UPVC HP Blind Flange

What Is a Blind Flange?

A blind flange is a solid, unpierced disc used to seal the end of a pipe, vessel nozzle, or valve opening. Unlike standard flanges, it has no bore, making it ideal for permanently or temporarily blanking off pipeline sections, isolating system segments during maintenance, or capping unused nozzles. The UPVC HP Blind Flange is engineered specifically for high-pressure thermoplastic piping systems where chemical compatibility and structural integrity are paramount.

Material Properties: UPVC and CPVC

Unplasticised Polyvinyl Chloride (UPVC) and Chlorinated Polyvinyl Chloride (CPVC) are high-performance thermoplastic materials widely used in industrial piping. Key material characteristics include:

• Excellent chemical resistance to acids, alkalis, salts, and many organic solvents
• Good UV resistance, suitable for outdoor and exposed installations
• High pressure ratings up to 16 bar (PN16) depending on size and temperature
• Lightweight compared to metallic alternatives, reducing installation load and cost
• Non-corrosive and non-conductive, eliminating galvanic corrosion concerns

CPVC variants extend the usable temperature range beyond standard UPVC, making them suitable for hot process lines up to approximately 90 °C.

Typical Applications

The UPVC HP Blind Flange is suited to a broad range of industrial and municipal applications:

• Chemical dosing systems — isolating dosing points and capping unused injection nozzles
• Water treatment plants — blanking off filter housings, membrane vessels, and distribution headers
• Industrial process piping — sealing pipe ends during pressure testing or system commissioning
• Swimming pool and aquaculture systems — corrosion-free termination of chlorinated water lines

Installation Notes

Blind flanges should be installed with a full-face gasket (typically EPDM or PTFE) to ensure a leak-free seal. Bolts must be tightened in a cross-pattern sequence to distribute clamping force evenly across the flange face. Over-torquing must be avoided, as excessive bolt load can crack thermoplastic flanges — always refer to the manufacturer's recommended torque values for the specific size and material grade. Ensure mating flange faces are clean, flat, and free of burrs before assembly.

Compliance and Standards

UPVC HP Blind Flanges are manufactured to internationally recognised standards, ensuring dimensional compatibility with existing piping infrastructure:

• ANSI/ASME B16.5 — American National Standard for pipe flanges and flanged fittings
• DIN 2501 / EN 1092-1 — European standard for flanges and their joints
• ISO 15493 — Plastics piping systems for industrial applications (ABS, PVC-U, PVC-C)

Compliance with these standards ensures that the blind flange integrates seamlessly with ANSI- or DIN-drilled mating flanges, reducing the need for adapters or custom machining.