Combustion Services

Leak Testing

Leak testing on a combustion fuel valve train is a critical safety procedure used to ensure that there are no fuel leaks (typically gas or oil) within the system that delivers fuel to a burner or combustion appliance. These valve trains are made up of components like shutoff valves, pressure regulators, pressure switches, solenoid valves, and piping—all of which must be tightly sealed to prevent hazardous leaks.

Why Leak Testing Matters

Safety
Fuel leaks can lead to fires, explosions, or carbon monoxide poisoning.

Code Compliance
NFPA (National Fire Protection Association) codes like NFPA 86 often require leak testing as part of startup, commissioning, or periodic maintenance.

System Integrity
Confirms all valves are seating properly and seals are intact.

Operational Efficiency
Helps detect worn or malfunctioning components before they fail.

When It’s Done

  • During startup and commissioning of a new or rebuilt system.
  • After maintenance or replacement of components.
  • As part of routine preventive maintenance.
  • After a shutdown, particularly in systems where pressure integrity may have been compromised.

Common Types of Leak Tests

Bubble Test
A low-pressure test where soap solution is applied to connections to look for bubbling, indicating a leak.

Pressure Decay Test
A section of the valve train is isolated, pressurized, and monitored to see if the pressure drops over time.

Differential Pressure Test
Measures pressure differences across valves to determine leakage.

Sniffer Test
Uses gas detectors to sense escaping fuel, often around seals or joints.

Thermographic Test
Use thermal imaging technology to detect and visualize emissions of volatile organic compounds (VOCs) and other invisible gases.

Where Testing Is Focused:

  • Main shutoff valves (both upstream and downstream)
  • Vent valves
  • Pipe joints and threaded fittings
  • Solenoid and blocking valves
  • Pilot lines

Step-by-Step Leak Test ProcedureCombustion Fuel Valve Train Leak Test Procedure

The following tools and equipment are required for the procedure: a calibrated pressure gauge or manometer, leak detection fluid (such as a soap solution or an approved leak detector), and an inert gas—typically air or nitrogen, but never fuel gas. Additionally, a pressure source with a regulator, appropriate isolation valves, and personal protective equipment (including safety glasses, gloves, and flame-resistant clothing) are essential for safe and effective operation.

1

Preparation

  • Lockout/Tagout the combustion system.
  • Ensure area is well-ventilated and free of ignition sources.
  • Visually inspect the valve train for any signs of wear, corrosion, or damaged seals.
  • Review system drawings and identify test points (test cocks, isolation valves, etc.).
2

Isolate the Section to be Tested

  • Close both the main gas supply and main shutoff valves.
  • Install a calibrated pressure gauge at the appropriate test point.
  • Pressurize the isolated section of the valve train (typically between the two main shutoff valves).
3

Apply Test Pressure

  • Introduce air or nitrogen up to the required test pressure (typically 1.5 times the operating pressure, but not exceeding component ratings).
  • NFPA 86 often recommends around 10 psig for leak testing.
  • Let pressure stabilize for 1–2 minutes.
4

Monitor for Pressure Drop

  • Observe the pressure gauge for a minimum of 10 minutes.
  • No drop in pressure = Pass
  • If pressure drops, re-check all valves and joints.
5

Check with Leak Detection Fluid (Optional Add-On)

  • Apply leak detection fluid to:
    • Valve bodies and seats
    • Flanges and unions
    • Threaded pipe joints
  • Look for bubbles forming—indicating a leak.
6

Vent and Reset System

  • Carefully vent the test gas to atmosphere.
  • Reopen isolation valves.
  • Remove test equipment.
  • Restore normal system operation.

Recordkeeping should include documentation of the date and time of the test, the test pressure used, the duration of the test, the results (Pass/Fail), and the name of the technician who performed it. These records should be kept on file to support compliance audits and maintain a reliable service history.

Ensure Safety, Compliance, and Performance with Professional Leak Testing

Don’t leave your combustion system’s safety to chance. Our expert leak testing services ensure your fuel valve train is tightly sealed, code-compliant, and operating at peak performance. Whether you’re commissioning a new system, performing routine maintenance, or recovering from a shutdown, we use proven methods like bubble testing, pressure decay, and gas detection to identify potential hazards before they become serious issues.
Protect your facility, your team, and your bottom line—schedule a leak test today.

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Enhancing Workplace Safety with Leak Testing

Beyond custom engineered solutions, we offer a full range of services to keep your operations running safely and efficiently. Our expertise extends to combustion system optimization, preventative maintenance, emissions analysis, equipment upgrades, and troubleshooting. Whether you’re looking to enhance performance, improve energy efficiency, or ensure compliance with industry standards, our team is here to provide tailored solutions to meet your needs.

Comprehensive Safety Solutions

Rockford Systems offers a full range of services to help businesses maintain compliance and create safer workplaces. Those include:

  • Standardized Valve Safety Trains

  • Design and Custom Engineering

  • Thermographic Leak Survey

  • Field Services & Repairs

  • Burner Tuning

  • Annual NFPA Combustion Safety Audit