In the world of industrial valves, ball valves—commonly known as ball plugs—hold an indispensable position. Utilized across countless sectors (chemical, energy, petrochemical, food processing, pharmaceutical, etc.), they are renowned for their ease of use, robustness, and ability to ensure reliable sealing, even under demanding conditions.

But how exactly do they work? What are their different versions, materials, possible connections? And most importantly, how do you choose the model best suited to your process?

This comprehensive guide provides the keys to understanding and selecting the right ball valve for your installations.

What is a ball valve?

A ball valve (BV) is part of the quarter-turn valve family: a simple 90° movement is enough to completely open or close the passage.

Behind this simple mechanism lies an ingenious design: a pierced sphere with an orifice allows or blocks fluid flow. This design makes it a device that is:

• reliable,

• easy to operate,

• compact,

• and suitable for many industrial fluids.

Materials Used: Mechanics and Sealing

A BV consists of two large families of components:

1. Mechanical parts: body, sphere, shaft, fasteners.

   • Common materials: carbon steel, stainless steel, brass, specific alloys (Hastelloy).

   • Possibility of treatments or coatings (chromium plating, FEP, PFA) for corrosion resistance.

   • Plastic versions (PP, PVC, PVDF) used in light chemistry, low temperature (10 to 90°C), and low pressure (<10 bar).

     
     

2. “Soft” parts: stuffing boxes, gaskets, seats.

   • Most common materials: PTFE (Teflon), glass-filled PTFE, graphite, stainless steel.

   • Their selection depends directly on the fluid, pressure, and temperature of the process.

👉 Keep in mind: Proper sizing of materials determines the reliability and lifespan of the valve.

Floating vs. Trunnion-Mounted Sphere: What's the Difference?

The sphere is the central element of the valve. Two main designs are distinguished:

Floating Sphere

• It is not attached to the shaft.

• Sealing is ensured by the pressure of the fluid pressing the sphere against the downstream seat.

• Advantage: excellent sealing, even at high pressure.

• Use: small to medium diameters.

Trunnion-Mounted Sphere

• Attached to the shaft, it is supported by bearings.

• Sealing is ensured by springs that keep the seats in contact.

• Advantage: reduced operating torque, more suitable for large diameters and high pressures.

👉 Good to know: The choice between floating and trunnion mounted depends on the DN, pressure, and service conditions.

Sealing Components: Seats, Gaskets, and Packing Glands

• Packing glands and body gaskets: ensure external sealing to protect the operator and prevent any leakage to the environment.

• Seats: ensure internal inline sealing. Their design directly affects operating torque and pressure resistance.

• Materials: PTFE, graphite, filled PTFE, according to the conditions of use.

👉 The packing gland is generally the most sensitive part: its choice is crucial for safety and reliability.

Available Connections

A key point in choosing a BV is the type of connection. Here are the main options:

• Welded (SW or BW) → common in process, requires adapting the standard (ISO, DIN, SMS).

• Threaded (Gas or NPT) → typical for small dimensions, often used in oil.

• Flanged → DIN, ISO (PN10, PN16, PN25, PN40) or ASA (150, 300) norms depending on the industry.

• Clamp → used in pharmaceuticals, but limited in heavy process.

• Specific thread → specific cases (e.g., Michelin with M25x150 or M36x200).

👉 Each connection meets specific mounting and maintenance constraints. Always verify compatibility with the existing network.

Full Bore vs. Venturi Passage

There are two types of passages:

• Full bore: constant nominal diameter, promotes maximum flow.

• Venturi (reduced) passage: internal diameter smaller by one size → allows for cost savings on the valve and reduces the necessary torque (and thus the actuators).

👉 Strategic choice: full bore to minimize pressure drops, venturi to optimize budget and actuator sizing.

Actuation and ISO Mounting Pad

BVs can be automated thanks to a standardized ISO mounting pad. This defines the fixing dimensions but not the shaft height—something to be validated on a case-by-case basis.

Common sizes: F03, F04, F05, F07, F10.

👉 Tip: Always ask the client if future actuation is considered, even if the valve is delivered manually. This prevents costly replacements in the future.

Available Variants and Ranges

The BV offering is extensive:

• Standard import (Sferaco, ICP) → economical, full bore, DN 8 to DN 100.

• Technical and adaptable (Cystek, Effebi, JC, Tyco, Starline) → designed to meet stringent specifications.

• Plastics (SAFI) → specific applications in chemistry and low pressure.

👉 Supplier selection depends on your budget, required standards, and expected technical level.

3-Way and 4-Way Valves

Multi-way versions (L, T, or even 4-way) allow for switching or mixing fluids.

Essential questions to ask:

• Must the valve be sealed in all ways?

• What is the position of the common path?

👉 Attention: depending on the manufacturer, seat design may vary (presence or absence of a seat on the 3rd way).

Conclusion

The ball valve is much more than just an “on/off” valve: it is a central element of any industrial network. Its selection must take into account:

• the fluid,

• the temperature,

• the pressure,

• the type of connection,

• the potential need for actuation,

• and budget constraints.

A poor choice can generate hidden costs (maintenance, replacement, non-compliance), while an appropriate selection ensures the long-term security of your installations.