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Gas Line Pressure Test: How It Works and What BC Requires

Gas Line Pressure Test: How It Works and What BC Requires

Gas fitter checking a pressure gauge on piping

A gas line pressure test seals a section of gas piping, fills it with air or an inert gas, and watches a gauge to confirm the pipe holds pressure. In BC, a licensed gas contractor does it after any new installation or alteration, and before the gas is turned on. The test pressure and hold time come from the CSA B149.1 code and depend on the pipe’s working pressure, size and length. Below you’ll find what the test checks, how it is done, why a gauge can drop without a leak, and what to expect on a job in Port Moody, Coquitlam or Port Coquitlam.

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TL;DR

  • A pressure test proves new or altered gas piping is gas-tight before it is energized. It uses air or an inert gas, never oxygen.
  • Pressure and duration come from CSA B149.1. For example, a 2-psi system 50 m long is tested at 15 psi for at least 15 minutes. A 70 m run holds for at least 60 minutes.
  • A leak test is a different check. It uses a bubble solution or an electronic detector on joints and connections.
  • In BC, regulated gas work is done under a permit by a certified gas fitter working for a licensed gas contractor.
  • Smell gas? Get everyone out, then call for help from outside. Do not try to find the leak yourself.

Table of Contents

What a gas line pressure test actually checks

The test answers one question: does this piping hold pressure? The installer isolates a section of pipe, fills it to a set pressure, and watches a gauge for a set time. If the needle holds, the piping is tight. If it drops, there is a leak, a temperature effect or a gauge problem to run down before the gas goes on.

Technical Safety BC’s information bulletin on de-energizing gas systems points to CSA B149.1: any alteration to a gas piping system must include a test procedure under clause 6.22, so the system is gas-tight at completion and before it is energized.

That covers more than brand-new houses. You can need a test when:

  • a new gas line goes in for a range, BBQ, fireplace or furnace
  • a section of existing piping is moved, extended or repaired
  • a water heater or boiler is replaced and the piping is altered
  • piping will be enclosed or concealed, such as inside a wall, and must be tested before it is closed in

If you are planning a gas stove, our guide to converting an electric stove to gas in BC walks through the job from the homeowner’s side. The pressure test is one of its final steps.

Pressure test vs. leak test

People use the two terms as if they were one. They are two checks that work together.

Pressure test Leak test
What it does Isolates piping, fills it with air or inert gas, and monitors a gauge Checks joints, valves and appliance connections for escaping gas
Tools Manometer or test gauge, test medium, isolation caps Non-corrosive bubble solution or an electronic combustible gas detector
Pressure Set by the code table Normal operating pressure
Result Gauge holds for the full time No bubbles, no detector reading

The OpenTextBC fuel gas course describes a Stage 2 leak test of untested control valves and appliance piping at normal operating pressure with a bubble solution. If the gauge drops during a pressure test, the installer searches for the leak, typically with a soap solution.

The Red Seal exam content for Class A gas fitters lists both skills: pressurizing with air, nitrogen or CO2, and leak testing with an approved solution or an electronic detector.

The two stages of testing

The same OpenTextBC resource describes testing in two stages.

  1. Stage 1 happens after the piping is installed and before any appliance is connected. This is the main pressure test of the pipe itself.
  2. Stage 2 happens after appliances are connected and before they operate. The pressure shown on the manometer or gauge is held for a minimum of 10 minutes, and connections are checked for leaks.

Testing in two stages means the pipe is proven tight on its own first. Then the final connections, the ones most often disturbed, get their own check.

What pressure and how long?

There is no single number. CSA B149.1 sets the pressure and duration in a table in Section 6, based on working pressure, pipe size and length. Two examples from the OpenTextBC course:

System Length Test pressure Minimum duration
2 psi working pressure 50 m 15 psi 15 minutes
2 psi working pressure 70 m 15 psi 60 minutes

Longer or larger piping holds more gas, so a small leak takes longer to show on the gauge. That is why the hold time grows with the run.

The code was updated in 2025. The CSA B149.1:25 edition clarifies leakage test requirements and allowable leakage rates in clauses 6.22.2 to 6.22.4 and Annex K. Your installer works to the edition adopted in BC, so ask which one applies to your job.

The gauge matters too

The same course sets requirements for the test gauge. It must be at least 3 in. (75 mm) in diameter. Its maximum range must exceed the test pressure by at least 15% but not more than 300%. Its increments cannot be larger than 2 psig (14 kPa) or 2% of the maximum dial reading, whichever is less. A cheap, oversized gauge can hide a slow leak. A correct one shows it.

Three requirements for a gas test gauge

Which test medium is safe?

Gas piping is tested with air or an inert gas such as nitrogen or CO2. Oxygen must never be used. The OpenTextBC course explains that it combines with oils and can cause spontaneous combustion. This is one more reason the work belongs to trained, licensed people with the right equipment.

Why the gauge can drop without a leak

A falling needle does not always mean a hole in the pipe. Common reasons a test reads low:

  • Temperature change. Air in the pipe cools or warms with the space around it. A cold basement or a sun-warmed exterior run can move the reading.
  • Settling at the start. Pressure often eases a little right after filling as the system stabilizes.
  • A weeping fitting on the test setup, such as a cap, gauge fitting or hose, rather than the house piping.
  • An unsuitable gauge, with a range too wide to show a small change.
  • A true leak at a joint, valve or appliance connection.

An experienced fitter sorts these out in order: check the test setup, let the temperature settle, then retest and go over every joint with solution. We would never sign off on a line because the drop “looks small.” The reading either holds for the required time or the cause gets found.

Who is allowed to do the test in BC

This is regulated work. Technical Safety BC says that to do regulated gas work in BC you must be licensed by Technical Safety BC, employed by a licensed contractor, or authorized to work on your own. A licensed contractor is responsible for compliance with the Safety Standards Act, regulations and safety orders.

The Gas Safety Regulation defines a gas fitter as someone who holds a certificate of qualification and a licensed gas contractor as someone who holds a contractor licence. Certificates come in classes:

A handyman is not on that list. If someone offers to add a gas line without a permit, that is a red flag for your safety and for your home insurance.

Paperwork you should see

On permitted residential work, municipalities use a test certificate. The City of Richmond’s Gas Piping Test Certificate for single-family dwellings states that the house piping was tested with air at a stated pressure for a stated time with no loss of pressure, and that piping, appliances and vents meet the gas code and were left safe. Your city’s form may differ, but the idea is the same.

The regulation also gives the province oversight. A gas installer must, when a provincial safety manager asks, provide copies of test pressure charts or test reports. A safety manager can also require a pressure test in the presence of a safety officer. So records are part of the job, not an extra.

What to expect on a job with us

Here is how a typical gas-line job runs when we do it:

  1. On-site quote. Jon looks at the run, the appliance and the meter location, and tells you what the job needs. The $60 call-out fee is waived if the work goes ahead.
  2. Permit and plan. Gas work is done under the right permit, with the pipe sized for the appliance load.
  3. Install. The line is installed and, where piping will be closed in, tested before the wall is closed.
  4. Pressure test. The section is isolated, filled with air or inert gas, and monitored for the required time.
  5. Connect and leak test. Appliances are connected and every connection is checked.
  6. Energize and commission. Only after the test passes is gas turned on and the appliance started.

Before any existing line is opened, the section must be isolated. Technical Safety BC’s bulletin says it is unsafe to remove or install appliances, or repair or alter gas systems, while that portion is live. The safest practice is for a qualified person to verify the portion is isolated first.

Pilot-light trouble is another sign of a gas-system issue worth understanding before work starts. This explainer on why a pilot light keeps going out covers common causes.

What does a gas line pressure test cost?

We do not publish a flat price for it, because the test is part of the gas job rather than a separate product. What moves the price:

  • the length and size of the piping
  • whether it is new work or a test on altered piping
  • permit requirements for the municipality
  • access: open basement, crawl space or closed walls
  • whether an appliance install is included

The simplest way to get a firm number is an on-site quote. Our call-out fee is $60 and is waived if the work goes ahead.

Our perspective

A pressure test is the part of a gas job nobody sees afterward, so it is the part we are most careful about. When a line is closed into a wall, the test is the only proof it is tight.

We run it the way the code lays it out: the right gauge, the right medium, the full hold time. We do not shorten it because the job is small or because the kitchen is waiting. If the needle moves, we find out why before anything gets energized.

That is the advantage of an owner-led company. I am the one on site, so the person who tests your line is the person who answers for it. You get a straight explanation of what the job needs and what the test showed.

Jon

Book a licensed gas fitter

If you are adding a gas range, BBQ line, fireplace or furnace hookup, or replacing a water heater or boiler, our gas fitting service covers the install, the pressure test and the leak check. We serve Port Moody, Coquitlam and Port Coquitlam, 24 hours a day, 7 days a week.

Paradigm Services and Installations

Water heater swaps involve gas connections too. See our water heater installation page for how we handle tank and tankless jobs, including free removal of your old tank. If something is wrong right now, our 24/7 emergency plumbing line is open.

If you smell gas

A pressure test is for planned work. A gas smell is an emergency. Get everyone out of the building first, then call for help from outside. Do not look for the source yourself and do not try to repair the line. Then call a licensed gas fitter to find and fix the problem. Our guide to gas fireplace smells explains which odors are normal and which are not.

FAQ

What PSI should a gas line be tested at?

It depends on the working pressure, pipe size and length, using the table in CSA B149.1. A 2-psi system 50 m long, for example, is tested at 15 psi for at least 15 minutes. Your fitter picks the figure from the code edition that applies to your job.

Can I pressure test my own gas line?

In BC, regulated gas work must be done by a certified gas fitter under a permit. That includes the test, because it is part of the installation or alteration. A licensed contractor also keeps the test records that inspectors may ask for.

Which gas must never be used to test gas piping?

Oxygen. It can combine with oils in the system and cause spontaneous combustion. Gas piping is tested with air or an inert gas such as nitrogen or carbon dioxide.

Is a leak test the same as a pressure test?

No. A pressure test checks that an isolated section of piping holds a set pressure for a set time. A leak test uses bubble solution or an electronic detector to pinpoint escaping gas at joints and connections. Most jobs use both.

Does a pressure drop always mean a leak?

Not always. Temperature changes, settling after filling, or a loose fitting on the test setup can move the gauge. A fitter rules those out and checks joints before deciding.

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