What Are Orifice Unions?


HART Industrial Unions can manufacture orifice unions for any style of union connection. An orifice union contains an orifice plate made of 316 stainless steel between the tailpiece and thread piece of the union. The orifice plate can be bored to spec or left blank (no bore). Orifice plates with a bore are used for flow control and flow reduction.

Orifice restriction unions are used to create a known pressure drop, restrict flow rate of fluid or gaseous media, or otherwise meter a piping system. HART Orifice Unions utilize a double o-ring seal on a flat, tabless 316 stainless steel orifice plate to offer leak free performance. Our orifice plates can be laser marked to order with custom identification and are available blank or drilled to your specifications at no additional charge.

All HART Unions utilize a flat face O-ring seal in which the O-ring is seated in a groove located on the flat face of the thread piece component. When tightening the union nut, the O-ring in the threadpiece compresses and seals with the flat face on the tailpiece. Orifice unions have an additional O-ring seated in a groove in the tailpiece that seals within the bottom flat face of the orifice plate, while the O-ring in the thread piece seals to the top flat face of the orifice plate.

Orifice Series Class 3000 and 6000 Unions

  • Specifications
    UNION SIZEORIFICE PLATE OUTSIDE DIAMETER (in)ORIFICE PLATE PART NUMBER
    11O-3-1
    21.375O-3-2
    31.375O-3-3
    41.625O-3-4
    52O-3-5
    62.5O-3-6
    72.75O-3-7
    83.24O-3-8
    93.95O-3-9

  • 3D Animations

Applications

HART orifice unions are versatile enough for many different industries needing pipe systems to control the flow of fluids. Their all-metal construction lends these unions to advantageous uses in wide-ranging temperature and pressure applications. Some of the most common applications for these unions include:

  • Chemical and petrochemical applications
  • Flow-control systems
  • Fluid-handling systems that need to be accurate and reliable
  • High-vacuum pipe systems
  • Liquefied natural gas (LNG) facilities
  • Power generation
  • Process-control systems for manufacturing and processing products at a controlled rate
  • Transportation applications

HART Industrial Unions’ Capabilities

HART Industrial Unions is a leading provider of domestically designed and manufactured unions. We create high-quality orifice unions from different metals, including brass and stainless steel, and with custom dimensions and bore sizes to meet the needs of virtually endless variations of pipe systems. These unions provide Class 3000 and 6000 service. We offer different styles of orifice unions that attach to pipes through different mechanisms for newly installed pipe systems, retrofitted piping, and more throughout commercial and industrial spaces.

With our precision-machining capabilities, our orifice plates are precision cut. We can supply customized, pre-drilled plates or blank plates without prior drilling. As for the union body, we can laser-mark it with the orifice bore.

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

Contact us today to place an order or learn more about the different styles and options of unions available in our inventory.