Millwright Certification Examination
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
Question 1
What is the primary purpose of a dial indicator when used in millwright alignment
procedures?
A. To measure surface hardness
B. To check rotational speed
C. To measure runout and alignment accuracy
D. To determine lubricant viscosity
Answer: C – To measure runout and alignment accuracy. Dial indicators are
precision tools used to detect minute displacements in rotating shafts, couplings,
and machine components, ensuring proper alignment and concentricity.
Question 2
When installing a taper-lock bushing, what is the correct sequence of tightening
the set screws?
A. Tighten the smallest screw first, then the largest
B. Tighten all screws evenly in a star pattern to final torque in one pass
C. Tighten the screws in a crisscross pattern to a preliminary torque, then to final
torque
D. Tighten the screws sequentially clockwise
,Answer: C – Tighten the screws in a crisscross pattern to a preliminary torque,
then to final torque. This ensures even seating of the bushing on the shaft and
prevents distortion or misalignment.
Question 3
Which type of bearing is most suitable for applications with high radial loads and
moderate thrust loads?
A. Deep-groove ball bearing
B. Angular-contact ball bearing
C. Spherical roller bearing
D. Tapered roller bearing
Answer: C – Spherical roller bearing. These bearings have high radial load
capacity and can accommodate moderate thrust loads in both directions, with
self-aligning capability.
Question 4
What is the recommended maximum allowable shaft misalignment for a flexible
coupling under normal operating conditions?
A. 0.001 inch per inch of spacer length
B. 0.005 inch total indicated reading (TIR)
C. 0.010 inch per foot of shaft diameter
D. Dependent on coupling type and manufacturer specifications
Answer: D – Dependent on coupling type and manufacturer specifications.
Different flexible couplings (gear, grid, elastomeric) have varying misalignment
tolerances; always follow OEM data.
Question 5
In laser alignment systems, what does the term "sweep" refer to?
A. The rotational speed of the shaft during measurement
,B. The angular movement of the laser detector around the shaft
C. The process of recording readings at multiple points around the coupling
D. The initial calibration of the laser emitter
Answer: C – The process of recording readings at multiple points around the
coupling. Sweeping involves taking measurements at 90° intervals to map the
alignment condition of two shafts.
Question 6
What is the primary reason for preheating cast iron before welding?
A. To increase tensile strength
B. To reduce thermal shock and prevent cracking
C. To improve machinability
D. To remove surface contaminants
Answer: B – To reduce thermal shock and prevent cracking. Cast iron has low
ductility and high carbon content; preheating slows cooling rates, reducing the
risk of martensite formation and cracking.
Question 7
Which fastener grade is typically required for high-strength structural applications
in millwright work?
A. Grade 2
B. Grade 5
C. Grade 8
D. Grade 10.9
Answer: C – Grade 8. Grade 8 bolts (SAE J429) have a minimum tensile strength
of 150,000 psi and are used in heavy-duty equipment and structural connections.
Question 8
When performing a hydrostatic test on a pressure vessel, the test pressure is
, generally what percentage of the maximum allowable working pressure (MAWP)?
A. 100%
B. 125%
C. 150%
D. 200%
Answer: C – 150%. ASME Boiler and Pressure Vessel Code typically requires
hydrostatic tests at 1.5 times the MAWP to ensure structural integrity.
Question 9
What is the function of a thrust bearing in a centrifugal pump?
A. To support radial loads only
B. To maintain rotor axial position
C. To increase pump efficiency
D. To reduce cavitation
Answer: B – To maintain rotor axial position. Thrust bearings absorb axial forces
generated by the impeller and keep the rotor within its designed operating
clearance.
Question 10
Which lubricant viscosity grade is commonly used for general-purpose plain
bearings in moderate-temperature industrial environments?
A. ISO VG 32
B. ISO VG 46
C. ISO VG 68
D. ISO VG 100
Answer: C – ISO VG 68. This mid-range viscosity provides adequate oil film
thickness for many journal bearings at typical operating temperatures (40–
60°C).
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
Question 1
What is the primary purpose of a dial indicator when used in millwright alignment
procedures?
A. To measure surface hardness
B. To check rotational speed
C. To measure runout and alignment accuracy
D. To determine lubricant viscosity
Answer: C – To measure runout and alignment accuracy. Dial indicators are
precision tools used to detect minute displacements in rotating shafts, couplings,
and machine components, ensuring proper alignment and concentricity.
Question 2
When installing a taper-lock bushing, what is the correct sequence of tightening
the set screws?
A. Tighten the smallest screw first, then the largest
B. Tighten all screws evenly in a star pattern to final torque in one pass
C. Tighten the screws in a crisscross pattern to a preliminary torque, then to final
torque
D. Tighten the screws sequentially clockwise
,Answer: C – Tighten the screws in a crisscross pattern to a preliminary torque,
then to final torque. This ensures even seating of the bushing on the shaft and
prevents distortion or misalignment.
Question 3
Which type of bearing is most suitable for applications with high radial loads and
moderate thrust loads?
A. Deep-groove ball bearing
B. Angular-contact ball bearing
C. Spherical roller bearing
D. Tapered roller bearing
Answer: C – Spherical roller bearing. These bearings have high radial load
capacity and can accommodate moderate thrust loads in both directions, with
self-aligning capability.
Question 4
What is the recommended maximum allowable shaft misalignment for a flexible
coupling under normal operating conditions?
A. 0.001 inch per inch of spacer length
B. 0.005 inch total indicated reading (TIR)
C. 0.010 inch per foot of shaft diameter
D. Dependent on coupling type and manufacturer specifications
Answer: D – Dependent on coupling type and manufacturer specifications.
Different flexible couplings (gear, grid, elastomeric) have varying misalignment
tolerances; always follow OEM data.
Question 5
In laser alignment systems, what does the term "sweep" refer to?
A. The rotational speed of the shaft during measurement
,B. The angular movement of the laser detector around the shaft
C. The process of recording readings at multiple points around the coupling
D. The initial calibration of the laser emitter
Answer: C – The process of recording readings at multiple points around the
coupling. Sweeping involves taking measurements at 90° intervals to map the
alignment condition of two shafts.
Question 6
What is the primary reason for preheating cast iron before welding?
A. To increase tensile strength
B. To reduce thermal shock and prevent cracking
C. To improve machinability
D. To remove surface contaminants
Answer: B – To reduce thermal shock and prevent cracking. Cast iron has low
ductility and high carbon content; preheating slows cooling rates, reducing the
risk of martensite formation and cracking.
Question 7
Which fastener grade is typically required for high-strength structural applications
in millwright work?
A. Grade 2
B. Grade 5
C. Grade 8
D. Grade 10.9
Answer: C – Grade 8. Grade 8 bolts (SAE J429) have a minimum tensile strength
of 150,000 psi and are used in heavy-duty equipment and structural connections.
Question 8
When performing a hydrostatic test on a pressure vessel, the test pressure is
, generally what percentage of the maximum allowable working pressure (MAWP)?
A. 100%
B. 125%
C. 150%
D. 200%
Answer: C – 150%. ASME Boiler and Pressure Vessel Code typically requires
hydrostatic tests at 1.5 times the MAWP to ensure structural integrity.
Question 9
What is the function of a thrust bearing in a centrifugal pump?
A. To support radial loads only
B. To maintain rotor axial position
C. To increase pump efficiency
D. To reduce cavitation
Answer: B – To maintain rotor axial position. Thrust bearings absorb axial forces
generated by the impeller and keep the rotor within its designed operating
clearance.
Question 10
Which lubricant viscosity grade is commonly used for general-purpose plain
bearings in moderate-temperature industrial environments?
A. ISO VG 32
B. ISO VG 46
C. ISO VG 68
D. ISO VG 100
Answer: C – ISO VG 68. This mid-range viscosity provides adequate oil film
thickness for many journal bearings at typical operating temperatures (40–
60°C).
