Oklahoma Residential Journeyman Plumbing and Natural Gas Exam: Complete 2026 Prep Guide
You've put in the hours on the job. Now it's time to prove it on paper. The Oklahoma Residential Journeyman Plumbing and Natural Gas exam is the final step between you and a state license — and knowing exactly what to expect on test day makes a real difference. This guide covers everything: exam format, topic breakdown, sample questions, approved study materials, and practical strategies to help you pass. Whether you're just starting your Oklahoma residential plumbing journeyman exam prep or doing a final review, you're in the right place.
Exam Overview
The Oklahoma Residential Journeyman Plumbing and Natural Gas exam is administered by PSI and consists of 85 scored questions. You'll have 180 minutes (3 hours) to complete it. To pass, you need to answer at least 64 questions correctly — that's 75% of the scored items.
This is an open-book exam, which is great news. But don't let that fool you into thinking it's easy. The questions are written to test whether you can apply code correctly under time pressure, not just flip to a page and copy an answer. You need to know your references well enough to find information fast.
The exam is computer-based at a PSI testing center. Your results appear on screen immediately after you finish, and an unofficial score report is printed on site. If you pass, the Oklahoma State Construction Industries Board will issue your license.
Topics Covered on the Exam
The exam spans ten topic areas. Here's how the 85 scored items are distributed — ranked from most to least heavily weighted:
- Isometric Analysis — 13 items: Reading drawings, calculating offsets, fitting allowances, and pipe lengths
- Fixtures and Equipment — 10 items: Installation requirements, water heaters, shower compartments, water closets
- Water Supply — 10 items: Distribution lines, potable water protection, backflow, pressure requirements
- Drains and Sewers — 10 items: Drain and sewer pipe, cleanouts, DFUs, building sewers
- Safety — 10 items: Ladders, fall arrest, PPE, fire prevention, construction activities
- General Plumbing Knowledge and Regulations — 8 items: Code requirements, definitions, area/volume calculations, testing systems
- Piping, Valves, and Control Valves — 8 items: Connections, cast iron, copper, steel, PVC/PEX piping
- Vents — 7 items: Installation, wet venting, air admittance valves, vent sizing
- Traps, Interceptors, Indirect, and Special Waste — 5 items: Trap types, ejector pumps, indirect waste, seal protection
- Fuel Gas — 4 items: Gas piping, valves, supports, pipe sizing, testing
Isometric Analysis carries the most weight at 13 items — more than any other single topic. If math and drawing interpretation aren't your strong suit, that's where to spend extra study time.
Sample Questions
Here's a look at five actual-style questions from the exam. Try them on your own first — then check your instincts against our free practice exam.
Question 1 — Isometric Analysis (Easy)
On an architectural blueprint, how is pipe typically indicated?
- A) By showing the full outside diameter with shading
- B) By displaying only the centerline of the pipe
- C) By drawing both the inside and outside walls of the pipe
- D) By using a double dashed line representing the pipe walls
Question 2 — Fixtures and Equipment (Easy)
What is the maximum water temperature to which the high limit stop on a shower control valve must be set?
- A) 130°F
- B) 120°F
- C) 110°F
- D) 140°F
Question 3 — Fixtures and Equipment (Medium)
You are a residential journeyman plumber explaining to a homeowner why the bathroom remodel drawings group certain fixtures together. What fixtures make up a 'bathroom group' as defined by the code?
- A) Any two or more plumbing fixtures located in the same room
- B) A water closet, lavatory, and kitchen sink located on the same floor
- C) A water closet, lavatory, and bathtub or shower, with or without a bidet, located together on the same floor level
- D) A water closet and lavatory only, regardless of floor level
Question 4 — Isometric Analysis (Medium)
When working with a 30° offset, what constant is multiplied by the offset to find the diagonal?
- A) 1.732
- B) 1.155
- C) 1.414
- D) 2.000
Question 5 — Safety (Medium)
What is the minimum illumination intensity required for first aid stations and offices on a construction site?
- A) 10 foot-candles
- B) 3 foot-candles
- C) 5 foot-candles
- D) 30 foot-candles
Want to know how you did? The answers — and 372 more practice questions — are waiting in our practice exam. Start with the free version and see where you stand.
What Types of Questions to Expect
Knowing the topic names is one thing. Understanding what the questions actually ask is another. Here's what our practice question bank covers in each area:
- General Plumbing Knowledge and Regulations: Code definitions, area and volume calculations, testing requirements, and rules for notches and holes in structural members.
- Piping, Valves, and Control Valves: Connection methods for cast iron, copper, steel, PVC, CPVC, and PEX — plus valve selection and control valve requirements.
- Fixtures and Equipment: Water heater installation, fixture clearances, shower receptor specs, flushing device requirements, and bathroom group definitions.
- Water Supply: Sizing distribution lines, backflow prevention, pressure-reducing valves, thermal expansion, and water hammer arrestor requirements.
- Drains and Sewers: Pipe material selection, building sewer requirements, cleanout placement, drainage fixture units (DFUs), and drain slope rules.
- Vents: Vent installation methods, wet venting rules, air admittance valve requirements, vent terminal heights, and developed length calculations.
- Traps, Interceptors, Indirect, and Special Waste: Allowable and prohibited trap types, ejector pump sizing, indirect waste connections, and trap seal protection methods.
- Isometric Analysis: Reading and sketching isometric drawings, center-to-end calculations, fitting allowances, 45-degree offset constants, and venting system isometrics.
- Fuel Gas: Gas piping materials, valve placement, pipe supports, sizing by BTU load, and pressure testing procedures.
- Safety: OSHA 29 CFR 1926 requirements for ladders, fall arrest systems, PPE selection, employer responsibilities, and fire prevention programs.
Across all ten topics, we offer 617 practice questions total. The full practice exam mirrors the real test — 85 questions, 180-minute timer, and a detailed score breakdown by topic so you can see exactly where to focus next.
Study Materials
This is an open-book exam, so the right references aren't optional — they're your lifeline. The three approved books are:
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IRC 2024 — International Residential Code for One-and Two-Family Dwellings (2018 edition accepted through December 13, 2026): This is your primary code reference for plumbing fixtures, water supply, drainage, and venting. Oklahoma uses the 2024 edition with state revisions (the 2018 edition is accepted through December 13, 2026). Tab it thoroughly — faucet temperature limits, bathroom group definitions, vent sizing tables — you'll return to these sections repeatedly.
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OSHA 29 CFR 1926 — Standards for the Construction Industry: Ten of your 85 exam questions come from the Safety section, and every one of them is drawn from this book. Know the ladder rules, fall protection thresholds, and PPE requirements cold. The illumination question in our sample set comes straight from this reference.
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Mathematics for Plumbers and Pipefitters (8th Edition): Isometric Analysis is the single heaviest topic on the exam at 13 items. This book covers offset calculations, 45-degree constants, pipe length formulas, and fitting allowances — exactly what those questions test. If you struggle with the math, work through this book cover to cover before test day.
Bring all three to the exam. You are not allowed to bring additional papers or unapproved materials, so keep your references clean and well-tabbed.
Study Tips for the Oklahoma Residential Journeyman Plumbing Exam
Give yourself 3–6 weeks of structured prep. Use the Candidate Information Bulletin (CIB) as your roadmap. Spend the bulk of your time on Isometric Analysis, Fixtures and Equipment, Water Supply, Drains and Sewers, and Safety — those five topics alone account for 53 of the 85 scored items.
Practice finding things fast, not memorizing them. On an open-book test, speed is the skill. Tab your IRC and CFR 1926 by topic. Run through practice questions with your books open and time yourself. Aim for three clean practice runs scoring 80% or higher before your test date — that cushion above the 75% cut score matters when nerves kick in.
Have a question strategy. Work through the exam once from start to finish — answer what you know, bookmark what you don't. Then circle back. Don't burn five minutes on one question when there are easier points still available.
Manage test-day nerves. Some anxiety is normal. If you feel yourself locking up on a question, set it aside, take a slow breath, and move on. The clock runs during any breaks, so use them wisely.
Start Your Prep Today
Passing the Oklahoma Residential Journeyman Plumbing and Natural Gas exam is a real achievement — it's not handed to anyone. But it's completely within reach with the right preparation. You know the trade. Now it's about knowing the code, the math, and how to work efficiently through 85 questions in 180 minutes.
Grab your three approved references, tab them well, and start testing yourself. Our free practice exam is a great first step — 10 questions, no account required, no pressure. See where you stand, then upgrade to the full practice exam when you're ready to do a serious timed run. You've got this.