ThePipingMart Blog flanges 7 Factors to Consider When Choosing Flanges

7 Factors to Consider When Choosing Flanges

flanges check

For any Flange or any product to perform properly it is fundamental to choose the right flanges for the job. The flange should fit in perfectly into the pipe joints in order to conduct its functions correctly. A minor mistake in selecting a flange may have an effect on an application resulting in an expensive mistake. Let us discuss the factors that are all associated in selecting the right flange for the correct application to ensure maximum usability.


It’s fairly easy to spot the type of flanges by the way it looks. First classify the top of the flange by deciding whether the flange has a welded neck, threaded bore, lap joint, flat face, socket weld, or tongue and groove. Next, the bottoms are identified by evaluating whether they have a flat face, which is completely flat, or a raised face, which is a slightly raised section on the face of the flange.

Types of Flanges


The size of the flange consists of factors that include the standard used (: DIN – Deutsches Institut für Normung / European, ANSI – American National Standards Institute, and JIS – Japanese International Standard), the pressure level needed, and the actual size of the flange. Factors include the inner diameter, the outer diameter, the number of bolt holes, the diameter of the bolt hole and the bolt circle.


Depending on the thickness of the flanges it can be determined how high a pressure it can handle, in any applications thicker flanges can resist higher pressures.

Bolt Holes

Bolt Holes enables to measure the size of the flange and the pressure class. The number of bolt holes, the pitch circle diameter, and the actual size of the bolt holes on the flange are 3 factors that need to be addressed. If the bolt is thicker and stronger it can more pressure.


There are a various standards from which you can choose these flanges. The flanges will be choosed based upon the application and the standard of the product it will be connected to (i.e. valves) 3 main standards used are: DIN – Deutsches Institut für Normung / European, ANSI – American National Standards Institute, and JIS – Japanese International Standard.

Pressure Class

Pressure class signifies the marginal level of pressure under which the flanges can sustain or safely function. Each standard has several levels of pressure available, from low pressure to high pressure tolerance. The pressure level of products to which the flange will be connected should be the same as that of the pipes and valves in the process.


It is the most important to choose the right material for a flange depending upon the application and understanding the elements it will encounter in an application that the piping system is being used. (Pressure, moisture, corrosion, temperature) Common materials include stainless steel, duplex steel, carbon steel, and copper nickel, etc.

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