What are orifice flanges

Orifice Flanges

Materials Used

Key Features

Uses

Orifice flanges are used instead of the standard pipe flanges when orifice plate or flow nozzle is used. In other words, orifice flanges are used with orifice meters. The basic purpose for this is to measuring the flow rate of either gases or liquids in the respective pipeline. They are, for all intensive purposes, the same as weld neck and slip-on flanges with extra machining. They have modifications of radial tapped holes in the flange ring for meter connections and orifice plate carriers for the reason of fitting meter connections.  The additional bolts act as a jack to allow the separation of the two flanges to change the orifice plate or for other inspection services.

Orifice flanges are for metering the volumetric flow rate of liquids and gasses through a pipe. Two orifice flanges are called an orifice flange union. Each flange comes with two pipe taps for measuring the pressure drop of the flow through an orifice plate. Orifice plates do not come with the flanges and are sized based on the requirements of the process. Two jack screws are used to spread the flanges apart in order to change the orifice plate. This flange is normally available in weld neck, slip-on, and threaded flanges. These flanges have a raised face.

Orifice flanges are installed in a straight run of pipe in order to avoid turbulence at the plate. As a rule of thumb, an orifice flange has ten diameters of straight pipe upstream and five diameters of pipe downstream.

When installing the orifice plate flange the pressure taps need to be at the same elevation to each other. The assumption when making the calculation for the orifice plate is that static head of the tubes is the same on both sides of the orifice plate. Pressure taps should not be installed facing down as the taps could become plugged with debris in the line.

Materials used:

• Aluminum
• Brass
• Bronze
• Cast iron
• Stainless Steel
• Carbon Steel
• Alloy
• Nickel
• Copper etc.

Key Features:

• Come with either raised faces or ring type joint (RTJ ) facings.
• The orifice flanges have modifications of radial tapped holes in the flange ring for meter connections.
• There are the orifice plate carriers in these flanges for the reason of fitting meter connections.
• The additional bolts available serve as a jack to allow the separation of the two flanges to change the orifice plate or for other relevant services like inspection.

Uses of orifice flanges:

• The basic purpose of an orifice flange is used to flow/rate metering of piping systems.
• They are used for all intensive purposes, similar to weld neck and slip-on flanges with extra machining.