164-184 Flashcards
164.What is a fire crack and is it considered dangerous? What is a tension crack and is it
considered dangerous?
A fire crack goes from a rivet hole to the edge of the plate and is generally not dangerous.
A tension crack goes from rivet to rivet and is very dangerous. The boiler should be removed from service.
- How do you wash and prepare a boiler for inspection? How often is your boiler inspected?
What is the most important item to check for?
Test safety valves two weeks prior so they can be observed for leakage. Call inspector for appointment. Reduce T.D.S. with blowdown so solids won’t adhere during cool down. Operate sootblower. Shut down boiler. Close, lock and tag all valves. Turn off, lock and tag electrical switches and breakers. Allow boiler to cool. Open vents and drain completely. Remove all manholes and handholes. Remove drains and blowdown lines. Save a sample of the boiler mud for your water treater. With high pressure water wash boiler from top to bottom, front to rear toward the drains. Clear the scale from hand holes and drains as needed. Remove plugs from water column, rod and wash piping. Remove and clean both low water devices. Open and clean ash, slag, and soot, from the fire side. Do not wash the fireside! Assemble any repair records. Accompany the inspector. The boiler is inspected annually. Tension cracks are the most important item to check for. SPO 7442-445 8463 9395 BOW 2220 3281 4294
- What precautions should be taken before removing a manhole cover?
Make sure the boiler shell is vented and drained.
- Give three reasons to vent a boiler shell. What would happen if the boiler shell was not vented when it was drained?
To let air out when filling the boiler with water, to break the vacuum when draining the boiler and to evacuate air from the boiler on start-up.
Air would not be drawn in and a vacuum would develop causing leaks, a boiler implosion, siphon treatment chemicals into the boiler or cause someone to be scalded when they remove the manhole cover.
BOW 365,281 468,295
- When operating a boiler with a pressurized furnace, why is it important to regularly inspect the outer skin of the boiler and how do you inspect it?
Pressurized furnaces are undesirable because flue gas leaking into the boiler room is a deadly health hazard.
Frequently check the outer skin and gaskets for visible damage and hot spots.
BOW 2nd194 3229 4237,238
- How is a leak in the shell detected on a negative pressure furnace?
A smoke stick or ultrasonic test.
BOW 2”d194 3rd230 4*238
- How many ways are there to patch boiler drums/shells?
Bolting, riveting, and welding.
SPO 6*319
- Why are hot water systems more desirable than steam systems for heating buildings? Name two types hot water boiler heating systems.
Hot water heat is more consistent because water retains its heat as it circulates and steam loses its heat rapidly as it condenses.
Two types are natural circulation and forced circulation.
- What is a diverter fitting?
A fitting that meters the water flow from the supply line to the individual heating units.
- Name four safety devices on a hot water boiler.
Temperature-pressure relief valve, water flow-proving switch, high-pressure cutoff switch, high temperature aqua-stat, flame scanners, low water cutoff.
- In hot water heating systems, how often do you test the safety relief valve and how long is
the valve held open?
It is tested every 30 days of boiler operation or after any period of inactivity and once a year under pressure. The try lever is lifted wide open for a minimum of 5 to 10 seconds or until clean water comes out.
LPB2nd216 3rd246
- What devices insure that a pump is running in a hot water system?
A water flow-proving switch or a differential switch.
- What is an aqua-stat?
The aqua-stat is a temperature-sensing device. On a heating system it is used start and stop the burner, open a valve or start a fan.
- If you had an expansion (compression) tank on your system, where would it be located and
where would the water level be in it? Why don’t all expansion tanks have sight glasses?
It will usually be located near the top of the system with the water level mid-way in the tank.
The level will go up and down as the temperature and pressure changes.
The tank may use a bladder or diaphragm eliminating the need for a sight glass
- You have a water boiler and you discover the sight glass on the expansion (compression) tank was completely full and the system pressure was higher than normal. What will happen next and how will you correct this?
The relief valve will relieve excess pressure.
I would isolate and drain the tank and repair the leaks by tightening fittings and replacing
sight glass washers before refilling the tank.
