How to Test a Check Valve: A Complete Guide for Engineers and Maintenance Professionals

When it comes to ensuring the performance and safety of your piping systems, testing check valves is a crucial step that should never be overlooked.
Whether you’re dealing with water systems, industrial pipelines, or critical process equipment, a properly tested check valve guarantees reliable backflow prevention and long-term operational stability.

In this comprehensive guide, we’ll walk you through everything you need to know about how to test a check valve — including methods, standards, tools, troubleshooting tips, and more.

What Is a Check Valve and Why Is Testing Important?

A check valve is a one-way valve that allows fluid (liquid or gas) to flow in one direction only.
If installed incorrectly or if the valve becomes faulty, it can lead to backflow issues, equipment damage, or even system failures.

Testing a check valve ensures:

• The valve seals properly under pressure.

• It opens at the correct cracking pressure.

• It withstands expected working conditions.

• It maintains system safety and efficiency.

Main Methods to Test a Check Valve

1. Visual Inspection

Before conducting any pressure test, start with a visual inspection:

• Check for visible cracks, corrosion, or physical damage.

• Inspect sealing surfaces and seats for wear.

• Verify that the valve size and specifications match your system.

Tip: Even new valves can suffer minor damage during shipping or storage!

2. Shell Pressure Test (Hydrostatic Test)

Purpose: Verify the structural integrity of the valve body.

Procedure:

• Fill the valve with water or another testing fluid.

• Apply a pressure typically 1.5 times the valve’s rated pressure (as per API 598 or ASME B16.34 standards).

• Hold the pressure for a specific duration (often 1-5 minutes).

• Monitor for any leakage from the body, bonnet, or cover.

✅ Pass Criteria: No visible leaks or deformation.

3. Seat Leakage Test

Purpose: Test the sealing capability of the valve seat.

Procedure:

• Apply a lower pressure (typically the working pressure or 1.1 times it) across the valve seat.

• Check for leakage through the sealing surfaces.

• Can be done with air (pneumatic) or water (hydraulic), depending on the system requirements.

✅ Pass Criteria: Minimal to no allowable leakage, depending on valve class and application.

4. Cracking Pressure Test

Purpose: Determine the minimum upstream pressure needed to slightly open the check valve.

Procedure:

• Gradually apply pressure to the inlet side while monitoring the pressure gauge.

• Note the exact pressure at which the disc/lift/ball first opens.

• Compare the measured cracking pressure with the manufacturer's specification.

Common Cracking Pressures:

✅ Pass Criteria: Within ±10% of specified cracking pressure.

Common Problems Found During Check Valve Testing

Tools and Equipment Needed for Testing

• Hydrostatic Test Pump

• Pressure Gauges (calibrated)

• Flowmeters

• Air Compressor (for pneumatic tests)

• Torque Wrenches

• Inspection Cameras (for internal visual checks)

• Certified Test Benches (for large industrial valves)

⚙️ Tip: Always use calibrated and certified equipment to ensure accurate results.

Applicable Testing Standards for Check Valves

When testing, it's important to follow recognized industry standards, such as:

• API 598 – Valve Inspection and Testing

• ASME B16.34 – Valves: Flanged, Threaded, and Welding End

• ISO 5208 – Industrial Valves — Pressure Testing of Valves

• MSS SP-61 – Pressure Testing of Steel Valves

Using standardized methods ensures consistency, compliance, and global acceptance.

How Often Should You Test a Check Valve?

Testing frequency depends on the application and industry, but general guidelines are:

Final Thoughts: Why Reliable Check Valves Matter

Proper testing ensures your check valves work as intended — protecting your system, minimizing downtime, and safeguarding your operations.
At FLOWX, we manufacture high-performance check valves that not only meet international standards but also undergo rigorous pressure and seat leakage testing before delivery.

If you're looking for:

• Reliable backflow prevention

• Long-lasting valve performance

• Expert technical support

Explore our full range of check valves or contact us today to find the right solution for your needs!