Butterfly Valves

Frequently Asked Questions

Concentric, double-offset, or triple-offset — how do I decide?

Concentric (rubber-lined): water, HVAC, fire service, low-pressure non-critical chemical service. Cheapest option, adequate when temperature stays below ~120°C and pressure below ~10 bar. Double-offset (high-performance or eccentric): general process service where seat life and pressure-temperature performance matter. Good up to ~ASME 300 and 200°C. Triple-offset (TOV): high-pressure, high-temperature, steam, hydrocarbon, emergency shutdown — anywhere you'd otherwise specify a gate or ball valve and want weight/cost savings. TOV can match gate-valve shutoff at ASME 600 class.

Wafer vs lug vs double-flange — what's the difference?

Wafer: no flanges on the valve — compressed between two pipe flanges using long bolts. Cheapest, most common for general service, but requires both pipe flanges to support weight and allows no downstream piping removal without shutting the line. Lug: threaded bolt-holes in the valve body accept stud bolts from each flange independently — allows downstream piping removal while the valve holds pressure (dead-end service, maintenance isolation). Double-flange: integral flanges on the valve body, most robust, specified for large sizes (typically 12"+) and higher pressure classes where wafer/lug construction isn't practical.

When do I need a triple-offset butterfly instead of a ball or gate valve?

Weight and cost. A 30" ASME 300 gate valve is a 3+ tonne installation. An equivalent 30" TOV is typically 500–800 kg and 40–60% cheaper, with equivalent shutoff performance when correctly specified. For sizes 10" and above in hydrocarbon, steam, or high-pressure process service, TOV is often the preferred choice. Below 6", the economics reverse and ball or gate valves are usually cheaper.

Are butterfly valves suitable for throttling and modulation?

Concentric and double-offset butterflies have reasonable modulating characteristics between ~25% and ~75% open — outside that range the flow characteristic is nonlinear and control becomes unstable. For dedicated modulating control-valve service, a characterised-trim control valve (often globe-style) is preferred. Butterflies are specified as throttling valves for HVAC, large-bore flow balancing, and cooling-water applications where fine control is not critical.

What's the MOQ for large-bore butterfly valves?

Large butterflies (24"+) are often supplied on a per-unit basis — MOQ can be 1 piece, especially for project-specific sizes and pressure classes. Standard sizes (4"–12") in wafer or lug carbon steel or SS316: typical MOQ 10–20 pieces per size. For HVAC and water service, bulk-order MOQs can reach 50–200 pieces at attractive pricing.

Can I specify butterfly valves for potable water service?

Yes. Concentric butterflies with WRAS-approved EPDM liner are a standard product — specify WRAS and we match to a qualified manufacturer. For the EU, similar approvals include ACS (France), KTW (Germany), and DVGW. For the GCC and Gulf potable-water projects, SASO/SABER approval for drinking-water contact is coordinated alongside the certification package.