An Overview of Orifice Unions
Orifice flange unions, commonly referred to as orifice unions, are simply a pair of orifice flanges used for holding an orifice plate in a line. Orifice plates are used for measuring the flow rate of fluids. In order to ensure that an orifice plate can produce accurate results consistently, it is important to secure the plate’s position in the pipe bore. This is where orifice flange unions can play a major role. They hold the orifice plate securely in line, so that the plate can provide accuracy in measurement. The two orifice flanges are usually attached with jackscrews, thus making it easy to remove or replace any plate whenever required. Read on this article to know about the different types of orifice unions and their uses.
The Different Types of Orifice Unions
Orifice unions are designed in different styles in order to match them with the different styles of orifice plates available. It is important to note that flange unions do not include an orifice plate. As such, separate orders should be placed for plates and flange unions. In general, depending upon the style of facings, flange unions come in two different types, namely, Raised Face type and Ring-type joint. Moreover, depending upon connection styles, flange unions can be categorized into the following categories.
- Weld Neck – These types of flange unions come with a pointed hub. This enables them to hold the orifice plate more securely in its position. Weld neck flanges provides a smooth transition from the flange to the pipe wall. This helps provide extra resistance to the pipe system. As such, they are commonly used for handling flammable and explosive liquids. Weld neck flange unions mostly available in the ring-type joint style.
- Slip-On – In this type of orifice unions, each flange slips over the pipe length. Slip-on unions are comparatively less costly than weld neck flange unions. However, they provide less durability and are also less sturdy than weld neck unions. In the long run, weld neck unions can help you save more both in terms of costs and durability.
- Threaded – This type of flange unions can assemble a flow metering section without welding. They are perfect for use in conditions where post-weld heat treatment is not viable option.
- Socket-Weld – This is another type of orifice flange unions that are available in sizes below 4". As such, these unions are used for holding small sized plates.
All these types of orifice unions and their features should be taken into consideration, when placing an order for flange unions.
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