Flange connections in piping, machinery, and pressure vessels contain fluids and gases under load. A compromised seal can mean production loss, safety exposure, and environmental release. Knowing the range of flange sealing methods, and where each fits, is essential for building leak-free systems. From Gaskets to Formed-in-Place Sealants Gaskets have long been the default: a deformable material compressed between mating surfaces to fill irregularities. Rising demands on pressure, temperature, and reliability have added specialized options alongside them. Traditional Gaskets Gaskets are physical barriers between flange faces. Their performance depends on material, design, and correct bolt load. Non-Metallic (Soft) Gaskets Made from rubber such as EPDM or nitrile, compressed non-asbestos fiber, PTFE, or graphite. They are compressible and conform to uneven surfaces, and suit lower pressure and temperature service. Full-face types cover the whole flange including bolt holes; ring types fit inside the bolt circle. Their main limitation is creep and relaxation over time, which loses bolt load and allows leaks. Semi-Metallic (Composite) Gaskets A combination of metal and soft filler, such as spiral-wound gaskets with graphite or PTFE filler, or metal-jacketed designs. They offer better resilience and pressure and temperature capability than soft gaskets and are common on steam, oil, and gas lines. They still rely on compression and can be damaged during handling. Metallic (Hard) Gaskets Solid metal, such as ring type joint gaskets with oval or octagonal sections. They seal by deforming into machined grooves and serve very high pressure and temperature service in oil, gas, and petrochemical plants. They require precise flange machining and are less forgiving of misalignment. Liquid Gasketing (Formed-in-Place Sealants) Liquid or semi-liquid materials that cure in place, filling the joint completely. Anaerobic Flange Sealants Single-component liquids that cure rapidly when confined between close-fitting metal surfaces without air. They give full surface contact and close microscopic leak paths, do not shrink or relax, resist fretting and galvanic corrosion, and can add shear strength to the joint. They suit rigid metal-to-metal flanges on gearboxes, pumps, compressors, engine sumps, and hydraulic systems, with gaps typically up to 0.5 mm. RTV Silicone Sealants Single or two-component systems that cure with atmospheric moisture or a catalyst to a flexible elastomer. They accommodate movement and thermal expansion, adhere to many substrates including some plastics, and offer good temperature resistance. They suit flexible or stamped flanges, larger gaps, and joints needing a conformable seal, such as valve covers and enclosures. Pressure resistance is generally lower than anaerobics. Selecting among these methods is a matching exercise between joint design and service conditions. Email Us to review your flange type, gap, and operating envelope with Incure's technical team. Choosing a Method Weigh these factors together: Operating conditions: pressure, temperature range, and chemical exposure. Flange type and material: rigid machined metal favors anaerobics; flexible or stamped flanges favor RTV silicones or gaskets. Gap tolerance: the measured gap dictates which sealant can cure and seal reliably. Disassembly needs: how often the joint must be opened, and how easily. Cost and efficiency: material, labor, inventory,…