Understanding and Preventing Swing Check Valve Failure

Figure 1: Swing check valves require regular maintenance to ensure they are working properly

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Swing check valve failure can cause major problems in fluid systems, as these valves are key to allowing flow in one direction and stopping backflow. Failures often happen due to worn-out parts, debris buildup, incorrect installation, or material fatigue. Regular maintenance and inspections can help prevent these issues and improve system reliability. By understanding these common failure causes and taking preventive steps, you can keep the system running smoothly for longer.

Common causes of swing check valve failure

Common causes of swing check valve failure are:

• Wear and tear: Regular use can cause the internal parts of a swing check valve to wear out, leading to leaks and reduced efficiency, so they should be checked and replaced as needed.
• Incorrect installation: Incorrect installation of swing check valves, such as improper direction or loose connections, can lead to misalignment, early failure, or poor performance.
• Debris and corrosion: Debris and rust can damage swing check valves by blocking movement and weakening the valve, so using filters and corrosion-resistant materials can help prevent these issues.
• Pressure and flow issues
  • Pressure surge: Sudden pressure changes, such as water hammer, can damage swing check valves by causing rapid opening and closing, but using surge protection devices and proper system design can mitigate these risks.
  • Low flow velocity: If the flow velocity is below the minimum required, the valve disc may not stay fully open, leading to chattering and excessive vibration.
  • Flow disturbances: Non-uniform or turbulent flow caused by improper upstream or downstream piping can lead to chattering and noise.
• Material and design selection
  • Wrong selection of disc material: Using materials with low impact strength, such as martensitic stainless steel (CA15), can lead to fatigue failure in dynamic loading conditions.
  • Disc slamming: Incorrect valve type or size can cause pressure pulsations and rapid disc closure, leading to slamming.
  • Disc tapping: Oversized valves with low flow velocity can cause the disc to tap against the seat, especially in gas applications with fluctuating flow.

Figure 2: Determine if the system needs a robust material like stainless steel (left) or a more cost-effective material like brass (right).

How to reduce swing check valve failures

Selection and sizing

• Selecting swing check valve sizes: Ensure the valve is appropriately sized to match the flow requirements. A valve that is too small can restrict flow, while one that is too large may not close properly. Choose materials that are compatible with the fluid and operating conditions to enhance durability and performance.
• Choosing the right valve type and size: Select a valve type with a shorter travel distance, like a tilting disc check valve, to prevent slamming. Ensure the valve is correctly sized to avoid disc tapping.
• Selecting appropriate disc material: Use materials with high fatigue resistance and ductility, such as carbon steel, for applications with dynamic loading.

Installation

• Proper installation guidelines: Follow the manufacturer's instructions carefully to avoid misalignment and loose connections. Ensure the valve is installed in the correct orientation and all connections are secure. Read our check valve installation article for more details.
• Maintaining proper piping layout: Ensure a minimum straight pipe length of 5D upstream and 10D downstream to promote uniform flow and reduce turbulence.

Operation and performance

• Ensuring adequate flow velocity: Size the valve to maintain a flow velocity above the minimum required (VMin) to keep the disc fully open. For systems with variable flow, ensure the disc opening angle is greater than 25% at minimum flow.
• Addressing swing check valve chattering: Investigate and resolve causes of chattering, such as pressure fluctuations or incorrect valve sizing. Consider installing dampeners or adjusting system settings to mitigate chattering.

Maintenance

• Routine maintenance and inspection: Conduct regular maintenance and inspections to identify and address issues early. Check for signs of wear, rust, and debris build-up to maintain optimal valve performance.
• Importance of cleaning and lubrication: Keep the valve clean to prevent blockages and ensure smooth operation. Regularly lubricate the valve to reduce friction and extend its lifespan.
• Regular monitoring and maintenance: Regularly inspect and maintain valves, especially in critical services, to detect wear and prevent mechanical failure.

FAQs

What causes swing check valve chattering?

Chattering is often caused by pressure fluctuations, improper sizing, or debris in the valve. Addressing these issues can help eliminate chattering.

How can I prevent swing check valve failure?

Regular maintenance, proper installation, and selecting the right size and material are key to preventing failure.

What are the benefits of using a full flow swing type check valve?

Full flow swing type check valves offer reduced pressure drop, increased efficiency, and are suitable for high flow applications.

What Is Check Valve

Figure 1. Check valve failure and solution

Check valves, also called one-way, retention, or non-return valves. It allows the material to flow in one direction. If fluid enters one of the two openings of the check valve, we call it the entrance. If fluid exits the valve through the other opening, we call it the outlet.

Check valves stop backflow and prevent fluid from flowing backward through the system where they are installed. You should use these rules when fluid release could contaminate the fluid entering the system. Since this is the case, a broken well check valve could cause oil to flow back into the well. 

Types of Check Valves

Understanding the types of checks before exploring the symptoms of a bad check valve is important.

• Check Swing Valve

Swing check valves obstruct the flow using a disc mounted on a hinge or trunnion. To prevent reverse flow, the disc either detaches and seats or retracts to permit forward flow. While available in various sizes, they are typically quite sizable. A swing check valve is demonstrated by the flapper valve found in toilets. The water pressure maintains the position of the valve until it is moved manually using a lever.

• Stop Check Valve

This valve features an override control that can halt flow irrespective of pressure or direction. Furthermore, apart from impeding backflow or forward pressure below average, these can be sealed by an external mechanism that obstructs all flow irrespective of pressure.

• In-Line Check Valve

Similar to a lift check valve. These are defined by the presence of a spring that rises in response to pressure upstream. When the &#;cracking pressure,&#; the force required to surmount the spring tension, is reduced, the spring automatically repositions the lift.

Diaphragm Check Valve
A flexing rubber diaphragm is positioned to create a closed valve. For the check valve to open, the pressure on the upstream side must be greater than the pressure downstream. Upon cessation of positive pressure, the diaphragm flexes back to its initial closed state.

Lift Check Valve
The lift check valves utilize a disc called the &#;lift,&#; which is propelled from its seat by the elevated pressure of the inlet or upstream fluid. Subsequently, the fluid proceeds downstream. The lift&#;s trajectory is maintained vertically and aligned by guides to ensure correct reseating. The lift will be reseated by gravity or higher downstream pressure once the pressure decreases.

Ball Check Valve:
The ball check valve is a prevalent type of valve that employs a ball as its closure element. The ball of certain types of valves is spring-loaded to assist in keeping it closed.
To form a seal, the ball must be moved by reverse flow without a spring. Ball check valves are compact, primitive, and inexpensive. They are frequently found in sprinkling nozzles and spigots.

Types of Check Valve Failures

Figure 2. Check valve failure

Although the signs of a malfunctioning check valve differ from machine to machine, there are some commonalities that you should be aware of.

Simple mechanisms valves are continuously used. Any frequently used object will degrade and finally become inoperable.

When designing the system, position the valves in a location that facilitates easy access and replacement by using appropriate maintenance procedures and closely monitoring the components. It is possible to avoid any failures, interruptions, or periods of inactivity.

• Flow Fluctuations and Disruptions

We implement valves to maintain a consistent and constant passage of gas or fluid. They ensure the valve will restrict the flow to meet the parameters, regardless of the set point or desired pressure.
Valves that malfunction give rise to flow variations, manifesting in the outcome. A failure of a bad check valve can result in an inadequate or excessive gas supply to the patient. To avoid problems, you should regularly maintain machines and replace faulty valves.

• Reverse Flow

Reverse flow is an extremely prevalent and potentially expensive valve issue. The purpose of valves is to restrict the passage of fluids or gases in a single direction. Constantly, the substance flows from upstream to downstream.
When something blocks or stops the flow, the material returns to its original location. This may result in the pump malfunctioning if it induces a reverse rotation during discharge. A shut-off valve that closes quickly and securely will prevent this from occurring.

• Water Hammer

Another frequent issue that can arise with check valves is the water hammer. A water hammer happens when a check valve abruptly changes direction or stops moving. This causes an increase in pressure in a liquid or vapor.
A valve closure causes this in pipeline systems or along the flow path. The water hammer of the check valve induces vibrations and striking sounds throughout the system. They are preventable with check valves that close more quickly, halting surges and shock waves.

Causes of Check Valve Failure

A failure check valve can cause catastrophic consequences when operating liquid handling equipment. Learn the causes and warning signs of impending valve failure to avoid valve failure and expensive repairs. Significantly, check valves are maintained if you operate a system that utilizes piping to transport fluid. By opening and closing in retort to hydraulic pressure, check valves to ensure unidirectional fluid flow and prevent reverse flow. The leading causes of check valve failure are as follows:

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Inadequate Maintenance

Consistent maintenance is a guarantee of protection against valve failure. Check the pipeline for dirt and signs of damage. Small pieces may become stuck in the valve, damaging the inside parts. As soon as you observe any indications of deterioration, replace your valves.

Higher Temperature

Check valve failure can occur in applications that operate at elevated temperatures, and it is imperative to note this. Inspecting the check valves and substituting them upon perceiving any sign of wear is imperative.

Inverse Stream

When water rushes upstream of the check valve, reverse flow occurs. If this happens while the pump runs, it can be extremely dangerous and costly. It can cause the pump to spin in the opposite direction, which leads to gradual damage. To mitigate this issue, verify that your valve is operating by ensuring that it closes quickly and securely.

Installation And Assembly Failures

Installing or assembling valves creates the basis for potential complications in the future. The application installation and selection of the appropriate check valve size are paramount. Properly installing the check valve can avoid premature valve failure.

Faulty Check Valve Symptoms 

Figure 5. Spring check valve

Failures of check valves can result in irreparable harm to the valves and the pipelines. However, these signs exhibit indications that, when detected and treated, could avert severe harm. The symptoms of check valve failure are as follows.

High Energy Consumption

High energy expenses may serve as an indication of faulty valves. The elevated expenses result from the valve&#;s inability to control the pressure at the inlet and outlet effectively. 

Wear and Tear of Valve Components

The deterioration of seat seals and other valve components indicates valve failure. Additionally, stubborn valve components may indicate that the valve is deteriorating due to corrosion or aging.

Valve Noise

This indicates the presence of a water hammer or check valve. Hammering is the sound produced by the valves when they are in action. The fluid striking the valve closure element produces the sound, causing it to break apart.

Internal Component Loss

If the fluid contains adrift elements in the check valve, we detect a diminished fluid flow rate. It is reasonable to infer that obstructions within the conduit impede the valve&#;s functioning.

Leaks in Pipe Joints and Other Connections

Leaks in pipe connections may mean a bad valve, so check the valve to find where the leak is coming from.

Equipment Failures

Equipment failures indicate broken check valves. Broken check valves can cause damage to valuable equipment. To fix the issue, you may need to replace the affected parts.

Faulty Check Valve: What Is the Solutions

You might need to replace valve parts or the whole valve to avoid costly fixes and ensure safety. You must do this if the non-return valve fails, as it can lead to system issues.

Tightening bolts or clearing debris might fix the valve in less serious instances. Among the possible remedies for check valve failures are:

• Leakages

Inspect and troubleshoot check valves to determine where and why the leaks are happening before doing anything else. Defective flappers, loosened fasteners, or compromised gaskets are all potential causes of swing check valve leaks. When necessary, you must tighten bolts and substitute replaceable valve components.
Additionally, it might be necessary to substitute the entire valve. A valve&#;s size, type, closing assembly, or reaction speed may be considered unsuitable for a given operation. It is advisable to substitute the valve in all its components.

• Damage Part of Valves

If a component stops functioning and you cannot repair it, you can replace the check valve components. Sometimes, it&#;s better to quickly replace a broken valve part to stop it from affecting how the whole valve works.

• Valve Obstruction

The debris buildup in the conduit could obstruct the opening and closing of valves. Incorrect valve diameters, improperly installed valves, or blocked components are additional causes.
To thoroughly analyze the issue, you need to disassemble the valves. Before reinstalling, clean and lubricate the residue in the valves, ensuring that the valve size matches the conduit size.

• Water Hammer

One can avert water pressure by following maintenance and prevention guidelines. Regardless of the procedures followed, you must first identify the water hammer conduit caused by the check valve.
When someone discovers a problem, they can implement various solutions. To solve the problem, you can use valves, water impact arresters, release air from valves, or change intake connections.

How To Avoid Check Valve Failure

Proper and consistent preventive maintenance is critical in assuring longevity and avoiding check valve failure.

Maintaining the pipeline and valves devoid of residue is the initial and most efficacious measure in averting check valve failure. As needed, this can be accomplished by installing filters and covers. Additionally, routine cleansing of the piping system can be executed to eliminate residue and reduce the accumulation of contaminants.

Preventing valve failure can also be accomplished by applying valve lubrication. Lubricating the interfaces between the various moving components of check valves can prolong their operational life, improve performance, and guarantee streamlined processes by minimizing friction.

Valves must be utilized and installed as specified. Inadequate valve installation or using an incorrect form of check valve can shorten the valve&#;s lifespan. Also, a scheduled maintenance routine should replace defective valves at the earliest sign of failure.

Conclusion

Failure can be avoided by maintaining sufficient caution in the check valve&#;s operations. Eliminating costly failures, such as those of the well or pump check valves, requires proper installation, testing, and maintenance procedures. This post emphasized the symptoms of bad check valves, causes, and solutions associated with check valve failures.