Types of AWWA Flanges and Their Applications

AWWA (American Water Works Association) flanges are essential components in waterworks and municipal water systems, providing reliable connections and facilitating maintenance and system modifications. This article explores the various types of AWWA flanges, their unique features, and their applications in different industries.

Ring Flanges

Ring flanges are the most common type of AWWA flange. They are designed for easy assembly and disassembly, making them ideal for systems that require frequent maintenance or modification.

  • Features: Flat circular flanges with bolt holes around the perimeter.
  • Applications: General water distribution systems, wastewater treatment plants, and potable water pipelines.

Blind Flanges

Blind flanges are used to close off the ends of piping systems, providing a secure seal. They are essential for systems that require frequent inspection and maintenance.

  • Features: Solid flange without a central bore, multiple bolt holes around the perimeter
  • Applications: End closures for pipelines, inspection ports, and access points in water treatment facilities.

Lap Joint Flanges

Lap joint flanges are designed for use with a stub end, providing flexibility in installation and alignment. They are suitable for systems that require frequent disassembly and reassembly.

  • Features: Two-part assembly with a loose flange and a stub end, allowing for easy rotation and alignment
  • Applications: Food and beverage processing, pharmaceutical industries, and systems requiring regular maintenance

Slip-On Flanges

Slip-on flanges are designed to slide over the end of a pipe and are then welded in place. They offer an easy and cost-effective method of connecting pipes.

  • Features: Flange with a bore slightly larger than the outer diameter of the pipe, requiring welding on both the inside and outside
  • Applications: Low to moderate pressure water systems, HVAC systems, and industrial piping networks

Socket Weld Flanges

Socket weld flanges are designed for small-diameter, high-pressure piping systems. The pipe is inserted into the socket end of the flange and then welded, creating a strong and leak-proof connection.

  • Features: Flange with a socket to fit the pipe end, requiring a fillet weld for a secure connection
  • Applications: High-pressure lines, small-diameter piping, and chemical processing systems

Threaded Flanges

Threaded flanges are designed for easy assembly and disassembly without welding. They are ideal for systems where welding is not feasible or for systems requiring frequent maintenance and modification.

  • Features: Internal threading to match the external threading of the pipe, allowing for a secure connection without welding.
  • Applications: Low-pressure systems, maintenance-intensive systems, and fire protection systems.

Orifice Flanges

Orifice flanges are used in flow measurement systems. They have a precision-machined bore that allows for accurate flow measurement when used with an orifice plate.

  • Features: Precision-machined bore, usually with pressure taps for differential pressure measurement
  • Applications: Flow measurement systems, chemical processing, and oil and gas industries

Integral Flanges

Integral flanges are designed as part of the equipment, such as pumps or valves. They provide a direct connection to the piping system without the need for additional fittings, ensuring a strong and leak-proof connection.

  • Features: Integrated flange with the equipment, eliminating the need for separate fittings.
  • Applications: Pumps, valves, pressure vessels, and other equipment requiring a direct connection.


Understanding the different types of AWWA flanges and their applications is essential for selecting the right flange for your specific project. Each type offers unique features and benefits, making them suitable for various industries and operating conditions. Whether you need easy assembly, high-pressure tolerance, or flexibility for frequent maintenance, there is an AWWA flange type that meets your needs. By choosing the appropriate flange, you can ensure the reliability, safety, and efficiency of your water-related infrastructure.

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