ECCENTRIC ORIFICE PLATE
Eccentric orifice plate is similar to a centric orifice plate with circular opening. Its bore position is offset from the centre line of the pipe. When the cross sectional area is oriented downward of circular piping, it enables flow of impurities in the measured fluid through the orifice plate without forming deposits and sediments in front of the aperture plate. This orifice plate is usually placed in the flanged joint. Except for CSN standard sealing surfaces of the orifice plates can be manufactured in compliance with EN, DIN, GOST, American ASME and ANSI standards or, on requirement and specification of the customer.
Ideal placement of differential pressure tapping is vertical in upward part of the orifice plate, differential pressure tapping are individual. Upon agreement with customers outlets of differential pressure are always customized to various options of primary element attachment to metering circuit.
ISO/TR 15377 standard in relation to ISO 5167-1 standard defines possibility to use eccentric orifice plates for diameters of piping ranging from 100 mm to 1,000 mm. Eccentric orifice plate is manufactured in design of orifice plate with individual tapping, the disc is placed between the flanges with individual pressure tapping, disc placed directly between the flanges or in design of the meter tube.
Eccentric orifice plate consists of these main parts: a two-piece flange with individual pressure tapping and a disc. The disc is clamped between two pieces of flange and attached by a seal. Pressure tapping is led out of the flanges. The disc is replaceable. Usual construction width of the orifice plate with individual tapping is 40 mm to 60 mm.
For the production of orifice plate flanges with individual tapping there is mostly used carbon steel or stainless steel material. Due to use of eccentric orifice plates in petrochemical, chemical and nuclear industries, material of the disc is made of stainless steel grades and steels with high nickel content. (E.g. Inconel, Hastelloy).
Eccentric orifice plate is manufactured as a working meter.
Eccentric orifice plate is used in piping where there could be formed sediments, tar deposits or condensates – i.e., in measurement of heterogeneous mixtures (mechanically contaminated liquids and gasses containing solid or liquid constituents) in pipelines. On agreement eccentric orifice plates can be manufactured in different nominal dimension ranges than stated above. Eccentric orifice plate can be incorporated both in horizontal and vertical piping.