To analyze previously the working conditions to which the flanges will be subjected, their materials and certifications, are the steps to follow.

Flanges (in English flanges) are elements that serve to assemble or join the parts of a pipe line (valves, pipes, pumps or any other type of accessory that is part of the line).

These elements may come as a part attached to an element - such as a valve, a pump or another part - or separately. There are a variety of designs, materials, and flange dimensions. As an example, you can mention: welding neck (with butt weld neck), slip-on (slide to weld), blind (blind), lap-joint (overlap), orifice (hole or restriction), backing (backup), threaded (with wire), weld socket (for welding inlay), reducing (reduction).

Regarding the standards for flanges, there are those published by institutions such as: ASTM (based on materials and manufacturing), ASME / ANSI (focuses on measures, working pressures and tolerances), MSS (focus on measures), API (to apply in the oil industry), AWWA (for lines of drinking water pipes), DIN (German standards that focus on dimensions, materials and manufacturing). The most popular in the region are ASTM and ASME / ANSI and to a lesser extent DIN standards.

It should be clarified that when talking about the nominal design pressure of a flange, the word CLASS is used. According to ASME / ANSI standards, the classes that exist are: 150, 300, 600, 900, 1500 and 2500 psi and according to DIN standards there are: PN 6, PN 10, PN 16, PN 25, PN 40, PN 64, PN 100, PN 250, PN 400 bar (ND is sometimes used by the word NENNDRUCK, which means nominal pressure, instead of using PN).

Three types of flanges are those that are manufactured:

Forged flanges: are manufactured based on ASTM A 182 (Alloy Steel Flanges, stainless steels), ASTM A105 (carbon steel), ASTM A350 (carbon steel and low temperature alloy steels), ASTM A694 (carbon steel and alloy steels for transmission lines), ASTM A707 (Carbon steel and alloy steels for low temperature pipelines), ASTM B564 (alloy 400, alloy 600, alloy 625) and others according to the specific material.

Cast flanges: manufactured according to ASTM A351 (austenitic stainless steels and duplex steels), ASTM A352 (ferritic and martensitic Alloy steel pipe fittings) and others.

Mechanized flanges (blind only): they are manufactured from plates according to ASTM A36 (carbon steel), ASTM A240 (austenitic, ferritic, martensitic and duplex stainless steels) and others.

stainless steel flanges manufacturer

Types of flange steels

When choosing the material, the working conditions to which the flanges will be subjected must be previously analyzed

• If what is needed is a flange that works for normal services at moderate temperatures and where corrosion resistance is not an important factor, then Carbon steel flanges will be used.


• On the other hand, if the service conditions that the flange must withstand are very severe, and the pressure and / or temperature vary within very high values, then special or alloy steels should be used.