Oklahoma Plumbing Contractor and Natural Gas

Key Concepts

IPC Chapter 1 — Scope, Intent, and Applicability - IPC §101.2 Scope: Applies to erection, installation, alteration, repair, relocation, replacement, and maintenance of plumbing systems. Fuel gas piping/equipment is regulated by the International Fuel Gas Code, not the IPC. - IPC §101.3 Intent: Establishes minimum standards for safety, health, property protection, and public welfare. - IPC §102.1: When a general requirement conflicts with a specific requirement, the specific requirement governs. When two sections conflict, the most restrictive governs. - IPC §102.2: Existing lawful plumbing systems may continue in use if maintained per original design and no new hazard is created. - IPC §102.4: Additions and repairs must meet new construction standards but do not require the entire existing system to be brought up to current code. - IPC §102.6: Historic buildings may be exempt from mandatory code…

Oklahoma Plumbing Contractor and Natural Gas Exam | 8 Questions (9%)

Key Concepts

Pipe Materials & Standards

• Copper tubing types: Type K (thickest wall, underground/high pressure), Type L (general interior supply), Type M (lighter duty, not for all applications), Type DWV (drain/waste/vent only — not pressure supply).
• CPVC: Rated for hot and cold water supply; requires solvent cement joints (ASTM F493); expansion allowed with listed fittings.
• PVC: Not approved for hot water supply; used for DWV and cold water; solvent-welded joints; schedule 40 or 80.
• PEX: Flexible cross-linked polyethylene; cannot be used for outdoor exposed locations (UV degrades it); connections via crimp, clamp, or expansion fittings — no solvent cement.
• Polyethylene (PE): Used primarily for underground gas and water service; heat fusion or mechanical fittings; not for interior above-ground gas piping.…

9% of exam | ~8 questions | Reference: IPC 2018 + IFGC 2018

Key Concepts

Minimum Fixture Counts by Occupancy (IPC Chapter 4, Table 403.1) - Fixture counts are based on occupancy type and occupant load. Assembly, business, educational, institutional, mercantile, and residential all have distinct requirements for water closets, lavatories, drinking fountains, and service sinks. - Male/female splits apply when occupant load exceeds 50% of a threshold; equal distribution is assumed unless otherwise stated. - A service sink is required in most occupancies with janitor functions.

Fixture Installation Clearances (IPC Section 405) - Water closets: minimum 15 inches from centerline to any side wall or obstruction; 21 inches clear in front (IPC 405.3.1). - Lavatories: minimum 4 inches from side wall; 21 inches clear in front. - Showers: minimum interior dimension of 30 × 30 inches; **900…

(10 questions, 12% of exam — IPC 2018 primary reference)

Key Concepts

Backflow Prevention - Air gap = most reliable protection; minimum 2× the diameter of the supply outlet, never less than 1 inch (IPC §608.15.1) - Reduced Pressure Zone (RPZ) assembly = required for high-hazard cross-connections (toxic/health-hazard fluids) - Double Check Valve Assembly (DCVA) = used for low-hazard (non-health-hazard) connections - Pressure Vacuum Breaker (PVB) = acceptable for irrigation when installed at least 12 inches above the highest downstream outlet; cannot be used where subject to back-pressure - Atmospheric Vacuum Breaker (AVB) = no shutoff valve downstream; installed at least 6 inches above flood level rim; cannot be under continuous pressure >12 hours - Backsiphonage protection is required wherever a submerged inlet connects to the potable supply (IPC §608)

Key Concepts

Pipe Materials (IPC Chapter 7) - Above-ground drainage: Approved materials include cast iron, galvanized steel, copper (DWV), ABS, and PVC. - Underground/below-slab: Cast iron, ABS, PVC, and vitrified clay are common; galvanized steel is not permitted underground. - Building sewer (outside the foundation): Cast iron, ABS, PVC, vitrified clay, and concrete pipe are permitted. The building sewer begins 2–5 feet outside the building foundation wall.

Fixture Unit Values & Pipe Sizing (IPC Section 709) - Every fixture is assigned a Drainage Fixture Unit (DFU) value. Common values: water closet = 4 DFU, lavatory = 1 DFU, bathtub/shower = 2 DFU, kitchen sink = 2 DFU, floor drain = 2 DFU. - Pipe sizing is determined by total DFU load using IPC Table 710.1(1) for horizontal branches/stacks and Table 710.1(2) for building drains/sewers.

(IPC 2018, Chapter 9 | 13 questions, 15% of exam)

Key Concepts

Trap Seal Protection (§901.2) The vent system must prevent pressure differentials exceeding 1 inch of water column (249 Pa) on any fixture trap seal. Every trap must be vented per one of the approved methods.

Roof Termination Heights (§903.1) - Standard roof extension: 6 inches minimum above the roof surface - Roofs used as assembly areas, promenades, observation/sunbathing decks: 7 feet minimum above the roof

Frost Closure (§903.2) Where the 97.5% outdoor design temp is 0°F or less, vent extensions through roof or wall must be ≥3 inches in diameter. Size increase must occur ≥1 foot inside the building's thermal envelope.

Traps, Interceptors, Indirect, and Special Waste (12% of Exam)

Key Concepts

Fixture Trap Requirements

• Every fixture must have a trap. Traps must be self-cleaning and installed as close to the fixture as possible.
• Prohibited trap types: S-traps, bell traps, crown-vented traps, drum traps (except for special applications), and traps with interior partitions are prohibited under IPC.
• Each trap serves one fixture only (with limited exceptions like a single trap for a 3-compartment sink of the same type).

Trap Seal Depth

• Trap seals must be a minimum of 2 inches and maximum of 4 inches deep (IPC Section 1002).
• Protect trap seals from: evaporation, siphonage, back-pressure, and momentum.
• Trap seal primers are required where evaporation is a concern (floor drains, infrequently used fixtures); primers must supply water from a potable…

Key Concepts

Isometric drawings represent 3D pipe runs on a 2D plane using 30° angle axes. You must be able to extract dimensional data and calculate actual pipe lengths.

Terminology you must know: - Offset – the perpendicular distance between two parallel pipe centerlines - Diagonal (Travel) – the actual pipe length running at an angle through the offset - Rise – vertical component of a rolling offset - Run – horizontal component - Center-to-center (c-c) – measured from fitting center to fitting center - End-to-end (e-e) – the actual cut pipe length after subtracting fitting allowances (also called make-up)

Pipe length calculation sequence: 1. Determine c-c length from the isometric diagram 2. Subtract the fitting allowances for each end 3. Result = e-e (end-to-end) pipe length

Key Concepts

Scope (IFGC 101.2.2): Covers natural gas systems ≤125 psig and LP-gas systems ≤20 psig, from point of delivery to appliance shutoff valve outlet. One- and two-family dwellings fall under the IRC, not IFGC.

Approved Piping Materials (IFGC Chapter 4): - Steel/wrought iron pipe – most common; black steel standard for interior gas piping - Copper tubing – permitted for natural gas only if gas is not corrosive; prohibited where gas contains more than 0.3 grains of hydrogen sulfide per 100 standard cubic feet - CSST (Corrugated Stainless Steel Tubing) – must be listed and installed per manufacturer instructions; requires bonding per manufacturer specs - Polyethylene (PE) – approved for underground use only; never above grade - Prohibited: galvanized steel for LP-gas, cast iron inside buildings, and aluminum in underground applications

Key Concepts

Fall Protection (Subpart M) - The 6-foot rule: employers must provide fall protection for any employee working at a height of 6 feet or more above a lower level on construction sites. - Personal Fall Arrest Systems (PFAS) must: limit free fall to 6 feet, limit deceleration distance to 3.5 feet, and have a breaking strength of 5,000 lbs per employee. - Guardrail systems: top rail at 42 inches (±3 inches) above walking surface; mid-rail at 21 inches; top rail must withstand 200 lbs of outward/downward force. - Safety nets must be installed as close as practicable under the work surface, never more than 30 feet below.