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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 organized into four topic areas drawn from the 2018 International Fuel Gas Code (Oklahoma) and OSHA 29 CFR 1926.

This practice exam is available in two formats:

• Free practice exam: 10 questions per attempt, drawn from a limited pool. You can retake it as many times as you like — it's a solid way to get familiar with the question style and see how the code language shows up in exam stems. Start here.
• Full practice exam (paid): Mirrors the real exam exactly — 40 questions, 120-minute time limit, drawn from a pool of 221+ questions. Every attempt pulls a unique set, so retaking it gives you fresh material each time. This is the tool for serious prep.

What You'll Be Tested On

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

This topic accounts for 25% of your exam. Questions focus on the language of the 2018 IFGC as adopted in Oklahoma, and they demand precision. You'll be tested on key definitions from Section 202 — knowing the code's exact vocabulary for terms like "appliance," "piping system," and "approved" matters because answer choices are often close synonyms designed to trip up guesswork.

Expect questions on the scope of the fuel gas code — what systems and appliances it covers and, critically, what falls outside its scope (see IFGC Section 101.2.2). Permit questions come up here too: when a permit is required, how applications are processed, and how annual permits work (Section 106.3.2). Code official authority is another tested area — what inspectors can and cannot do, their enforcement powers, and their duties.

The exam also tests applicability rules for existing installations. When gas piping is added to, altered, or repaired, specific code provisions apply — and the exam will probe whether you know the difference between a new installation and a repair scenario under Section 301.15.

Pipe Sizing (12 items)

At 30% of the exam, Pipe Sizing is the heaviest calculation-based section. You will not pass this exam by memorizing facts alone — you need to be able to work through problems.

Maximum gas demand is the starting point. You'll calculate total connected load by summing appliance BTU/hr ratings and converting to cubic feet per hour using the appropriate heating value for natural gas.

Pipe sizing methods are a major focus. You need to know the difference between the longest length method, the branch length method, and the hybrid pressure method — not just conceptually, but operationally. The exam presents scenarios and asks which method applies or how to apply it (Sections 402.1 and 402.2).

Sizing tables are tested directly. Table 402.4(1) covers Schedule 40 metallic pipe at low pressure (0.5 in. w.c. pressure drop). Table 402.4(2) covers different pressure drop conditions. You need to find the correct table for a given pressure, locate the right pipe diameter column, and read flow capacity values accurately.

CSST sizing uses EHD (equivalent hydraulic diameter) flow designations rather than nominal pipe size — a distinction the exam tests. Table 402.4(15) and its notes are specifically cited in the question bank, including the adjustment equation for additional bends (L = 1.3n). Semirigid copper tubing has its own sizing tables as well.

Allowable pressure drop and minimum appliance supply pressure round out this topic. Know the standard pressure drop limits and what happens when a system exceeds them.

Pipe Installation (15 items)

This is the largest topic, worth 37.5% of your score. Questions span a wide range of practical installation knowledge.

Allowable materials are tested: which metals, which grades of CSST, and what polyethylene pipe is approved for underground use. Material standards matter — the exam cites specific ASTM and ANSI designations embedded in code references.

Joints and connections are heavily tested. Know the code requirements for threaded joints, brazed joints, welded connections, and press-connect fittings. Different connection methods have different applicability — you can't braze where the code requires welding, and vice versa.

Prohibited locations come up repeatedly. Underground piping through buildings, concealed piping through certain spaces, and piping through specific structural elements are restricted under Sections 302.3.2, 302.3.3, and 302.3.4. The exam will describe an installation scenario and ask whether it is permitted.

Garage and elevated clearance requirements are also tested (Section 305.3 and 305.5). Appliances in private garages must meet specific height requirements above floor level.

Pressure testing and purging requirements are tested procedurally — test pressure, test medium, duration, and when purging is required before placing a system into service (Sections 401.4, 401.5, and 401.6).

Piping support intervals are specific and numerical. Know the required support spacing for different pipe materials and diameters.

Safety (3 items)

Safety is 7.5% of the exam — three questions — but skipping it costs you points you can't afford near the pass line. Questions come from OSHA 29 CFR 1926 (the construction safety standard). Topics include employer accident prevention responsibilities (§1926.20), employee safety training obligations (§1926.21), PPE duties, emergency action plans and evacuation procedures (§1926.35), and first aid and medical services requirements (§1926.50). Fire protection responsibilities under §1926.150 are also cited in the question bank.

Worked Sample Questions

Sample 1 — Pipe Installation

Question: According to the Oklahoma Fuel Gas Code, the building shall not be weakened by the installation of any gas piping. What must be left in a safe structural condition after installing or repairing gas piping?

• A. Only the walls and ceilings that were modified
• B. Only the floor structure that was penetrated
• C. The finished floors, walls, ceilings, tile work or any other part of the building that is required to be changed or replaced
• D. Only load-bearing structural members

Correct Answer: C

The code does not limit the restoration obligation to a single building component. Under 2018 International Fuel Gas Code (IFGC) (Oklahoma), Section 302.1, any part of the building or premises that is required to be changed or replaced during piping installation or repair must be left in a safe structural condition. Answers A, B, and D all artificially narrow this obligation. The exam tests whether you recognize that the code casts a wide net here.

Sample 2 — Pipe Sizing

Question: You are installing a CSST gas piping system. The tubing run has six 90-degree bends and two end fittings instead of the standard four bends and two fittings the sizing table accounts for. How should you account for the additional bends?

• A. No adjustment is needed for additional bends
• B. Add an equivalent length of tubing calculated by the equation L = 1.3n, where n is the number of additional bends
• C. Increase the pipe size by one nominal size for every two additional bends
• D. Double the total equivalent length shown in the table

Correct Answer: B

Per 2018 International Fuel Gas Code (IFGC) (Oklahoma), Table 402.4(15), Note 1, tubing runs with more bends or fittings than the table standard require an added equivalent length using L = 1.3n, where n is the number of additional fittings or bends beyond the standard. Here, 6 bends − 4 standard = 2 additional bends, so L = 1.3 × 2 = 2.6 feet of additional equivalent length. The other answers describe approaches with no basis in the code table notes.

Sample 3 — General Fuel Gas Piping

Question: A homeowner wants a new gas furnace placed directly on the floor of a residential private garage. What is the minimum clearance above the floor for this appliance?

• A. 18 inches above the floor
• B. 4 feet above the floor
• C. 6 feet above the floor
• D. 8 feet above the floor

Correct Answer: C

Under 2018 International Fuel Gas Code (IFGC) (Oklahoma), Section 305.5, appliances in private garages must be installed with a minimum clearance of 6 feet (1829 mm) above the floor unless they are protected from motor vehicle impact and installed per Section 305.3. The 18-inch figure is a common distractor from other code contexts. This is a memorization item — know the number cold.

How to Read Your Score

The passing score is 70%, which means 28 out of 40 correct on the real exam.

Treat your first practice attempt as a diagnostic, not a verdict. Most people score lower on the first attempt than they expect — the code language is precise and the distractor answers are engineered to catch half-remembered rules. A low first score tells you exactly where to focus, which is far more useful than a false confidence boost.

Use the topic breakdown after each attempt. If you're dropping points on Pipe Sizing, that's 12 questions — nearly a third of the exam — and every percentage point gained there shows up directly on your final score. If Safety looks weak, that's only 3 questions, but at a 70% threshold you cannot afford to give away free ones.

Scoring between 70% and 80% on practice usually means the real exam could go either way. Aim for consistent 80%+ scores across multiple full-exam attempts before you test. Because the full practice exam pulls from a pool of 221+ questions, retaking it exposes you to new material each time rather than re-testing memorized answer positions.

Where Candidates Lose Points

Misreading pipe sizing tables. The most common error in the Pipe Sizing section is pulling a value from the wrong table — using a 0.5 in. w.c. pressure drop table when the problem specifies 3 in. w.c., or reading the wrong pipe diameter column. Table 402.4(1) and Table 402.4(2) are both tested, and the exam will set up a scenario where the pressure drop matters.

Missing CSST adjustments. Candidates often forget the L = 1.3n bend correction for CSST runs. If you skip it, you undersize the tubing.

Getting clearance numbers wrong. Garage appliance clearances, corridor clearances, and spacing requirements involve specific numbers. "18 inches" and "6 feet" are both plausible to a tired candidate — one is right, one costs you the point.

Confusing "allowed" with "required." Prohibited piping location questions under Sections 302.3.2 through 302.3.4 are framed as scenarios. Candidates who skim lose track of whether a material or location is restricted or merely subject to conditions.

Underestimating the Safety section. Three questions is small, but candidates who skip OSHA 29 CFR 1926 entirely often miss all three. The employer vs. employee duty distinctions (§1926.20 vs. §1926.21) are specifically tested.

Time management. At 120 minutes for 40 questions, you have 3 minutes per question — but pipe sizing calculations can eat 5–7 minutes each. Flag them, move on, and return.

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