Oklahoma Plumbing Journeyman and Natural Gas

Oklahoma Plumbing Journeyman and Natural Gas Exam: Complete 2026 Prep Guide

You've put in the hours on the job. Now you need one more thing to make it official: passing the Oklahoma Plumbing Journeyman and Natural Gas exam. This test covers everything from IPC code and drainage design to fuel gas piping and jobsite safety — and with 85 scored questions in 180 minutes, there's no room for guessing your way through. The good news? It's open book, and with the right prep strategy, a 75% passing score is absolutely within reach. This guide walks you through the exam format, what each topic covers, study resources, and tips to help you walk in confident on test day.

Oklahoma Plumbing Journeyman and Natural Gas Exam Overview

The exam is administered by PSI on behalf of the Oklahoma Construction Industries Board. Here's what you need to know before you sit down at the testing center:

• Scored questions: 85
• Time limit: 180 minutes (3 hours)
• Passing score: 75%, which equals 64 correct answers out of 85
• Format: Multiple-choice, open book
• Allowed references: Four specific books (detailed in the Study Materials section below)

Because the exam is open book, raw memorization matters less than knowing where to find things fast. Candidates who tab and highlight their references before test day consistently outperform those who rely on memory alone. Plan your prep accordingly.

Topics Covered on the Exam

The exam spans ten topic areas drawn from the IPC, IFGC, and OSHA standards. Here's how the real exam weights them, from heaviest to lightest:

Vents (13 items) — The single largest topic. Expect vent sizing, developed length, termination requirements, air admittance valves, and all the major venting methods (individual, wet, circuit, island fixture, and more).

General Plumbing Knowledge and Regulations, Water Supply, Drains and Sewers, and Traps/Interceptors (10 items each) — These four areas together account for nearly half the exam. Code scope, backflow prevention, drainage sizing, trap seal requirements, and grease interceptors all fall here.

Piping, Valves, and Control Valves and Fixtures and Equipment (8 items each) — Pipe materials and joining methods, valve types and placement, fixture clearances, water heaters, and flushing devices.

Isometric Analysis (7 items) — Pipe length calculations from isometric drawings, including 45° offset constants and fitting allowances. These questions reward practice more than any other topic.

Fuel Gas (5 items) — Gas pipe sizing, approved materials, pressure requirements, appliance venting, and combustion air.

Safety (4 items) — OSHA fall protection rules, guardrail and ladder requirements, and PPE selection.

When planning your study schedule, put the most time into Vents, followed by the four 10-item topics. That's where the points are.

Sample Questions

Here are five questions from the exam topic areas. Work through them on your own — the answers are not given here, but you can check how you do by taking our free practice exam.

Question 1 — Water Supply (Medium)
Which backflow prevention device is limited to protection against backsiphonage ONLY and is NOT effective against backpressure?
- A) Dual-check-valve-type backflow preventer
- B) Pressure vacuum breaker assembly
- C) Double check backflow prevention assembly
- D) Reduced pressure principle backflow prevention assembly

Question 2 — General Plumbing Knowledge and Regulations (Medium)
As a plumbing contractor installing PVC pipe, you need to cut a piece to fit between a 90° ell and a 45° ell with a center-to-center distance of 10 inches. The fitting allowances from the manufacturer are ⁹⁄₁₆" for the 90° ell and ⁵⁄₁₆" for the 45° ell. What is the end-to-end pipe length you should cut?
- A) 10⅞"
- B) 8¾"
- C) 9⅛"
- D) 9⅞"

Question 3 — Drains and Sewers (Medium)
You are a journeyman plumber installing a water closet fixture drain. What limitation applies to the developed length of the fixture drain from the trap weir to the vent fitting for this self-siphoning fixture?
- A) The developed length shall not exceed 16 feet
- B) The developed length shall not be limited
- C) The developed length shall not exceed 12 feet
- D) The developed length shall not exceed 6 feet

Question 4 — Piping, Valves, and Control Valves (Medium)
You are a journeyman plumber pressure testing a new gas piping system in a single-family dwelling. The system volume is less than 10 cubic feet. What is the minimum test duration you must maintain?
- A) 30 minutes
- B) 5 minutes
- C) 10 minutes
- D) 15 minutes

Question 5 — General Plumbing Knowledge and Regulations (Easy)
For a 45° offset, what constant is used to find the diagonal when the offset distance is known?
- A) 2.000
- B) 1.414
- C) 0.707
- D) 1.732

How did you do? Try the free exam to see where you stand across all ten topic areas.

What Types of Questions to Expect

Our Oklahoma plumbing journeyman exam prep bank covers all ten exam topics with 401 total practice questions. Here's what each area tests and how many practice questions we offer:

• General Plumbing Knowledge and Regulations (47 questions): IPC scope and permit procedures, inspection authority, required system tests, and pipe length calculations using fitting allowances for threaded, copper, and PVC fittings.
• Piping, Valves, and Control Valves (39 questions): Pipe joints and connection methods, approved water supply materials, valve types and required locations, pressure-reducing and backflow prevention assemblies, and pipe support spacing.
• Fixtures and Equipment (40 questions): Minimum fixture counts by occupancy, spacing and clearance requirements, individual fixture standards, flushing devices, shower valve controls, and water heater safety devices.
• Water Supply (46 questions): Backflow prevention application, distribution system design including flow rates and pipe sizing, cross-connection control, and valve requirements at various points in the system.
• Drains and Sewers (43 questions): Sanitary drainage pipe materials, fixture unit values and sizing tables, horizontal pipe slope, cleanout placement and spacing, and below-grade sump and ejector systems.
• Vents (64 questions): Vent pipe sizing and developed length for every vent type in the IPC, termination heights and clearances, venting methods from individual to island fixture, air admittance valve rules, and proper vent grades and connections.
• Traps, Interceptors, Indirect, and Special Waste (45 questions): Trap dimensions and prohibited types, seal depth and primer devices, grease interceptors and grease removal devices, oil and sand interceptors, and air gap versus air break distinctions.
• Isometric Analysis (33 questions): Reading isometric diagrams to calculate center-to-center and end-to-end pipe lengths, applying 45° offset constants (1.414 and 0.707 multipliers), and working through three-pipe offset diagrams with rise, run, and diagonal relationships.
• Fuel Gas (24 questions): Gas pipe sizing using longest-length and branch-length methods, approved piping materials including CSST and polyethylene, allowable pressure drop, appliance venting, and combustion air requirements.
• Safety (20 questions): OSHA fall protection trigger heights, personal fall arrest system components and specifications, guardrail requirements, ladder safety, and PPE selection for head, eye, foot, and hearing protection.

Study Materials

The Oklahoma Plumbing Journeyman and Natural Gas exam is open book, and the four allowed references are fixed. You must own, tab, and know all four before test day.

International Plumbing Code 2018 — Your primary reference. Roughly two-thirds of the exam draws from the IPC. Tab every major table and chapter you'll need: fixture unit tables, vent sizing tables, trap dimensions, and drainage slope requirements.

2018 International Fuel Gas Code (IFGC) — Covers the five Fuel Gas questions. Tab the gas pipe sizing tables, approved materials, and combustion air sections. Fewer questions doesn't mean you can skip it — those five points count.

Mathematics for Plumbers and Pipefitters, 8th Edition — Essential for pipe length calculations and isometric analysis. Work through the offset constants and fitting allowance chapters before test day. The math questions on this exam are straightforward once you've practiced the process a few times.

OSHA 29 CFR 1926 — Covers the four Safety questions. Tab the fall protection, guardrail, ladder, and PPE subparts. The questions here are code-lookup style, so knowing which subpart to flip to is the skill.

Study Tips for Oklahoma Plumbing Journeyman Exam Prep

Give yourself three to six weeks. Use the exam topic list as your roadmap and work through each area systematically. Vents alone gets 13 questions — give it proportional study time.

Build tabbing systems that actually work. Color-code by code book if that helps. During the exam, speed of lookup matters as much as knowing the answer.

Set your practice target at 80%. The real cut score is 75%, so aiming higher in practice gives you a comfortable buffer if nerves show up on test day. Aim for three clean practice runs at 80% or above before scheduling your exam.

Treat isometric analysis as a skill, not knowledge. These seven questions test your ability to apply constants and work through diagrams step by step. Repetition with worked examples is the only way to get comfortable — the math itself isn't hard, but the process needs to be automatic.

On exam day, work in passes. Answer every question you know on the first pass and skip the ones you don't. Flag the uncertain ones and come back. Don't let one hard question eat up ten minutes while easier ones wait.

Manage test anxiety the same way. A little nerves before an exam is normal. If you feel stuck, a few slow breaths can reset your focus. The clock keeps running during breaks, so use any break time efficiently.

Frequently Asked Questions

How many questions are on the Oklahoma Plumbing Journeyman and Natural Gas exam, and how long do I have?
The exam has 85 scored questions and a 180-minute time limit. That's about two minutes per question — enough time if you don't stall on any single item.

What is the passing score?
You need 75% correct, which means 64 out of 85 scored questions. That gives you some room for error, but not a lot — focused prep on the heavier topics pays off.

How much does the exam cost?
The exam fee is $92 per examination portion. The fee is non-refundable and non-transferable, and it applies whether you're testing for the first time or retesting.

How do I register?
First, you need approval from the Oklahoma Construction Industries Board. Once approved, you can register online through PSI's website or call PSI at (855) 834-8750. You cannot schedule the exam until the state approves your application.

What happens if I fail?
If you fail the first time, you must wait 30 days before retesting. Starting with the second failure, the waiting period extends to 90 days for each subsequent attempt. Budget your prep time accordingly — retakes are costly in both fees and time.

Does my eligibility expire?
No. According to the candidate bulletin, there is no expiration on your eligibility once you've been approved.

Is the exam open book?
Yes. You may bring the IPC 2018, IFGC 2018, Mathematics for Plumbers and Pipefitters (8th edition), and OSHA 29 CFR Part 1926. No other references are permitted.

Can I write in my books?
You may highlight, underline, and use permanent tabs before the exam, but you cannot write in your references before or during the exam session. Post-It notes and other removable tabs are not allowed.

What ID do I need?
Bring one valid, non-expired, government-issued photo ID that also bears your signature — a state driver's license, state ID, US passport, US military ID, Alien Registration Card, or Canadian government-issued ID all qualify. The name on your ID must match your registration exactly.

Can I use a calculator?
Yes, but only a silent, battery-operated, non-programmable calculator without a paper tape printer or alphabetic keyboard. Leave the smartphone and scientific graphing calculators at home.

You've Got This

Passing the Oklahoma Plumbing Journeyman and Natural Gas exam is a real milestone — it validates the skills you've built on the job and opens doors to more responsibility and earning potential. The exam is challenging, but it's designed to be passable for someone who prepares methodically. Tab your books, drill the calculation topics, and hit your practice targets before you schedule the real thing.

Start right now with our free practice exam — 10 questions, no account required, and a good first read on where you stand. When you're ready to go deeper, the full practice exam matches the real test format with 85 questions, a full topic breakdown, and a fresh question draw every attempt. Good luck.