Page 607 - 2018_IRC

FUEL GAS

TABLE G2417.7.1.1 (406.7.1.1) 2. The piping being purged is constructed entirely from
SIZE AND LENGTH OF PIPING pipe or tubing not meeting the size and length crite-
NOMINAL PIPE SIZE LENGTH OF PIPING ria of Table G2417.7.1.1.
(inches) a (feet)
1
≥ 2 / < 3 > 50 G2417.7.2.1 (406.7.2.1) Purging procedure. The pip-
2
≥ 3 < 4 > 30 ing system shall be purged in accordance with one or
more of the following:
≥ 4 < 6 > 15
≥ 6 < 8 > 10 1. The piping shall be purged with fuel gas and shall
discharge to the outdoors.
≥ 8 Any length
2. The piping shall be purged with fuel gas and shall
For SI: 1 inch = 25.4 mm, 1 foot = 304.8 mm.
discharge to the indoors or outdoors through an
a. CSST EHD size of 62 is equivalent to nominal 2-inch pipe or tubing size. appliance burner not located in a combustion
G2417.7.1.2 (406.7.1.2) Placing in operation. Where chamber. Such burner shall be provided with a
gas piping containing air and meeting the criteria of continuous source of ignition.
Table G2417.7.1.1 is placed in operation, the air in the 3. The piping shall be purged with fuel gas and shall
piping shall first be displaced with an inert gas. The discharge to the indoors or outdoors through a
inert gas shall then be displaced with fuel gas in accor- burner that has a continuous source of ignition
dance with Section G2417.7.1.3. and that is designed for such purpose.
G2417.7.1.3 (406.7.1.3) Outdoor discharge of 4. The piping shall be purged with fuel gas that is
purged gases. The open end of a piping system being discharged to the indoors or outdoors, and the
pressure vented or purged shall discharge directly to an point of discharge shall be monitored with a
outdoor location. Purging operations shall comply will listed combustible gas detector in accordance
all of the following requirements: with Section G2417.7.2.2. Purging shall be
stopped when fuel gas is detected.
1. The point of discharge shall be controlled with a
shutoff valve. 5. The piping shall be purged by the gas supplier in
accordance with written procedures.
2. The point of discharge shall be located not less
than 10 feet (3048 mm) from sources of ignition, G2417.7.2.2 (406.7.2.2) Combustible gas detector.
Combustible gas detectors shall be listed and shall be
not less than 10 feet (3048 mm) from building
openings and not less than 25 feet (7620 mm) calibrated or tested in accordance with the manufac-
turer’s instructions. Combustible gas detectors shall be
from mechanical air intake openings.
capable of indicating the presence of fuel gas.
3. During discharge, the open point of discharge G2417.7.3 (406.7.3) Purging appliances and equip-
shall be continuously attended and monitored ment. After the piping system has been placed in opera-
with a combustible gas indicator that complies tion, appliances and equipment shall be purged before
with Section G2417.7.1.4. being placed into operation.
4. Purging operations introducing fuel gas shall be
stopped when 90 percent fuel gas by volume is
detected within the pipe. SECTION G2418 (407)
PIPING SUPPORT
5. Persons not involved in the purging operations G2418.1 (407.1) General. Piping shall be provided with sup-
shall be evacuated from all areas within 10 feet port in accordance with Section G2418.2.
(3048 mm) of the point of discharge.
G2418.2 (407.2) Design and installation. Piping shall be
G2417.7.1.4 (406.7.1.4) Combustible gas indicator. supported with metal pipe hooks, metal pipe straps, metal
Combustible gas indicators shall be listed and shall be bands, metal brackets, metal hangers or building structural
calibrated in accordance with the manufacturer’s components suitable for the size of piping, of adequate
instructions. Combustible gas indicators shall numeri- strength and quality, and located at intervals so as to prevent
cally display a volume scale from zero percent to 100 or damp out excessive vibration. Piping shall be anchored to
percent in 1-percent or smaller increments. prevent undue strains on connected appliances and shall not
G2417.7.2 (406.7.2) Piping systems allowed to be be supported by other piping. Pipe hangers and supports shall
conform to the requirements of MSS SP-58 and shall be
purged indoors or outdoors. The purging of piping sys- spaced in accordance with Section G2424. Supports, hangers
tems shall be in accordance with the provisions of Section
G2417.7.2.1 where the piping system meets both of the and anchors shall be installed so as not to interfere with the
following: free expansion and contraction of the piping between
anchors. The components of the supporting equipment shall
1. The design operating gas pressure is 2 psig (13.79 be designed and installed so that they will not be disengaged
kPa) or less. by movement of the supported piping.

582 2018 INTERNATIONAL RESIDENTIAL CODE ®
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