What Are Buttweld Unions?

HART Industrial Unions offers a wide range of welded connection styles, including butt weld pipe unions. Butt weld unions are used as a permanent, welded connection between two pipes or piping systems. HART Industrial Unions has the capability to manufacture standard and customized butt weld unions specified to S10, S40, S80, S160 , and XXH welding schedules in both Class 3000 and Class 6000 applications.

Buttweld Unions come with ASME B16.9 standard butt weld connections with a standard 37.5 degree bevel. This allows industry standard buttweld stainless or steel pipe to be mated and welded for a secure and seamless connection.
HART’s butt weld connections are interchangeable with other HART welded and threaded connection styles and can be manufactured in a variety of materials including but not limited to carbon steel 12L14 or A105, stainless steel 304 or 316, Monel 400, Hastelloy, and Aluminum.

HART O-Ring Union Features:

  • Turbulence Free: All unions provide a turbulence-free fit across the seats
  • O-Ring Isolation: The O-Ring seal is strategically located in the thread
    piece face, eliminating O-Ring media contact and added protection against abrasives and erosion. A variety of O-Rings for any application are available.
  • Precision Machined Components: All unions are precision machined to provide high quality and fail-safe leak proof reliability.
  • Interchangeable End Connections: HART’s male threaded connections feature interchangeable configurations with other threaded or welded connections, reducing the need for nipples or additional fittings.
  • Material Versatility: Unions can be provided in all standard metals or combinations of metals. This includes 304 Stainless, 316 Stainless, A105 Carbon Steel, Brass, Monel 400, Hastelloy, and Titanium.
  • Excellent Vibration Resistance: Seals will not loosen, even under extreme pressure and pressure surges.
  • No Maintenance: Once the initial seal is made, no further tightening is required.

3535 Series Butt Weld, Class 3000 Unions

Class 3000 Series butt weld unions are ideal for permanent welded connections in piping systems that are pressure rated up to 3000 psig W.O.G.

  • Specifications
    SizeA-NPSBC-HEXDE-TAILF-THREADG-FLATWEIGHT (LBS)
    3535-11/4"2.711.380.751.311.410.630.33
    3535-23/8"2.901.821.131.411.491.000.7
    3535-31/2"2.901.821.131.411.491.000.7
    3535-43/4"2.982.151.381.451.531.151
    3535-51"3.012.501.751.451.561.501.75
    3535-61-1/4"3.243.062.161.621.621.882.5
    3535-71-1/2"3.143.382.381.541.602.133.5
    3535-82"3.473.882.891.641.832.564.25
    3535-92-1/2"3.595.003.611.781.813.256
    3535-103"3.655.754.301.841.814.008

    Buttweld Unions

  • 3D Animations

6565 Series Butt Weld, Class 6000 Unions

HART Industrial Unions Class 6000 series butt weld unions are suited for permanent welded connections in piping systems that are pressure rated up to 6000 psig W.O.G.

  • Specifications
    SizeA-NPSBC-HEXDE-TAILF-THREADG-FLATWEIGHT (LBS)
    6565-11/4"2.901.821.131.411.491.000.7
    6565-23/8"2.901.821.131.411.491.000.7
    6565-31/2"2.982.151.381.451.531.151
    6565-43/4"3.012.501.751.451.561.501.75
    6565-51"3.243.062.161.621.631.882.5
    6565-61-1/4"3.143.382.381.541.602.133.5
    6565-71-1/2"3.473.882.881.641.832.564.25
    6565-82"3.595.003.611.781.813.256
    6565-92-1/2"3.655.754.301.841.814.008

    Buttweld Unions

  • 3D Animations

Applications

Buttweld unions are a common fitting solution for fluid pipe systems in virtually any industry. As the fittings can transport liquids and gases with little to no risk of degradation, they’re commonly used for systems that need to change the direction or flow rate of fluids. Given their strength and the robustness of their design, some of the most common applications that rely on buttweld unions include:

  • Breweries
  • Cryogenics
  • Chemical, petrochemical, and gas processing
  • Nuclear energy systems
  • Paper production plants
  • Wastewater treatment systems

HART Industrial Unions’ Capabilities

At HART Industrial Unions, we specialize in creating hardworking, long-lasting unions for pipe and tube systems. We build all of our precision-machined parts in the USA, so we can control the material and construction quality every step of the way. Our buttweld unions, available with Class 3000 and 6000 services, are turbulence-free and vibration resistant. We strategically place our Sure Seal O-rings on a union’s thread piece face to increase erosion resistance as well.

To learn more about our Engineering and Manufacturing Capabilities, visit our Capabilities.

Contact our team of manufacturing specialists today to learn more about the specifications and standard requirements our products can meet, our commitment to quality, and details about how to start your order of buttweld unions.