Installation Basics for Ball Valves

Three piece industrial ball valve, manually operated
Image courtesy of Duravalve, Inc.

Ball valves are characterized by their closure mechanism. Most often, a ball valve has a spherically shaped fabrication (ball) that is inserted in the fluid flow path. The ball has an opening through its center, often circular in cross section and matching the diameter and shape of the connected pipe. The ball is contained within the body of the valve and rotated around its central axis by torque applied to the stem. The stem, which extends through a seal to the exterior of the valve body, can be manually or automatically controlled via several methods.

During valve operation, the ball is rotated through a ninety degree arc from a fully closed to fully open position. When fully closed, the opening in the ball faces the sidewalls of the valve body and is cut off from the fluid by seals that secure the ball in place and prevent fluid flow around the ball. As the valve stem is rotated toward the open position, the cross sectional area of the opening is increasingly exposed to the fluid flow path until the open area through the ball is aligned with the flow path in the fully open position.

Here are some general installation and removal guidelines for ball valves.

• Verify whether the valve is unidirectional or bidirectional. If valve function is limited to a single direction, make sure the inlet and outlet ports are properly oriented to the piping system flow direction.
• Adequate access for handle movement, along with an operator's hand, should be confirmed prior to installing the valve.
• Ball valves will function in any orientation.
• If automated with an actuator, maintain sufficient clearance around the valve and actuator to provide adequate maintenance access.
• Keep the installation area free of debris and dirt. Protect any valve parts that are removed or are awaiting installation. Avoid introducing any foreign matter, dirt or debris into the valve.
• Valves may have any of a number of connection methods, including threaded, flanged, or socket weld. Disassembly of the valve may be appropriate when installing some types, especially socket weld. Care should be taken to avoid any damage to the ball surface, seals, or sealing surfaces. Scratches and nicks can produce leakage when the valve is reassembled.
• If disassembling a currently installed valve, verify that the piping system is not under pressure prior to starting. Cycle the valve through open and closed positions a couple times to relieve any pressure that may be retained in the valve body.
• Follow all manufacturer recommendations for applied torque on any fasteners.
• When a ball valve is disassembled, for any reason, it may be a good time to replace seats.
• Leak check final installation. Tighten packing gland nut to eliminate leaks at the stem.

These are general recommendations. In every instance, a review of the valve manufacturer's specific instructions prior to starting installation or service is good practice. Share your fluid control challenges with industrial valve specialists. Leverage your own knowledge and experience with their product application expertise to develop effective solutions.

Thermoplastic Industrial Ball Valves

Thermoplastic ball valves, TBH Series.
Image courtesy Hayward Flow Control

Ball valves are a mainstay of fluid control
throughout many industries. Like most valve types, the ball valve is named for its closure mechanism. A spherical shaped element is placed in the fluid flow path, with the ability to rotate its position around an axis. The axis is a shaft or other device that connects to an actuator on the exterior of the valve. The actuator can be a simple handle or an element of a valve automation system. The “ball” in the ball valve has an opening through its center, usually round to mimic the shape of the connected pipe. As the ball is rotated, the opening aligns with the inlet and outlet of the valve body, allowing fluid to pass. A counter-rotation that aligns the port (opening) with the sides of the valve body, away from the flow path, stops the fluid flow. A seat between the exterior surface of the ball and the containing valve body prevents fluid from flowing around the ball.

The basic ball valve design centers around either a floating ball or trunnion mounted ball. A floating ball valve uses the body and the seats to hold the ball in place, with the connecting shaft serving primarily as the rotating mechanism. This design can provide bidirectional closure, since the fluid flow seats the ball against one of the sealing surfaces. A trunnion mounted ball valve has positioning support pins that mate with machined portions of the valve body to hold the ball in place and serve as the axis of rotation. Trunnion valves are available in sizes larger than those of the floating ball design.

Various common and exotic metals are routinely used for body and internal construction. Thermoplastic ball valves are an alternative that provides high levels of corrosion resistance to the media, as well as the surrounding environment.

Typical applications for thermoplastic ball valves:

• Municipal waste and water treatment
• Clean water technology
• Chemical transfer and processing
• Aquatic and animal life support systems
• Mining and mineral processing
• Metal plating
• Marine
• Pulp and paper
• Landfills and environmental infrastructure

Some detailed information about thermoplastic ball valves from Hayward Flow Control is provided below. There are more variants to fulfill a wide band of applications. Share your fluid control challenges with a process control specialist and leverage your own knowledge and experience with their product application expertise to develop an effective solution.

Thermoplastic Floating Ball Valves from MSJacobs-Cali

One, Two, or Three Piece Ball Valve?

Examples of one, two, and three piece ball valves.
Image courtesy Duravalve

Ball valves are employed throughout many commercial, institutional, and industrial venues where the need to isolate part of a system is necessary, or even just to regulate the on/off condition of system fluid flow. The product variants are almost uncountable, with a version to accommodate almost any application.

When selecting a ball valve, one facet of construction will be evident in your research. There are three common types of ball valve construction; one piece, two piece, and three piece. Here are some general considerations and differences among the three types.

• A one piece ball valve has a body and end connections formed from a single piece of material. This construction presents a comparatively reduced number of opportunities for leakage. The valve trim and seals are inserted through one of the end connections. This type of valve will not have a port size equal to the line size. The simplicity of the one piece body design tends to make their cost lower than the other versions. Once the valve is in place, it cannot be serviced without removing the entire valve assembly from the piping system.
• Two piece ball valves generally have one piece that includes an end connection and the body, plus a second piece that fits into the first that will hold the trim in place and provide the second end connection. The construction presents an additional leak potential where the two pieces are joined, but also allows disassembly of the valve for replacement of the internals. These valves can provide full port service and bidirectional flow shutoff.
• A three piece ball valve essentially separates the connection portions of the valve assembly from the body of the valve. These will be more expensive than either of the other two types, but their allowance for removing the valve body and trim from the piping system while leaving the connections in place may prove valuable for many applications. Full port and bidirectional shutoff can be provided by this construction.

Properly applied, all these valves will provide good service. Your selection depends on the demands of the application. Share your fluid measurement and control requirements and challenges with process control specialists, leveraging your own knowledge and experience with their product application expertise to develop effective solutions.

New Metal Seated Ball Valves Introduced

Cutaway view of a metal seated ball valve
Courtesy SVF Flow Controls

Ball valves are utilized across a wide range of industrial process fluid flow control applications. Consequently, there are many ball valve variants, each designed to satisfy a particular range of application requirements.

Reviewing some of the attributes of ball valves that might make them the best choice:

• Tight closure.
• Very low resistance to flow.
• Best suited for applications requiring fully closed or open control.
• 90 degrees of rotational motion from open to closed position yields rapid response.
• Comparatively compact, without the space requirement for extending stem movement as required by some other valve types.
• Wide range of construction materials for the body, stem, ball, and seals.
• Moderate force required for actuation.
• A full size port provides for very low pressure drop across the valve when fully open.
• Requirements for maintenance are generally low. 
• No lubrication required.

One limiting factor for the application of ball valves, as with many other valve types, is the seat material. Most often, seats are fabricated from elastomeric or other "soft" materials. While these materials provide good sealing performance, their inability to withstand higher fluid temperatures makes them unsuitable for some industrial applications. To satisfy a wider range of process applications, some manufacturers offer metal seated ball valves. The metal seated valves are designed to meet severe service applications involving high temperature, erosive fluids and other challenging shutoff requirements where soft seats would rapidly deteriorate.

One manufacturer, SVF Flow Controls, provides metal seated ball valves in sizes 1/2" through 12" with a full port design. Because of their intent for severe service applications, metal seated ball valves are generally provided with other design features that enable their application across a wide range of high temperature or erosive fluid applications.

I have included a data sheet below that provides additional technical information, or you may contact a valve application specialist for any assistance you need. Share you fluid control challenges and get effective solutions.

SVF Flow Control M-Seat Metal Seated Ball Valves from MSJacobs-Cali