MARYLAND STATIONARY ENGINEER GRADE
4 EXAM PREP | 200 PRACTICE QUESTIONS
WITH ANSWERS & DETAILED
EXPLANATIONS (2026–2027) | LOW-
PRESSURE BOILER OPERATOR LICENSING
STUDY GUIDE
• This 200-question practice bank mirrors the Maryland Stationary Engineer Grade 4
/ Low-Pressure Boiler Operator licensing exam, covering every domain tested —
boiler operations, safety controls, fuel systems, water treatment, steam systems,
and applicable codes.
• Study by attempting each question independently before checking the highlighted
correct answer and EXPERT RATIONALE below it — repetition across all 200
questions builds the pattern recognition needed to pass.
MARYLAND STATIONARY ENGINEER GRADE 4 EXAM PREP 200 PRACTICE
QUESTIONS | LOW-PRESSURE BOILER OPERATOR LICENSING 2026–2027
EDITION
SECTION 1: BOILER FUNDAMENTALS & CLASSIFICATION
1. What is the maximum allowable working pressure (MAWP) for a low-
pressure steam boiler?
A. 50 psi
B. 100 psi
C. 15 psi
D. 30 psi
E. 25 psi
C. 15 psi
,EXPERT RATIONALE: Low-pressure steam boilers are defined as operating at or
below 15 psi steam pressure. This is the threshold established by the ASME Boiler
and Pressure Vessel Code and adopted by Maryland boiler regulations.
2. A hot water heating boiler is classified as low-pressure when it operates at
or below what temperature?
A. 180°F
B. 212°F
C. 250°F
D. 300°F
E. 200°F
C. 250°F
EXPERT RATIONALE: Hot water heating boilers operating at or below 250°F and
160 psi are classified as low-pressure. Above 250°F, the boiler is considered a high-
temperature hot water boiler requiring different licensing.
3. Which of the following best describes a fire-tube boiler?
A. Water flows through tubes surrounded by fire and hot gases
B. Fire and hot gases pass through tubes surrounded by water
C. Steam is generated in a coil submerged in water
D. Combustion occurs outside the pressure vessel entirely
E. Water circulates through an external heat exchanger
B. Fire and hot gases pass through tubes surrounded by water
EXPERT RATIONALE: In a fire-tube boiler, combustion gases travel through tubes
that are immersed in water. The heat transfers from the gases through the tube
walls into the surrounding water, generating steam.
,4. What type of boiler is most commonly found in low-pressure heating
systems in Maryland commercial buildings?
A. Water-tube boiler
B. Cast iron sectional boiler
C. Coil-type boiler
D. Once-through boiler
E. Waste heat boiler
B. Cast iron sectional boiler
EXPERT RATIONALE: Cast iron sectional boilers are widely used in low-pressure
heating applications because of their durability, ease of on-site assembly, and
suitability for hot water and low-pressure steam systems in commercial buildings.
5. The term "boiler horsepower" is equivalent to the evaporation of how
many pounds of water per hour from and at 212°F?
A. 24.5 lbs/hr
B. 34.5 lbs/hr
C. 44.5 lbs/hr
D. 54.5 lbs/hr
E. 29.5 lbs/hr
B. 34.5 lbs/hr
EXPERT RATIONALE: One boiler horsepower equals the evaporation of 34.5
pounds of water per hour from and at 212°F, equivalent to 33,475 BTU/hr. This is
the standard industry definition used in boiler sizing and licensing exams.
6. Which code governs the construction and inspection of boilers in Maryland?
, A. NFPA 85
B. ASME Boiler and Pressure Vessel Code
C. API 510
D. OSHA 1910.217
E. ANSI B31.1
B. ASME Boiler and Pressure Vessel Code
EXPERT RATIONALE: The ASME Boiler and Pressure Vessel Code is the
foundational standard for boiler construction and is adopted by Maryland as the
basis for its boiler safety regulations and inspection requirements.
7. What does the term "heating surface" refer to in a boiler?
A. The outer casing of the boiler shell
B. Any surface exposed to fire or hot gases on one side and water or steam on the
other
C. The surface area of the burner flame
D. The area of the firebox floor
E. The total square footage of the boiler room floor
B. Any surface exposed to fire or hot gases on one side and water or steam
on the other
EXPERT RATIONALE: Heating surface is the area through which heat is transferred
from combustion gases to water. It is a key factor in determining boiler capacity
and is expressed in square feet.
8. A scotch marine boiler is an example of which boiler type?
A. Water-tube boiler
B. Electric boiler
4 EXAM PREP | 200 PRACTICE QUESTIONS
WITH ANSWERS & DETAILED
EXPLANATIONS (2026–2027) | LOW-
PRESSURE BOILER OPERATOR LICENSING
STUDY GUIDE
• This 200-question practice bank mirrors the Maryland Stationary Engineer Grade 4
/ Low-Pressure Boiler Operator licensing exam, covering every domain tested —
boiler operations, safety controls, fuel systems, water treatment, steam systems,
and applicable codes.
• Study by attempting each question independently before checking the highlighted
correct answer and EXPERT RATIONALE below it — repetition across all 200
questions builds the pattern recognition needed to pass.
MARYLAND STATIONARY ENGINEER GRADE 4 EXAM PREP 200 PRACTICE
QUESTIONS | LOW-PRESSURE BOILER OPERATOR LICENSING 2026–2027
EDITION
SECTION 1: BOILER FUNDAMENTALS & CLASSIFICATION
1. What is the maximum allowable working pressure (MAWP) for a low-
pressure steam boiler?
A. 50 psi
B. 100 psi
C. 15 psi
D. 30 psi
E. 25 psi
C. 15 psi
,EXPERT RATIONALE: Low-pressure steam boilers are defined as operating at or
below 15 psi steam pressure. This is the threshold established by the ASME Boiler
and Pressure Vessel Code and adopted by Maryland boiler regulations.
2. A hot water heating boiler is classified as low-pressure when it operates at
or below what temperature?
A. 180°F
B. 212°F
C. 250°F
D. 300°F
E. 200°F
C. 250°F
EXPERT RATIONALE: Hot water heating boilers operating at or below 250°F and
160 psi are classified as low-pressure. Above 250°F, the boiler is considered a high-
temperature hot water boiler requiring different licensing.
3. Which of the following best describes a fire-tube boiler?
A. Water flows through tubes surrounded by fire and hot gases
B. Fire and hot gases pass through tubes surrounded by water
C. Steam is generated in a coil submerged in water
D. Combustion occurs outside the pressure vessel entirely
E. Water circulates through an external heat exchanger
B. Fire and hot gases pass through tubes surrounded by water
EXPERT RATIONALE: In a fire-tube boiler, combustion gases travel through tubes
that are immersed in water. The heat transfers from the gases through the tube
walls into the surrounding water, generating steam.
,4. What type of boiler is most commonly found in low-pressure heating
systems in Maryland commercial buildings?
A. Water-tube boiler
B. Cast iron sectional boiler
C. Coil-type boiler
D. Once-through boiler
E. Waste heat boiler
B. Cast iron sectional boiler
EXPERT RATIONALE: Cast iron sectional boilers are widely used in low-pressure
heating applications because of their durability, ease of on-site assembly, and
suitability for hot water and low-pressure steam systems in commercial buildings.
5. The term "boiler horsepower" is equivalent to the evaporation of how
many pounds of water per hour from and at 212°F?
A. 24.5 lbs/hr
B. 34.5 lbs/hr
C. 44.5 lbs/hr
D. 54.5 lbs/hr
E. 29.5 lbs/hr
B. 34.5 lbs/hr
EXPERT RATIONALE: One boiler horsepower equals the evaporation of 34.5
pounds of water per hour from and at 212°F, equivalent to 33,475 BTU/hr. This is
the standard industry definition used in boiler sizing and licensing exams.
6. Which code governs the construction and inspection of boilers in Maryland?
, A. NFPA 85
B. ASME Boiler and Pressure Vessel Code
C. API 510
D. OSHA 1910.217
E. ANSI B31.1
B. ASME Boiler and Pressure Vessel Code
EXPERT RATIONALE: The ASME Boiler and Pressure Vessel Code is the
foundational standard for boiler construction and is adopted by Maryland as the
basis for its boiler safety regulations and inspection requirements.
7. What does the term "heating surface" refer to in a boiler?
A. The outer casing of the boiler shell
B. Any surface exposed to fire or hot gases on one side and water or steam on the
other
C. The surface area of the burner flame
D. The area of the firebox floor
E. The total square footage of the boiler room floor
B. Any surface exposed to fire or hot gases on one side and water or steam
on the other
EXPERT RATIONALE: Heating surface is the area through which heat is transferred
from combustion gases to water. It is a key factor in determining boiler capacity
and is expressed in square feet.
8. A scotch marine boiler is an example of which boiler type?
A. Water-tube boiler
B. Electric boiler
