10.1 Fuel Gas Piping Installation

10.1 Fuel Gas Piping Installation

The installation of fuel gas piping in commercial properties is governed by the International Fuel Gas Code (IFGC) Chapter 4. As a P2 Commercial Plumbing Inspector, you must verify that gas piping systems are designed, sized, installed, and tested to prevent leaks, resist physical damage, and ensure safe delivery of fuel gas to appliances.

Fuel Gas Piping Materials and Listings

Gas piping systems can be constructed using various materials, each subject to strict code requirements. The table below outlines the primary materials, their standards, and key installation rules:

Material Traps and Rules

1. Copper Restrictions: Copper and brass piping are restricted because hydrogen sulfide reacts with copper to form copper sulfide flakes, which can clog orifices and control valves.
2. Plastic Piping Transition: PE gas piping must transition to metal prior to entering a building. This transition must be made using a listed anodeless riser or transition fitting. The minimum depth of burial for PE piping is 12 inches under normal conditions, and 18 inches under driveways or parking areas.
3. Concealed Piping (IFGC 404.10): Mechanical joints such as threaded unions, running threads, right-and-left couplings, tubing fittings, and bushings must not be installed in concealed locations. If joints are concealed within walls or floors, they must be welded, brazed, or made with approved press-connect fittings listed for concealed use.

---

Gas Piping Sizing Methods

Proper sizing of a fuel gas piping system ensures that appliances receive the correct volume of gas at the required pressure during peak demand. Sizing must be done using one of the following methods under IFGC Section 402:

1. Longest Length Method:
   • The sizing is based on the total developed length from the point of delivery (usually the gas meter or regulator) to the most remote appliance in the system.
   • Every section of the piping network is then sized using the sizing table columns corresponding to this single, maximum longest length.
2. Branch Length Method:
   • The pipe size for each section of the piping is determined based on the distance from the point of delivery to the specific appliance served by that branch.
3. Hybrid Sizing:
   • Sizing utilizing elevated pressure (e.g., 2 psi or 5 psi) and inline regulators (such as line pressure regulators) to reduce pipe sizes.

---

Corrugated Stainless Steel Tubing (CSST) Electrical Bonding

One of the most critical safety inspections for commercial plumbing inspectors is verifying the electrical bonding of Corrugated Stainless Steel Tubing (CSST). Because CSST has thin walls, it is susceptible to perforation from lightning-induced electrical arcs.

Bonding Requirements (IFGC Section 310.1.1):

• Ground Connection: The CSST gas piping system must be electrically bonded to the building's electrical service grounding electrode system.
• Bonding Conductor: The bonding conductor must be copper, minimum 6 AWG in size, or equivalent.
• Connection Point: The bonding clamp must be connected to an accessible metallic pipe segment or a CSST brass fitting upstream of the CSST run.
• Maximum Length: The developed length of the bonding conductor must not exceed 75 feet.

[!WARNING] Standard copper gas piping and steel gas piping do not require the specific 6 AWG bonding conductor unless CSST is present in the system, in which case the entire system must be bonded.

---

Piping Protection and Sleeving

Gas piping installed in masonry or concrete must be protected from physical damage and chemical corrosion.

Sleeves for Masonry/Concrete (IFGC Section 404.3):

• Piping passing through concrete or masonry walls must be sleeved in a conduit.
• The sleeve must extend at least 2 inches beyond each face of the wall.
• The annular space between the gas pipe and the sleeve must be sealed using an approved elastomeric compound to prevent gas migration into the wall cavity.
• The sleeve must not be constructed of materials that react chemically with the pipe.

Hanger Spacing (IFGC Table 415.1):

• 1/2-inch Steel Pipe: Max horizontal support spacing is 6 feet.
• 3/4-inch to 1-inch Steel Pipe: Max horizontal support spacing is 8 feet.
• 1-1/4-inch and larger Steel Pipe: Max horizontal support spacing is 10 feet.
• CSST: Must be supported horizontally every 4 feet (for 3/8" and 1/2" tubing) or every 6 feet (for 3/4" and larger).

---

Appliance Connections and Sediment Traps

Every fuel-gas-burning appliance must be connected to the gas supply in accordance with IFGC Section 411:

• Shutoff Valve: A listed gas shutoff valve must be installed in the same room as the appliance, within 6 feet of the appliance, and upstream of the connector.
• Flexible Appliance Connectors (IFGC Section 411.1.1):
  • Standard domestic or light commercial flexible connectors are limited to a maximum length of 6 feet.
  • Commercial ranges and dryers must be connected with flexible connectors that do not exceed 3 feet in length.
• Sediment Traps (IFGC Section 408.4):
  • A sediment trap must be installed upstream of the automatic control valve of appliances such as boilers, furnaces, and water heaters to collect moisture, scale, and debris.
  • The sediment trap must consist of a tee with a minimum 3-inch long nipple and cap in the bottom outlet, installed as close to the appliance inlet as practical. Illuminating appliances, ranges, dryers, and outdoor grills are exempt from sediment trap requirements.

---

Inspection and Testing Requirements (IFGC Section 406.4)

Before any gas piping system is put into service, the commercial plumbing inspector must witness a pressure test to verify the integrity of all joints.

Low-Pressure Systems (14 inches water column / 0.5 psi or less):

• Minimum Test Pressure: 3 psig (pounds per square inch gauge).
• Minimum Duration: 10 minutes.
• Medium: Air, nitrogen, or carbon dioxide (oxygen is strictly prohibited).

Medium- and High-Pressure Systems (Greater than 0.5 psi):

• Minimum Test Pressure: 1.5 times the maximum working pressure, but not less than 3 psig.
• Minimum Duration: 30 minutes for every 500 cubic feet of pipe volume.

Isolation Rules:

• Appliance Isolation (IFGC Section 406.4.1): All connected appliances and equipment must be disconnected or isolated from the piping system during the test by closing their individual shutoff valves or capping the lines. High test pressures can damage appliance gas valves and controls which are typically rated for less than 0.5 psi.