Basic of Flanges and Flange type..

Flange

                            A flange is a method of connecting pipes, valves, pumps and other equipment to form a piping  system. It also provides easy access for cleaning, inspection or modification. Flanges are usually welded or screwed. Flanged joints are made by bolting together two flanges with a gasket between them to provide a seal.

Types of Flanges:

The most used flange types :

• Welding Neck Flange
• Slip On Flange
• Socket Weld Flange
• Lap Joint Flange
• Threaded Flange
• Blind Flange

Special Flanges

Except the most used standard flanges, there are still a number of special flanges such as:

• Orifice Flanges
• Long Welding Neck Flanges
• Weldo flange / Nipo flange
• Expander Flange
• Reducing Flange

 

Materials for Flanges

                                 Pipe flanges are manufactured in all the different materials like stainless steel, cast iron, aluminum, brass, bronze, plastic etc. 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.

 Flange types

  

Most common flange types

Welding Neck Flange:

                        Welding Neck Flanges are easy to recognize at the long tapered hub, that goes gradually over to the wall thickness from a pipe or fitting.

             The long tapered hub provides an important reinforcement for use in several applications involving high pressure, sub-zero and / or elevated temperatures. The smooth transition from flange thickness to pipe or fitting wall thickness affected by the taper is extremely beneficial, under conditions of repeated bending, caused by line expansion or other variable forces.

                   These flanges are bored to match the inside diameter of the mating pipe or fitting so there will be no restriction of product flow. This prevents turbulence at the joint and reduces erosion. They also provide excellent stress distribution through the tapered hub and are easily radio graphed for flaw detection.

 This flange type will be welded to a pipe or fitting with a single full penetration, V weld .

Details of Welding Neck flange.

Slip On flange

               The calculated strength from a Slip On flange under internal pressure is of the order of two-thirds that of Welding Neck flanges, and their life under fatigue is about one-third that of the latter.

          The connection with the pipe is done with 2 fillet welds, as well at the outside as also at the inside of the flange.

The X measure on the image, are approximately:
Wall thickness of pipe + 3 mm.

    This space is necessary, to do not damage the flange face, during the welding process.

Details of Slip On flange

Socket Weld flange

               Socket Weld flanges were initially developed for use on small-size high pressure piping. Their static strength is equal to Slip On flanges, but their fatigue strength 50% greater than double-welded Slip On flanges.

              The connection with the pipe is done with 1 fillet weld, at the outside of the flange. But before welding, a space must be created between flange or fitting and pipe.

                  The purpose for the bottoming clearance in a Socket Weld is usually to reduce the residual stress at the root of the weld that could occur during solidification of the weld metal. The image shows you the X measure for the expansion gap.

Details of Socket Weld Flange

Lap Joint Flange

               Lap Joint Flanges have all the same common dimensions as any other flange named on this page however it does not have a raised face, they used in conjunction with a "Lap Joint Stub End".

               These flanges are nearly identical to a Slip On flange with the exception of a radius at the intersection of the flange face and the bore to accommodate the flanged portion of the Stub End.

                Their pressure-holding ability is little, if any, better than that of Slip On flanges and the fatigue life for the assembly is only one tenth that of Welding Neck flanges.

                They may be used at all pressures and are available in a full size range. These flanges slip over the pipe, and are not welded or otherwise fastened to it. Bolting pressure is transmitted to the gasket by the pressure of the flange against the back of the pipe lap (Stub End).

Lap Joint flanges have certain special advantages:

• Freedom to swivel around the pipe facilitates the      lining up of opposing flange bolt holes.
• Lack of contact with the fluid in the pipe often permits the use of inexpensive carbon steel flanges with corrosion resistant pipe.
• In systems which erode or corrode quickly, the flanges may be salvaged for re-use.

Details of Lap Joint Flange

Stub End

                 A Stub End always will be used with a Lap Joint flange, as a backing flange.

          This flange connections are applied, in low-pressure and non critical applications, and is a cheap method of flanging.
          In a stainless steel pipe system, for example, a carbon steel flange can be applied, because they are not come in contact with the product in the pipe.

 Lap Joint Flange with a Stub End

Threaded Flange

                     Threaded Flanges are used for special circumstances with their main advantage being that they can be attached to the pipe without welding. Sometimes a seal weld is also used in conjunction with the threaded connection.

                   Although still available in most sizes and pressure ratings, screwed fittings today are used almost exclusively in smaller pipe sizes.

                     A threaded flange or fitting is not suitable for a pipe system with thin wall thickness, because cutting thread on a pipe is not possible. Thus, thicker wall thickness must be chosen...what is thicker ?

Details of Threaded flange

Blind Flange

Blind Flanges are manufactured without a bore and used to blank off the ends of piping, Valves and pressure vessel openings.

From the standpoint of internal pressure and bolt loading, blind flanges, particularly in the larger sizes, are the most highly stressed flange types.

However, most of these stresses are bending types near the center, and since there is no standard inside diameter, these flanges are suitable for higher pressure temperature applications.

Details of Blind flange

SPECIAL TYPES OF FLANGES

Nipoflange

Weldoflange

Elboflange

Swivel ring flanges

Expander flanges

Reducing flanges

If u like this post please like, share and comments. 

Follow Us and Like

youtube.

https://www.youtube.com/channel/UC_jP2k154vrmS9kOfv4j1Cg 

Website.

 https://www.thermalpowertech.com/

Facebook.

https://www.facebook.com/Thermalpowertech/ 

E-Mail.

thermalpowert@gmail.com

Subscribe , Like and follow us get more information.

Thermal Power Tech

Welcome you to online tutorial Thermal Power Tech. This Website create For thermal power plants knowledge. It's a great platform to knowledge who working in thermal power plants. It's very Useful For Boiler operation Engineer(BOE), 1St Class, 2nd Class Attendant, Turbine Engineer, Oilman, Water Chemist and technical students.