Flat flanges (PL): Suitable for low pressures, welded to the pipe and cost-effective.
Welding neck flanges (WN): Provide high strength, ideal for high-pressure and high-temperature applications thanks to welding on the pipe neck.
Socket weld flanges (SW): The pipe is inserted into the flange before welding, offering good strength and easy assembly.
Threaded flanges (TH): Screwed onto the pipe, suitable for non-critical applications.
Blind flanges (BL): Close the ends of pipes or valves, creating a tight seal.
Face type: flat face (FF), raised face (RF), male-female (MF), ring type joint (RTJ).
Pressure rating: indicates the maximum pressure that can be withstood.
Material: carbon steel, stainless steel, special alloys.
Dimensions: diameter, thickness, hole diameter.
Chemical and petrochemical industry: for the transport of fluids and gases.
Heating and cooling systems: for the transport of water and steam.
Food and pharmaceutical industry: for the transport of liquids and sensitive products.
Power plants: for the transport of fluids at high pressure and temperature.
A spool is the portion of pipe between two flanges.
Type of fluid: the flange material must be compatible with the transported fluid to avoid corrosion.
Pressure and temperature: the flange must be able to withstand operating conditions.
Application: the type of flange must be suitable for the specific application.
Reference standards: flanges must comply with international or national standards (ANSI, DIN, UNI, EN, JIS).
AISI 316 steel contains molybdenum, which makes it more resistant to corrosion than AISI 304 steel, making it preferable in chemical, petrochemical, food and pharmaceutical environments.
(RF): It is the most commonly used flange face type. It is called “raised” because the raised surface of this flange is positioned above the bolt circle where the gasket is located.
The main difference between ANSI and EN flanges lies in dimensions, pressure classification and country of origin. ANSI flanges are standardized in the United States, while EN flanges are standardized in Europe. In addition, ANSI uses inches and psi for dimensions and pressures, while EN uses millimeters and bar.
Flanges with schedule 40 have a greater thickness than those with schedule STD, for the same nominal diameter.
Micro-casting is suitable for complex shapes and can be more economical for small production batches or flanges with particular shapes, but it is not ideal for applications requiring high pressure resistance and tight sealing, as the presence of inclusions may compromise structural integrity. Forging, especially hot forging, produces a more compact and homogeneous metal structure without inclusions, resulting in greater strength and sealing performance. It is therefore the preferred choice for flanges operating under high pressure, high temperatures and where perfect tightness is required.