Titanium heating tubes are widely equipped with titanium flanges for installation in corrosion-resistant reaction tanks, fermentation equipment and chemical circulating systems. The sealing gasket between titanium flanges bears long-term erosion of organic acid, alkali cleaning fluid and salt brine, while also avoiding galvanic corrosion between dissimilar metals. Improper gasket material selection leads to medium leakage, flange surface abrasion and accelerated titanium passive film damage. Gasket selection must combine medium composition, operating temperature, pressure and anti-galvanic isolation requirements to pick the optimal sealing material.
Polytetrafluoroethylene (PTFE / Teflon) gaskets are the universal first choice for most titanium heating tube assemblies. PTFE is chemically inert against nearly all organic acids, weak alkali, chloride brine and food-grade cleaning agents, with a continuous service temperature range from -20℃ to 180℃. Its insulating property completely cuts off conductive metal contact between titanium flanges and external steel supports, fundamentally eliminating galvanic corrosion risks. Solid PTFE flat gaskets suit low-pressure normal temperature fermentation tanks; expanded PTFE soft tape is used for uneven flange sealing surfaces to fill tiny gaps. The only limitation is poor compression rebound under high pressure above 0.6MPa, requiring thicker gasket pads for high-load equipment.
Fluorinated ethylene propylene (FEP) coated rubber composite gaskets apply to medium temperature and moderate pressure working conditions. A silicone rubber elastic inner core provides excellent compression resilience, and the outer FEP film isolates all corrosive media from contacting the rubber layer. Compared with pure PTFE, composite gaskets seal tighter under fluctuating pressure cycles and fit flanges with slight machining flatness errors. They are ideal for CIP alternating acid-base cleaning lines with temperature below 120℃. Avoid long-term exposure to boiling strong alkali, which will gradually degrade the surface fluoropolymer coating layer.
Silicone rubber gaskets are only suitable for clean neutral low-corrosion media. Silicone withstands high temperature up to 200℃ and has outstanding elasticity, but it will swell, soften and crack after long-term immersion in concentrated organic acid or hot alkali. This material is cheap, yet its corrosion resistance cannot meet chemical and fermentation anti-corrosion standards. It can only be temporarily used in pure water heating systems without acid-base cleaning procedures, and must be replaced with fluorine-containing gaskets for formal corrosive process production.
Metal composite gaskets (graphite stainless steel spiral wound) are strictly prohibited for direct contact with titanium flanges. Stainless steel metal strips are conductive and create a potential difference with titanium in ion-containing liquid, triggering severe galvanic corrosion on the titanium flange surface. If high-pressure working conditions require metal reinforced gaskets, a full PTFE inner lining must be added to isolate the titanium flange from all metal parts of the gasket, and insulating PTFE sleeves are required for connecting bolts simultaneously.
Special medium targeted adjustment rules: Media containing trace fluoride must use fully dense PTFE gaskets, as fluororubber (Viton) will degrade rapidly in fluoride environment; high-concentration hot alkali processes choose thick solid PTFE gaskets to resist alkali erosion; food-grade pharmaceutical production must adopt food-certified virgin PTFE without recycled filler additives to prevent medium contamination.
表格
| Gasket Material | Applicable Working Condition | Key Advantage & Hidden Risk |
|---|---|---|
| Solid PTFE flat gasket | Full range organic acid, weak alkali, brine, -20~180℃, low-medium pressure | Complete chemical inertness + insulation to block galvanic corrosion; weak rebound under high pressure |
| FEP coated silicone composite gasket | Alternating acid-base CIP, ≤120℃, fluctuating pressure | Good elastic sealing performance; not resistant to long-term boiling strong alkali |
| Ordinary silicone rubber gasket | Only neutral clean pure water, no acid-base circulation | High temperature resistance and low cost; swelling failure in acid/alkali media |
| Stainless steel spiral wound metal gasket | High pressure industrial pipeline (only with full PTFE lining) | High pressure resistance; direct contact with titanium causes severe galvanic corrosion |
Brief Summary
PTFE gaskets are the most versatile matching sealing material for titanium heating tube flanges, balancing corrosion resistance and electrical isolation to avoid dissimilar metal corrosion. Composite fluoropolymer gaskets are selected for pressure-fluctuating CIP lines, while silicone and bare metal spiral gaskets are limited or forbidden in corrosive media. Matching gasket material to medium, temperature and pressure ensures long-term leak-free operation of titanium flange connections.
