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Oklahoma Natural Gas Contractor — Practice Exam

What This Practice Exam Covers

The Oklahoma Natural Gas Contractor licensing exam is 40 questions with a 120-minute time limit. You need a 70% (28 out of 40) to pass. The exam is built around four topic areas drawn directly from the 2018 International Fuel Gas Code (IFGC) as adopted in Oklahoma, and it tests both code knowledge and hands-on calculation skills.

This practice exam gives you two ways to prepare:

• Free practice exam: 10 questions per attempt, drawn from a limited pool. You can retake it as many times as you like to get a feel for the format and question style — no account required.
• Full practice exam (paid): Mirrors the real exam with 40 questions and a 120-minute time limit. Questions are pulled from a pool of 215+ items, so every attempt gives you a different mix. No two practice exams are identical, which means repeated attempts keep building your knowledge rather than just reinforcing memorized answers.

Both versions are based on the exact topic breakdown provided by the official test provider.

What You'll Be Tested On

General Fuel Gas Piping — Knowledge, Definitions, and Regulations (10 exam items)

This topic accounts for 25% of your exam and is almost entirely code-literacy work. You need to know how the IFGC is organized, how conflicts between general and specific requirements are resolved, and what the code's defined terms actually mean. Expect questions on definitions like appliance, approved, listed, gas piping, and service pressure. You'll also be tested on the scope of the code — what installations it covers and what it excludes — and on administrative provisions such as permit requirements, inspections, and the authority of the code official. This is the topic where candidates who skimmed the front chapters of the IFGC instead of reading them carefully lose easy points.

Pipe Sizing (12 exam items)

This is the single heaviest calculation topic, worth 30% of the exam. You will read sizing tables, apply pressure drop criteria, and determine the correct pipe diameter for a given load and run length. The exam tests your ability to use Table 402.4(1) for Schedule 40 metallic pipe, match inlet pressure conditions (less than 2 psi vs. higher pressures), select the right pressure drop column (0.3 in. w.c., 0.5 in. w.c., etc.), and read off capacity in cubic feet per hour (cfh). You also need to understand the altitude correction requirement from Section 402.2 — installations above 2,000 feet require a volumetric flow rate adjustment. Multi-appliance systems add complexity: you'll need to know how to add loads, assign pipe segments, and work through a branching system. Bring your code book and know your tables cold.

Pipe Installation (15 exam items)

At 15 items, this is the largest single topic and worth 37.5% of your total score. It covers the physical requirements for installing gas piping: acceptable materials, fittings, joints, and connections; support spacing and protection requirements; clearances from electrical equipment, dryer vents, and other hazards; underground installation depth and sleeving requirements; and requirements for piping inside buildings (concealed vs. exposed). You'll also be tested on the rules governing appliance connections — flexible connectors, shutoff valves, and union requirements. Testing and purging procedures fall here as well. Candidates who do field work every day sometimes lose points on this topic because the exam wants the IFGC's specific numbers (support intervals, burial depths, test pressures) rather than field habits.

Safety (3 exam items)

Three questions, worth 7.5% of the exam. This topic covers leak testing requirements, gas shutoff procedures, and general safety precautions tied to natural gas work. The item count is small, but these are straightforward questions — you should expect to get all three right. Focus on test pressure requirements, the correct medium for leak testing (never an open flame), and emergency shutoff provisions.

Worked Sample Questions

Question 1 — Pipe Installation

When sizing gas piping, the volumetric flow rate of gas to be provided shall be adjusted for altitude when the installation is above what elevation?

• A. 1,000 feet
• B. 1,500 feet
• C. 2,000 feet
• D. 3,000 feet

Correct Answer: C — 2,000 feet

The IFGC is specific here: the altitude adjustment kicks in at 2,000 feet (610 m), not at 1,000 or 1,500. At higher elevations, air density decreases, which affects combustion and gas delivery calculations. Options A and B are common wrong answers because candidates assume the threshold is lower. Look this up in your code book before exam day so the number is locked in.

Source: 2018 International Fuel Gas Code (IFGC) (Oklahoma), Section 402.2

Question 2 — Pipe Sizing

Using Table 402.4(1) for Schedule 40 metallic pipe with natural gas at less than 2 psi inlet pressure and 0.3 in. w.c. pressure drop, what is the capacity in cubic feet per hour for a 1-inch nominal pipe at a length of 100 feet?

• A. 79 cfh
• B. 148 cfh
• C. 304 cfh
• D. 455 cfh

Correct Answer: B — 148 cfh

This question tests direct table-reading under specific conditions. You must match three variables simultaneously: pipe size (1-inch nominal, 1.049-inch actual ID), run length (100 feet), and pressure condition (less than 2 psi inlet, 0.3 in. w.c. drop). Get any one of those wrong and you land on a different cell in the table. Option A (79 cfh) corresponds to a smaller pipe or longer run. Option C and D are for larger pipe sizes. Practice navigating this table under time pressure — on exam day you don't want to spend four minutes on a table-lookup question.

Source: 2018 International Fuel Gas Code (IFGC) (Oklahoma), Table 402.4(1)

Question 3 — General Fuel Gas Piping — Knowledge, Definitions, and Regulations

According to the IFGC, when there is a conflict between a general requirement and a specific requirement in the code, which shall govern?

• A. The general requirement
• B. The specific requirement
• C. The most recently adopted requirement
• D. The code official's interpretation

Correct Answer: B — The specific requirement

This is a pure code-organization question. The IFGC establishes clearly that specific requirements override general ones — this principle applies throughout the code and shows up in administrative questions across many code-based exams. Options C and D are wrong; neither recency nor the code official's preference determines hierarchy when a direct conflict exists.

Source: International Fuel Gas Code 2021, Page 1-2

How to Read Your Score

The passing score on the real exam is 70% — 28 correct out of 40 questions.

Your first practice attempt is a diagnostic, not a verdict. Most candidates score below 70% on their first try, and that result is useful information, not a warning sign. What matters is which topics pulled your score down. A topic-by-topic breakdown tells you exactly where to focus: if you're losing points on Pipe Sizing (12 items), every hour you spend on table work returns more value than reviewing Safety (3 items).

Scoring between 70% and 80% on a first practice attempt usually means the knowledge is there but needs sharpening — especially on multi-step Pipe Installation and Pipe Sizing questions where one wrong assumption compounds through the whole problem. Scoring consistently above 80% across multiple full practice attempts, with different question sets each time, is a much stronger indicator of readiness than a single high score.

Be honest with yourself: a score right at 70% on practice means you're on the edge. The real exam may weight questions differently on the day you sit it. Give yourself a clear margin.

Where Candidates Lose Points

Pipe Sizing table errors. The most common source of lost points on this exam. Candidates use the right table but the wrong pressure condition column, or misread the nominal pipe size vs. the actual ID column. On Table 402.4(1), being off by one row or one column costs you the question entirely.

Forgetting the altitude correction. The 2,000-foot threshold in Section 402.2 trips up candidates who know piping but haven't read the sizing section carefully. Oklahoma has areas above that elevation, so this is a real-world and exam issue.

Installation numbers vs. field habit. Pipe Installation carries 15 questions. Candidates with field experience sometimes answer from memory rather than from the IFGC's specific figures for support spacing, burial depth, or test pressure. The exam wants the code number, not the shop standard.

Running out of time on heavy topics. With 40 questions in 120 minutes, you have 3 minutes per question. Multi-step Pipe Sizing and Pipe Installation problems can eat 5–6 minutes if you're not practiced. Candidates who bank time on the General Knowledge questions and then rush the sizing section make avoidable mistakes.

Misreading units. Confusing cubic feet per hour with BTU/hr, or psi with inches of water column, produces wrong table entries and wrong answers. Always verify your units before looking up a table value.

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