Underground gas piping shall
be installed with approved clearance from other underground
structures to avoid contact therewith, to allow maintenance,
and to protect against damage from proximity to other structures.
In addition, underground plastic piping shall be installed
with approved clearance or shall be insulated from
sources of heat so as to prevent the heat from impairing the
serviceability of the pipe. [NFPA 54:7.1.1]
Underground piping
systems shall be installed with a cover not less than 12
inches (305 mm). Where external damage to the pipe or
tubing from external forces is likely to result, the cover
shall be not less than 18 inches (457 mm). Where a cover
not less than 12 inches (305 mm) cannot be provided, the pipe shall be installed in conduit or bridged (shielded).
[NFPA 54:7.1.2.1]
The trench shall be graded so that
the pipe has a firm, substantially continuous bearing on
the bottom of the trench. [NFPA 54:7.1.2.2]
Where flooding of the
trench is done to consolidate the backfill, care shall
be exercised to see that the pipe is not floated from
its firm bearing on the trench bottom. [NFPA 54:7.1.2.3]
Gas piping in
contact with earth or other material that is capable of corroding
the piping shall be protected against corrosion in
an approved manner. Where dissimilar metals are joined
underground, an insulating coupling or fitting shall be
used. Piping shall not be laid in contact with cinders. Uncoated
threaded or socket-welded joints shall not be used
in piping in contact with soil or where internal or external
crevice corrosion is known to occur. [NFPA 54:7.1.3]
Where the formation
of hydrates or ice is known to occur, piping shall
be protected against freezing. [NFPA 54:7.1.4]
Underground
piping installed through the outer foundation or
basement wall of a building shall be encased in a protective
sleeve or protected by an approved device or
method. The space between the gas piping and the sleeve
and between the sleeve and the wall shall be sealed to
prevent entry of gas and water. [NFPA 54:7.1.5]
Where gas piping is installed underground beneath
buildings, the piping shall be one of the following:
- Encased in an approved conduit designed to withstand the imposed loads and installed in accordance with Section 1210.1.6.1 or Section 1210.1.6.2.
- A piping or encasement system listed for installation beneath buildings. [NFPA 54:7.1.6]
The conduit shall extend into an accessible portion of the building and, at the point
where the conduit terminates in the building, the
space between the conduit and the gas piping shall
be sealed to prevent the possible entrance of a gas
leakage. Where the end sealing is of a type that will
retain the full pressure of the pipe, the conduit shall
be designed for the same pressure as the pipe. The
conduit shall extend not less than 4 inches (102 mm)
outside the building, be vented outdoors above finished
ground level, and be installed so as to prevent
the entrance of water and insects. [NFPA 54:7.1.6.1]
Where the conduit originates and terminates
within the same building, the conduit shall
originate and terminate in an accessible portion of
the building and shall not be sealed. [NFPA
54:7.1.6.2]
Plastic piping shall be installed
outdoors, underground only.
Exceptions:
Exceptions:
- Plastic piping shall be permitted to terminate aboveground where an anodeless riser is used.
- Plastic piping shall be permitted to terminate with a wall head adapter aboveground in buildings, including basements, where the plastic piping is inserted in a piping material permitted for use in buildings. [NFPA 54:7.1.7.1]
Connections made between metallic
and plastic piping shall be made with fittings that
are in accordance with one of the following:
- ASTM D2513
- ASTM F1973
- ASTM F2509 [NFPA 54:7.1.7.2]
An electrically continuous
corrosion-resistant tracer wire (not less than AWG
14) or tape shall be buried with the plastic pipe to
facilitate locating. One end of the tracer wire or tape shall be brought aboveground at a building wall or
riser. [NFPA 54:7.1.7.3]
Piping installed aboveground
shall be securely supported and located where it will be protected
from physical damage. Where passing through an exterior
wall, the piping shall be protected against corrosion by
coating or wrapping with an inert material approved for such
applications. The piping shall be sealed around its circumference
at the point of the exterior penetration to prevent the
entry of water, insects, and rodents. Where piping is encased
in a protective pipe sleeve, the annular spaces between the
gas piping and the sleeve and between the sleeve and the wall
opening shall be sealed. [NFPA 54:7.2.1]
The installation of gas piping
shall not cause structural stresses within building
components to exceed allowable design limits. Approval
shall be obtained before beams or joists are cut or
notched. [NFPA 54:7.2.2]
Permission shall be obtained from the Authority Having Jurisdiction.
Permission shall be obtained from the Authority Having Jurisdiction.
Piping for other than
dry gas conditions shall be sloped not less than 1/4 inch in
15 feet (1.4 mm/m) to prevent traps. [NFPA 54:7.2.3]
Gas piping shall be
permitted to be installed in accessible spaces between
a fixed ceiling and a dropped ceiling, whether
or not such spaces are used as a plenum. Valves shall
not be located in such spaces.
Exception: Appliance or equipment shutoff valves required by this code shall be permitted to be installed in accessible spaces containing vented appliances.
Exception: Appliance or equipment shutoff valves required by this code shall be permitted to be installed in accessible spaces containing vented appliances.
Gas piping inside a building
shall not be installed in or through a clothes chute,
chimney or gas vent, dumbwaiter, elevator shaft, or air
duct, other than combustion air ducts. [NFPA 54:7.2.4]
Exception: Ducts used to provide ventilation air in accordance with Section 506.0 or to above-ceiling spaces in accordance with Section 1210.2.2.1.
Exception: Ducts used to provide ventilation air in accordance with Section 506.0 or to above-ceiling spaces in accordance with Section 1210.2.2.1.
Piping shall
be supported with metal pipe hooks, metal pipe straps,
metal bands, metal brackets, metal hangers, or building
structural components; approved for the size of piping; of
adequate strength and quality; and located at intervals so
as to prevent or damp out excessive vibration. Piping
shall be anchored to prevent undue strains on connected
appliances and equipment and shall not be supported by
other piping. Pipe hangers and supports shall comply
with the requirements of MSS SP-58. [NFPA 54:7.2.5.1]
Spacing of supports in gas piping
installations shall not exceed the distance shown
in Table 1210.2.4.1. Spacing of supports for CSST
shall be in accordance with the CSST manufacturer's
instructions. [NFPA 54:7.2.5.2]
For SI umts: 1 Inch = 25 mm, 1 foot = 304.8 mm
| STEEL PIPE, NOMINAL SIZE OF PIPE (inches) |
SPACING OF SUPPORTS (feet) |
NOMINAL SIZE OF TUBING SMOOTH-WALL (inches O.D.) |
SPACING OF SUPPORTS (feet) |
|---|---|---|---|
| 1/2 | 6 | 1/2 | 4 |
| 3/4 or 1 | 8 | 5/8 or 3/4 | 6 |
| 11/4 or larger (horizontal) |
10 | 7/8 or 1 (horizontal) | 8 |
| 11/4 or larger (vertical) |
Every floor level |
1 or longer (vertical) |
Every floor level |
Supports,
hangers, and anchors shall be installed so as not to
interfere with the free expansion and contraction of
the piping between anchors. Parts of the supporting
system shall be designed and installed so they are
not disengaged by movement of the supported piping.
[NFPA 54:7.2.5.3]
Where piping containing
gas is to be removed, the line shall be first disconnected
from sources of gas and then thoroughly purged with air,
water, or inert gas before cutting or welding is done.
[NFPA 54:7.2.6]
Gas piping in concealed
locations shall be installed in accordance with this section.
[NFPA 54:7.3.1]
Where gas piping is to be concealed,
connections shall be of the following type:
- Pipe fittings such as elbows, tees, couplings, and right/left nipple/couplings.
- Joining tubing by brazing (see Section 1208.5.8.2).
- Fittings listed for use in concealed spaces or that have been demonstrated to sustain, without leakage, forces due to temperature expansion or contraction, vibration, or fatigue based on their geographic location, application, or operation.
- Where necessary to insert fittings in gas pipe that has been installed in a concealed location, the pipe shall be reconnected by welding, flanges, or the use of a right/left nipple/coupling.
Concealed gas piping
shall not be located in solid partitions. [NFPA 54:7.3.3]
This provision shall not
apply to tubing that pierces walls, floors, or partitions.
Tubing installed vertically and horizontally inside hollow
walls or partitions without protection along its entire
concealed length shall be in accordance with the
following requirements:
- A steel striker barrier not less than 0.0508 of an inch (1.3 mm) thick, or equivalent, shall be installed between the tubing and the finished wall and extend not less than 4 inches (102 mm) beyond concealed penetrations of plates, firestops, wall studs, and similar construction features.
- The tubing shall be installed in single runs and shall not be rigidly secured. [NFPA 54:7.3.4]
In industrial occupancies, gas
piping in solid floors such as concrete shall be laid in
channels in the floor and covered to permit access to the
piping with minimum damage to the building. Where
piping in floor channels is exposed to excessive moisture
or corrosive substances, the piping shall be protected in
an approved manner. [NFPA 54:7.3.5.1]
Exception: In other than industrial occupancies and where approved by the Authority Having Jurisdiction, gas piping embedded in concrete floor slabs constructed with portland cement shall be surrounded with not less than 11/2 inches (38 mm) of concrete and shall not be in physical contact with other metallic structures such as reinforcing rods or electrically neutral conductors. Piping, fittings, and risers shall be protected against corrosion in accordance with Section 1208.5.6. Piping shall not be embedded in concrete slabs containing quick-set additives or cinder aggregate. [NFPA 54:7.3.5.2]
Exception: In other than industrial occupancies and where approved by the Authority Having Jurisdiction, gas piping embedded in concrete floor slabs constructed with portland cement shall be surrounded with not less than 11/2 inches (38 mm) of concrete and shall not be in physical contact with other metallic structures such as reinforcing rods or electrically neutral conductors. Piping, fittings, and risers shall be protected against corrosion in accordance with Section 1208.5.6. Piping shall not be embedded in concrete slabs containing quick-set additives or cinder aggregate. [NFPA 54:7.3.5.2]
Where gas piping exceeding
5 psi (34 kPa) is located within vertical chases in accordance
with Section 1210.5(2), the requirements of Section
1210.4.1 through Section 1210.4.3 shall apply. [NFPA 54:7.4]
Where pressure reduction
is required in branch connections in accordance with Section
1210.5, such reduction shall take place either inside
the chase or immediately adjacent to the outside wall of
the chase. Regulator venting and downstream overpressure
protection shall comply with Section 1208.7.1 and
Section 1208.7.5. The regulator shall be accessible for
service and repair, and vented in accordance with one of
the following:
- Where the fuel gas is lighter than air, regulators equipped with a vent limiting means shall be permitted to be vented into the chase. Regulators not equipped with a vent limiting means shall be permitted to be vented either directly to the outdoors or to a point within the top 1 foot (305 mm) of the chase.
- Where the fuel gas is heavier than air, the regulator vent shall be vented directly to the outdoors. [NFPA 54:7.4.1]
Chase construction shall comply
with local building codes with respect to fire resistance
and protection of horizontal and vertical openings.
[NFPA 54:7.4.2]
A chase shall be ventilated to the
outdoors and at the top. The openings shall have a minimum
free area [in square inches (m2)] equal to the product
of one-half of the maximum pressure in the piping
[in psi (kPa)] times the largest nominal diameter of that
piping [in inches (mm)], or the cross-sectional area of
the chase, whichever is smaller. Where more than one
fuel gas piping system is present, the free area for each
system shall be calculated and the largest area used.
[NFPA 54:7.4.31
The maximum
design operating pressure for piping systems located inside
buildings shall not exceed 5 psi (34 kPa) unless one or
more of the following conditions are met:
- The piping system is welded.
- The piping is located in a ventilated chase or otherwise enclosed for protection against accidental gas accumulation.
- The piping is located inside buildings or separate areas of
buildings used exclusively for one of the following:
- Industrial processing or heating
- Research
- Warehousing
- Boiler or mechanical equipment rooms
- The piping is a temporary installation for buildings under construction.
- The piping serves appliances or equipment used for agricultural purposes.
- The piping system is an LP-Gas piping system with a design operating pressure exceeding 20 psi (138 kPa) and in accordance with NFPA 58. LP-Gas systems designed to operate below -5°F (-21°C) or with butane or a propane-butane mix shall be designed to either accommodate liquid LP-Gas or to prevent LP-Gas vapor from condensing back into liquid. [NFPA 54:5.5]
The maximum
operating pressure for piping systems serving appliances designed
to operate at 14 inches water column (3.5 kPa) inlet
pressure or less shall be 2 pounds-force per square inch gauge
(psig) (14 kPa) unless an over-pressure protection device designed
to limit pressure at the appliance to 2 psig (14 kPa) upon
failure of the line gas pressure regulator is installed.
Changes in direction of gas pipe
shall be made by the use of fittings, factory bends, or field
bends. [NFPA 54:7.5]
Metallic pipe bends shall comply
with the following:
- Bends shall be made with bending equipment and procedures intended for that purpose.
- Bends shall be smooth and free from buckling, cracks, or other evidence of mechanical damage.
- The longitudinal weld of the pipe shall be near the neutral axis of the bend.
- The pipe shall not be bent through an arc of more than 90 degrees (1.57 rad).
- The inside radius of a bend shall be not less than six times the outside diameter of the pipe. [NFPA 54:7.5.1]
Plastic pipe bends shall comply
with the following:
- The pipe shall not be damaged, and the internal diameter of the pipe shall not be effectively reduced.
- Joints shall not be located in pipe bends.
- The radius of the inner curve of such bends shall be not less than 25 times the inside diameter of the pipe.
- Where the piping manufacturer specifies the use of special bending equipment or procedures, such equipment or procedures shall be used. [NFPA 54:7.5.2]
Factory-made welding elbows or
transverse segments cut therefrom shall have an arc
length measured along the crotch of not less than 1 inch
(25.4 mm) for pipe sizes 2 inches (50 mm) and larger.
[NFPA 54:7.5.3]
For other than dry gas conditions, a drip shall be provided at a point in the line of
pipe where condensate is capable of collecting. Where required
by the Authority Having Jurisdiction or the serving gas
supplier, a drip shall also be provided at the outlet of the
meter. This drip shall be so installed as to constitute a trap
wherein an accumulation of condensate will shut off the flow
of gas before it will run back into the meter. [NFPA 54:7.6.1]
Drips shall be installed in such locations that they will be readily accessible to permit
cleaning or emptying. A drip shall not be located
where the condensate is likely to freeze. [NFPA 54:7.6.2]
The installation of sediment traps shall comply with Section 1212.8. [NFPA 54:7.6.3]
Outlets shall be located and installed in accordance
with the following requirements:
- The outlet fittings or piping shall be securely fastened in place.
- Outlets shall not be located behind doors.
- Outlets shall be located far enough from floors, walls, patios, slabs, and ceilings to permit the use of wrenches without straining, bending, or damaging the piping.
- The unthreaded portion of gas piping outlets shall extend not less than 1 inch (25.4 mm) through finished ceilings or indoor or outdoor walls.
- The unthreaded portion of gas piping outlets shall extend not less than 2 inches (51 mm) above the surface of floors or outdoor patios or slabs.
- The provisions of Section 1210.9(4) and Section 1210.9(5) shall not apply to listed quick-disconnect devices of the flush-mounted type or listed gas convenience outlets. Such devices shall be installed in accordance with the manufacturer's installation instructions. [NFPA 54:7.7.1]
Each outlet, including a valve,
shall be closed gastight with a threaded plug or cap immediately
after installation and shall be left closed until
the appliance or equipment is connected thereto. Where
an appliance or equipment is disconnected from an outlet,
and the outlet is not to be used again immediately, it
shall be capped or plugged gastight.
Exceptions:
Exceptions:
- Laboratory appliances installed in accordance with Section 1212.3.1 shall be permitted.
- The use of a listed quick-disconnect device with integral shutoff or listed gas convenience outlet shall be permitted. [NFPA 54:7.7.2.1]
Appliance
shutoff valves installed in fireplaces shall be removed
and the piping capped gastight where the
fireplace is used for solid-fuel burning. [NFPA
54:7.7.2.2]
Where a branch outlet is
placed on a main supply line before it is known what size pipe
will be connected to it, the outlet shall be of the same size as
the line that supplies it. [NFPA 54:7.8]
An accessible gas
shutoff valve shall be provided upstream of each gas pressure
regulator. Where two gas pressure regulators are installed in
series in a single gas line, a manual valve shall not be required
at the second regulator. [NFPA 54:7.9.1]
Main
gas shutoff valves controlling several gas piping systems
shall be readily accessible for operation and installed so
as to be protected from physical damage. They shall be
marked with a metal tag or other permanent means attached
by the installing agency so that the gas piping systems
supplied through them are readily identified. [NFPA
54:7.9.2.1]
In multiple-tenant buildings supplied
through a master meter, through one service regulator
where a meter is not provided, or where meters or
service regulators are not readily accessible from the
appliance or equipment location, an individual shutoff
valve for each apartment or tenant line shall be
provided at a convenient point of general accessibility.
In a common system serving a number of individual
buildings, shutoff valves shall be installed at
each building. [NFPA 54:7.9.2.2]
An exterior shutoff
valve to permit turning off the gas supply to each
building in an emergency shall be provided. The emergency
shutoff valves shall be plainly marked as such and
their locations posted as required by the Authority Having
Jurisdiction. [NFPA 54:7.9.2.3]
Each laboratory
space containing two or more gas outlets installed on
tables, benches, or in hoods in educational, research, commercial
and industrial occupancies shall have a single shutoff
valve through which such gas outlets are supplied. The
shutoff valve shall be accessible and shall be located within
the laboratory or located adjacent to the laboratory's egress
door and shall be identified. [NFPA 54:7.9.2.4]
No device shall be placed inside
the gas piping or fittings that will reduce the cross-sectional
area or otherwise obstruct the free flow of gas, except where
an allowance in the piping system design has been made for
such a device and where approved by the Authority Having
Jurisdiction. [NFPA 54:7.10]
Where gas-air mixing machines are
employed to produce mixtures above or below the flammable
range, they shall be provided with stops to prevent adjustment
of the mixture to within or approaching the flammable range.
[NFPA 54:7.11]
Systems containing flammable gas-air mixtures shall
be in accordance with NFPA 54.