Gas Piping System Notes

Sizing (402…)
Pipe Materials
Installation
Testing
- 402.4.1 – Longest Length Method
- 402.4.2 – Branch Length Method
- 402.4.3 – Hybrid pressure
- 402.6 – 5 psi maximum indoor pressure except when…
  - Welded Fittings
  - In a Ventilated Chase
  - Industrial / Agricultural applications
  - Temporary installations for construction
  - LP gas up to 20 psi
Indoor gas piping systems are typically:
- 7” WC
- 2 psi – (may need special permission from gas utility)
- 5 psi – (may need special permission from gas utility)

Longest Length Method: All pipe sections are sized using the 80-foot column.
Branch Length Method: (Refer to specific tables for sizing based on length and flow rate).
- Example: Table 402.4(2) for Schedule 40 Metallic Pipe.

Do not run gas piping through ducts, chimneys, elevator shaft, etc.
Concealed piping inside solid walls or solid partitions is prohibited unless in a chase or casing.
In concealed locations only with threaded fittings, brazed fittings, welded fittings, or specially listed fittings.
404.12 - Can run gas piping underground – minimum 12” bury.
404.12 - Can run gas piping underground to an individual outside appliance at 8” bury and if not susceptible to damage.
404.14 - Don’t run gas piping under a building! If you must, then run it in a sleeve open to the outdoors.
404.6 - Underground penetrations of foundations prohibited.
CSST – Must be protected from damage (Shield Plates 404.7.3)
CSST – Must be bonded to the electrical grounding system.
404.17 - Plastic Pipe (Polyethylene, PE)
- Outdoors underground only
- Not within or under any building or slab
- Not more than 100 psi.
- Must be installed with a yellow 18ga tracer wire

Must be accessible
Protected from physical damage
Where located indoors, the regulator must be vented to the outdoors OR Equipped with a leak-limiting device.

A sediment trap shall be installed downstream of the appliance shutoff valve as close to the inlet of the appliance as practical.
The sediment trap shall be either a tee fitting having a capped nipple of any length installed vertically in the bottommost opening of the tee.
Exceptions: Illuminating appliances, ranges, clothes dryers, decorative vented appliances for installation in vented fireplaces, gas fireplaces and outdoor grills need not be so equipped.

Fuel-burning equipment requires supply air for combustion and ventilation of the space.
Protects not just equipment operation, but more importantly protects occupants against oxygen depletion and buildup of gasses.
Supply air sources: Outdoor Air, Indoor Air, Mechanical Supply

Two Openings Method
- Openings sized and located in accordance with Sections 304.6, 304.6.1
Single High Opening Method
- Openings sized and located in accordance with Sections 304.6, 304.6.2
Indoor Air
- Standard Method Sections 304.5, 304.5.1
- Calculate required volume 50 ft² per 1000 Btu
- Known Air Infiltration Rate Method Sections 304.5, 304.5.2
- Calculate required volume for other than fan-assisted appliances Equation 3.1
- Calculate the required volumes for fan-assisted appliances Equation 3.2
Combination Indoor/Outdoor Air
- Determine indoor volume ratio and outdoor opening(s) size in accordance with Section 304.7
Engineered System
- Approval required in accordance with Section 304.8
Mechanical Supply
- Air flow rate and system design in accordance with Sections 304.9 through 304.9.3