3-Piece vs. 2-Piece Ball Valves

A ball valve serves the purpose of shutting off fluid flow in a piping system by employing a quarter turn operation. This operation is facilitated by a ball-shaped element with a central hole, connected to a handwheel through a shaft. This article delves into the distinctions between 3-piece and 2-piece ball valve constructions.

What is a 3-Piece Ball Valve? A 3-piece ball valve comprises three main body parts – the main body and two connectors. These connectors are designed to fit into the main body through threads or welding, allowing for easy removal of the main body for repair or cleaning. Components like ball seats, ball, and stem can be replaced independently after valve installation. Noteworthy advantages include robust construction, in-line repair capability, and protected seats guarding against fluid damage.

Figure: Three-piece ball valve

Advantages of 3-piece Ball Valves:

• Simple and robust construction suitable for high-pressure and extreme conditions.
• Facilitates in-line repairs without removing critical components.
• Protected seats increase service life at a lower maintenance cost.

What is a 2-Piece Ball Valve? A 2-piece ball valve consists of two separate body pieces connected through threads or a flange and bolt assembly. These valves find widespread use due to their versatility in fluid control applications. The valve has one body and one end connection, with the end connection fitting into the body. Installation of the threaded version is tool-free, but repair necessitates valve removal.

Figure: Two-piece ball valve

Advantages of 2-piece Ball Valves:

• Minimal flow resistance, providing seamless fluid flow.
• Easy installation due to its simple design, small size, and low weight.
• Substantial seals ensure excellent performance and prevent fluid leakage.
• Quick opening/closing capabilities save time.
• Maintenance is easy due to the simple structure.

Factors to Consider When Selecting a 3-Piece or 2-Piece Ball Valve:

1. Weight: Opt for lightweight valves to reduce stresses on pipes and pumps, preventing premature damage to components.
2. Pressure Level: Consider the specific pressure limit of each valve; exceeding this limit may lead to leakage and damage.
3. Versatility: Evaluate the valve’s ability to serve in various situations and tasks, with 3-piece valves generally being more versatile.
4. Durability: Check the valve design and casings to ensure resistance against wear and tear, particularly from corrosive media.
5. Control Method: Choose a valve that closes/opens quickly for enhanced efficiency, potentially considering an actuator for extreme torque requirements.

This comparison aids in making an informed decision based on specific operational needs and requirements.