Valves and Valve Equipment

Full Bore 3-Piece Ball Valve: Flow Control with Minimum Pressure Loss

Explore flanged, ductile iron full bore 3-piece ball valves, whose bore equals the pipe bore for very low pressure loss.

ORFA Technical TeamUpdated: Oct 30, 20263 min read

In industrial installations, the resistance a valve creates against flow is a direct cost in pump energy and system efficiency. A full bore 3-piece ball valve barely restricts the flow because the ball bore equals the pipe bore, creating a pressure loss close to that of an equal length of straight pipe.

The three-piece body also makes maintenance and seal replacement easier. This article covers the operating principle, features and applications of flanged, ductile iron full bore 3-piece ball valves.

What Is a Full Bore 3-Piece Ball Valve?

In a ball valve the closing element is a ball with a hole through its centre. When the ball is turned 90° by a lever or actuator, the bore lines up with the flow and the valve is fully open; when the bore is perpendicular to the flow, the valve is fully closed.

Full bore: The ball bore equals the nominal pipe/valve size. Flow is not restricted, pressure loss is minimal and the line can be pigged.
Three-piece: The body consists of a centre body and two end pieces. As the parts are bolted together, the ball and seat seals are easy to access.

Ball valves are designed for on-off (fully open / fully closed) service; using them for long periods in a partly open position to throttle flow can wear the seats.

Advantages

Low pressure loss: The full bore design gives a pressure loss close to straight pipe of the same size and reduces pumping energy.
Fast opening and closing: A 90° (quarter-turn) movement opens or shuts the flow quickly.
Easy operation: Low operating torque makes it easy to open and close.
Good sealing: Ball and stem sealing are provided in two stages.
Easy maintenance: The three-piece design allows the ball and seals to be inspected and replaced easily.
Actuator compatibility: The ISO 5211 top flange allows pneumatic or electric actuators to be fitted for automation.

Technical Specifications

Feature	Value
Body material	GGG40.3 (EN-GJS-400-18-LT) ductile iron
Connection	Flanged
Nominal size	DN15 (1/2″) – DN200 (8″)
Maximum pressure	16 bar
Temperature range	-10 °C to +180 °C depending on seals and materials
Top flange	ISO 5211 (for actuator mounting)

Tip: Maximum pressure and maximum temperature may not apply at the same time. The allowable working pressure falls at higher temperatures; check the manufacturer’s pressure-temperature chart when selecting.

Applications

Heating and cooling lines
Water, steam and utility lines in food plants
Shipbuilding and shipyard applications
Paper mills
General industrial water, air and oil lines

Installation and Maintenance Recommendations

Clean the pipeline before installation and remove welding slag and particles, which can damage the ball and seats.
Tighten flange bolts in a crosswise sequence with even torque.
Keep the valve fully open during installation and pressure testing.
If an actuator is to be fitted, size it according to the valve’s operating torque with a safety margin.

Frequently Asked Questions

What is the difference between full bore and reduced bore ball valves?

In a full bore valve the ball bore equals the pipe size and pressure loss is minimal. In a reduced bore valve the bore is one size smaller; it is more compact and economical but causes more pressure loss.

What is the advantage of the three-piece design?

Because the body consists of three bolted parts, the ball and seals are easy to reach; maintenance and seal replacement are more practical than with one-piece valves.

Can an actuator be fitted to this valve?

Yes. Its ISO 5211 top flange allows pneumatic or electric actuators to be mounted.

Conclusion

With low pressure loss, fast quarter-turn operation, easy maintenance and actuator compatibility, full bore 3-piece ball valves are an efficient and reliable shut-off solution for industrial installations. Explore other materials and connection options on our Ball Valves page.

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