Natural Gas Piping
Corpus sync: neutrality remakes, note hygiene, datasheet relocation, transformer-split cross-refs
Showing changes from Rev 3
to Rev 4
in Natural Gas Piping.
---
title: Natural Gas Piping
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- A written pressure-test and purging plan describing the test medium, test pressure and hold duration by pressure tier, the instrument used, the leak-test method, the witness, and the indoor/outdoor purging procedure
+### The Contractor shall submit the action submittals listed above for the Engineer's review and return before procurement and installation.
+
```datasheet
label: Action Submittals Required
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```
−### The Contractor shall submit the action submittals listed above for the Engineer's review and return before procurement and installation.
−
### Action submittals shall be complete and internally coordinated with the serving utility's delivered pressure and the connected appliance loads before any item is submitted.
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- Operation and maintenance data for line-pressure regulators and for any automatic shutoff or excess-flow devices, including the relief or overpressure setting
+### At substantial completion, the Contractor shall provide the closeout submittals listed above before the gas systems are accepted and placed in service.
+
```datasheet
label: Closeout Submittals Required
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```
−### At substantial completion, the Contractor shall provide the closeout submittals listed above before the gas systems are accepted and placed in service.
−
# Quality Assurance {toc}
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### A low delivered pressure forces larger pipe to carry the same load within the allowable pressure drop; an elevated delivered pressure allows smaller pipe but requires line-pressure regulators with overpressure protection at the point of pressure reduction. {note}
+### The gas pressure delivered at the meter outlet (natural gas) or at the second-stage regulator outlet (LP gas) shall be confirmed with the serving utility.
+
```datasheet
label: Delivered Service Pressure at Meter Outlet
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```
−### The gas pressure delivered at the meter outlet (natural gas) or at the second-stage regulator outlet (LP gas) shall be confirmed with the serving utility.
−
## Piping Environment {toc}
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### Buried piping is exposed to soil moisture and corrosive soils and is the principal corrosion concern for steel. {note}
+### The Contractor shall identify the environment for each section and select materials and coatings accordingly.
+
```datasheet
label: Piping Environment
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```
−### The Contractor shall identify the environment for each section and select materials and coatings accordingly.
−
# System Pressure and Materials {toc}
## The system pressure tier is the single most consequential decision in a fuel-gas system, because it cascades into pipe size, regulator requirements, overpressure protection, and test pressure. {note}
## A low-pressure system operating at or below ½ psig (about 7 to 14 in. w.c.) delivers gas to appliances at the pressure they require without any in-building regulation beyond what the meter set provides, so it is the simplest system and the default for most light-commercial and residential work. {note}
## An elevated-pressure system operating at 2 psig or 5 psig carries the same load in smaller pipe, which is valuable on long runs and high-rise risers, but each branch serving an appliance must drop to appliance pressure through a line-pressure regulator equipped with overpressure protection.
−## The elevated-pressure approach trades smaller, cheaper pipe for the added cost, venting, and maintenance of distributed regulators. {note}
```datasheet
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default: "Low pressure, ≤ ½ psig (≈ 7-14 in. w.c.) — no in-building regulation (standard)"
```
+## The elevated-pressure approach trades smaller, cheaper pipe for the added cost, venting, and maintenance of distributed regulators. {note}
## Pipe Material by Location {toc}
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### A low-pressure system is conventionally sized for a drop of about 0.5 in. w.c. across the longest run so that every appliance sees adequate pressure at full demand; an elevated-pressure system tolerates a larger drop, in psi, because the line-pressure regulators restore appliance pressure at each branch. {note}
−```datasheet
−label: Pipe Sizing Method
−type: radio
−options:
− - "Longest-length method per NFPA 54 (standard)"
− - "Branch-length method per NFPA 54"
− - "Manufacturer's sizing tables (CSST)"
−default: "Longest-length method per NFPA 54 (standard)"
−```
+### The allowable pressure drop for the low-pressure gas piping system shall be specified for use in the pipe sizing calculation.
```datasheet
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### Pipe sizes shall be determined by an accepted NFPA 54 sizing method (the longest-length method, the branch-length method, or the manufacturer's sizing tables for CSST) for the connected appliance load, the specific gravity of the gas, the system pressure tier, and the allowable pressure drop.
+```datasheet
+label: Pipe Sizing Method
+type: radio
+options:
+ - "Longest-length method per NFPA 54 (standard)"
+ - "Branch-length method per NFPA 54"
+ - "Manufacturer's sizing tables (CSST)"
+default: "Longest-length method per NFPA 54 (standard)"
+```
+
### The connected load at each appliance, and the total demand at the meter, shall be the actual input ratings of the served equipment, not assumed values.
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### Providing valves at risers and sectional isolation points lets the system be shut down for service without de-gassing the entire building. {note}
+### Each manual gas valve shall be listed for fuel-gas service and rated for the system pressure.
+
+### A valve serving a single appliance shall be the appliance shutoff valve described under Appliance Shutoff Valve.
+
+### Valves shall be provided at the base of each riser and at points required for sectional isolation so the system can be shut down for service without de-gassing the entire building.
+
```datasheet
label: Sectional Shutoff Valves
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```
−### Each manual gas valve shall be listed for fuel-gas service and rated for the system pressure.
−
−### A valve serving a single appliance shall be the appliance shutoff valve described under Appliance Shutoff Valve.
−
−### Valves shall be provided at the base of each riser and at points required for sectional isolation so the system can be shut down for service without de-gassing the entire building.
−
## Line-Pressure Regulators {toc}
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### This is a life-safety requirement: an unprotected regulator failure can over-fire appliances and rupture low-pressure components, exposing downstream piping and appliance controls to the full upstream pressure, which they are not rated to withstand. {note}
+### Each line-pressure regulator shall be provided with overpressure protection so that a failure of the regulator cannot expose downstream piping and appliance controls to the full upstream pressure.
+
+### Overpressure protection shall be by an internal relief device integral to the regulator, a separate downstream relief valve, a monitoring (series) regulator, or an automatic shutoff device, selected so the downstream pressure cannot exceed the limit established by NFPA 54 for the served appliances.
+
```datasheet
label: Overpressure Protection Method
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```
−### Each line-pressure regulator shall be provided with overpressure protection so that a failure of the regulator cannot expose downstream piping and appliance controls to the full upstream pressure.
−
−### Overpressure protection shall be by an internal relief device integral to the regulator, a separate downstream relief valve, a monitoring (series) regulator, or an automatic shutoff device, selected so the downstream pressure cannot exceed the limit established by NFPA 54 for the served appliances.
−
## Regulator and Relief Venting {toc}
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### The trap protects the appliance's gas valve, which is the most failure-sensitive component on the appliance: scale, moisture, and pipe debris carried by the gas drop into the dead leg rather than reaching the appliance gas valve and burner orifices, where they would cause erratic operation and nuisance shutdowns. {note}
+### A sediment trap shall be installed downstream of the appliance shutoff valve and as close to the appliance inlet as practical, except where the appliance manufacturer's instructions exclude it or the appliance is equipped with one.
+
```datasheet
label: Sediment Trap
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```
−### A sediment trap shall be installed downstream of the appliance shutoff valve and as close to the appliance inlet as practical, except where the appliance manufacturer's instructions exclude it or the appliance is equipped with one.
−
### The sediment trap shall be a tee with a capped nipple in the bottom outlet, or another device recognized as an effective trap.
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### The preferred practice for new buried gas piping is to avoid buried steel altogether by using polyethylene with an anodeless riser, which needs no coating or cathodic protection. {note}
+### Buried steel gas piping shall be protected against corrosion by a factory-applied bonded dielectric coating.
+
```datasheet
label: Buried Steel Corrosion Protection (where buried steel is used)
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```
−### Buried steel gas piping shall be protected against corrosion by a factory-applied bonded dielectric coating.
−
### The dielectric coating shall be inspected for holidays and repaired before backfill.
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### See [[sync/grounding-and-bonding]] for the building bonding system. {note}
+### The bonding jumper for CSST shall be not smaller than 6 AWG copper, shall connect to the steel gas-pipe segment at the meter outlet or the point the manufacturer specifies, and shall terminate on the grounding electrode system, all with listed bonding clamps in accordance with NFPA 70.
+
```datasheet
label: CSST Bonding
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```
−### The bonding jumper for CSST shall be not smaller than 6 AWG copper, shall connect to the steel gas-pipe segment at the meter outlet or the point the manufacturer specifies, and shall terminate on the grounding electrode system, all with listed bonding clamps in accordance with NFPA 70.
−
### CSST listed with an arc-resistant jacket to ANSI LC 1 / CSA 6.26 may have different supplemental-bonding allowances, but the system bonding to the grounding electrode is required in all cases.
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## Aboveground gas piping is identified so that anyone working near it knows it carries fuel gas and can trace it to its shutoff. {note}
+## Aboveground gas piping shall be identified so that anyone working near it knows it carries fuel gas and can trace it to its shutoff.
+
```datasheet
label: Gas Piping Identification
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```
−## Aboveground gas piping shall be identified so that anyone working near it knows it carries fuel gas and can trace it to its shutoff.
−
## Piping shall be marked with the legend and a directional flow arrow at intervals along each run, at each side of a wall or floor penetration, and at each valve and regulator, in accordance with [[sync/equipment-labeling]].
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# Installation {toc}
−## General {toc}
+## The Contractor shall install all gas piping in accordance with this standard, the contract drawings, NFPA 54 (and NFPA 58 for LP gas), and the equipment manufacturer's installation instructions.
−### The Contractor shall install all gas piping in accordance with this standard, the contract drawings, NFPA 54 (and NFPA 58 for LP gas), and the equipment manufacturer's installation instructions.
+## Where these conflict, the more stringent governs.
−### Where these conflict, the more stringent governs.
+## Open pipe ends shall be capped or plugged whenever work stops so that debris and moisture do not enter the bore.
−### Open pipe ends shall be capped or plugged whenever work stops so that debris and moisture do not enter the bore.
−
## Routing {toc}
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## Any leak attributable to a field joint, any regulator or overpressure device that fails to perform as specified, and any corrosion failure of buried steel within the warranty period shall be corrected at the Contractor's expense, including the cost of locating the leak, repairing the piping, re-testing, and re-purging the affected section.