100+ Free AZ ROC Boilers, Steamfitting & Process Piping (C-4/CR-4) Practice Questions

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2026 Statistics

Key Facts: AZ ROC Boilers, Steamfitting & Process Piping (C-4/CR-4) Exam

Official Scored Questions

AZ ROC / PSI Bulletin

120 min

Exam Time Limit

PSI Services

70%

Passing Score (35/50)

Arizona ROC

$66

Trade Exam Fee

PSI / AZ ROC

20%

Boilers Blueprint Weight

PSI Content Outline

36%

Piping Blueprint Weight (Steam/Hot Water, Gas, Process)

PSI Content Outline

The Arizona ROC C-4/CR-4 exam is a 50-question, 120-minute open-book computer-delivered trade exam administered by PSI requiring a 70% passing score ($66 fee). Content covers 9 blueprint sections: Boilers (10 questions), Steam & Hot Water Piping (6), Gas Piping (6), Process Piping (6), Burners (5), Controls (5), Flues & Vents (4), Sizing & Estimating (4), and Testing & Inspection (4). Local practice MCQs are an English-language MCQ study adaptation.

Sample AZ ROC Boilers, Steamfitting & Process Piping (C-4/CR-4) Practice Questions

Try these sample questions to test your AZ ROC Boilers, Steamfitting & Process Piping (C-4/CR-4) exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Under ASME Boiler and Pressure Vessel Code (BPVC) Section IV, what are the maximum allowable operating pressure limits for a heating boiler?

A.30 psig for steam boilers and 200 psig for hot water boilers

B.15 psig for steam boilers and 160 psig for hot water boilers

C.100 psig for steam boilers and 250 psig for hot water boilers

D.50 psig for steam boilers and 125 psig for hot water boilers

Explanation: ASME BPVC Section IV covers heating boilers and strictly limits steam boilers to a maximum allowable working pressure (MAWP) of 15 psig. Hot water heating boilers under Section IV are limited to 160 psig MAWP and a maximum water temperature of 250°F. Pressures or temperatures exceeding these thresholds fall under ASME Section I Power Boilers.

2Which of the following boiler classifications falls under the scope of ASME Boiler and Pressure Vessel Code Section I (Power Boilers)?

A.A low-pressure steam heating boiler operating at 12 psig

B.A hot water supply boiler operating at 120 psig and 210°F

C.A steam boiler operating at an allowable working pressure of 100 psig

D.A hydronic space heating boiler operating at 30 psig and 180°F

Explanation: ASME Section I applies to power boilers in which steam or other vapor is generated at a pressure greater than 15 psig, or high-temperature water boilers exceeding 160 psig or 250°F. A steam boiler operating at 100 psig exceeds 15 psig and must be constructed and stamped according to ASME Section I.

3What is a mandatory code rule regarding shutoff valves installed on the inlet connection between a steam boiler shell and its safety relief valve?

A.No stop valve or shutoff device of any description may be placed between the boiler and the safety valve

B.A lockable gate valve is permitted provided it remains sealed open during normal operation

C.A full-port ball valve may be installed only if equipped with a high-pressure bypass interlock

D.A check valve must be installed to prevent backflow into the boiler vessel

Explanation: ASME Section I and Section IV strictly prohibit any stop valve or isolation valve between the boiler shell and its safety valve or safety relief valve. Placing a valve in this line could allow accidental isolation of the safety relief device, creating a catastrophic overpressure explosion hazard.

4When installing a two-valve bottom blowdown line on a high-pressure steam boiler (operating above 100 psig), in what sequence should the valves be arranged from the boiler shell outward?

A.A slow-opening valve closest to the boiler, followed by a check valve

B.Two quick-opening blowoff valves placed in series

C.A quick-opening valve closest to the boiler, followed by a non-return valve

D.A quick-opening valve closest to the boiler shell, followed by a slow-opening valve

Explanation: According to ASME Section I (PG-59.1), when two valves are used on a bottom blowoff line, the quick-opening valve must be installed closest to the boiler shell and the slow-opening valve (requiring at least five 360-degree turns to open) is placed downstream. During blowdown operation, the quick-opening valve is opened first, then the slow-opening valve is cracked open to control flow and absorb wire-drawing wear.

5What is the primary operational function of a spray-tray deaerator installed in a commercial high-pressure steam boiler feed system?

A.To filter out total dissolved solids (TDS) and scale-forming calcium carbonates

B.To strip dissolved oxygen and carbon dioxide gases from feedwater by heating it to saturation temperature

C.To inject chemical water softeners and phosphates into the boiler drum

D.To condense high-pressure flash steam into low-temperature domestic hot water

Explanation: A deaerator heats incoming condensate and makeup water with steam to saturation temperature (typically 212°F to 227°F at slight positive pressure), which reduces the solubility of dissolved non-condensable gases (oxygen and CO2) to near zero (under 7 ppb O2). Removing oxygen prevents severe pitting corrosion in boiler tubes and feedwater piping.

6When performing a gauge glass blowdown on a steam boiler, what indication confirms that both the top steam connection and bottom water connection are clear and unobstructed?

A.Water remains static at the top of the glass when the drain valve is opened

B.Steam blows out with the drain open, and upon closing the drain, water rapidly returns to its normal operating level

C.The water level slowly trickles back up to the middle of the glass over 5 to 10 minutes

D.Water continuously overflows into the top gauge valve fitting

Explanation: During a proper gauge glass blowdown sequence, testing the steam and water valves individually should result in strong discharge. Upon closing the drain valve, water should immediately and rapidly snap back to the true boiler water level. A slow return indicates a restricted or clogged lower water piping passage.

7When assembling cast-iron sectional boilers, what material is used between the push nipples or section joints to seal against steam and water leaks, and how should draw rods be adjusted?

A.High-temperature elastomeric seals or sealant compound; draw rods must be backed off to finger-tight after pulling sections together

B.RTV silicone rubber; draw rods must remain torqued to 150 ft-lbs permanently

C.Asbestos rope packing; draw rods must be welded to the outer end sections

D.Lead gaskets; draw rods are tightened continuously until sections crack slightly

Explanation: Cast iron sectional boilers use machined push nipples or specialized elastomeric gaskets coated with sealant compound between section ports. Assembly tie-rods (draw rods) draw sections together; however, once sections are pulled tight, tie-rods must be backed off to finger-tight (or tensioned only via thermal expansion washers) to allow the cast iron sections to expand and contract without cracking during thermal cycles.

8What operational problem occurs when the Net Positive Suction Head Available (NPSHA) at a boiler feedwater pump inlet drops below the Net Positive Suction Head Required (NPSHR) by the pump manufacturer?

A.Pump motor overspeed and electrical breaker tripping

B.Boiler water level rises rapidly due to excessive pump discharge pressure

C.Thermal shock causes immediate cracking of the pump impeller shaft

D.Cavitation occurs, causing vapor bubble formation, impeller erosion, noise, and loss of pump capacity

Explanation: If NPSHA is less than NPSHR at a boiler feed pump handling high-temperature water (e.g., from a deaerator at 215°F), local fluid pressure drops below vapor pressure inside the impeller eye. Water flashes into steam bubbles that violently collapse as pressure rises, causing severe cavitation, pitting erosion of impellers, vibration, and loss of head.

9What is the primary structural difference between a firetube boiler and a watertube boiler?

A.In firetube boilers, water flows inside the tubes while hot gases surround them

B.In firetube boilers, hot combustion gases pass inside the tubes while water surrounds the outside of the tubes

C.Watertube boilers cannot be used for high-pressure steam applications above 15 psig

D.Firetube boilers contain no shell or drum and store zero water inventory

Explanation: In a firetube boiler, hot combustion gases from the burner travel through the inside of steel tubes immersed in a shell filled with water. In a watertube boiler, water circulates inside the tubes while hot combustion gases flow around the outside of the tubes. Watertube boilers are used for very high capacities and pressures.

10Why is the accumulation of mineral scale (such as calcium carbonate) on boiler heating surfaces extremely hazardous to boiler operation?

A.Scale increases electrical conductivity of the shell, causing stray ground faults

B.Scale reacts with steel to generate explosive hydrogen gas inside the boiler drum

C.Scale acts as an thermal insulator, preventing heat transfer to water and causing tube metal overheating, deformation, and rupture

D.Scale lowers the boiling point of water, preventing steam generation at operating pressure

Explanation: Mineral scale has very low thermal conductivity compared to steel. Even a thin layer of scale (e.g., 1/16 inch) insulates the metal tube wall from boiler water, preventing the water from cooling the tube. Combustion heat causes tube metal temperatures to surge past design limits, leading to overheating, bulging, and catastrophic tube rupture.

About the AZ ROC Boilers, Steamfitting & Process Piping (C-4/CR-4) Exam

The Arizona Registrar of Contractors (AZ ROC) C-4 Commercial and CR-4 Dual Boilers, Steamfitting and Process Piping examination evaluates candidate knowledge in low and high-pressure steam boilers, hot water heating systems, industrial process piping, burners, safety controls, gas piping, flues and vents, system sizing, and hydrostatic testing/inspection under ASME, NFPA, and OSHA codes.

Assessment

50 computer-delivered open-book multiple-choice questions administered at PSI centers. Passing score is 70% (35/50).

Time Limit

120 minutes

Passing Score

70%

Exam Fee

$66 (Arizona Registrar of Contractors / PSI Services LLC)

AZ ROC Boilers, Steamfitting & Process Piping (C-4/CR-4) Exam Content Outline

20%

Boilers

10 questions on official exam (20 out of 100 practice questions). Low and high-pressure steam boilers, hot water heating boilers, ASME Section I and IV construction codes, boiler trim, water level controls, relief valves, blowdown systems, and feed pumps.

12%

Steam and Hot Water Piping

6 questions on official exam (12 out of 100 practice questions). Steam supply and return mains, condensate piping, traps (thermostatic, float and thermostatic, inverted bucket), expansion joints, pipe pitch/slope, air vents, hydronic pumps, and balancing valves.

12%

Gas Piping

6 questions on official exam (12 out of 100 practice questions). NFPA 54 / IFGC fuel gas piping sizing, pressure drop tables, pipe materials (black steel, CSST), sediment traps, shutoff valves, gas pressure regulators, and purge procedures.

12%

Process Piping

6 questions on official exam (12 out of 100 practice questions). ASME B31.3 process piping design, chemical/industrial pipe materials, flanged and welded joints, gasket selection, valve types (gate, globe, ball, butterfly, check), pipe supports/hangers, and thermal stress relief.

10%

Burners

5 questions on official exam (10 out of 100 practice questions). Natural gas, LP, and fuel oil burner operation, atmospheric vs. power burners, combustion air requirements, air-to-fuel ratio, flame safeguards (flame rods, UV scanners), ignition systems, and stack gas draft.

10%

Controls

5 questions on official exam (10 out of 100 practice questions). Operating and safety controls, flame safeguard systems (ASME CSD-1), low water cutoffs (LWCO), high-pressure limits, high-temperature cutouts, aquastats, gas pressure switches, and safety interlocks.

Flues and Vents

4 questions on official exam (8 out of 100 practice questions). Category I-IV venting systems, draft hoods, barometric dampers, induced/forced draft fans, chimney height/clearances, vent sizing tables, and combustion clearance rules.

Sizing and Estimating

4 questions on official exam (8 out of 100 practice questions). Heat load calculations (BTU/hr, EDR), pipe sizing based on flow rate and velocity, expansion tank sizing, boiler horsepower conversion, takeoffs, and material estimations.

Testing and Inspection

4 questions on official exam (8 out of 100 practice questions). Hydrostatic testing of boilers and pressure piping (1.5x MAWP), pneumatic pressure testing, non-destructive examination (NDE/NDT), leak detection, safety valve pop testing, and national board / state inspection requirements.

How to Pass the AZ ROC Boilers, Steamfitting & Process Piping (C-4/CR-4) Exam

What You Need to Know

Passing score: 70%
Assessment: 50 computer-delivered open-book multiple-choice questions administered at PSI centers. Passing score is 70% (35/50).
Time limit: 120 minutes
Exam fee: $66

Keys to Passing

Work through all 100 available questions
Review every answer and explanation
Track weak areas and revisit them
Use our AI tutor for tough concepts

AZ ROC Boilers, Steamfitting & Process Piping (C-4/CR-4) Study Tips from Top Performers

1Master boiler horsepower and BTU conversions early: 1 Boiler HP = 33,475 BTU/hr = 34.5 lbs of steam per hour evaporated from and at 212°F.

2Tab your ASME and NFPA 54 reference books cleanly with permanent tabs for fast lookup during the timed test.

3Memorize key ASME Section IV and CSD-1 safety rules, such as mandatory manual-reset low water cutoffs (LWCO) and pressure relief valve discharge piping limits.

4Understand gas pipe sizing tables in NFPA 54, accounting for specific gravity, pipe length, pressure drop, and appliance demand in MBH.

5Practice hydrostatic test pressure calculations: standard ASME B31.1 and B31.3 hydrotests require 1.5 times the maximum allowable working pressure (MAWP).

Frequently Asked Questions

Which contractor license classifications use this examination?

This examination covers the Arizona Registrar of Contractors C-4 (Commercial) and CR-4 (Dual Commercial & Residential) Boilers, Steamfitting and Process Piping contractor licenses.

What is the format and passing score of the AZ ROC C-4 exam?

The examination consists of 50 open-book multiple-choice questions administered on a computer at PSI testing centers. Candidates have 120 minutes (2 hours) to complete the test and must achieve a minimum passing score of 70% (35 correct answers).

What reference books are permitted in the testing center?

Permitted reference manuals include approved code books such as ASME BPVC Sections I & IV, ASME B31.1 Power Piping, ASME B31.3 Process Piping, NFPA 54 National Fuel Gas Code, and ASME CSD-1, as listed in the official PSI Candidate Information Bulletin (L-4 outline).

What is the distinction between ASME Section I and ASME Section IV boilers?

ASME Section I governs Power Boilers (steam pressure over 15 psig or hot water pressure over 160 psig / temperature over 250°F). ASME Section IV governs Heating Boilers (steam pressure up to 15 psig or hot water up to 160 psig / 250°F).

How do I schedule my AZ ROC C-4 trade exam?

Exams are scheduled online through PSI Services at test-takers.psiexams.com/azcon or by phone. PSI operates testing centers in Phoenix, Tucson, Flagstaff, Yuma, and other locations.

100+ Free AZ ROC Boilers, Steamfitting & Process Piping (C-4/CR-4) Practice Questions

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