Exam Cheat Sheet · Quick Reference
Maryland Master Plumber / Gas Fitter
Maryland · PSI Services Contractor
Verified, not estimated. Every figure below is drawn from the official exam structure we maintain — question counts, passing standard and topic weighting. Practice questions are grounded in the source law with statute citations. We omit any figure we can't verify rather than guess at it.
Total questions
100
Passing score
70%
Exam time
240 min
Administered by
PSI Services Contractor
Format
Reference materials allowed
Maryland State Portion 100 questions
Plumbing Fundamentals and Safety
5 Q · 5%
IPC and IFGC scope, intent, and applicability provisionsPlumbing and fuel gas code administration: permits, inspections, and code official authorityKey IPC and IFGC defined terms and their code significanceOSHA construction site safety: employer responsibilities and accident prevention programsJobsite sanitation requirements: potable water, toilet facilities, and washing facilitiesOccupational health hazards: permissible exposure limits for airborne contaminantsFirst aid, medical services, and emergency action planning on construction sitesPersonal protective equipment requirements for construction workers
Materials, Uses, and Specifications
6 Q · 6%
Approved piping materials and applicable standards (steel, copper, CSST, polyethylene, aluminum alloy)Prohibited materials and material restrictions (cast iron pipe, PVC/CPVC for fuel gas, aluminum underground/exterior)Pipe and tubing identification requirements (manufacturer markings, 'Gas' labeling, spacing intervals)Metallic pipe joints and fittings specifications (threaded, brazed, welded, press-connect, flared)Plastic pipe and fitting standards (polyethylene ASTM D2513, prohibited PVC/CPVC for fuel gas)Protective coatings and corrosion resistance requirements for metallic pipingThread specifications and joint compound requirements for metallic pipeReferenced standards for plumbing materials (ASME, ASTM, ANSI standards for pipe, fittings, and valves)
Traps, Interceptors, and Backwater Valves
4 Q · 4%
Fixture trap requirements: vertical and horizontal distance limits from fixture outlet to trapProhibited trap types (bell traps, S-traps, drum traps, crown-vented traps, moving-part traps)Trap seal depth requirements and protection methods (primer valves, barrier devices)Grease interceptor requirements: where required, sizing, capacity, and prohibited additivesOil separator requirements: where required, design specifications, and capacity for garages/service stationsSand interceptors, clothes washer interceptors, and special-use interceptors (bottling, slaughterhouses)Venting and access/maintenance requirements for interceptors and separators
Plumbing Fixtures, Fixture Fittings, and Plumbing Appliances
4 Q · 4%
Minimum number of plumbing fixtures by occupancy type (Table 403.1)Fixture installation requirements — spacing, clearances, and securing methodsStandards and approval requirements for specific fixtures (water closets, urinals, lavatories, bathtubs, showers, sinks, bidets)Faucets and fixture fittings — shower valves, temperature-limiting devices, and backflow protectionFlushing devices — flushometer valves, flush tanks, fill valves, and overflow requirementsWater heater installation — location, access, clearances, seismic supports, and drain valvesWater heater safety devices — pressure/temperature relief valves, discharge piping, vacuum relief, and pan requirementsGas-fired appliances — cooking appliances, clothes dryers (exhaust duct requirements), pool/spa heaters, and unvented room heaters
Water Supply Systems
8 Q · 8%
Water supply pipe and distribution pipe materials and applicable standards (copper, PEX, CPVC, PVC, PE, galvanized steel)Pipe joining methods by material type (solvent cement, solder, braze, mechanical, push-fit, heat fusion)Water pressure regulation, booster systems, and water hammer controlFixture supply pipe sizing and minimum flow rates and pressures at outletsValve placement requirements (full-open valves and shutoff valves) and valve identificationWater pressure, head, and volume calculations (psi/head conversion, tank capacity, pipe capacity ratios)
Backflow Prevention
10 Q · 10%
Backflow preventer device types and applicable standards (air gap, reduced pressure principle assembly, double check assembly, vacuum breaker, dual check valve)Hazard classification for backflow prevention selection (high hazard contamination vs. low hazard pollution, backpressure vs. backsiphonage)Cross-connection control requirements and prohibited connectionsSpecific application requirements for backflow protection (boilers, lawn irrigation, fire sprinkler systems, carbonated beverage dispensers, chemical dispensers, hose connections)Installation requirements for backflow preventers (location, critical level height, access, freeze protection, relief port termination)Air gap requirements and minimum dimensionsIdentification and labeling of nonpotable water systemsThermal expansion control where backflow preventers are installed on water heater supply
Drain, Waste, and Vent Systems
13 Q · 13%
Drainage fixture unit (DFU) values and load calculationsSizing of building drains, sewers, and horizontal branchesSlope requirements for horizontal drainage pipingCleanout requirements, placement intervals, and access clearancesVent types, sizing, and developed length requirementsIndirect waste piping, air gaps, and waste receptorsPipe length calculations including fitting allowances and offsets for DWV systems
Special Topics
3 Q · 3%
Storm drainage system sizing and rainfall rate designRoof drain types, installation, and secondary (emergency) overflow systemsSubsoil drains, building subdrains, and sump pumping systemsNonpotable water system general requirements: signage, permits, and cross-connection protectionNonpotable water storage tank requirements: location, access, venting, overflow, and testingOn-site nonpotable water reuse systems: approved sources, prohibited sources, filtration, and disinfectionRainwater collection and conveyance systems: collection surfaces, first-flush diverters, debris excluders, and storageSubsurface landscape irrigation systems: percolation testing, absorption area sizing, and site location requirements
Gas Appliances and Piping
40 Q · 40%
Gas piping materials and allowable pipe types (steel, copper, CSST, polyethylene)Pipe sizing methods and use of capacity tables for natural gas and LP-gasGas piping pressure requirements, pressure drop, and testing proceduresCombustion air requirements for gas appliances (indoor, outdoor, and mechanical methods)Venting systems for gas appliances: types, sizing, and termination requirementsAppliance installation requirements: clearances, location restrictions, and prohibited locationsSpecific appliance requirements (furnaces, water heaters, fireplaces, dryers, pool heaters, and other Chapter 6 appliances)Safety inspection procedures for existing gas appliance installations
Plumbing Mathematics
7 Q · 7%
Fitting allowances for threaded, copper, PVC, and welded pipe fittingsOffset calculations using 45°, 60°, 22½°, and other angle constantsPipe length unit conversions between feet, inches, fractions, and decimalsVolume, capacity, and weight calculations for water and cylindrical containersWater pressure, head, and force calculationsGrade, drop, run, and elevation calculations for drainage pipingGas piping sizing methods and pressure drop calculationsRatio of pipe capacities and pipe sizing by units of flow
Key Distinctions
Longest Length MethodvsBranch Length Method
The Longest Length Method uses the single longest pipe run length for sizing every section, while the Branch Length Method reduces conservatism by sizing each branch using only the actual distance from the meter to that branch's most remote outlet.
2018 International Fuel Gas Code (IFGC), Appendix A, Section A.3.2Tee-Wye DWV FittingvsStandard Tee DWV Fitting
A tee-wye has two long allowances and one short allowance with a built-in ¼-inch-per-foot slope on the branch, whereas a standard tee has three equal allowances and no built-in slope.
Mathematics For Plumbers And Pipefitters, Unit 23Regular Wye DWV FittingvsReducing Wye DWV Fitting
A regular wye uses the same allowance for both the run and branch, while a reducing wye applies a different (E-dimension) allowance to the branch when the branch size differs from the run size, requiring use of Data 9.
Mathematics For Plumbers And Pipefitters, Unit 23Cast-Iron PipevsSteel / Copper / Aluminum-Alloy Pipe
Cast-iron pipe is explicitly prohibited in fuel gas piping systems, whereas steel (≥Schedule 10), copper (if H₂S ≤0.3 gr/100 scf), and aluminum-alloy pipe are all permitted under specific IFGC conditions.
2018 International Fuel Gas Code (IFGC), Section 403.4.1PVC / CPVC Plastic PipevsPolyethylene (PE) Plastic Pipe
PVC and CPVC are explicitly prohibited from supplying fuel gas, while polyethylene conforming to ASTM D2513 and marked 'Gas' and 'ASTM D2513' is permitted.
2018 International Fuel Gas Code (IFGC), Section 403.6Permit Expiration (Work Not Commenced)vsPermit Application Abandonment
An issued permit expires and becomes null and void if work is not commenced within 180 days of permit issuance (or is suspended 180 days after commencement), whereas an application (not yet a permit) is deemed abandoned 180 days after filing without good-faith pursuit.
2018 International Fuel Gas Code (IFGC), Section 106.5.3Specific Requirement (Code)vsGeneral Requirement (Code)
When a conflict exists between a general and a specific requirement in the fuel gas code, the specific requirement governs; where different sections specify different materials or methods, the most restrictive governs.
2018 International Fuel Gas Code (IFGC), Section 102.1Dry VentvsWet Vent
A dry vent carries only air and serves solely as a vent, while a wet vent simultaneously carries the waste discharge of one fixture and provides the vent for one or more other fixtures in the same bathroom group.
Wet VentvsIsland (Loop) Vent
A wet vent is used for conventional bathroom groups where a single pipe carries both waste and venting, while an island (loop) vent is used for fixtures such as kitchen sinks located in islands with no nearby wall for a conventional vertical dry vent.
Engineering / Administrative Controls (Noise)vsPersonal Protective Equipment (Noise)
OSHA requires feasible engineering or administrative controls to be used first when noise exceeds permissible limits; personal protective equipment is only required when those controls fail to reduce levels within permissible limits.
29 CFR 1926, §1926.52(b)Schedule 40 (and heavier) Steel PipevsPipe Lighter than Schedule 40
Schedule 40 and heavier fuel gas pipe may be joined by threaded joints, press-connect fittings, flanges, brazing, or welding, while pipe lighter than Schedule 40 is restricted to press-connect fittings, flanges, brazing, or welding only—threaded joints are not permitted.
2018 International Fuel Gas Code (IFGC), Section 403.4.28-Hour TWA PEL ("C"-designated substances)vs8-Hour TWA PEL (non-"C"-designated substances)
Substances preceded by a "C" designation in OSHA Table 1 are ceiling limits that must never be exceeded at any time, while substances without a "C" designation are measured as an 8-hour time-weighted average over any work shift.
29 CFR 1926, §1926.55(a)(2)Key Terms
Fuel Gas Permit Expiration 2018 International Fuel Gas Code (IFGC), Section 106.5.3
Per IFGC Section 106.5.3, an issued permit becomes null and void if work is not commenced within 180 days of issuance or is suspended/abandoned for 180 days after commencement.
Permit Application Abandonment (IPC) International Plumbing Code 2018, Section 106.3.3
Per IPC Section 106.3.3, a plumbing permit application is deemed abandoned 180 days after filing if it has not been pursued in good faith or a permit has not been issued.
Permit-Exempt Plumbing Work International Plumbing Code 2018, Section 106.2
Per IPC Section 106.2, clearing stoppages or repairing leaks in pipes, valves, or fixtures is exempt from permits provided no replacement or rearrangement of valves, pipes, or fixtures is required.
Plastic Pipe Third-Party Certification International Plumbing Code 2018, Page 24, Section 303.3
Per IPC Section 303.3, all plastic pipe, fittings, and components used in plumbing systems must be third-party certified as conforming to NSF 14.
Cast-Iron Soil Pipe Listing Requirement International Plumbing Code 2018, Page 24, Section 303.5
Per IPC Section 303.5, cast-iron soil pipes, fittings, and their couplings must be third-party listed and labeled; unlisted product must be rejected.
Fuel Gas Piping Purpose (IFGC) 2018 International Fuel Gas Code (IFGC), Section 101.4
Per IFGC Section 101.4, the IFGC establishes minimum standards to provide a reasonable level of safety, health, property protection, and public welfare by regulating the design, construction, installation, materials, location, operation, and maintenance of fuel gas systems.
CSST Bonding Jumper Minimum Size 2018 International Fuel Gas Code (IFGC), Section 310.2.2
Per IFGC Section 310.2.2, the bonding jumper for CSST gas piping without an arc-resistant jacket or coating shall be no smaller than 6 AWG copper wire or equivalent.
Aluminum-Alloy Pipe Restrictions (Fuel Gas) 2018 International Fuel Gas Code (IFGC), Section 403.4.4
Per IFGC Section 403.4.4, aluminum-alloy pipe is prohibited in exterior locations or underground and must be coated where in contact with masonry, plaster, insulation, or subject to repeated wetting.
Copper Pipe Hydrogen Sulfide Limit (Fuel Gas) 2018 International Fuel Gas Code (IFGC), Section 403.4.3
Per IFGC Section 403.4.3, copper and copper-alloy pipe shall not be used if the gas contains more than an average of 0.3 grains of hydrogen sulfide per 100 standard cubic feet of gas.
Competent Person (OSHA) OSHA 1926 CFR 29, Page 31
Per 29 CFR 1926.32(f), a competent person is one capable of identifying existing and predictable hazards in working conditions and who has the authority to take prompt corrective measures to eliminate them.
Maximum Permissible Noise Exposure (8-Hour) 29 CFR 1926, §1926.52(a)
Per 29 CFR 1926.52(a), the permissible noise exposure limit for an 8-hour work duration on a construction site is 90 dBA slow response.
Pressure-Reducing Valve Failure Mode IPC 2018, Section 604.8.1
Per IPC Section 604.8.1, a pressure-reducing valve installed on a building water supply must be designed to remain open (fail-open) in the event of valve failure to permit uninterrupted water flow.
Wet Vent
A wet vent is a single pipe that simultaneously carries the waste discharge of one fixture and serves as the vent for one or more other fixtures in the same bathroom group.
Formulas to Know
Static Water Pressure from Elevation Head
Pressure (psi) = Height (ft) × 0.433 psi/ftElevation Head Required for a Given Pressure
Height (ft) = Pressure (psi) ÷ 0.433 psi/ftNatural Gas Pipe Capacity Correction for Specific Gravity
Adjusted Capacity = Table Capacity (at SG 0.60) × Gravity Factor (from IFGC Table A.2.4)Minimum Toilet Facilities Required (OSHA)
Toilets required = 1 for ≤20 employees; increases per OSHA Table D-1 as employee count risesShower Facilities Ratio (OSHA)
Showers = 1 per 10 employees of each sex (or fraction thereof) required to shower in the same shift