When sealing raised or flat face flanges, there are two choices of gasket shape: ring-type or full-face. Each has its own advantages, so you should know which will best suit your application before ordering and installing. First, let's discuss the types of flanges in which gaskets are installed.
Different types of flange faces are used as the contact surface to seat the sealing gasket materials. ASME B16.5 and B16.47 define various types of flange facings, including the raised face, the large male and female facings which have identical dimensions to provide a relatively large contact area.
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. Diameter and height are in ASME B16.5 defined, by pressure class and diameter. Pressure rating of the flange determines the height of the raised face.
This blog provides guidance to maintenance operators, engineers and fitters to ensure successful gasket installation and assembly of bolted flange connections. However always check plant-approved installation procedures first.
The successful operation of a gasket depends upon a multiplicity of factors including the style and quality of the gasket material, but also the medium being sealed, the flange design, the amount of pressure applied to the gasket by the bolts and how the gasket is assembled onto the flanges and tightened. Very basic causes often lead to leakage in bolted joints, and in most cases, it is not just the gasket but also the human element. Users should evaluate all conditions to validate the products are suitable for the intended process.
Specific tools are required for cleaning the flange and tensioning the bolts. Always use standard safety equipment and follow good safety practices. The following tools are required for removal of the old gasket and installation of the new gasket:
Over time, and for any number of reasons, flanges are prone to surface deviations. Damaged areas will tend to create a leak path that the gasket must try to seal.
Flange damage most commonly occurs when removing previously used gasket material from the sealing surface - tools such as chisels, or screw drivers, should be avoided. A brass wire brush is suggested.
The video below proves how well GORE® Gasket Tape Series 500 works on flanges with surface deviations versus a standard filled PTFE gasket.
[embed]https://www.youtube.com/watch?v=nwuxtiFbxH0[/embed]
A spool of GORE® Gasket Tape Series 500 provides an immediate, cost-effective solution to sealing challenges that demand reliable performance and extended durability. This advanced product, with its industry-leading creep resistance, is designed to maximize the operational reliability of large steel-flanged applications, especially those with thermal cycling.
It eliminates the lag time, costs and complexities associated with engineering, specifying, procuring, shipping, storing and installing traditional one-piece prefabricated gaskets. It also delivers exceptionally reliable sealing performance, while making multiple gasketing installations faster, more cost-effective and simpler.