Oklahoma Residential Contractor Plumbing and Natural Gas

Based on the 2024 International Residential Code (Chapters 2, 25, 26) and Mathematics for Plumbers and Pipefitters

Key Concepts

Testing and test gauges (IRC 2024, Chapter 25) - Building sewer test (P2503.4): Insert a test plug at the point of connection with the public sewer, fill with water, and pressurize to not less than a 10-foot head of water. Test pressure shall not decrease during a period of not less than 15 minutes; the sewer shall be watertight at all points. - Forced sewer test (P2503.4): Pressurize to not less than 5 psi greater than the pump rating, held not less than 15 minutes. - Test gauges (P2503.9): Tests at 10 psi or less → increments of 0.10 psi or less; higher than 10 psi up to 100 psi → increments of 1 psi or less; **higher than 100…

Oklahoma Residential Contractor — Plumbing and Natural Gas

Key Concepts

Pressure requirements and pressure-reducing valves - Static water pressure shall be not greater than 80 psi (551 kPa). Where main pressure exceeds 80 psi, an approved pressure-reducing valve conforming to ASSE 1003 or CSA B356 shall be installed on the domestic water branch main or riser at the connection to the water service pipe — P2903.3.2 (2018 ed.: P2903.3.1). - Water distribution pipe and tubing: pressure rating not less than 100 psi at 180°F — P2906.5. - Water service pipe/tubing installed underground and outside the structure: working pressure rating not less than 160 psi at 73°F — P2906.4.

Oklahoma Residential Contractor: Plumbing and Natural Gas (8 questions, 9% of exam)

Key Concepts

Fixture clearances and installation (IRC P2705.1) - A water closet, lavatory or bidet shall not be set closer than 15 inches from its center to any side wall, partition or vanity, nor closer than 30 inches center-to-center between adjacent fixtures; clearance in front shall be not less than 21 inches (P2705.1, Item 5). - Floor-outlet or floor-mounted fixtures must be secured to the drainage connection and floor with screws, bolts, washers and nuts of copper, copper alloy or other corrosion-resistant material (P2705.1, Item 1). - Slip-joint connections are permitted only on tubular waste piping, must be accessible, and access must provide an opening not less than 12 inches in its smallest dimension (P2704.1). - Tailpieces: not less than 1½ inches for sinks, dishwashers, laundry tubs…

Key Concepts

Potable water required / nonpotable uses. Potable water shall be supplied to plumbing fixtures and appliances except where treated rainwater, treated graywater or municipal reclaimed water is supplied to water closets, urinals and trap primers (IRC 2024 P2901.1).

Nonpotable system identification. - Distribution piping shall be purple in color or installed with purple identification tape or wrap; purple identifies reclaimed water, rainwater and graywater systems (P2901.2.2, P2901.2.2.1). - Pipe identification repeated at intervals not exceeding 25 feet and at each point the piping passes through a wall, floor or roof (P2901.2.2). - Identification tape: not less than 3 inches wide, white or black lettering on a purple field, installed on top of the pipes and fastened not greater than every 10 feet (P2901.2.2.3). - Signage on nonpotable outlets: letters not less than 0.5 inches in height, contrasting…

Oklahoma Residential Contractor Plumbing and Natural Gas · 10 questions (12%)

Key Concepts

Materials (P3002) - DWV piping within buildings must be per Tables P3002.1(1) and P3002.1(2), "except that galvanized wrought-iron or galvanized steel pipe shall not be used underground and shall be maintained not less than 6 inches (152 mm) above ground" (P3002.1). Galvanized steel appears in the above-ground table only. - Drainage fittings must have a smooth waterway of the same diameter, no ledges or shoulders, and "shall be designed to maintain 1/4 unit vertical in 12 units horizontal (2-percent slope) grade" (P3002.3.1).

Joints (P3003) - Prohibited joints (P3003.2): cement or concrete; mastic/hot-pour bituminous; fittings not approved for the installation; elastomeric rolling O-rings between different diameters; solvent-cement joints between different plastic types (except per P3003.13.4); saddle-type fittings. Piping also shall not be drilled, tapped, burned or welded.…

Key Concepts

Purpose and trap seal protection. The vent system must allow admission or emission of air so the liquid seal of any fixture trap is not subjected to a pressure differential of more than 1 inch of water column (249 Pa) (P3101.2). Every trap and trapped fixture must be vented by one of the chapter's methods (P3101.2.1), and the vent system may not be used for any other purpose (P3101.3). Where the 97.5-percent outside design temperature is 0°F or less, exterior vent pipes must be protected against freezing by insulation, heat or both (P3101.4).

Required vent extension. Each building drain needs at least one vent pipe extending outdoors (P3102.1). It must be a dry vent and shall not be an island fixture vent (P3102.2), sized per P3113.1 based on the required size of the building drain (P3102.3).

IRC 2024 (Chapters 27, 30, 31, 32)

Key Concepts

Trap design and materials (P3201.1) — Traps must be of standard design, have smooth uniform internal waterways, be self-cleaning, and have no interior partitions except where integral with the fixture. Permitted materials: lead, cast iron, copper or copper alloy, or approved plastic. Copper or copper-alloy traps: not less than No. 20 gage (0.8 mm). Lead bends and lead traps: not less than ⅛-inch (3 mm) wall thickness (P3002.4.2). Slip joints are permitted at the trap inlet, outlet, or within the trap seal and must comply with P2704.1 (accessible, opening not less than 12 inches in its smallest dimension).

Trap seal (P3201.2) — Each fixture trap shall have a liquid seal of not less than 2 inches (51 mm) and not more than 4 inches (102 mm).

Oklahoma Residential Contractor: Plumbing and Natural Gas — 7 questions (8%)

Key Concepts

Reading isometrics. On an architectural blueprint, pipe is indicated by displaying only the centerline of the pipe; fittings are described by hash marks across the indicated pipe (Ch 1 — Allowance for Threaded Fittings). In a DWV isometric legend, the solid heavy line is drainage and the dashed line is vent piping. A vertical drainage line receiving a fixture branch is the soil stack; dashed runs, including the stack vent continuing through the roof (VTR), carry air only — no waste or water. Stacks that receive the discharge of at least one water closet are soil stacks; drain stacks receive fixtures other than water closets; vent stacks supply air to the sanitary system (Unit 31).

Oklahoma Residential Contractor Plumbing and Natural Gas

Key Concepts

Underground piping and burial depth - Underground piping systems shall be installed a minimum depth of 12 inches (305 mm) below grade — G2415.12 (404.12). - Exception: individual lines to outdoor lights, grills and other appliances shall be installed not less than 8 inches (203 mm) below finished grade, where approved and in locations not susceptible to physical damage — G2415.12.1 (404.12.1). - Zinc coating (galvanizing) is not adequate protection for underground gas piping — G2415.11.1. Where dissimilar metals are joined underground, an insulating coupling or fitting shall be used — G2415.11.3. - Piping underground beneath buildings is prohibited unless encased in approved conduit — G2415.14.

29 CFR 1926 (OSHA Construction) — Safety

Key Concepts

Fall protection — guardrails (§1926.502(b)) - Top edge height of top rails: 42 inches (1.1 m) plus or minus 3 inches (8 cm) above the walking/working level — §1926.502(b)(1). - Guardrail systems must withstand, without failure, a force of at least 200 pounds (890 N) applied within 2 inches of the top edge, in any outward or downward direction, at any point along the top edge — §1926.502(b)(3).

Personal fall arrest systems (§1926.502(d)) - Maximum arresting force: 1,800 pounds (8 kN) with a body harness; the 900-pound limit applies when a body belt is used — §1926.502(d)(16)(ii). - Systems/components subjected to impact loading must be immediately removed from service and not reused until inspected and determined by a competent person to be undamaged and suitable for reuse — §1926.502(d)(19).