Manufactured without a bore, these flanges are used to blank off the end of piping, valves and pressure vessel openings. They are also most suitable for high pressure temperature applications.
With a static strength equal to the Slip-on flange, the Socket-weld is connected with the pipe with 1 fillet weld on the outside of the flange. Due to corrosion issues, some processes do not allow this flange. To find out more what machines can be used to create the right sealing surface on flange connections take a look at the Enerpac range of Flange Facing Machines. Get more expert insight like this.
To ensure your always familiar with these, here are 6 of the most common flange types and a description of what they are best used for: Weld-neck Complete with a tapered hub, these flanges are recognisable and used in high pressure environments. Slip-on A flange which is slipped over the pipe and welded both inside and outside to increase strength and prevent leakage. Threaded Used in special circumstances, the threaded flange can be attached to the pipe without being welded.
Integral flanges are those, which are cast along with the nozzle neck or the vessel or pipe wall, butt-welded thereto, or attached by other forms of arc or gas welding of such a nature that the flange and the nozzle neck or vessel or pipe wall is considered to be the equivalent of an integral structure. In welded construction, the nozzle neck or the vessel or pipe wall is considered to act as a hub.
Thickness of integrally cast flanges and welded on flanges differ in certain sizes. The flanges can also be classified based on the facings as below:. The Raised Face flange is the most common type used in process plant applications, and is easily to identify. It is referred to as a raised face because the gasket surfaces are raised above the bolting circle face.
This face type allows the use of a wide combination of gasket designs, including flat ring sheet types and metallic composites such as spiral wound and double jacketed types.
The purpose of a RF flange is to concentrate more pressure on a smaller gasket area and thereby increase the pressure containment capability of the joint. For and flanges, the raised face is of 1. For higher rating, the flange thickness does not include the raised face thickness.
The raised face thickness for higher rating is 6. The Flat Face flange has a gasket surface in the same plane as the bolting circle face. Applications using flat face flanges are frequently those in which the mating flange or flanged fitting is made from a casting. Flat face flanges are never to be bolted to a raised face flange. This is to keep the thin, brittle cast iron flange from being sprung into the gap caused by the raised face of the carbon steel flange.
They have grooves cut into their faces which seats ring gaskets. The flanges seal when tightened bolts compress the gasket between the flanges into the grooves, deforming the gasket to make intimate contact inside the grooves, creating a metal to metal seal.
An RTJ flange may have a raised face with a ring groove machined into it. This raised face does not serve as a part of the sealing means. For RTJ flanges that seal with ring gaskets, the raised faces of the connected and tightened flanges may contact each other. In this case the compressed gasket will not bear additional load beyond the bolt tension, vibration and movement cannot further crush the gasket and lessen the connecting tension.
Ring Type Joint gaskets are metallic sealing rings, suitable for high-pressure and high-temperature applications. The octagonal cross section has a higher sealing efficiency than the oval and would be the preferred gasket. The sealing surfaces on the ring joint grooves must be smoothly finished to 63 microinches and be free of objectionable ridges, tool or chatter marks. They seal by an initial line contact or a wedging action as the compressible forces are applied.
The hardness of the ring should always be less than the hardness of the flanges. For more on Gaskets, check out: Introduction to Gaskets. The Tongue and Groove faces of this flanges must be matched.
Tongue-and-groove facings are standardized in both large and small types. They differ from male-and-female in that the inside diameters of the tongue-and-groove do not extend into the flange base, thus retaining the gasket on its inner and outer diameter. These are commonly found on pump covers and Valve Bonnets. Tongue-and-groove joints also have an advantage in that they are self-aligning and act as a reservoir for the adhesive. The scarf joint keeps the axis of loading in line with the joint and does not require a major machining operation.
With this type the flanges also must be matched. One flange face has an area that extends beyond the normal flange face Male. The outer diameter of the female face acts to locate and retain the gasket. Custom male and female facings are commonly found on the Heat Exchanger shell to channel and cover flanges. The female face and the male face are smooth finished. The reason for this is that the contact surfaces do not match and there is no gasket that has one type on one side and another type on the other side.
Flanges can withstand different pressures at different temperatures. In addition, flanges, like fittings and pipes, for specific purposes sometimes internally equipped with layers of materials of a completely different quality as the flanges themselves, which are "lined flanges".
The material of a flange, is basically set during the choice of the pipe, in most cases, a flange is of the same material as the pipe. ASME B If the flange is ordered, the supplier want to know the material quality.
The flange above has 8 bolt holes, and a welding bevel of All given dimensions are in millimeters. All these various elements are interrelated and depend upon one another to achieve a successful result. The reliability of the flanged joint depends critically upon competent control of the joint making process. Quoting from John H. Bickford's book, "An Introduction to the Design and Behavior of Bolted Joints": That all important clamping force which holds the joint together - and without which there would be no joint - is not created by a good joint designer, nor by high quality parts.
It is created by the mechanic on the job site, using the tools, procedures, and working conditions we have provided him with And further: The final, essential creator of the force is the mechanic, and the time of creation is during assembly. So it's very important for us to understand this process.
The industry has recognized the critical nature of installation and assembly for several years. In Europe, the emphasis has been on ensuring that joint making is undertaken by trained and validated technicians and this has led to the publication of a European Technical standard: TS EN Part 4 entitled "Flanges and their joints.
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