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The restriction orifices are used for reducing fluid pressure and are designed somewhat different from the orifice plates that are used for measuring flow rates. They are designed to slip between the piping flanges.
While single restriction orifices are often sufficient to meet the requirements, there are situations where limitations arise due to process conditions making the single restriction orifices unacceptable. In such situations, use of multiple restriction in series is a better solution.
The foremost consideration for the case of multiple restriction is the pressure drop. This applies whether or not the fluid is liquid or vapor/gas. Higher pressure drop implies higher velocities resulting in vibration and noise problems.
The other consideration is not just about maximum permitted pressure drop and this is particularly for gas flow. If the process condition indicates that critical flow will occur with the use of single restriction plate, care should be exercised to avoid operating well beyond the critical pressure drop. Critical implies a pressure drop across the device exceeding 50 percent of the absolute upstream pressure at which point sonic velocity is reached.
Construction of Multistage Orifice Assembly comprises of multiple restriction orifice plates separated by a distance of one pipe diameter and welded with the pipes in between them. End connection is either suitable for butt welding or with end flanges.
||Conforms to ISA RP 3.2 , DIN 1952 , BS 1042, ISO-5167
||Square edge concentric, Quadrant edged, Conical entrance, Eccentric, Segmental
||SS304 , SS316 , SS316L as standard. Hastelloy-C , Monel , PP , PVC , PTFE coated , etc. can be given on request.
||In accordance with ISO-5167, BS-1042, ASME MFC 3M, R.W.Miller, L.K.Spink, AGA-3
||In the same material as plate & is welded to orifice plate. Tab plate integral to the Orifice plate (i.e. without welding) can also be offered as a special case.
|Vent / Drain
||Vent or Drain holes are provided as per customer's requirement. The diameter of the vent or drain holes are as per ISA RP 3.2
|Flange Union||Weld neck, Slip on, Threaded, Socket welded with RF or RTJ facing Orifice flanges are in accordance with ANSI B16.36 with minimum flange rating of 300# for sizes up to 8" or male - female flanges in accordance with ANSI B16.5
||Corner tappings are recommended for sizes upto 1 ¬Ĺ"; Flange taps from 2" to 16" ; D - D/2 taps for higher sizes
CAF as per IS: 2712 Gr 0/1 , SS spiral wound + CAF , SS spiral wound + Grafoil, SS spiral wound + PTFE are normally supplied as per process requirement. Other materials available on request. For RTJ flanges , the plate is fixed on the plate holder. The plate holder is in Soft Iron material & acts as a gasket.
|Studs / Nuts||ASTM A193 Gr.B7/A-194 Gr.2H as standard, Other material on request.
|Jack Screw||ASTM A193 Gr.B7/A-194 Gr.2H as standard, Other material on request.