Orifice Fittings — orifice fittings (primary flow element assemblies) for gas measurement by differential pressure
Orifice fittings for measuring gas and liquid flow by differential pressure across a calibrated plate. Plates to ISO/BS or API, flange, corner and D and D/2 pressure taps. Used in metering stations at gas distribution stations, gas measurement stations and compressor stations.
- Principle
- flow measurement by differential pressure across a calibrated orifice plate
- Media
- gas and liquid
- Plate
- to ISO/BS or API
- Pressure taps
- flange, corner, D and D/2
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
Orifice fittings are primary flow element assemblies for measuring gas and liquid flow by the variable differential pressure method. The flow restriction creates a pressure drop whose value is related to the flow rate. A calibrated orifice plate is installed in the fitting body, the pressure difference before and after it is measured by a differential manometer or a differential pressure transmitter, and a flow computer converts it into flow rate. The method remains one of the main ones for custody and process measurement of large gas flows on trunk gas pipelines, at gas distribution stations and at metering stations of gas production companies.
Calibrated plates are made to ISO/BS or API standards. Pressure taps are provided at the flanges, at the corners or to the D and D/2 scheme, depending on the chosen calculation method. The method itself is set by the metering station design. On request, flow straighteners to API, BS and ISO standards are supplied. They shorten the straight pipe lengths required before and after the primary element.
The fittings are made from a wide range of materials for both the body and the internal parts: carbon steel, low-alloy steels, stainless steels, duplex steels 22 Cr and 25 Cr, nickel alloys. This range allows them to be used on raw and sour gases, on offshore platforms and in corrosive media.
In the 1990s the company developed the first orifice fitting for plate replacement without shutting down and fully emptying the pipeline (Orifice Fitting Depressurized). The fittings are made at the same production sites as trunk line valves, with hydraulic and gas testing and documentation as required by the project. Supply is in line with European directives, and PED and ATEX declarations are available.
Orifice fittings are used in custody gas metering stations at gas measurement stations and gas distribution stations, at compressor stations for fuel and process gas measurement, at underground gas storage and at gas treatment plants. Size and pressure class ranges are not given in the available sources and are specified for each project. Pipeline diameter, pressure class, body material and type of pressure taps are determined separately for each station.
Technical specifications
| Principle | flow measurement by differential pressure across a calibrated orifice plate |
|---|---|
| Media | gas and liquid |
| Plate | to ISO/BS or API |
| Pressure taps | flange, corner, D and D/2 |
| Options | flow straighteners to API, BS, ISO |
| Materials | carbon and low-alloy steel, stainless steel, duplex 22/25 Cr, Ni alloys |
| History | first orifice fitting with plate change without depressurization (Orifice Fitting Depressurized), developed by the company in the 1990s |
Request a price and lead time
Orifice Fittings — orifice fittings (primary flow element assemblies) for gas measurement by differential pressure. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Questions and answers
To which standards are the plates and pressure taps made?
Calibrated plates are made to ISO/BS or API. Pressure taps are made at the flanges, at the corners or to the D and D/2 scheme, depending on the calculation method.
Which materials are the orifice fittings made of?
Carbon and low-alloy steels, stainless and duplex steels 22 Cr and 25 Cr, nickel alloys. This allows operation on raw and sour gases and on offshore platforms.
Can the plate be replaced without shutting down the pipeline?
In the Orifice Fitting Depressurized version the plate is removed and replaced without shutting down and fully emptying the pipeline. Size and pressure class ranges are specified for the project.
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