Flange Gasket Selection Guide for Industrial Piping

Why Gasket Selection Matters

Gaskets provide the seal between flange faces and are critical to leak prevention and safety. The gasket type must match the flange facing, pressure class, temperature, and media. A gasket that is too soft may extrude under high pressure, while a gasket that is too hard may not seat properly on low pressure services. Spiral wound gaskets are common for raised face flanges, ring joint gaskets are used for RTJ flanges in high pressure service, and sheet gaskets are used for flat face or low pressure connections. Proper selection reduces maintenance, prevents fugitive emissions, and improves reliability.

Gasket Type Comparison

Facing Compatibility

Facing style determines which gasket can be used. Raised face (RF) flanges use gaskets that sit inside the raised face area; spiral wound gaskets are the standard choice for many industrial services. Ring type joint (RTJ) flanges require metallic ring gaskets that seat in a machined groove and provide high integrity under high pressure. Flat face (FF) flanges require full-face gaskets to avoid bending the flange. Mixing the wrong gasket with a face can result in leakage or flange damage. Procurement should specify facing type and gasket type together, and confirm gasket standards such as ASME B16.20 for metallic gaskets.

Pressure, Temperature, and Media

Gasket materials must withstand the maximum pressure and temperature while resisting the process media. Spiral wound gaskets with graphite or PTFE fillers handle higher temperatures and provide good resilience. Ring joint gaskets are typically used for high pressure and high temperature pipelines where seating stress is high. Sheet gaskets are used for lower pressure systems but may be limited by temperature or chemical compatibility. For aggressive chemicals, PTFE or expanded PTFE gaskets are common. Buyers should confirm the gasket material is compatible with the fluid and that the pressure class and facing match the flange specification.

Installation and Bolting

Even the correct gasket can fail if bolting and installation are poor. Proper bolt material, lubrication, and tightening sequence are essential to achieve uniform gasket compression. Over-tightening can crush soft gaskets, while under-tightening leads to leakage. For critical systems, follow a controlled torque procedure or use tensioning to achieve uniform load. Flange faces should be clean and free of damage, and gasket storage should prevent contamination. Procurement should specify bolting grades and request installation guidance when gaskets are supplied with valves or flanged equipment.

Procurement Checklist

Define flange facing type, pressure class, temperature, and media, then select a gasket type and material accordingly. Specify gasket standard, size, and whether inner or outer rings are required for spiral wound gaskets. Confirm bolt material and torque procedure. For critical service, request gasket certificates and traceability. When mixing standards or suppliers, verify gasket dimensions and facing finish requirements. A clear gasket specification reduces leakage risk and avoids last-minute field substitutions.