Bonyan Tajhiz Jonoub, materials engineering company

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Steam, Air, Water Equipments

Steam, Air, Water



Orifice plates

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Orifice plates are one of the most popular devices for the measurement and control of fluid flow. The shape and manufacturing tolerances of plates used in measurement applications are defined in the international standardization publications of ISO, AGA, ASME and others. From the formulas and data within these publications, the relationships and values of flow, differential pressure, and plate bore are determined.

In flow control applications, orifice plates are used as restriction devices to regulate fluid flow or reduce the flowing pressure downstream of the orifice plate. The use of a fixed restriction orifice can be beneficial and economic by reducing the demands on other flow system components.

Unlike measurement orifices, the sizing and design of restriction orifices are not defined by standardization organizations. Additionally, restriction orifices, abbreviated "RO", are often exposed to severe flow conditions associated with large pressure reductions and the related fluid conditions caused by liquids flashing to a gas, cavitation, and sonic (choked) flow. In torturous applications, mimicking the design of measurement orifices is not sufficient.

Orifice Plates are normally mounted between a set of Orifice Flanges and are installed in a straight run of smooth pipe to avoid disturbance of flow patterns from fittings and Valves.


RTJ type orifice plates may be machined in one piece, or alternatively from two pieces, with an orifice plate screwed onto a carrier ring/gasket.

Standard material grades for orifice plates include 316 Stainless Steel, 304 Stainless Steel, 310 Stainless Steel, Hastelloy® C276, Hastelloy® B3, Duplex Stainless Steel, Super Duplex Stainless Steel, Monel® 400, Carbon Steel, Titanium, Incoloy® 800, Incoloy® 825, Inconel® 600 and Inconel® 625.

Common carrier ring/gasket materials include Stainless Steel and soft iron. To ensure correct sealing when installed between flanges, the hardness of the carrier ring/gasket material is limited to a maximum value, typically 120 for soft iron rings and 160 for Stainless Steel Rings.

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