While stainless steel valves and flanges are popular options to meet the needs of complex piping systems, bleed rings — also known as drip rings, bleeder rings, vent rings, or test inserts — offer unique benefits for a range of processes and piping systems. 

In this guide, we’ll cover both what bleed rings are, common uses, and what you should consider to ensure you find the perfect solution for your needs.

What Are Bleed Rings?

Able to be matched with any flange type, bleed rings are a ring section with one or more radial pipe connections designed to fit between standard flanges with the bolt circle, using conventional gasket materials.

Standard bleed rings are manufactured with at least one 1/2-inch or 3/4-inch tapping to allow easy connection of valves and instruments.

While bleed rings with multiple taps or alternative tap sizes are available, these may impact the overall thickness of the ring.

Bleed rings are available in a variety of materials such as stainless steel, carbon steel and special alloys as required.

Bleed Ring Usage 

Bleed rings are commonly used in place of orifice flanges.

They are easier to install and more affordable than orifice flanges — particularly in brownfield operations where hazardous materials or contamination are concerns.

Typical uses for bleed rings include providing easy access to drain piping, taking samples, or attaching instruments.

They can also reduce or dispose of pressure before removing a flange through the use of valves or blind flanges.

This procedure is common when replacing leaky valves in a piping system.

Bleed Ring Sizing and Fitting

While exact requirements will vary based upon your intended use, environment, and materials involved, bleed rings are produced using ANSI/ASME standards and available in a range of common ratings and sizes.

Options range from classes 150# to 2000#.

Most are 1.5-inches thick, however, thicker bleed rings are available for use with additional hardware to secure the connection between components if needed. This can allow for a larger tap size or meet other needs.

Apart from sizing, you’ll also want to ensure that the finish and shape of the gasket surfaces meet the interfacing requirements of your intended application.

Tappings are available in both threaded and socket weld varieties as well to ensure compatibility and safe operation of any instruments or valves you wish to connect.

You can find out more about the Bleed Rings offered by Unified Alloys in our Bleed Ring Dimensional Data section.

Although dimensions will vary depending on Pipe NPS and Flange rating, the below images help illustrate bleed ring engineering.

diagram of bleed ring dimensions

Example of threaded and socket weld connections on a bleed ring

Example of an assembled bleed ring, complete with flanges and bolt-up accessories

Bleed Ring Standards and Regulations

For more information on bleed ring standards, consult the following ASME standards:

  • ASME B16.5 – Pipe Flanges and Flanged Fittings: NPS 1/2 through NPS 24 Metric/Inch Standard
  • ASME B16.20 – Metallic Gaskets for Pipe Flanges: Ring-Joint, Spiral-Wound, and Jacketed
  • ASME B16.47 – Large Diameter Steel Flanges: NPS 26 Through NPS 60 Metric/Inch Standard
  • ASME B16.48Line Blanks

It’s also important to consider that despite being comparable to very thick, solid metal gaskets, bleed rings may require registration as a fitting and a CRN depending on your intended usage and use environment.

Serving industries across North America for more than four decades, Unified Alloys offers a wide range of bleed rings to meet the needs of your piping process or system design. If you’re unsure how to implement bleed rings in your project or have questions about your specific needs, our expert analysts are available to help you find the ideal solution.