Orifice Flanges ASME B16.36

Orifice Flanges are used with orifice meters for the purpose of measuring the flow rate of either liquids or gases in the respective pipeline. Pairs of pressure "Tappings" and "Jack Screws", mostly on 2 sides, directly opposite each other, are machined into the orifice flange. This makes separate orifice carriers or tappings in the pipe wall unnecessary.

Orifice Flanges generally come with either Raised Faces or RTJ (Ring Type Joint) facings. They are, for all intensive purposes, the same as weld neck and slip on flanges with extra machining.

The image below shows a set Orifice Flanges, where a Orifice Plate, and a Jack Screw is mounted.

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.

Usually two jack screws are mounted, and they are used to separate the flanges so that the orifice plate can be inspected and/or replaced. There should be one jack screw per flange and when the flanges are installed, the jack screws should be 180° apart. Orifice flanges are purchased with flange taps and jackjack screws.

The range of orifice flanges covers all standard sizes and ranges, and all common flange materials. Flanges are available in Welding Neck, Slip On, and Threaded form, and are typically supplied with two 1/2" NPT tappings in each flange.

The American National Pipe Thread Tapered

NPT is the best known and most widely used connection where the pipe thread provides both the mechanical joint and the hydraulic seal. NPT has a tapered male and female thread which seals with Teflon® tape or jointing compound.

ASME B1.20.1 covers dimensions and gaging of NPT pipe threads for general purpose applications.

The American National Pipe Thread Tapered (NPT)

ASME B16.36 covers Dimensions and dimensional tolerances from orifice flanges (similar to those covered in ASME B16.5) that have orifice pressure differential connections. Coverage is limited to the following flanges..

Welding Neck Classes 300, 400, 600, 900, 1500, 2500
Slip On Class 300
Threaded Class 300

Rosemount Orifice Flanges and Orifice Plates

Drawing of Orifice Flange

Large image of the entire drawing as shown above