สำหรับผู้ซื้อ, the first question is whether the project needs an ASME B16.36 orifice flange union with integral flange taps, or a different pressure-tapping arrangement around an orifice plate. This distinction affects the hardware, การวาดภาพ, inspection points and RFQ.

Tap Location Map

D means the internal diameter used by the applicable calculation. It is not automatically the nominal pipe size or outside diameter. Confirm the actual bore and the adopted standard before locating D-D/2 taps.

Flange Taps

Flange taps are the arrangement most directly associated with ASME B16.36 orifice flanges. The pressure connections are machined or threaded into the flange pair, with their centers one inch from the corresponding orifice-plate face. This provides a compact assembly and avoids deciding tap positions in the field.

The flange drawing must still define nominal size, ระดับความดัน, หันหน้าไปทาง, เบื่อ, tap size and orientation. The plate, gaskets, jack screws where required, companion piping and differential-pressure instrument connections remain part of the complete installation rather than properties of the flange alone.

Corner Taps

Corner taps sense pressure immediately adjacent to the two plate faces. Their geometry is useful where a standard or calculation method calls for corner tapping, including some smaller-bore applications. Because the openings are at the plate faces, the tapping chamber, gasket and plate-holder geometry must be coordinated carefully.

A corner-tap specification should not be converted into a standard flange-tap orifice flange merely because both use an orifice plate. The pressure locations differ, and the calculation inputs and hardware details must remain consistent.

D-D/2 Taps

D-D/2 taps—also called radius taps in some references—locate the upstream pressure connection at D and the downstream connection at D/2 from the plate. These connections normally belong in the pipe run rather than in the flange body. Their actual distances therefore depend on the defined internal diameter.

Before fabrication, identify the plane from which each distance is measured, the finished bore, tap orientation and straight-run arrangement. A schedule or bore change can alter the intended D and D/2 locations.

ASME B16.36 และ ISO 5167-2 Cover Different Parts of the Decision

ASME B16.36 is the dimensional standard for orifice flanges with pressure-differential connections within its stated type and class scope. ISO 5167-2 addresses orifice plates used for differential-pressure flow measurement and includes flange, corner and D-D/2 pressure-tapping arrangements. The project must state the adopted standard and edition.

ISO 5167-2 does not treat every historical tapping style as an equivalent option. ตัวอย่างเช่น, pipe taps and vena-contracta taps fall outside its stated scope. Do not substitute one tapping geometry for another without recalculating and obtaining engineering approval.

Installation Checks That Affect Measurement

• Plate orientation: install the plate in the marked flow direction; a beveled plate normally has the sharp edge upstream unless the approved design states otherwise.
• Concentricity: align the plate bore with the pipe bore and prevent gasket intrusion into the flow path.
• Tap condition: keep pressure openings clear, burr-free and correctly oriented for the service and impulse piping.
• Straight runs: follow the adopted standard or flow-calculation requirement for upstream and downstream piping.
• Joint control: use the specified gasket, bolt-tightening procedure and plate gap; check for leakage before service.
• Instrument layout: route impulse lines to avoid trapped gas or liquid and follow the instrument supplier’s installation requirements.

These are general checks, not a commissioning procedure. The approved piping drawing, calculation, instrument specification and site safety procedure control the installation.

Which Orifice Flange Product Route Fits the RFQ?

The product route identifies the requested material family; it does not prove stock, เวลานำ, ใบรับรอง, tests or suitability for a particular fluid. Those items remain order-specific.

Orifice Flange RFQ Checklist

1. adopted dimensional and flow-measurement standards, including editions;
2. ประเภทหน้าแปลน, ขนาดที่กำหนด, ระดับความดัน, facing and matching pipe bore;
3. material grade and governing material specification;
4. tap arrangement, tap thread/size, orientation and number of tapped holes;
5. orifice-plate bore, ความหนา, material and flow direction;
6. gasket, jack-screw and companion-flange requirements;
7. service fluid, ความดัน, temperature and corrosion allowance; และ
8. ปริมาณ, drawings, MTC/inspection requirements, destination and schedule.

คำถามที่พบบ่อย

What are the different types of orifice tapping?

Common arrangements include flange taps, corner taps and D-D/2 taps. Other historical arrangements exist, but the selected standard and calculation method determine which are permitted.

Why do orifice flanges have tappings?

The openings transmit upstream and downstream static pressure to a differential-pressure instrument. The measured pressure difference, together with the plate and process data, is used to calculate flow.

What is the difference between flange taps and corner taps?

Flange taps are centered one inch from the plate faces; corner taps are located at the plate faces. Their geometry and calculation coefficients are therefore different.

Are D-D/2 taps the same as pipe taps?

เลขที่. D-D/2 taps use defined locations of D upstream and D/2 downstream. “Pipe taps” can refer to a different historical arrangement and should not be assumed equivalent.

What is an orifice flange used for?

It holds an orifice plate between a matched flange pair and provides pressure connections for differential-pressure flow measurement.