In the Field · Part 4
Gas piping in practice: sizing, CSST bonding, the pressure test, appliance connectors and shutoffs, sediment traps, and seismic shutoff valves
Gas is the system where a plumber's mistake is not a callback. This lesson is the working rules a C-36 uses on every gas job: how to size a line by the longest-length method against the code tables, why every CSST installation must be bonded to the electrical grounding electrode system, the California pressure test (10 psi for at least 15 minutes, no perceptible drop), what an appliance connection must consist of and where the shutoff has to be, the sediment trap the inspector always looks for, and the seismic gas shutoff valve that Los Angeles requires on sale and on alterations over $10,000, which is a permit item a plumber can sell honestly and install correctly.
What the full lesson covers
- Size gas piping by the longest-length method (CPC 1215.1.1): total the appliance inputs, find the longest run from the meter to the farthest outlet, and size every section from that length in Table 1215.2 for the pipe material and pressure. Undersized gas is a low-fire complaint on the day the heater and the furnace run together.
- CSST, and any system with a single segment of CSST, must be bonded to the electrical service grounding electrode system with a jumper on a fitting (1211.2). Lightning finds the unbonded run.
- The test: air, CO2, or nitrogen at not less than 10 psi, held at least 15 minutes with no perceptible drop, gauge on, inspector able to see it (1213.3). Never test with gas.
- Each appliance: one listed connector per appliance in the same room (1212.1); an accessible shutoff with a nondisplaceable member within 6 feet, upstream of the connector, union downstream (1212.6); a sediment trap downstream of the shutoff as close to the inlet as practical, except ranges, dryers, and fireplaces (1212.9).
- Los Angeles requires a seismic gas shutoff valve before sale and on permitted alterations over $10,000 (LAMC 94.1217.0); other cities have their own rules. Check the city before quoting one, and install it per the listing with the utility's clearance.
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More lessons in The Field: Method, Code, and Cases
- 1The diagnostic method: verify, isolate, cheapest test first, cause not symptom, the options ladder, document
- 2Permits: when one is required, what is exempt, pulling it online, the inspection sequence, what inspectors look for, and handling corrections
- 3Daily-use code: drainage slope, venting, water sizing, cleanouts, trap arms, and fixture units, with the section for each
- 4Gas piping in practice: sizing, CSST bonding, the pressure test, appliance connectors and shutoffs, sediment traps, and seismic shutoff valvesYou are here
- 5Water heaters I: tank. Seismic strapping, the T&P discharge line, expansion tanks, sediment traps, pans, venting, and the garage rules
- 6Water heaters II: tankless and heat pump. Gas sizing, venting, condensate, the 2025 Energy Code direction, and where the gas-ban ordinances stand
- 7Sewer and drain I: the camera, the locator, hydro-jetting vs. cabling, and when each is the right tool
- 8Sewer and drain II: trenchless vs. open trench, whose lateral it is (it varies by city), backwater valves, and point-of-sale lateral ordinances
- 9Case: the hissing line. The meter test, the supply leak that fed the roots, the lateral to the city tap, and the contract and permit trail
- 10Leak detection: slab leaks, acoustic and pressure methods, thermal imaging, and repipe vs. reroute
- 11Low pressure: the PRV, galvanized pipe, and the sequence that finds which one it is
- 12Sewer gas: trap seals, trap primers, vents, and the sequence that finds the smell
- 13Water treatment: where softeners are restricted in California, filtration, pressure regulators, and thermal expansion
- 14Fixtures and conservation: CALGreen flow rates, SB 407 retrofit-on-alteration and disclosure-on-sale, 1.28 gpf, and the ADA basics a plumber needs
- 15Materials and methods: PEX vs. copper vs. CPVC, ABS vs. PVC (it is regional), cast iron, and the transitions that fail
- 16Commercial basics: grease interceptors, the backflow program, and the tester certification that opens a second line of work
- 17Cal/OSHA for a small shop: the IIPP every employer must have, heat illness prevention, trenching and the 5-foot permit, confined space, silica, and ladders
- 18Environmental rules: EPA lead-safe certification for any pre-1978 home, asbestos and transite pipe, and stormwater
- 19Job-site craft: sequencing with the other trades, protecting the home, and the punch list that ends the job
- 20Case: the water heater that failed inspection twice
- 21Case: the gas leak call. The protocol, and the walk-away
- 22Case: the "customer doesn't want a permit" job
- 23Template: the job-site checklist, from the truck to the walk-through
- 24Template: the pre-inspection checklist by stage. Underground, rough, water heater final, gas, and trim
- 25Template: the Injury and Illness Prevention Program starter for a plumbing shop of one to five
- 26Template: the Heat Illness Prevention Plan for a plumbing shop, outdoor and indoor
- 27Template: the customer options sheet (good / better / best) with the cost band, the permit path, and the code trail on each rung