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Non-metallic flange gaskets are made from stuff like asbestos rubber, PTFE, rubber, and flexible graphite. These materials are super bendy, bounce back well, and don’t cost a ton. They work great in chill, low-pressure spots—think under 200°C and below 10 MPa. They’re perfect for water lines, steam systems, or chemical pipes with mildly harsh stuff. PTFE gaskets, especially, handle strong acids and bases like champs, making them rad for pharmaceutical or food processing gigs.
In hot or high-pressure setups, they might creep or bust over time, losing their sealing mojo.
Semi-metallic gaskets mix non-metallic fillers like graphite or PTFE with metal bits like stainless steel or carbon steel. This combo brings bendy vibes and tough strength.
Common types include:
· Metal-clad gaskets: A thin metal layer wraps a soft core, great for moderate pressure swings.
· Spiral-wound gaskets: Metal strips and filler wound in a spiral give awesome self-tightening and pressure resistance.
These gaskets shine up to 500°C and 25 MPa with low bolt force needed.
Metallic gaskets are all-metal, using annealed carbon steel, stainless steel (304/316), or fancy alloys like Monel. They handle wicked high temps (over 800°C) and pressures (above 40 MPa).
They’re used in:
· Extreme spots like nuclear reactors or refinery cracking units.
· Systems with frequent startups or pressure pulses.
But they need super smooth flange surfaces for tight sealing due to their stiff build. Installation costs are pricier too.
Graphite gaskets are champs at handling chemicals like acids, alkalis, and organic solvents. They stay steady up to 800°C. They’re ideal for harsh, hot media like sulfuric acid or chlorine gas. Add-ons like resin binders or metal reinforcements boost their strength and toughness.
These have a sturdy metal shell (like SS304) around a sealing core like graphite or PTFE. They handle pressure swings well in valve or pump connections. For example, a chemical plant cut flange leaks from 2.3% to 0.5% after switching to metal-clad gaskets on reactor vessels.
Spiral-wound gaskets come in a few flavors:
· Basic type (C): For smooth flange surfaces.
· Reinforced type (R): Rocks under pressures above 25 MPa or big temp shifts.
They need grooved or raised face flanges to avoid slipping on smooth surfaces.
PTFE stays bendy at crazy low temps like -196°C but caps at about 200°C. It’s great for cryogenic stuff like liquid nitrogen systems. For outdoor use, metal reinforcement or UV-resistant versions help fight UV damage.
Asbestos fibers are risky, so these gaskets are mostly replaced by safer options like graphite composites or ceramic fiber materials. They’re now used only in low-risk cases.
Picking a gasket means checking the media (corrosive or neutral), temp range, system pressure, and flange face design (flat, grooved, male-female, or ring-joint). Pre-treatment steps include:
· Cleaning flange faces with acetone or industrial degreasers.
· Checking gasket condition—skip ones with damaged edges or delamination. Metallic types need hardness testing.
Installation steps are:
· Center the gasket right on the flange surface.
· Tighten bolts evenly in a cross-pattern. Use maker-recommended torque—like 250–300 N·m for DN200 flanges.
· Run a pressure test at 1.5 times operating pressure for 30 minutes, no leaks allowed.
Common problems include:
· Intermittent leaks: Often from bolt loosening due to temp swings. Try semi-metallic gaskets.
· Persistent seepage: Shows aging gasket material or damaged flange surfaces. Swap the gasket and fix the flange if needed.
In harsh settings, tools like infrared thermography spot issues early. High-temp systems should swap gaskets every 3–5 years based on use logs.
Since 1994, FLUIDO has been a top player in flanges, offering a wide range of pipe fittings like forged flanges for trusty performance in oil & gas, power generation, water treatment, and more.
FLUIDO’s factories are ISO9001 certified with strict quality checks. Products meet global standards, including CE-certified valves and SGS-audited systems.
With years of casting and forging know-how, plus one-stop sourcing in Shandong and Hebei, FLUIDO delivers custom flange gasket solutions. Reach out at info@fluidovalve.com for help picking the perfect flange gasket for safety, efficiency, and compliance in piping systems.
