up-Stationary Grade 3 Engineering License Exam Questions
and Answers
Page 1 of 149
,Question 1
why is a row of tubes sometimes left out of an HRT boiler?
Correct Answer
to improve circulation reducing carryover
Question 2
what is a water wall?
Correct Answer
a set of tubes containing boiler water set in the refractory. they absorb heat that would otherwise be lost to the
refractory and they increase the capacity of the boiler
Question 3
What type stays are used in wet back (Scotch Marine) type boilers?
Correct Answer
stay bolts and through stays. these sometimes will have a telltale drilled in them
Page 2 of 149
,Question 4
what is a lap joint?
what is a butt joint?
what is a butt-strap joint?
Correct Answer
LAP JOINT = when one plate overlaps the other and is joined
BUTT JOINT = when two ends of the plate meet end to end and are joined
BUTT-STRAP JOINT = when two ends of the plate meet end to end and are joined by a plate. (one plate is a single
butt strap joint / two plates are a double butt strap joint)
Question 5
what are tube ligaments?
Correct Answer
the area between the tube holes on the tube sheet
Page 3 of 149
, Question 6
two boilers are make of the same grade of steel, same thickness of plate and same type of joints. one is 30" in
diameter the other is 60" diameter. which will withstand the greatest pressure and demonstrate your answer
Correct Answer
the 30" boiler-it has less total pressure on the shell.
DxDx.7854(1/4pi)xpsi
30x30x.7854x120 psi = 84,823 lbs. total pressure
60x60x.7854x120 psi = 339,292 lbs. total pressure
show your work on everything!
Question 7
what is a radiant type superheater?
what is a convection type superheater?
what is the third type of superheater?
Correct Answer
A radiant superheater is set over the fire to absorb radiant heat from the furnace by direct radiation
a convection superheater is placed in the gas passage of the furnace, usually between the first and second pass. little
to no radiation will reach this type
the third type is a combination of radiant and convection
Page 4 of 149
and Answers
Page 1 of 149
,Question 1
why is a row of tubes sometimes left out of an HRT boiler?
Correct Answer
to improve circulation reducing carryover
Question 2
what is a water wall?
Correct Answer
a set of tubes containing boiler water set in the refractory. they absorb heat that would otherwise be lost to the
refractory and they increase the capacity of the boiler
Question 3
What type stays are used in wet back (Scotch Marine) type boilers?
Correct Answer
stay bolts and through stays. these sometimes will have a telltale drilled in them
Page 2 of 149
,Question 4
what is a lap joint?
what is a butt joint?
what is a butt-strap joint?
Correct Answer
LAP JOINT = when one plate overlaps the other and is joined
BUTT JOINT = when two ends of the plate meet end to end and are joined
BUTT-STRAP JOINT = when two ends of the plate meet end to end and are joined by a plate. (one plate is a single
butt strap joint / two plates are a double butt strap joint)
Question 5
what are tube ligaments?
Correct Answer
the area between the tube holes on the tube sheet
Page 3 of 149
, Question 6
two boilers are make of the same grade of steel, same thickness of plate and same type of joints. one is 30" in
diameter the other is 60" diameter. which will withstand the greatest pressure and demonstrate your answer
Correct Answer
the 30" boiler-it has less total pressure on the shell.
DxDx.7854(1/4pi)xpsi
30x30x.7854x120 psi = 84,823 lbs. total pressure
60x60x.7854x120 psi = 339,292 lbs. total pressure
show your work on everything!
Question 7
what is a radiant type superheater?
what is a convection type superheater?
what is the third type of superheater?
Correct Answer
A radiant superheater is set over the fire to absorb radiant heat from the furnace by direct radiation
a convection superheater is placed in the gas passage of the furnace, usually between the first and second pass. little
to no radiation will reach this type
the third type is a combination of radiant and convection
Page 4 of 149
