How to extend the life of a ball valve
Proper preventive measures can extend the life of ball valves by years
A ball valve is designed for gas and fluid handling in process systems servicing the oil & gas and chemical processing industries. They also are commonly used in food & beverage equipment, mechanical engineering and automotive manufacturing and maintenance (see Figure 1).
Compared to gate valves or globe valves, ball valves are often preferred for their:
Compact, economical designs
Fast shut-off speeds
Durability in high-pressure, high-volume and high-temperature applications
Resistance to corrosion or damage
Long service life
Versatility in various industrial applications.
Most ball valves are designed to be maintenance-free and are intended to eventually be replaced rather than repaired. That said, the proper preventive measures can extend the life of ball valves by years.
Factors that impact ball valve lifespan
Many ball valve manufacturers provide an estimate of expected ball valve lifespan (usually eight to 10 years), and proper maintenance can certainly extend this range. However, ball valve lifespan can be influenced by a variety of other factors.
Actuation: By choosing the appropriate power source for the application, users can reduce maintenance expenses, increase uptime and maximize safety. Pneumatic actuated ball valves are the most durable option in high-pressure environments, provided there is access to compressed air (see Figure 2).
Design: Ball valves come in one-, two- and three-piece designs, the first two of which do not allow for maintenance and must be replaced when components fail. Three-piece ball valves are designed so that the seats and seals can be removed and replaced without removing the entire valve from the system (see Figure 3).
Temperature and pressure rating: Ball valves used in high-pressure or high-cycle settings must be serviced or replaced more often than those in lower-pressure applications. The closer the media’s temperature/pressure rating is to the ball valve’s rating, the more frequently the valve will need to be replaced.
Media: Ball valves are intended for the on/off control of fluids and gases without solid particulates. Any particles in the media can abrade the valve mechanism, leading to repairs, valve failure or actuator failure.
Valve materials: Ball valves can be made of stainless steel, brass, bronze or plastic (PVC). While PVC offers flexibility and cost savings, metal ball valves are more durable, corrosion resistant, able to withstand high temperatures and pressures and are compatible with almost all media types (see Figure 4). Use the Cole-Parmer Chemical Compatibility Database to compare valve material and media.
Source: Some valve retailers source their products from all over the world, but products from overseas carry the risk of incompatibility with products made in the U.S. Quality aside, it’s best to buy ball valves from domestic sources to ensure compatibility and longevity and prevent premature replacements.
Why ball valve maintenance is important
Longevity: Valves that last longer and require few to no repairs help plants save money, prevent downtime and keep plant production on schedule. Without routine maintenance and quality checks, any issues with ball valves may be overlooked, leading to equipment failures, damaged parts or injured workers.
Security and safety: The worst-case scenario on a plant floor is a preventable accident that causes injuries or costly repairs. Maintenance experts who are properly trained in installing and assessing ball valves can identify potential issues easily and early, thereby lowering the chance of an emergency repair or violating OSHA.
Reduced need for shutdowns: Unplanned downtime is expensive, since any time the plant is not producing is money wasted or revenue missed. Some ball valve maintenance can be performed while the valve is in operation, allowing plant production to continue uninterrupted.
Cost savings: Just as increased uptime means increased revenue, fewer maintenance issues keep more money for the company. If ball valves are regularly inspected, maintained and replaced on a projected schedule, there will be less need to allocate funds to unexpected repairs or replacements.
The what and why of ball valves
Ball valves use a metal ball with a hole bored through the center, sandwiched between two seats to control flow. Used in many hydrocarbon process applications, ball valves are capable of throttling gases and vapors and are especially useful for low flow situations.
According to Wikipedia, a ball valve is a flow control device which uses a hollow, perforated and pivoting ball to control liquid flowing through it. It is open when the ball’s hole is in line with the flow inlet and closed when it is pivoted 90-degrees by the valve handle, blocking the flow. The handle lies flat in alignment with the flow when open, and is perpendicular to it when closed, making for easy visual confirmation of the valve’s status. The shut position 1/4 turn could be in either clockwise or counter-clockwise direction.
According to Home Depot, ball valves are more effective at forming a tight seal and have more reliability and longevity than gate valves but tend to be more expensive. They are often used for shutoff and control applications. Because ball valves can open and close immediately, they are more likely than gate valves to cause water hammer.
Ball valve maintenance
Preventive or predictive maintenance should begin long before you detect any issues with your ball valves. Build the following steps into the plant’s maintenance management program to extend the life of ball valves.
Proper installation: Correctly installed ball valves have a much lower chance of needing repairs or replacement. Make sure the engineer installing the ball valves has relevant experience and knowledge.
Regular cleanings: Clean valves last longer, since there’s little chance for debris to build up and negatively impact the performance of the piping system. Be sure to use cleaning agents that don’t react negatively with the valve materials: Gas-based or compressed air cleaners work well for metal components, and alcohol- or water-based cleaners are ideal for non-metal parts. Clean ball valves at least once a year, and more frequently if the plant environment contains dirt or dust.
Valve lubrication: Lubrication keeps ball valves operating smoothly, prevents abrasion and helps increase the effectiveness of the valve seals. Stick to synthetic, water-insoluble, oil-based lubricants; avoid clay- or solid-based lubricants that may build up inside the valve cavity. Be sure to choose a lubricant compatible with the valve materials and system media.
Routine inspections: Have valves checked by a skilled inspector on a routine basis. Once a year is ideal, but ball valves in high-pressure and high-cycle applications should receive more frequent inspections. Inspections should include:
Tightness of nuts, bolts and other hardware
The presence of mineral buildup or corrosion
Proper opening and closure of valves
Position indicator accuracy (even on static valves)
Proper exhausting and air filtration in the area.
In conclusion, annual shutdowns are an ideal time to perform ball valve inspections. Remove valves from the piping system, disassemble them, clean the interiors and replace broken or worn components, paying particular attention to seals or other rubber parts.