ITI Plumber Viva Questions and Answers
In the plumber practical, you cut, thread and join pipes or fit a fixture, test it for leaks, and the examiner then asks you how you did it. These are the questions asked most often, with short answers you can say in the viva.
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Your job first: correct lengths and angles, clean threads or solvent joints, the fixture level and firm, and no leak on test. Then your knowledge of pipes, fittings, traps, valves, drainage and safety.
Plumber viva questions with answers
Pipes and joints
Name the pipes used in water supply and how each is joined.
GI pipes are joined by threads. CPVC and uPVC pipes by solvent cement. PPR and HDPE pipes by heat fusion. Copper pipes by soldering, brazing or compression fittings.
How to say it: Name the pipe you used in your job first.
Why is CPVC used for hot water and not uPVC?
CPVC can carry hot water; uPVC softens at higher temperatures, so it is used for cold water and drainage.
How do you make a threaded joint leak-proof?
Cut a clean thread with the die, wrap PTFE (Teflon) tape in the direction of the thread, then tighten with a pipe wrench without over-tightening.
Which tools did you use to cut and thread the pipe?
A pipe vice to hold it, a pipe cutter or hacksaw to cut, a reamer to remove the burr, and a die stock with the right die to cut the thread.
What is the use of a union?
A union lets you open a pipe line for repair without turning the whole pipe.
Traps and drainage
What is a trap, and why is it fitted?
A bend that holds water, called the water seal. The water blocks bad smell and sewer gas from coming back into the room.
Name the common types of traps.
P-trap, S-trap and Q-trap by shape, plus the floor trap (nahani trap) and the gully trap outside the building.
Why is a vent pipe provided?
It lets air into the drainage system so the water seal in the traps is not sucked out, and it carries foul gases above the roof.
Why is an inspection chamber made?
To inspect and clean the drain where pipes join or change direction.
Why is a drain pipe laid with a slope?
So waste water flows by gravity and solids do not settle inside the pipe.
Valves and fittings
What is the difference between a gate valve and a globe valve?
A gate valve opens fully with little loss and is used to isolate a line. A globe valve controls the flow but causes more pressure loss.
Where is a non-return valve used?
Where water must flow one way only, such as the delivery side of a pump, so it does not flow back.
What does a float valve (ball valve) in a tank do?
The float rises with the water and closes the inlet when the tank is full.
What is water hammer?
A knock in the pipe when a valve shuts suddenly and the moving water stops. Closing valves slowly and air chambers or arrestors reduce it.
Testing and safety
How do you test a new pipe line?
Close the ends, fill it with water, raise the pressure with a hand test pump to the test pressure given for the job, and watch the gauge and joints for a drop or a leak.
What safety do you follow while plumbing?
Gloves and goggles while cutting and using solvent, ventilation when using solvent cement, isolate the water and electricity before repairs, and never enter a manhole or septic tank without proper safety arrangements.
Your opening answer to practise
Copy the lines that are true for you, replace every [bracket] and delete the rest. Every number should be one you can repeat in a practical test.
Opening answer for the Plumber viva
- My name is [name], roll number [number], trainee of ITI Plumber, [ITI name], session [year].
- Today my practical job was [e.g. cutting, threading and joining a GI pipe line with an elbow, tee and union].
- I followed the safety steps: [goggles and gloves worn, pipe held in the pipe vice, water isolated before testing].
- The result: [e.g. line tested with the hand test pump, no leak at any joint].
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Common questions
What questions are asked in the ITI plumber viva?
Pipe types and how each is joined, threading with a die, PTFE tape, union, traps and water seal, vent pipes, inspection chambers, slope of drains, gate, globe, non-return and float valves, water hammer, pressure testing and safety.
Which question is asked most often?
What a trap and water seal are, and how you made your joints leak-proof.
Will they test my job for leaks?
Often yes. Be ready to explain how you tested it and what you would do if a joint leaked.
Can I get these viva questions as a PDF?
Open the page, choose Print in your browser menu, then Save as PDF. The page prints without menus.
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