CPVC Van-Stone Flange

Product Overview

The CPVC Van-Stone Flange is a thermoplastic flanging solution designed for demanding industrial piping applications. It consists of a CPVC stub end (the van-stone end) and a separate loose backing ring — typically manufactured from steel or polypropylene — that slides freely over the pipe. This design allows the backing ring to rotate independently, greatly simplifying bolt-hole alignment during assembly and reducing installation time.

Material Properties of CPVC

Chlorinated Polyvinyl Chloride (CPVC) offers a superior combination of chemical resistance and elevated temperature performance compared to standard PVC, making it the material of choice for aggressive fluid handling:

• Excellent resistance to a wide range of acids, bases, salts, and oxidising agents
• Continuous service temperature up to 93 °C (200 °F)
• Inherently flame-retardant and self-extinguishing
• Low thermal conductivity and excellent insulating properties
• Lightweight yet dimensionally stable under pressure and temperature cycling

Van-Stone / Loose Backing Ring Design

The van-stone flange design separates the sealing face from the structural backing ring. The CPVC stub end is solvent-cemented or thermally welded to the pipe, forming a permanent, leak-tight joint. The loose backing ring — which carries the bolt load — remains free to rotate around the stub end collar. Key installation advantages include:

• Rotating backing ring eliminates the need to align bolt holes before welding or cementing
• Only the CPVC face contacts the process fluid, preventing corrosion of the backing ring
• Backing ring can be replaced independently without disturbing the piping system
• Reduced installation time and labour costs compared to fixed-flange alternatives

Compatibility and Standards

CPVC Van-Stone Flanges are manufactured to match both DIN (metric) and ANSI (imperial) bolt circle patterns, ensuring straightforward integration with existing pipework, pumps, valves, and equipment flanges across international projects. Pressure ratings of PN10/PN16 (DIN) and 150 lb (ANSI) are supported.

Available Size Range

The flange is available in nominal pipe sizes from DN25 (1") through DN200 (8"), covering the most common industrial piping diameters. Custom sizes may be available upon request.

Typical Applications

CPVC Van-Stone Flanges are well suited for a broad range of industrial environments where chemical resistance and temperature performance are critical:

• Chemical processing plants handling acids, alkalis, and solvents
• Water and wastewater treatment facilities
• Industrial cooling and process water systems
• Semiconductor and electronics manufacturing (ultrapure water lines)
• Pharmaceutical and food-grade piping where corrosion-free materials are required
• Mining and mineral processing with aggressive slurries or leach solutions