A flange is a mechanism by which tubing, valves, pumps and other machinery are linked to create a piping structure. It also makes washing, review or alteration easy to access. Flanges are usually welded or bolted together. Pipe flanges are constructed of all kinds of materials, such as stainless steel, cast iron, copper, silver, bronze, rubber, etc., but the most commonly used type is carbon steel manufactured and machined surfaces. Flanges are available in various sizes and dimensions. During the choosing of the pipe the design of a flange is basically set, in most situations a flange is of the same type as the plug of Pipe. The Flanges are used in various piping systems depending upon the material and environment of applications. For example, for application in highly corrosive environments, Stainless steel 304 and 316 are recommended. The Selection process of the Flanges is altogether a different topic.
How to Choose the Right Flanges?
Choosing the right Flanges depends majorly on the diameter and size of the piping systems. It is also important to note whether the Pipes are seamless or welded. The Flanges are available in various specifications and designs which can be customized according to the requirements of the customers.
A wide range of grades and types are available for Stainless Steel Flanges. The Flanges are decided on the requirements and the budget of the customers. The highly durable flanges are generally found out to be the most expensive ones. Stainless Steel 304 and Stainless Steel 316 Flanges are most versatile and common flanges found across the industry. They offer high resistivity against corrosion and are capable enough to resist most of the chemicals. The Flanges that are used should be basically capable of withstanding the stress and pressure of the piping systems in all the required temperatures.
Standard types of Flanges
Weld Neck Flanges
SS 304 Weld Neck flanges are flanges which can be welded to the pipe ends. They are made with an elongated neck which can be welded to the pipe. They are connected by single full penetration of the V-shaped butt weld.
The Weld Neck Flanges are used in high pressure applications. These are also used in low temperature applications where the fluid movement in the piping system needs no hole. The Welded neck helps in eliminating the pressure and prevent any types of turbulence or corrosion of the metal.
Slip On Flange
Two Fillet welds are used to connect the SS 310 Slip-on Flanges to the Piping systems. The two fillet weld are performed on both, inner and outer sides of the flange cavity. Also known as Hubbed flanges, the slip-on flanges are very slim and compact in size.
The width of the pipe that passes through the flange is tend to be smaller than the width of the Bore of the Slip-on flange. This enables the pipe to be fastened with the help of a filet weld.
SS 316 Threaded flanges are linked by screwing the wire onto the flange, without surface welding. Threaded flanges are also a mandatory requirement in hazardous locations, such as gas stations and mines, since it would be unsafe to conduct welded links in such conditions.
Threaded flanges are available in sizes up to 4 inches and various pressure levels, but are primarily used in low-pressure and low-temperature applications such as water and air utilities.
Lap Joint Flange
SS 321 Lap joint flanges resemble slip-on flanges in shape with the exception of the radius at the flange face crossing and the bore to accommodate the flanged part of the stub end.
The use of lap joint flanges in conjunction with stub ends is a cost-effective solution for stainless steel or nickel alloy pipes, as the lap joint flange content may be of a lower grade (usually carbon steel) than the stub end material.
SS 904 Blind flanges do not have a middle opening, and are used to blind or close a tube, a valve / pressure vessel and obstruct the fluid flow, as compared to all the flange forms seen above. Blind flanges enable easy access to the pipeline, as they can be easily unbound to allow the operator to carry out activities inside the pipe terminal.
Blind flanges have to endure tremendous mechanical stress because of the weight of the framework and the bolting forces needed.