101 Guide To Check Valve Problems And Troubleshooting

Check valve failures result from wrong installation techniques, poor maintenance practices, and inadequate research before valve application, among other reasons. These failures prevent the valves from functioning properly and may damage the pipe systems, pumps, and well equipment.

If you want to learn more, please visit our website.

Check valves, also called non-return valves, are devices through which fluid flows in only one direction. They function to prevent the reversal of fluid flow (backflow) in the system to which they are applied. Therefore a well check valve failure may result in fluid flowing back into the well. 

For check valve failures to be prevented, the valves need to be installed correctly, regularly tested for quick notice of impending valve failures, and maintained properly.

This post discusses how to test, install and assemble check valves. It also highlights some check valve failures, with their symptoms, causes, and solutions.

How To Test Your Check Valve

Source: Pinterest

Tests are required to prevent check valve failure. Checking the valves for seal integrity or leakages in the seat and shell ensures that problems in the valves are noticed quickly, and the system is protected from failure.

The success of many operations depends on the working of the check valve in the system. Therefore check valves should be tested regularly to avoid backflow, water hammer, and other consequences of failed check valves. 

For proper testing, check valves should be subjected to MSS SP-61. The MSS SP-61 is an ANSI standard that issues the proper requirements for testing shell and seat closure in a check valve.

Below are the ways check valves can be properly tested: 

Shell Test

For the Shell test, the test fluid is water, and the valves are tested at a pressure greater than or equal to 1.5 times the 100-degree Fahrenheit rating, rounded to the next 25psi increment. The valve sizes and their test time are: 

Valve SizesTest Time< 2inches 15 seconds2.5 to 6 inches60 seconds 8 to 12 inches120 seconds 14 inches and above300 seconds 

For a successful result, there should be no leakages in the valve.

Seat Closure Test (With Water)

For this seat closure test, the test fluid is water, and the valves are tested at a pressure greater than or equal to 1.1 times the 100-degree Fahrenheit rating, rounded to the next 25psi increment. The valve sizes and their test time are:

Valve SizesTest Time< 2 inches 15 seconds2.5 to 8 inches30 seconds 10 to 18 inches60 seconds 20 inches and above120 seconds 

The max leakage allowed for metal seated valves is 40 ml/hr of water per inch of nominal valve size. No leakage is allowed for soft seated valves.

Max leakage allowed after one hour is 80 ml for 2 inches, 240 ml for 6 inches, 560 ml for 14 inches, and 800 ml for 20 inches.

Seat Closure Test (With Air)

For the seat closure test, the test fluid is air, and the valves are tested at an air pressure greater than or equal to 80 PSIG. The valve sizes and their test time are:

Valve SizesTest Time< 2 inches15 seconds3 inches30 seconds

The max allowable leakage for metal seated valves is 0.4 SCFH/inch of inlet size. For soft seated valves, no leakage is allowed.

Other Testing Methods

Lift-type and Swing check valves can also be tested using the pressure test. The axis of the lift check valve&#;s closure element is positioned perpendicular to the horizontal surface. In contrast, the axis of the swing check valve&#;s closure element and the channel is positioned almost parallel to the surface.

The pressure test involves two tests: The strength test, which tests for leakages in the valve body, and the cover and sealing test, which tests for leakages around the sealing surface.

• Strength Test

The test fluid is introduced from the inlet, and the outlet is closed. If there is no observable leakage from the valve body and cover, the valve passes the test.

• Sealing Test

The test fluid is introduced from the outlet, and the valve is shut. If there is no observable leakage from the sealing surface, gasket, and packing, the valve passes the test.

Common Check Valve Failures and How To Fix Them

Source: Pinterest

Check valves, even though solidly constructed and properly structured, are like every other piece of equipment in their need for careful use, tests, and maintenance. 

If the check valve is not tested or maintained as often as it should, it may develop problems that worsen with time and eventually lead to the check valve failure.

Pump check valve failure may result from the piling up of suspended particles in the check valve, and well check valve failure may result from the use of the valve in functions with incompatible materials, leading to the slow destruction of the valve parts. Hence, different modes of check valve failures exist in their different functions and are usually caused by poor research, wrong installation, and irregular maintenance.

Non-return valve failures vary as check valves are of different types and, in some cases, different parts. However, below are some common check valve failures: 

Check Valve Failures

Source: Pro Boat Mag

Some check valve failures in pipe systems, wells, and pumps include:

Reverse Flow

A reverse flow occurs when water flows back from the outlet to the inlet area. Check valves are one-way valves, and a reverse flow is an indication of the check valve failure.

The backflow is especially disadvantageous when it occurs in discharge pump operations, as the backflow of fluid into the pump may cause the impeller to spin in a different direction, resulting in pump damage.

Debris In Pipeline 

Debris can be deposited in the check valves by fluids moving through the pipeline, causing the valve to get stuck in an open or closed position. Irregular check valve maintenance encourages the accumulation of debris over a long period.

Also, debris moving in the fluid at high speed may damage the valve&#;s internal parts. These broken internal parts of the valve then contribute to the accumulation of debris.

Water Hammer

A water hammer occurs when fluid flowing through the pipe is suddenly restricted or forced to move in another direction. It is a pressure surge or vibration which damages pipes, fittings, and the check valve.

This is a common swing check valve failure, in which fluid backflow causes the valve to shut off suddenly, resulting in pressure vibrations throughout the pipe.

• Failing Seat Seal

Check valve discs, balls, or plugs are sealed to the seats using seals such as elastomer rings to ensure proper shutoff. This sealing happens when the inlet pressure falls below the valve cracking pressure, or a fluid backflow occurs.

These sealing materials lose their ability to seal properly over time due to constant friction and frequent use. With decreasing sealing integrity, fluids seep through the shutoff valves, resulting in the check valve failure.

• Inconsistent Fluid Flow 

Check valve failure can lead to flow disruptions and fluctuations in the valve. Check valves ensure a constant fluid flow in one direction until the fluid is shut off. Therefore, any flow stoppage or inconsistency in flow indicates a failed check valve.

Causes of Check Valve Failures

Source: Pro Boat Mag

Alt text: Check Valve Operation

Troubleshooting of well pump check valve failures and other modes of check valve failures indicate that valve failures are caused by the actions and conditions below.

• Wrong Installation, assembly, and maintenance practices 

The Installation, assembly, and maintenance of check valves, if done wrongly, may lead to serious damage to the valve. Improper installation causes premature wear and tear in the valve, which could result in the valve failing at the early stage of operations.

• High Temperatures 

High temperatures cause the expansion of valve parts and contribute to their quick degradation. It also negatively affects valve sealing integrity, leading to leakages in the valve. Therefore, high-temperature conditions result in check valve failure.

• Low Fluid Pressure

Check Valves function properly with adequate pressure. The insufficient pressure of the fluids causes the valves to open and close frequently, resulting in wear out of the valve parts. 

Also, low pressure caused by clogged or wide pipelines affects the valves negatively and could lead to their failure.

Symptoms, Preventive Measures, And Solutions

Source: Pro Boat Mag

Symptoms 

Check valve failures can cause irreparable damage to the valves and the pipes. However, they show symptoms that, if noticed and attended to, can prevent serious damage. Some of these symptoms are:

• Noise In The Valve: This is a symptom of a water hammer. The valves produce a hammering sound when in operation. This sound is caused by the slamming of the valve closure element when the fluid hits it. 
• High Energy Consumption: Increased energy costs indicate malfunctioning valves. These increased costs are caused by the failure of the valve to regulate the inlet and outlet pressure.
• Wear And Tear of Valve Parts: The wear out of seat seals and other parts of the valve are indications that the valve is failing. Also, when the parts of the valve are sticky, the valve may be failing due to age or corrosion.
• Loss of Internal Parts: If fragments of the check valve parts float on the fluid and a low fluid flow rate is observed, it can be assumed that debris in the pipe is hampering the valve operations.
• Pipe Leakages: Leakages in the pipe joints and other connections may signify valve failure, and the valve should be checked to confirm the cause of leakage.
• Failed Equipment: Equipment failures are late signs of failed check valves as valuable equipment has been affected, and the damage may only be correctable by replacing affected parts.

Preventive Measures

Water hammer, backflow, and other check valve failures can be prevented by following these maintenance guides: 

• Clean Valves: Ensure that debris, fragments of valve parts, and other solid particles are cleaned out of the valves regularly. These particles should be flushed out, and filters and covers should be installed in the valve to prevent the entry of solid particles.
• Install and Use Check Valve Properly: Installation of check valves should be done correctly and preferably using the valve manufacturer&#;s installation guides. Different check valve types should be used for their suitable operations.
• Lubricate Valves Regularly: Valve parts should be lubricated to ensure smooth operations. Lubrication reduces friction in the valve parts and hence reduces wear and tear. This increases the service life of the valves.

Other check valve maintenance and preventive measures include considerations in selecting appropriate valve sizes, material compatibility, and reaction speeds of the valves.

Solutions

For the safety of your valves and to prevent the non-return valve failures from transforming into system failures and more costly repairs, you may need to replace the valve parts or the entire valve. 

But in less critical cases, the valve could be repaired by tightening bolts or removing debris. Some solutions to check valve failures include: 

• Leakages: 

Check valves should first be tested and troubleshot to know the exact areas of the valve leaking and the causes of the valve leakages. For example, swing check valve leakages may be caused by loosened bolts, damaged gaskets, or bad flappers. Bolts should be tightened in the necessary cases, and replaceable valve parts should be replaced. 

• Damaged Valve Parts: 

Check valve parts can be replaced if a part is ineffective and cannot be repaired. In some cases, as soon as the valve part malfunctions, it&#;s safer to change the part at once to prevent that part from affecting the entire valve operation.

There could also be a need to replace the entire valve. In situations where the valve size, type, closing assembly, or reaction speed is inappropriate for the operation, it&#;s best to replace the entire valve.

• Water Hammer

Water hammer can be prevented using the preventive and maintenance guides above. Still, in cases where a water hammer occurs, regardless of the procedures, the pipe where the water hammer occurs should first be located. 

When discovered, some of the various solutions that can be implemented are the installation of water hammer arresters, the release of air pockets in the valve, replacement of intake connections, installation of pressure limiting valves, etc.

• Valve Obstruction 

Obstruction of valve opening and closing may be caused by accumulated debris in the pipeline. Other causes include stuck parts, wrongly installed valves, or the use of wrong valve sizes.

Valves should be disassembled for proper analysis of the problem. The debris in the valves should be cleaned, lubricated, and the valve size should be confirmed with the pipe size before reinstallation. 

Check Valve Assembly And Installation Guide

Source: Hpm Mag

Different modes of check valve failures occur due to improper assembly and installation of the valves. For valves to be installed properly, valve installation rules and guidelines must be followed.

Below are three pipe design rules that must be followed for effective installation and operation of check valves:

Pipe Design Rules

Install Check Valves in Non-turbulent (Laminar) Conditions

Pipes connected to the check valves should be designed straight, upstream, and downstream, as valves work best with smooth and non-turbulent (laminar) flow. 

Five times the nominal pipe size (NPS) of straight pipe is recommended. However, some check valves can be installed with fewer straight pipes. 

Properly Calculate Valve Size

For optimum operation of check valves, appropriately sized valves are important. The sizing rules applied to check valves differ from on-off and control valve sizing rules.

Nominal valve and nominal pipe sizes should not always be assumed to match, and sizing calculations should be done for minimum, maximum, and normal flow conditions.

LEFLOW Product Page

Recommended article:
Ancient Art of Lost Wax

Install in the proper orientation 

Installing the valve connected to a horizontal or vertical line matters for the smooth operation of the valve. Horizontal lines are usually preferred because of the absence of gravity effect on the valves.

Also, even though many valves work when connected to horizontal pipelines, silent or axial flow check valves are best on vertical lines.

Installation Guides

Error in the installation of the valves results in check valve failure and possible damage to the pipe system. Check valves differ in types and parts. Hence installation depends on the check valve type. 

However, below are some installation best practices for flapper-type swing check valves:

• Check inside the valve to confirm that all material used in transportation and storage has been removed.
• Check the operation of the flapper and make sure it operates freely to the seating surface and back.
• Confirm that there are no materials at the edges that may cause the valve not to seal properly.
• The valve should be installed facing the direction of the flow arrow. Ensure a 3-diameter straight pipe upstream.
• If installed vertically, the flow direction must be against gravity (up-flow).
• A cover must be on the top of the valve if installed horizontally.
• Valves should be inspected and test-run after installation to avoid premature swing check valve failure.

Qualified and licensed professionals should handle the installation of industrial check valves. 

Check Valve Seat Replacement Guide

Valve seats are essential parts of the check valve. The closure elements of check valves seal against the valve seats to ensure proper shutoff. 

Valves seats are replaced for reasons such as: 

• Wear and tear due to friction or age.
• Misalignment with check valve closure element during installation.
• Seat damage by fragments and particles on the surface of the closure element and in the valve.

If valve seats are not replaced, the damaged seats can cause leakages in the valve, backflow, and ultimately, non-return valve failure.

Check valve seats can be replaced by following these steps:

• The fluid should be drained from the pipeline.
• Loosen connecting bolts and nuts, and remove the valve from the pipeline if required.
• Loose and remove the cover bolts, as well as the valve cover.
• Remove the gasket and closure element from the valve.
• Uncouple and remove the damaged seat.
• Replace the seat with a new part.
• Reassemble the valve with the new seat part.
• Put the valve back in operating service.
• Test-run the valve seat to ensure that the problem has been solved.

Check Valve Handle Replacement Guide

Check valves, unlike other valves, mostly work automatically and do not require an on-site or remote control. Hence, most check valves do not have handles, stems, or actuators.

Check valves are mostly influenced by the fluid pressure to open or close. When the inlet fluid pressure is above the valve cracking pressure, the valve opens, and when the inlet fluid pressure is lower than the cracking pressure or there is backflow, the valve closes.

However, the stop check valve has a handle and can be controlled externally. Stop check valves are used to isolate and throttle fluid flow, as well as shut it off. 

Handles on stop check valves can be replaced following these steps: 

• Fluid should be drained from the pipeline.
• The valve should be turned to a closed position.
• Loosen connecting bolts and nuts.
• Uncouple and remove the valve handle.
• Replace the old valve handle with a new one.
• Reassemble the valve with the new handle part.
• Put the valve back in operating service.
• Test-run the valve handle to ensure that the problem has been solved.

Conclusion 

Check valve failures are preventable when adequate attention is given to the operations of the valve. With proper installation, testing, and maintenance practices, costly failures such as well or pump check valve failures can be avoided.

In this post, test procedures, installation guidelines, and proper maintenance practices of check valves were outlined. Also check valve failures, their symptoms, causes, and solutions were highlighted in the post.

Dombor is an industrial valve manufacturer that offers superior valve solutions that complies with market requirements and pipe specifications. We are highly rated for manufacturing suitable valve types in various conditions. You can contact us to get high-quality check valves for free flow of media.

What Is Check Valve

swing check valve 2 inch

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

Inline Spring Loaded Check Valve with a box

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

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:

1/2&#; Brass Swing Check Valve Failure and Partial disassembly
From YuDaMan

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 

Structure of vertical check valve

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.

Spring check valve inside 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.

lift spring check valve

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.

The company is the world’s best cast steel swing check valve supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.