How to Test a Check Valve

Check valves, also called non-return valves, help make sure that fluid flows in only one direction. Many systems use them, including water pipes, heating and cooling systems, and factories that handle oil, gas, or chemicals. Their main job is to prevent backflow, which can cause pollution, system failures, or even safety hazards. But like any mechanical component, check valves are subject to wear, corrosion, and functional failure.

You should test check valves often to keep the system working well. This guide shows you how to test a check valve. It includes easy steps, the tools you’ll need, important rules to follow, and tips to fix common problems.

As a valve maker, we want to help you learn the right way to test valves. We make and test valves that work great, even when things get tough.

Why Testing a Check Valve Matters

Regular check valve testing is critical for:

• • Ensuring tight sealing and preventing backflow

• • Protecting pumps, compressors, and pipelines from pressure surges

• • Complying with safety and industry regulations (e.g., API 598, MSS-SP-61)

• • Reducing maintenance costs by identifying issues early

• • Extending the operational lifespan of the valve and connected equipment

If a check valve breaks in places like water or oil plants, it can cause serious problems and cost a lot.

1. Understanding Types of Check Valve Tests

A. Hydrostatic Shell (Body Strength) Test

Purpose: Checks if the valve body stays strong and doesn’t leak under pressure.

Procedure:

• • Seal the outlet port.

• • Introduce water at 1.5 times the rated pressure.

• • Hold for 60–120 seconds.

• • Check for leakage or pressure drop.

Applicable Standards: API 598, EN 12266, MSS-SP-61.

Typical Failures:

• • Body casting cracks

• • Seal weld failures

B. Seat Leakage Test

Purpose: Measures the sealing performance of valve seats to prevent backflow.

Procedure:

• • Apply pressure from the downstream side.

• • Check for reverse leakage at the upstream port.

• • Use water or air depending on test protocol.

Note: For swing-type valves, special attention is paid to disc movement and complete sealing.

C. Air Tightness or Pneumatic Test

Purpose: Detects minor leaks not visible during hydrostatic testing.

Procedure:

• • Use compressed air or nitrogen.

• • Pressure usually set at 80–100 psi.

• • Use soap solution or bubble test to detect leaks.

D. Backflow Prevention Test (for Double Check Valves)

Based on municipal protocols :

• • Attach test gauges.

• • Close test cocks in sequence.

• • Monitor pressure drop to identify if the internal check modules are holding.

E. Cracking Pressure Test (for Hydraulic Valves)

Purpose: Determines the pressure at which the valve begins to open.

Procedure:

• • Slowly increase fluid pressure.

• • Record the pressure point when flow just begins.

• • Compare with design specification.

2. Step-by-Step: How to Test a Check Valve On-Site

Whether you're testing a valve in a water system or an industrial plant, follow this structured procedure:

Tools Needed:

• • Pressure source (hand pump, air compressor, or hydrostatic pump)

• • Pressure gauges

• • Test plugs or adapters

• • Isolation valves

• • Soap solution (for air tests)

• • Clean test fluid (air, water, or hydraulic oil)

Step 1: Pre-Test Inspection

• • Ensure the valve is isolated and depressurized.

• • Remove the valve (if needed) and clean the ports.

• • Inspect for visible damage, corrosion, or dirt.

Step 2: Shell (Body) Pressure Test

• • Connect the valve to a test bench or piping system.

• • Apply hydrostatic pressure at 1.5× rated pressure.

• • Monitor for body leakage or pressure drop.

• • Record time and pressure.

Step 3: Seat Leakage Test

• • Introduce pressure from downstream.

• • Make sure you monitor the upstream port.

• • If you see or measure any leaks, it means the seat is not working properly.

• • For critical applications, use calibrated leak detectors.

Step 4: Functional (Flow Direction) Test

• • Apply pressure from the normal flow direction.

• • Ensure that fluid flows smoothly.

• • Reverse pressure to verify that the valve blocks backflow.

Step 5: Cracking Pressure Check (Hydraulic or Low-Pressure Systems)

• • Slowly raise inlet pressure.

• • Observe and record the pressure when flow starts.

• • Compare with design specs to confirm spring or disc function.

Step 6: Air Bubble Test (Optional for Small Valves)

• • Submerge the valve in water.

• • Introduce compressed air at 80 psi.

• • Observe for air bubbles indicating leaks.

Step 7: Documentation

• • Record test pressure, duration, leak rate (if any), and test method.

• • Label valve with test result (PASS/FAIL).

3. Testing Tips for Different Valve Types

Swing Check Valves:

• • Ensure free disc movement.

• • Valve must close with gravity or spring.

• • Common in water and wastewater systems.

Ball Check Valves:

• • Ball must seat properly.

• • Debris often causes seat damage.

• • Use transparent housing during testing for visual inspection.

Piston Check Valves:

• • Used in high-pressure applications.

• • Cracking pressure and seat tightness are critical.

Lift Check Valves:

• • Vertical installation preferred.

• • Pressure should lift disc straight up.

Dual Plate Check Valves:

• • Requires precise spring alignment.

• • Often tested for tight shut-off and spring resilience.

4. Common Failures & Troubleshooting Tips

Issue: Continuous Leakage in Seat Test

• • Cause: Worn seat, debris, misaligned disc

• • Solution: Clean internals, re-lap or replace seat

Issue: Valve Doesn’t Open at Expected Pressure

• • Cause: High cracking pressure caused by spring wear

• • Solution: Replace spring or adjust

Issue: Backflow Even at Normal Conditions

• • Cause: Cracked disc, warped body, wrong installation

• • Solution: Replace valve, ensure correct flow direction

Issue: Chattering or Vibration

• • Cause: Oversized valve, low flow rates

• • Solution: Resize valve or add flow dampener

Issue: Water Hammer During Test

• • Cause: Sudden closure

• • Solution: Use slow-closing check valves

5. Frequency of Testing

Application	Recommended Interval
Domestic/Commercial Water Systems	Every 6–12 months
Fire Protection Systems	Once a year
Industrial/Chemical Plants	Quarterly
Municipal Infrastructure	Biannually
High-Cycle Hydraulic Systems	Annually or per cycles

6. Industry Standards for Check Valve Testing

Following the rules makes things reliable and builds trust with customers. Common standards include:

• • API 598 – Valve inspection and test requirements

• • ASME B16.34 – Valve pressure-temperature ratings

• • EN 12266 – European standard for valve leakage and strength testing

• • MSS-SP-61 – Pressure testing for metallic valves

Understanding these ensures correct test conditions, especially during FAT (Factory Acceptance Testing) or SAT (Site Acceptance Testing).

7. Why Choose a Manufacturer Who Understands Testing

Buying a valve is not just about selecting a model. You choose a product that we rigorously test, certify, and back with technical support.At COVNA, we:

• • Conduct 100% factory testing on all check valves

• • Provide certificates of compliance and test reports

• • Offer tailored solutions to meet exact cracking pressure or flow rate

• • Supply valves that meet API, ASME, and ISO certifications

Our valves are widely used in industries including:

• • Water and wastewater

• • Oil and gas

• • Power generation

• • Food and beverage

• • Healthcare and biotech

Final Thoughts: Test Right, Choose Smart

A properly tested check valve can mean the difference between smooth operation and catastrophic failure. If you follow the steps in this guide, you’ll keep your system safe and running smoothly.

Remember:

• • Test regularly

• • Use correct procedures

• • Choose valves that meet your exact needs

Looking for reliable, tested, and certified check valves? Contact us today for expert consultation, custom solutions, or a free quote.

Let performance, not assumptions, drive your decisions.