A projecting rim, collar, or ring on a structural member, pipe, or fitting that provides connection points, structural support, or sealing surfaces.

A flange is a projecting rim, collar, or ring on a structural member, pipe, fitting, or other building component that serves multiple functions including providing connection points for joining elements together, creating structural support and load distribution, establishing sealing surfaces for pressure-tight connections, and facilitating assembly and disassembly of building systems. Flanges are fundamental components in construction, mechanical systems, and structural engineering, appearing in applications ranging from steel beam connections and pipe joints to HVAC ductwork and plumbing systems. The design and configuration of flanges vary significantly based on their intended application, load requirements, environmental conditions, and connection methods, making them versatile and essential elements in modern construction and building systems.

The primary purposes of flanges include providing mechanical connection points between structural members, pipes, or equipment, distributing loads over larger areas to reduce stress concentrations, creating sealing surfaces for pressure vessels, piping systems, and ductwork, facilitating assembly and maintenance access for building systems, enabling standardized connections between different manufacturers’ components, providing mounting surfaces for equipment, valves, and accessories, and allowing for thermal expansion and contraction in piping and structural systems.

Types of flanges vary significantly based on their application and design requirements, including structural flanges found on steel beams, columns, and other building members, pipe flanges used to connect sections of piping in plumbing, HVAC, and industrial systems, equipment flanges that provide mounting and connection points for mechanical equipment, duct flanges used in HVAC systems for connecting ductwork sections, specialty flanges designed for specific applications such as fire sprinkler systems or process piping, and custom flanges fabricated for unique connection requirements in construction projects.

Fun Fact: The word “flange” comes from the French word “flanche,” meaning “flank” or “side.” The first standardized pipe flanges were developed in the 1920s by the American petroleum industry to ensure compatibility between different manufacturers’ equipment.

• Z-Flange (used in metal building systems)