100 has an outer diameter of 220 mm, a bolt circle diameter of 180 mm, and eight 18 mm bolt holes.

– A DN 200 has an outer diameter of 340 mm, a bolt circle diameter of 295 mm, and twelve 22 mm bolt holes.

DIN Flange standards also provide guidelines for the materials used in construction, ensuring that the flanges can withstand specific pressures and temperatures. The standards cover a wide range of flange types, including slip-on, weld neck, blind, threaded, and socket weld.

Flange Manufacturer

With over 20 years of experience in the industry. The company specializes in producing high-quality products that adhere to international standards, ensuring reliability and safety across various applications.

For those seeking reliable and high-performance flanges, Hebei Pengrun Pipe Fittings Co, Ltd is a top choice. With their extensive product range, stringent quality control, and commitment to customer satisfaction, they deliver solutions that meet the highest standards of excellence.

If you are choosing your supplier, welcome to contact us at Lucy@pr-pipefittings.com.


1. American Society of Mechanical Engineers (ASME). (n.d.). ASME B16.5 Standard.

2. Deutsches Institut für Normung (DIN). (n.d.). DIN Flange Standards.

3. International Organization for Standardization (ISO). (n.d.). ISO 7005-1: Steel Flanges.

4. Engineering Toolbox. (n.d.). Flange Dimensions and Pressure Ratings.

Picture of Lucy yang

Lucy yang

Flange fittings Specialists Hey, I’m the author of this post, If you have any problems with it, call us for a free, no-obligation quote
or discuss your solution

Need Tools? Share your Needs!

Recent Post

Send Your Inquiry Today


    Get Custom Quote

    Have a question? Get in touch instantly using the form below.
    Our customer support team would get back to you soon.

      Get Custom Quote