Comparison sheet · the quarter-turn pair
Ball valve vs butterfly valve.
Both close in a quarter turn. What separates them is what stays in the flow — and what the installed metre of pipe costs.
For large-diameter, weight-sensitive or economical isolation a butterfly valve usually wins; for tight shutoff, pigging and higher pressure classes a ball valve does. A butterfly disc stays in the flow path, so some pressure drop is permanent; a full-bore ball passes flow unobstructed. This page compares body patterns, shutoff, torque, installed cost and where Malaysian services typically use each.
The one-line rule
Where shutoff is the point, price the ball valve; where the diameter is the point, price the butterfly valve. Both patterns swing shut in a single quarter turn, both actuate simply, and on small utility lines either will do the job — which is why the decision is usually settled by the two ends of the duty range. High pressure classes, pigged lines and bubble-tight isolation pull the selection towards the ball; large bores, cooling water, tank farms and weight-limited structures pull it towards the butterfly. This sheet walks the reasoning, then puts it in one table.
Bore and flow path compared
Open a full-bore ball valve and the fluid cannot tell it is there: the port through the sphere lines up with the pipe, giving the lowest resistance of any common pattern and a passage that scrapers and pigs traverse — one reason pipeline and product-transfer duty specifies it. The butterfly cannot make that offer. Its disc pivots on a stem through the middle of the bore, so even fully open the disc edge sits in the stream and a permanent pressure loss comes with it — modest, but never zero. Reduced-bore balls split the difference: a smaller port trims weight and cost while keeping the seat geometry, and the enquiry should say which bore is meant.
Shutoff and seat design
The ball closes against seats that wrap the port — soft-seated designs seal bubble-tight, and trunnion-mounted patterns hold that seal at high differential pressure; the choice between trunnion and floating mounting is its own memo. The butterfly seals along the rim of its disc: resilient-lined bodies grip the disc edge in an elastomer and shut off tightly at moderate conditions, while high-performance offset designs carry the pattern into hotter, higher-class service. Fire-safe and soft-versus-metal seat questions apply to both families, and where a specification names a fire-test standard the enquiry should repeat it — see the fire-safe memo.
Weight, footprint and installed cost
Put both patterns at the same nominal size on a bench and the argument makes itself: the ball is a solid body with a machined sphere inside it, the butterfly is little more than a ring, a disc and a stem. As diameter grows, the gap grows faster — the sphere’s mass climbs steeply while the wafer or lug butterfly body stays a slim disc-holder that bolts between existing flanges; the body styles are compared in their own memo. Weight is also structure: on racks, on tank tops and offshore — where every kilogram is designed for — the lighter valve saves steel around itself. That is why economical large-bore isolation defaults to the butterfly unless a harder duty overrules it.
Torque and actuation
A quarter turn is easy to automate, which is why both patterns dominate actuated isolation. Small sizes take a lever; larger sizes take a gearbox or an actuator, and the mounting pad is standardised so the enquiry only needs to say which operator is wanted. Seating torque behaves differently between the two: the ball’s torque rises with the friction of its seats under pressure, while the resilient-seated butterfly works against its liner’s grip and dynamic loads on the disc. Actuator sizing therefore belongs to the manufacturer’s torque data for the exact valve, trim and differential pressure — state the service conditions on the enquiry and let the data answer, rather than carrying a figure across from a different line.
The comparison table
Seven lines, qualitative on purpose — size, class and seat material move every number, so the numbers belong on the quotation.
Full comparison — scroll →
| Factor | Ball valve | Butterfly valve |
|---|---|---|
| Geometry | Bored sphere between wrapped seats | Disc pivoting on a stem in the bore |
| Flow path | Straight through — full bore piggable | Disc stays in the stream when open |
| Shutoff | Bubble-tight, holds high differential | Tight in resilient designs at moderate duty |
| Weight & footprint | Heavy — grows steeply with size | Light — slim wafer or lug body |
| Torque & actuation | Seat friction sets the torque | Liner grip and disc loads set it |
| Typical duty | Pigged, pressured, tight-shutoff lines | Large-bore water, terminal and utility duty |
| Relative cost basis | Higher — rises fast with diameter | Lower, especially at large bore |
Qualitative comparison for pattern selection only — ratings, torques and seat limits come from the governing standards and the manufacturer’s data for the valve quoted. Confirm against the current edition; your purchase order governs.
Which to enquire for
State the duty and the bore honestly and the pattern usually declares itself — and where it genuinely could go either way, ask for both prices on the same quotation and let the installed cost decide. Either way the enquiry states the same six things: size, pressure class, end connection, body and seat material, operator, and the tests and certificates required — the full checklist is on specifying industrial valves. NF Teguh quotes both patterns across power plant, petrochemical, oil and gas, terminal, offshore and natural gas service; the route from list to delivery is on how ordering works, and the counter answers by phone, email or WhatsApp.