Oklahoma Natural Gas Journeyman

General Fuel Gas Piping: Testing & Inspection, Pipe Material Properties & Requirements

Key Concepts

Testing and Inspection

Pressure Testing Requirements - All new gas piping must be tested and proven leak-free before being placed in service or concealed. - Test medium: air, CO₂, nitrogen, or other inert gas — never use oxygen and never use natural gas for pressure testing new installations. - IFGC/NFPA 54 standard test pressure: 3 psi minimum for systems operating at 14 inches w.c. (½ psi) or less; 10 psi for medium-pressure systems (above ½ psi to 2 psi); 1½ times the working pressure for systems above 2 psi — hold for minimum 10 minutes. - Low-pressure piping (≤ ½ psi): tested at 3 psi for at least 10 minutes with no pressure drop. - After pressure testing, the system must be inspected joint-by-joint using an approved leak-detection solution (soap and water or listed detector fluid) — never an open flame.

Inspection Requirements - Concealed piping must be inspected and approved before walls are closed. - All piping must be visually inspected for proper support, correct material, and correct fittings prior to pressure test. - Gas piping systems shall be re-tested if extended or modified.

OSHA 29 CFR 1926.350 – Welding/Cutting Relevance - Compressed gas cylinders must be stored with oxygen separated from fuel-gas cylinders by a minimum of 20 feet (6.1 m) or a noncombustible barrier ≥5 feet high with a ½-hour fire-resistance rating. - Cylinders must be secured upright at all times (except briefly during hoisting). - Damaged or defective cylinders shall not be used. - Valve protection caps must be in place during transport and storage. - Do not use open flame to check for leaks on cylinders or connections.

Pipe Material Properties and Requirements

Key Concepts

Maximum Gas Demand & Connected Load Total connected load is the sum of all appliance BTU/h ratings on a system. To find maximum gas demand in cubic feet per hour (CFH), divide total BTU/h by the heating value of the gas (typically 1,000 BTU/ft³ for natural gas): CFH = Total BTU/h ÷ 1,000.

Three Pipe Sizing Methods (IFGC Section 402) - Longest Length Method: Use the total length from the meter to the farthest appliance for every pipe segment. Conservative — results in slightly oversized pipe throughout. - Branch Length Method: Each branch segment is sized using the actual length of that specific branch to its appliance. More accurate than longest length. - Hybrid Pressure Drop Method: Combines pressure-drop calculations for segments using actual lengths and pressure drops. Used when greater precision or higher pressure systems are involved.

Pressure Drop & Minimum Supply Pressure - For low-pressure systems (≤ 0.5 psi / 14 inches W.C.), the standard allowable pressure drop is 0.5 inch W.C. for systems with a 7-inch W.C. delivery pressure. - Minimum gas pressure at the appliance inlet must meet the manufacturer's requirement — typically 5 to 7 inches W.C. for most residential appliances. - Medium-pressure systems (above 0.5 psi) use different drop allowances; consult appropriate table column.

Maximum Operating Pressure Inside Buildings (IFGC Section 402.3 / Table 402.4) - 0.5 psi (14 inches W.C.) — standard maximum for most residential/commercial piping inside buildings. - 2 psi — allowed for larger commercial/industrial systems with approved regulators. - 5 psi — permitted in industrial occupancies and certain systems with specific approval.

Altitude Adjustment (IFGC Section 402.6) For installations above 2,000 feet elevation, gas capacity tables must be adjusted. Multiply the sea-level CFH capacity by a de-rating factor (typically reduce capacity approximately 4% per 1,000 feet above sea level, or use the code-provided altitude correction table). Oklahoma has areas exceeding this threshold — know this rule applies.

Key Concepts

Structural Safety (Section 302) - Gas piping installation must never weaken the building structure (302.1). Floors, walls, and ceilings disturbed during installation must be restored to a safe structural condition per the IBC. - Cutting, notching, and boring in wood framing members must comply with IBC Section 2308.6 (302.3). - Engineered wood products (trusses, I-joists, glulam): Cuts, notches, and holes are prohibited unless specifically permitted by manufacturer recommendations or a registered design professional (302.3.1). - Truss members cannot be cut, drilled, notched, spliced, or altered in any way without written concurrence of a registered design professional (302.4).

Hangers and Supports - Pipe must be supported at intervals appropriate to pipe material and size. Steel pipe ½"–¾" requires support every 6 feet; 1" and larger every 8 feet. CSST and corrugated pipe follow manufacturer specs. - Vertical pipe must be supported at each floor level and at intervals not exceeding those required for the pipe material. - Supports must be made of approved materials — hangers, brackets, or straps that won't corrode or damage the pipe.

Joints and Connections - Only approved joining methods are permitted: threaded, welded, brazed, or approved mechanical fittings. - Joints in concealed locations must be welded or brazed where metallic pipe is used — threaded joints are not permitted concealed in certain assemblies. - Pipe joints exposed to the atmosphere in concealed spaces must be accessible or permanently sealed.

Drip Legs and Sediment Traps - A sediment trap (drip leg) must be installed upstream of each appliance where the gas contains moisture or condensate. - Drip legs should be installed as close to the appliance inlet as practical, oriented vertically downward, using a tee fitting with a capped nipple at least 3" long on the bottom opening.

(10% of Exam | ~3 Questions)

Key Concepts

Employer Responsibilities (§1926.20) - Employers must initiate and maintain safety programs with frequent and regular inspections by competent persons. - Unsafe machinery/tools must be tagged, locked out, or physically removed — not simply set aside. - Only employees qualified by training or experience may operate equipment and machinery. - PPE failures are cited per employee — each unprotected worker is a separate violation.

Excavations (Subpart P) - Trenches 5 ft or deeper require a protective system (sloping, shoring, or trench box) unless excavated in solid rock. - A competent person must classify soil and inspect excavations daily and after rain/hazard events. - Spoil piles must be kept at least 2 ft from the edge of the excavation. - Exits (ladders, ramps, stairs) required every 25 ft of lateral travel in trenches 4 ft or deeper.

Confined Space & Ventilation (Subpart AA / Subpart D) - A permit-required confined space has: limited entry/exit, potential for hazardous atmosphere, and/or engulfment hazard. - Atmospheric testing order: oxygen → flammable gases → toxic contaminants. - Acceptable oxygen range: 19.5% – 23.5%. - Flammable atmosphere threshold: >10% of Lower Explosive Limit (LEL) requires action. - Forced air ventilation must be continuous; never use oxygen to ventilate.

PPE (§1926.95) - Employer must provide and ensure use of appropriate PPE at no cost to employees. - PPE must be maintained in sanitary and reliable condition. - Hard hats, safety glasses, gloves, and steel-toed boots are standard on construction/gas job sites.

Signs, Signals & Barricades (Subpart G / §1926.200) - Danger signs: Red/black — immediate hazard. - Caution signs: Yellow/black — potential hazard or unsafe practices. - Safety instruction signs: Green/white — general safety info. - Barricades and flagging required for excavations and work zones on public ways.