Safety and Relief Valves

Question 1

Safety valves “pop” open because the force of the steam

a) acts upon a blowdown ring
b) acts upon a huddling chamber
c) is suddenly increased due to a larger area
d) increases due to the discharge ports
e) decreases the force created by the spring

Answer 1

c) is suddenly increased due to a larger area

Question 2

If a safety valve is too small then the boiler pressure will
a) rise 5% above the maximum allowable working pressure
(MAWP)
b) not rise more than 15% above the MAWP
c) remain at the MAWP
d) rise to 6% above the MAWP
e) rise more than 6% above the MAWP

Answer 2

e) rise more than 6% above the MAWP

Question 3

Boiler fittings

a) are not regulated by the ASME Codes
b) must be registered by the government
c) requires only the manufacturer’s identity attached
d) may be used at the discretion of power plant personnel
e) are tested by a destructive test

Answer 3

b) must be registered by the government

Question 4

It is necessary to clearly mark or identify valves
and fittings so that
a) they can be properly stored in the warehouse
b) the manufacturer’s reputation is known
c) strength and material can be applied for a particular use
d) the operator knows how it works
e) a proper safety inventory can be maintained

Answer 4

c) strength and material can be applied for a particular use

Question 5

An agency or code with which fittings must comply with is the

a) Health and Safety code
b) Fittings and Boiler Parts Act
c) Boiler Repair code
d) Plumbing Gas Act
e) ASME code

Answer 5

e) ASME code

Question 6

If a safety valve fails to open at its popping pressure, you should

a) tap it gently
b) try the lifting lever
c) shut the boiler down
d) raise the pressure
e) reface the valve

Answer 6

b) try the lifting lever

Question 7

The lip on a safety valve

a) allows it to close slowly
b) is only required if the steam is superheated
c) supplies a drain lip for condensate to collect on
d) makes the valve stronger
e) allows it to “pop” open

Answer 7

e) allows it to “pop” open

Question 8

What does the boiler inspector install to prevent tampering with
a safety valve setting?
a) a restraining order
b) a gag
c) a seal
d) a plug
e) a cover plate

Answer 8

c) a seal

Question 9

What is the maximum heating surface for a boiler
to have only one safety valve?
a) 75 square metres
b) 47 square metres
c) 36 square metres
d) 28 square metres
e) 19 square metres

Answer 9

b) 47 square metres

Question 10

If a boiler has a maximum allowable working pressure of 1000 kPa,
what would be the maximum pressure allowed when the safety
valve is open?
a) 1060 kPa
b) 1400 kPa
c) 1600 kPa
d) 2000 kPa
e) 2500 kPa

Answer 10

a) 1060 kPa

Question 11

A stop valve is allowed between the safety valve and the boiler
drum when
a) the stop valve is locked open
b) there is more than one safety valve
c) a rupture disc is placed between the stop valve and the
safety valve
d) no stop valves are allowed before or after the safety valve
e) the stop valve is the quick opening type

Answer 11

d) no stop valves are allowed before or after the safety valve

Question 12

Two safety valves are required on a high pressure steam boiler
that has a heating surface larger than
a) 12 square metres
b) 40 square metres
c) 47 square metres
d) 45 square metres
e) 27 square metres

Answer 12

c) 47 square metres

Question 13

If the boiler was fired up with the main steam stop valve closed,
the safety valves should ensure that:
a) the pressure cannot exceed the maximum working pressure by more
than 6%
b) the water glass will not burst with the pressure
c) the fuel cut-off will operate
d) the pressure is never more than the hydrostatic test pressure
e) the pressure cannot exceed the maximum working pressure by more
than 3%

Answer 13

a) the pressure cannot exceed the maximum working pressure by more
than 6%

Question 14

What is the minimum number of safety valves required on a
boiler having a heating surface of 42 square metres?
a) none
b) one
c) two
d) three
e) four

Answer 14

b) one

Question 15

Each boiler must have a safety valve, preferably
a) placed in a pipe system leading from a boiler valve
b) welded in a horizontal position to the top of the boiler
c) fitted securely to a shut-off valve directly connected
to the top of the boiler
d) at eye level on the front surface of the boiler
e) fitted in a vertical position directly connected
to the top of the boiler

Answer 15

e) fitted in a vertical position directly connected

to the top of the boiler

Question 16

The safety valves on a boiler meet code requirements and are set
to a popping pressure of 1380 kPa. What would be the maximum
permissible pressure rise in the boiler, if the boiler was fired
at full capacity with the main steam stop valve closed?
a) 25 kPa
b) 37.5 kPa
c) 47 kPa
d) 72.4 kPa
e) 82.8 kPa

Answer 16

e) 82.8 kPa

Question 17

The discharge pipe of a safety valve should be separately
supported
a) because the safety valve is not capable of supporting the
mass
b) so that drainage of the discharge line can occur
c) so that allowance for expansion prevents stress on the
safety valve
d) in order to prevent leakage at the joint
e) so that the valve can be quickly and easily removed

Answer 17

c) so that allowance for expansion prevents stress on the

safety valve

Question 18

Cast iron fittings for a boiler can be deemed to have upper
limitations of
a) 1,720 kPa and 232 degrees C
b) 17,200 kPa and 1,100 degrees C
c) 1,100 kPa and 173 degrees C
d) 8,000 kpa and 670 degrees C
e) 3,000 kPa and 150 degrees C

Answer 18

a) 1,720 kPa and 232 degrees C

Question 19

The popping pressure of a safety valve

a) cannot be changed
b) can only be increased by 5%
c) can only be decreased by 5%
d) can be increased or decreased by up to 5%
e) can be changed any amount

Answer 19

d) can be increased or decreased by up to 5%

Question 20

The blowdown on a safety valve is adjusted by turning the

a) inspector’s seal
b) valve disc
c) adjusting nut
d) adjusting ring
e) valve seat

Answer 20

d) adjusting ring

Question 21

A blowdown ring on a safety valve is used to

a) adjust the operating pressure of the valve
b) set the opening pressure
c) increase the effectiveness of the safety valve
d) increase the life of the cone shaped lip
e) adjust the blowdown differential

Answer 21

e) adjust the blowdown differential

Question 22

A try lever safety valve test will

a) ensure the popping pressure is correct
b) indicate that valve capacity is adequate
c) ensure the closing pressure is correct
d) take approximately 2 seconds
e) ensure the valve is free to operate

Answer 22

e) ensure the valve is free to operate

Question 23

When performing a safety valve pop test one of the first
things to do is
a) notify the boiler inspector
b) verify the accuracy of the applicable steam pressure gage
c) notify the chief engineer
d) check the blowdown of the safety valve
e) check the popping pressure

Answer 23

b) verify the accuracy of the applicable steam pressure gage

Question 24

A safety relief valve is like a safety valve except it
a) does not have a blowdown ring or bottom guides
b) must have greater blowdown
c) may have an isolation valve placed between it and the
pressure vessel
d) must discharge directly to the atmosphere
e) is prone to leakage

Answer 24

a) does not have a blowdown ring or bottom guides

Question 25

Temperature relief valves can open on a rise in temperature
by the expansion of a wax-filled rod or by the
a) melting of the alloy in a fusible plug
b) melting of a fusible link
c) action of a bi-metal strip
d) action of a Bourdon tube
e) action of a bellows

Answer 25

a) melting of the alloy in a fusible plug

Question 26

If the safety valve starts to leak steam

a) phone the inspector immediately
b) report it to the insurance company
c) pull the test lever and try to clear the seat face
d) break the seal, and tighten down on the spring
e) adjust the blowdown of the safety valve

Answer 26

c) pull the test lever and try to clear the seat face

Question 27

An operator should check that a boiler safety valve will open
at its set pressure by
a) sending for the inspector to bring his or her test gauge
b) increasing the boiler pressure until the valve opens and noting
the pressure on the pressure gauge when the valve opened
c) putting a piece of pipe over the lifting lever and lifting the
valve off its seat when the seat pressure is reached
d) connecting the boiler to an air compressor during shut down and
raising the pressure in the boiler until the set pressure is
reached
e) listening to the alarms of the set pressures

Answer 27

b) increasing the boiler pressure until the valve opens and noting
the pressure on the pressure gauge when the valve opened

Question 28

Testing the safety valve by means of the try lever method is
considered good practice when carried out on a
a) weekly basis
b) monthly basis
c) six month basis
d) yearly basis
e) bi-weekly basis

Answer 28

b) monthly basis

Question 29

If, during the testing of a safety valve, the valve does not
open, you would first
a) continue to increase the steam pressure
b) try to open the valve with the lifting lever
c) force it open by striking it with a hammer
d) take the boiler out of service
e) stop the boiler and notify the boiler branch

Answer 29

b) try to open the valve with the lifting lever

Question 30

Test levers on safety valves should not be used until the boiler
pressure is at least \_\_\_\_\_\_\_\_\_ or more of the safety valves normal
popping pressure.
a) 75%
b) 60%
c) 50%
d) 40%
e) 25%

Answer 30

a) 75%

Question 31

If a safety valve leaks after a try lever test, the operator
should
a) plug the safety valve outlet
b) reduce the boiler pressure
c) operate the try lever several times to blow away foreign
material
d) fit a gag to the safety valve
e) reduce boiler pressure and call the team leader

Answer 31

c) operate the try lever several times to blow away foreign

material

Question 32

Do not open the safety valve with the test lever

a) if the valve is less than 2.5 cm inlet diameter
b) if the pressure is less than 75% working pressure
c) after 9 p.m. in populated areas
d) if the valve is not vented to the roof
e) if there are more than two safety valves on the boiler

Answer 32

b) if the pressure is less than 75% working pressure