Conoscere i tipi di superfici flangiate: RF, FF, RTJ e quando utilizzarli

Introduzione

The flange face type is one of the most critical design considerations in piping systems. Choosing the wrong face type can lead to leaks, premature gasket failure, and costly maintenance. This guide explains the main flange face types and their optimal applications.

Faccia rialzata (RF)

Characteristics

Raised Face flanges have a raised ring around the bore that concentrates gasket pressure for better sealing. The raised height varies by pressure class:

• Class 150 & 300: 1.6mm (1/16″) raised face
• Class 600 and above: 6.4mm (1/4″) raised face

Applicazioni

• Most common in oil & gas industry
• Suitable for temperatures from -20°C to 400°C
• Works with spiral wound, graphite, and non-asbestos gaskets
• Pressure ratings up to Class 2500

Faccia piana (FF)

Characteristics

Flat Face flanges have a completely flat sealing surface with no raised portion. The gasket covers the entire face.

Applicazioni

• Cast iron and brittle material flanges
• Low pressure applications (Class 125 & 250)
• Prevents bending stress on brittle materials
• Common in water treatment and HVAC systems

Giunto ad anello (RTJ)

Characteristics

RTJ flanges use a metal ring gasket that sits in a machined groove. When bolted, the ring deforms to create a metal-to-metal seal.

Applicazioni

• High-pressure systems (Class 600 to 2500)
• High-temperature applications up to 800°C
• Offshore platforms and subsea pipelines
• Refineries and petrochemical plants

Other Face Types

Maschio e femmina (T&G)

Provides excellent gasket alignment and compression. Used in pump housings and valve bonnets.

Maschio e femmina (M&F)

Self-aligning design with good gasket retention. Common in heat exchangers.

Selection Guide

Application	Recommended Face Type
General oil & gas	Faccia rialzata (RF)
High pressure (>600#)	RTJ or RF
Cast iron piping	Faccia piana (FF)
Offshore/subsea	RTJ
Water systems	Faccia piana (FF)

Conclusione

Understanding flange face types ensures proper sealing and system integrity. Always consult with your flange manufacturer to confirm the best choice for your specific application.

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