TSSA G3 gas piping and tubing practice questions (Module 8).

Five free practice questions on gas piping and tubing: module 8 of the nine modules of Ontario's Gas Technician 3 (G3) certificate exam, which TSSA runs. The exam is all multiple choice; these have four options and one correct answer, as every question in our bank does. Answer each one before opening the explanation. No account, no email.

01The questions

1. Recall · Corrugated stainless steel tubing and its fittings

   Replacing a damaged length of CSST, a G.3 finds that the only tubing on the truck is from a different CSST maker than the installed system. According to the installed tubing maker's instructions, how can the two systems be joined?

   1. The two tubings are brazed together after the jackets are stripped back from the joint.
   2. The new maker's fitting is used on both tubings, since both are stainless steel of the same nominal size.
   3. Either maker's fittings may be mixed on the two tubings, provided the repaired run passes its pressure test.
   4. Each tubing ends in its own maker's fitting, joined through standard malleable iron NPT fittings.
   Show the answer

   D. Correct. CSST tubing and fittings are engineered as one system and are not interchangeable between makers. Where two makers' tubing must meet, each ends in its own listed fitting and the two are joined with malleable iron pipe fittings with standard NPT threads, as the maker's instructions describe.

   Why not the others

   A. CSST joints are made with the maker's listed mechanical fittings, not by brazing the thin corrugated wall. The two systems meet through each maker's own fitting and standard NPT pipe fittings.

   B. Matching nominal size does not make the corrugation profiles and fitting seals match. The maker states its tubing and fittings are not interchangeable with other CSST systems; each tubing takes its own maker's fitting, joined through standard NPT pipe fittings.

   C. A pressure test does not make an unlisted combination acceptable; the fitting has not been tested with the other maker's tubing. The maker's instructions prohibit mixing components; each tubing takes its own fitting, and the fittings are joined with standard threaded pipe fittings.

2. Recall · Manual shut-off valves: types and open/closed indication

   On the drop to a furnace, the lever handle of a quarter-turn manual gas valve lies at right angles to the pipe. What does this tell the G.3?

   1. The valve is closed.
   2. The valve is fully open.
   3. The valve is half open, throttling the gas.
   4. The handle is off its stop, so the position is unknown.
   Show the answer

   A. Correct. In a quarter-turn ball or plug valve the lever is set in line with the bore through the ball or plug. Across the pipe, the bore lies across the flow and the valve is closed; in line with the pipe, it is open. A quarter turn moves it between the two.

   Why not the others

   B. A quarter-turn valve is open when its lever lies along the pipe, in line with the bore. A lever across the pipe means the bore is turned across the flow: closed.

   C. A manual shut-off valve is used fully open or fully closed; half open, the lever would sit at about 45°. At right angles to the pipe the valve is closed.

   D. The handle's stops limit it to the quarter turn between open and closed, and its position shows the bore's. A lever at right angles to the pipe shows the valve closed.

3. Recall · Protection from corrosion and physical damage, including depth of cover underground in Ontario

   After the CSST and connector joints at a new range are made up, the G.3 leak-tests them at operating pressure. Which leak-detection liquid should be brushed on the stainless steel parts?

   1. a solution of dish soap in water, mixed fresh on site
   2. a non-corrosive leak-detection solution low in chlorides and sulphur
   3. any leak-detection spray at all, since every one is made for gas joints
   4. an ammonia-based glass cleaner, which leaves no residue
   Show the answer

   B. Correct. Chlorides attack stainless steel, so CSST and connector makers call for a non-corrosive leak-detection solution: one CSST maker specifies sulphur and halogen contents below 10 ppm each, and the connector maker says household soaps and detergents containing chlorides are not used. Rinse and dry the joints afterwards.

   Why not the others

   A. Dish soaps can contain chlorides, which corrode stainless steel CSST and connectors; the makers' instructions warn against them. Use a non-corrosive leak-detection solution.

   C. Not every leak-detection product suits stainless steel. The CSST maker specifies a solution with sulphur and halogen contents below 10 ppm each, and the connector maker asks for a non-corrosive fluid; a product is chosen for that, not just for its label.

   D. Ammonia is among the chemicals the connector maker lists as corrosive to its connectors, and a glass cleaner is not a leak-detection solution. Use a non-corrosive leak-detection solution.

4. Recall · How gas type changes capacity: propane and natural gas compared

   A designer wants to size a propane system using a capacity table built for natural gas. What is the correct judgement?

   1. Use a propane table only where the propane is at elevated pressure
   2. Use it, once the load is converted to cubic feet per hour of propane
   3. Use a propane table, as capacity depends on density and heating value
   4. Use it, but choose one size larger, since propane is heavier than air
   Show the answer

   C. Correct. A capacity table is calculated for one gas: its specific gravity (natural gas about 0.58, propane vapour about 1.52) sets how much volume a pipe passes at the allowed drop, and its heating value sets how much heat that volume carries. Propane differs in both, so size with a table made for propane at the system's pressure and drop.

   Why not the others

   A. The difference in density and heating value is there at every pressure, so a natural gas table misstates what a pipe carries as propane at low pressure too. Size any propane system with a table made for propane at the system's pressure and drop.

   B. Converting the load to propane's volume fixes only half the difference. The table's volumes assume natural gas's specific gravity; propane vapour is about 2.6 times denser (1.52 ÷ 0.58), so a given pipe passes less propane volume than the table shows.

   D. A heavier gas does pass less volume, but each cubic foot of propane carries much more heat, so for the same Btuh a propane pipe is usually no larger and often smaller. An arbitrary size-up is not a method; use a propane table.

5. Recall · The Ontario pressure-test tag: contents, who attaches it, where

   A signed-off G.3 under general supervision finishes the pressure test of a new 1/2 in. branch to a dryer late in the day. The dryer will not be connected until next week. Under Ontario's amendment to B149.1, when is the test tag attached?

   1. When the dryer is connected and its joints are tested
   2. Within 14 days, with any notice sent to the distributor
   3. Immediately after the pressure test is completed
   4. Before the gas is turned on to the new branch
   Show the answer

   C. Correct. Ontario's amendment to B149.1 (CAD amendment FS-279-26) has the person who performed the pressure test attach the tag immediately afterward, and completing the tag is part of the piping work O. Reg. 215/01 s. 22(1) gives a signed-off G.3. It goes on now, not when the dryer is set.

   Why not the others

   A. The tag records this pressure test, so it is not held back until the dryer is connected. Ontario's amendment has the person who did the test attach the tag immediately afterward.

   B. 14 days is the period O. Reg. 212/01 gives a certificate holder for written notice to the distributor of an unacceptable condition; it has nothing to do with test tags. The tag is attached immediately after the test.

   D. Turning on the gas is not the deadline. Ontario's amendment ties the tag to the test itself: the person who did it attaches the tag immediately afterward, whenever the gas is turned on.

02Answer key

03What module 8 covers

Gas piping and tubing from the meter or service valve to the appliance: steel pipe, copper, aluminum, polyethylene and corrugated stainless steel tubing, appliance connectors, threaded and flared joints, fittings and manual valves and the tools for each, planning, supporting and protecting a run, drip pockets and shut-off valves under Ontario's rules, what G.3 piping work covers, sizing by load and length, pressure and leak tests and Ontario's test tag, purging and activating, and the water piping met at water heaters and boilers.

TSSA names module 8 “Introduction to Piping and Tubing Systems”. It gives its G3 curriculum only to accredited training providers, so the seven objectives below are TicketPrep's own, built from public sources such as college course outlines and Ontario's regulations, not TSSA's. TSSA does not publish the G3 question count or how many exam questions come from each module: its prep guide gives no G3 count and no per-module count, and candidates who fail get a mastery report broken down by module. The right-hand column is how many questions our bank holds on each objective, Standard and Advanced together, not a count from the exam.

04What the questions turn on

Read the table at the longest length

With the longest-length method, every section is read at the length to the farthest outlet, branches included, not at its own short length. When that length falls between two columns, the next longer column is used. Add an outlet farther out and the longest length grows, so every section is checked again, even those whose load has not changed.

Ontario's figures for pockets, valves and cover

Ontario's amendments set figures used on almost every job: a drip pocket at least 3 in. (75 mm) deep or the pipe's inside diameter, whichever is greater; a manual shut-off valve for a residential appliance within 50 ft (15 m) of it, readily accessible and identified by a metal tag or a permanent sign; and at least 15 in. (400 mm) of cover over buried piping, 24 in. (600 mm) under a commercial driveway or parking lot.

Test before it is hidden, and read the test fairly

Piping is pressure-tested before it is concealed, while every joint can still be reached. A falling gauge is not always a leak: piping that cools as the sun moves off it loses pressure, and a lit pilot draws gas from a closed system. In both cases the test is repeated under steady conditions, with nothing burning.

Purge every run, to a safe place

New piping is purged so the burner gets gas, not air or an air-gas mix. Gas reaches only the open purge point, so each run beyond it is purged in turn. Propane is purged in open air, clear of window wells and low spots where the heavier vapour would collect. Before a line is cut into, the gas trapped behind the closed valve is bled off to a safe point outdoors.

05The other modules

The G3 exam covers nine modules, 1 to 9. Each has its own page of free questions:

The TSSA G3 practice test page describes the full question bank. How these questions are written and checked: how our questions are made. Found a mistake? Tell us and we will fix it.