Exam Cheat Sheet · Quick Reference

Oklahoma Natural Gas Contractor

Oklahoma  ·  PSI Services Contractor

Verified, not estimated. Every figure below is drawn from the official exam structure we maintain — question counts, passing standard and topic weighting. Practice questions are grounded in the source law with statute citations. We omit any figure we can't verify rather than guess at it.
Total questions
40
Passing score
70
Exam time
120 min
Administered by
PSI Services Contractor
Format
Reference materials allowed

Oklahoma State Portion 40 questions

General Fuel Gas Piping -- Knowledge, Definitions, and Regulations 10 Q · 25%
Pipe Sizing 12 Q · 30%
Pipe Installation 15 Q · 38%
Safety 3 Q · 8%

Key Distinctions

Natural Gas Piping (IFGC scope)vsLP-Gas Piping (IFGC scope)

Natural gas piping is covered by the IFGC up to 125 psig operating pressure, while LP-gas piping is covered only up to 20 psig.

International Fuel Gas Code 2021, Page 1-1
Max pressure inside buildings (IFGC)vsMax pressure for full IFGC scope (natural gas)

Piping inside buildings is generally limited to 5 psig unless special conditions are met, whereas the overall IFGC scope covers natural gas systems up to 125 psig.

International Fuel Gas Code 2021, Page 4-2
General requirement (IFGC)vsSpecific requirement (IFGC)

Where a general and specific requirement conflict, the specific requirement governs; where sections specify different materials or methods, the most restrictive governs.

International Fuel Gas Code 2021, Page 1-2
Attic passageway < 6 ft high (IFGC)vsAttic passageway ≥ 6 ft high (IFGC)

An attic passageway less than 6 feet high may be at most 20 feet long from opening to appliance, while one at least 6 feet high for its entire length may extend up to 50 feet.

International Fuel Gas Code 2021, Page 3-8
Steel pipe and CSST (piping identification)vsOther exposed gas piping (piping identification)

Steel pipe and CSST are exempt from the yellow-label identification requirement, whereas all other exposed gas piping must bear a yellow label marked 'Gas' in black letters at intervals not exceeding 5 feet.

International Fuel Gas Code 2021, Page 4-1
Prime contractor (OSHA responsibility)vsSubcontractor (OSHA responsibility)

The prime contractor bears overall responsibility for OSHA compliance for all work under the contract and cannot be relieved of it, while subcontractors share joint responsibility only for their portion of the work.

OSHA 1926 CFR 29, §1926.16, Page 29
Fire extinguisher rated 2A (OSHA placement)vsFire extinguisher rated 10B (OSHA placement)

A 2A extinguisher must be within 100 feet travel distance from any point of the protected area (one per 3,000 sq ft), while a 10B extinguisher must be within 50 feet of any location where more than 5 gallons of flammable liquid or 5 pounds of flammable gas are in use.

OSHA 1926 CFR 29, §1926.150(c)(1)(i), Page 177
Written emergency action plan (OSHA)vsOral emergency action plan (OSHA)

Employers with more than 10 employees must maintain a written emergency action plan, while employers with 10 or fewer employees may communicate the plan orally and need not maintain it in writing.

OSHA 1926 CFR 29, §1926.35(e)(3), Page 33
Boring holes in joists (IFGC structural limits)vsNotching ends of joists (IFGC structural limits)

Bored holes must be at least 2 inches from the top or bottom of the joist and cannot exceed one-third the joist depth, while notches at joist ends cannot exceed one-fourth of the joist depth.

International Fuel Gas Code 2021, Page 3-2
Interconnected meters on same premises (IFGC)vsSeparate consumers on same premises (IFGC)

When two or more meters on the same premises supply separate consumers, the piping systems must not be interconnected on the outlet side of the meters.

International Fuel Gas Code 2021, Page 4-1
Competent person (OSHA definition)vsQualified person (general usage)

A competent person under OSHA is specifically defined as one who can identify existing and predictable hazards AND has authorization to take prompt corrective measures to eliminate them.

OSHA 1926 CFR 29, §1926.32(f), Page 31
Diversity of load (pipe sizing)vsTotal connected load (pipe sizing)

Pipe sizing is normally based on the total connected load assuming all appliances operate simultaneously at full capacity; diversity of load may only be used as the basis where it can be established.

International Fuel Gas Code 2021, Page 4-1

Key Terms

IFGC Scope – Natural Gas Pressure Limit International Fuel Gas Code 2021, Page 1-1
Per IFGC Section 101.2.2, the code covers natural gas piping systems with an operating pressure of 125 psig or less.
IFGC Scope – LP-Gas Pressure Limit International Fuel Gas Code 2021, Page 1-1
Per IFGC Section 101.2.2, the code covers LP-gas piping systems with an operating pressure of 20 psig or less, except as provided in Section 402.7.
Maximum Inside-Building Piping Pressure International Fuel Gas Code 2021, Page 4-2
Per IFGC Section 402.7, gas piping inside buildings shall not exceed 5 psig unless special conditions such as welded/brazed joints, ventilated chases, or industrial use are met.
Exposed Piping Identification Requirement International Fuel Gas Code 2021, Page 4-1
Per IFGC Section 401.5, exposed gas piping other than steel pipe and CSST must carry a yellow label marked 'Gas' in black letters at intervals not exceeding 5 feet.
Ignition Source Elevation in Garages International Fuel Gas Code 2021, Page 3-7
Per IFGC Section 305.3, appliances with an ignition source in garages or hazardous locations must be elevated so the ignition source is at least 18 inches above the floor, unless listed as flammable vapor ignition resistant.
Standard Method – Indoor Combustion Air Volume International Fuel Gas Code 2021, Page 3-4
Per IFGC Section 304.5.1, the standard method for indoor combustion air requires a minimum of 50 cubic feet of volume per 1,000 Btu/h of appliance input rating.
Permit Application Abandonment Period International Fuel Gas Code 2021, Page 1-5
Per IFGC Section 106.3.1, a gas piping permit application is deemed abandoned 180 days after filing if not pursued in good faith or if a permit has not been issued.
Specific vs. General Requirement Rule International Fuel Gas Code 2021, Page 1-2
Per IFGC Section 102.1, where a general and specific requirement conflict, the specific requirement governs; where sections differ on materials or methods, the most restrictive governs.
Joist Boring Clearance International Fuel Gas Code 2021, Page 3-2
Per IFGC Section 302.3.2, holes bored in joists for piping must be at least 2 inches from the top and bottom of the joist and diameter must not exceed one-third the joist depth.
Meter Piping Non-Interconnection Rule International Fuel Gas Code 2021, Page 4-1
Per IFGC Section 401.6, where two or more meters on the same premises supply separate consumers, the piping systems shall not be interconnected on the outlet side of the meters.
Competent Person (OSHA) OSHA 1926 CFR 29, §1926.32(f), Page 31
Per OSHA 29 CFR 1926.32(f), a competent person is one who can identify existing and predictable hazards and who has authorization to take prompt corrective measures to eliminate them.
Non-Compliant Equipment Procedure (OSHA) OSHA 1926 CFR 29, §1926.20(b)(3), Page 29
Per OSHA 29 CFR 1926.20(b)(3), equipment not in compliance with OSHA requirements must be tagged or locked to render it inoperable, or physically removed from its place of operation.
First Aid Certificate Requirement (OSHA) OSHA 1926 CFR 29, §1926.50(c), Page 33
Per OSHA 29 CFR 1926.50(c), when no clinic, hospital, or physician is reasonably accessible, the employer must have a person with a valid first-aid certificate (American Red Cross or equivalent) available at the worksite.
Permissible Noise Exposure – 8-Hour Day (OSHA) OSHA 1926 CFR 29, §1926.52, Table D-2, Page 36
Per OSHA 29 CFR 1926.52 Table D-2, the maximum permissible noise exposure for an 8-hour workday is 90 dBA slow response.
Total Connected Load (Pipe Sizing) International Fuel Gas Code 2021, Page 4-1
Per IFGC Section 402.2, pipe sizing must be based on the total connected hourly load, assuming all appliances operate at full capacity simultaneously unless diversity of load can be established.
Existing Piping Capacity Check International Fuel Gas Code 2021, Page 4-1
Per IFGC Section 401.4, before adding an appliance to an existing system, the contractor must verify the existing piping has adequate capacity for all appliances served, enlarging it if necessary.

Formulas to Know

Required Indoor Combustion Air VolumeTotal Volume (ft³) = (Appliance Input Rating in Btu/h ÷ 1,000) × 50 ft³
Maximum Joist Hole DiameterMax Hole Diameter = Joist Depth ÷ 3
Maximum Joist End Notch DepthMax Notch Depth = Joist Depth ÷ 4
Fire Extinguisher (2A) Coverage AreaOne 2A extinguisher per 3,000 ft² of protected area; max travel distance = 100 ft
Fire Extinguisher (10B) Proximity RuleOne 10B extinguisher within 50 ft whenever >5 gal flammable liquid or >5 lb flammable gas are in use
Total Gas Demand for Pipe SizingTotal Demand (Btu/h) = Sum of maximum input ratings of ALL appliances served (assume simultaneous full operation)
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