248 CMR 5.05
Modifications to Chapter 5, Gas Piping System Design, Materials, and Components
5.1.1 Installation of Piping Systems over Five Million BTU/hr. In addition to the permit
requirements of 248 CMR 3.00: General Provisions Governing the Conduct of Plumbing and
Gas Fitting Work Performed in the Commonwealth, for gas installations of over 5,000,000
BTU/hr the following is required:
(a) All piping systems over 5,000,000 BTU/hr shall be designed by a Massachusetts
registered professional engineer. The design shall assure that the piping installation,
including pipe sizing, dimension, and other aspects, meet the requirements for proper
functioning, safety, and this code. The installer must submit drawings to the Inspector
stamped by the engineer reflecting this design prior to being issued a permit. The installer
shall also submit with the drawings a written statement from the serving gas supplier that it
is able to provide fuel meeting the volume, pressure, and maximum gas demand required by
the drawings as well as that required by any existing gas systems.
(b) Once the installation is complete but prior to final inspection, the installer must provide
the Inspector with a written certification by a Massachusetts registered professional engineer
that the installation complies with the stamped drawings and specifications. The Inspector
shall not be responsible for approving or inspecting design specifications, but must ensure
the installation adheres to the provisions of 248 CMR 5.00.
(2) Add a new sub-section 5.1.3 as follows:
5.1.3 Dual Fuels Installed in Buildings and Structures. When Utility/Natural Gas and Undiluted
Liquefied Petroleum Gas (Propane Gas) systems are installed within the same building or
structure, the following additional conditions must be satisfied as well as those conditions
required for each individual fuel system:
(a) Written permission for the installation must be obtained by local fire officials and
applicable utilities.
(b) The natural gas and propane gas piping systems shall be labeled in the following
manner:
1. at a minimum of every ten feet;
2. at all changes of direction;
3. on each side of a penetration through a partition, wall or ceiling;
4. at every gas shut off valve;
5. for natural gas (color-coded yellow) and propane gas (color coded light green), the
labels shall be;
a. black lettering indicating the type of gas within the piping system;
b. the letters shall be sized equal to a minimum of the pipe diameter. However, for
piping with a diameter exceeding two inches, said lettering does not need to be larger
than two inches.
(3) Add a new sub-section 5.4.2.3 as follows:
5.4.2.3 Diversity Factor for Domestic Ranges. Diversity factor is an important factor
determining the correct gas piping size to be used for supplying domestic ranges in multiple
family dwellings; it applies to domestic ranges only and shall not apply to any other gas
appliances.
TABLE 5.4.2.3
Multi-family Dwellings
Diversity Factor in Percent of Total Load for
Domestic Gas Ranges with connected Load Ratings
of 63,000 Btu/hr. or more per Range
No. of Ranges
Demand
cubic ft/hour
Percent of
Ratings
No. of Ranges
Demand
cubic ft/hour
Percent of
Ratings
24 & Over
(4) Replace sub-section 5.5.1 with the following:
5.5.1 Maximum Design Operating Pressure.
(a) General Rules. See 248 CMR 4.03(1)(b)
(b) Elevated Pressure.
1. All elevated pressure systems shall be designed by a Massachusetts registered
professional engineer. The design shall assure that the piping installation, including pipe
sizing, dimension, and other aspects, meet the requirements for proper functioning,
safety, and this code. The installer must submit drawings to the Inspector stamped by the
engineer reflecting this design prior to being issued a permit. The installer shall also
submit with the drawings a written statement from the serving gas supplier that it is able
to provide fuel meeting the volume, pressure, and maximum gas demand required by the
drawings as well as that required by any existing gas systems. The provisions of this
paragraph shall not be in effect until July 1, 2015. Prior to July 1, 2015, elevated pressure
systems shall be subject to the special permission requirements of 248 CMR 3.04(3).
2. Once the installation is complete but prior to final inspection, the installer must
provide the Inspector with a written certification by a Massachusetts registered
professional engineer that the installation complies with the stamped drawings and
specifications. The Inspector shall not be responsible for approving or inspecting design
specifications, but must ensure the installation adheres to the provisions of 248 CMR
5.00.
3. When the maximum design operating pressure exceeds five PSIG, all piping shall be
welded in accordance with subsection 5.6.2.2.1.
4. Elevated pressure piping shall be labeled in the following manner:
a. At a minimum of every ten feet;
b. At all changes of direction;
c. On each side of a penetration through a partition, wall or ceiling;
d. At every gas shutoff valve; and
e. The labels shall be yellow with black lettering that:
i. indicates the type of gas and the pressure contained within the piping system,
and
ii. the letters shall be sized equal to a minimum of the pipe diameter. However,
for piping with a diameter exceeding two inches, said lettering does not need to
be larger than two inches; and
iii. for elevated dual fuel applications, labels for propane systems shall be
color-coded light green.
f. Labeling shall not be required for elevated pressure piping that is between the first
and second stage regulator in a liquefied petroleum gas installation.
5. Exceptions. The requirements of a professional engineer for elevated pressure
installations shall not be required for:
a. installations of propane gas piping systems utilizing elevated pressure that are
located between the first and second stage regulator when the second stage regulator
is located on the exterior of a building; and
b. installations of gas piping between a meter and a regulator not installed/supplied
by a gas company when the gas piping from the meter to the regulator does not
exceed ten feet.
(5) Add a new sub-section 5.5.1.1 as follows:
5.5.1.1 Gas Pressure Boosters. Gas pressure boosters may be installed in that portion of the gas
piping system extending from the outlet of the meter set assembly to the inlet of the equipment
requiring elevated or increased pressure when the following conditions have been satisfied:
(a) All gas pressure boosters must meet Product-acceptance requirements;
(b) the serving gas supplier has provided written authorization;
(c) If not part of the booster, the equipment served by the booster shall be equipped with a
manual re-set low gas pressure switch and a check valve upstream of the booster. By-passes
for pressure boosters shall include a manual shut off and a check valve;
(d) A pressure regulator shall be provided to maintain a constant outlet pressure and be
installed immediately downstream of the booster except when the pressure booster is
equipped with an integral pressure regulator;
(e) Gas pressure boosters shall be installed on a firm foundation or surface capable of
supporting the imposed load, and the booster shall be kept free of vibration by the installation
of vibration arrestors; and
(f) Gas pressure boosters shall be located in well ventilated spaces and be readily accessible
for examination, maintenance or replacement.
(6) Add a new sub-section 5.6.2.2.1 with the following:
5.6.2.2.1 Welding of Steel and Wrought Iron Pipe.
(a) Welding shall not be construed as the practice of gas-fitting, however, a licensed
plumber or gas fitter may not utilize welded pipes and fittings unless they conform to the
specifications cited in subsections 5.6.2.2 and A.5.5.1 (1).
(b) Gas piping systems with pressures under or equal to 70 P.S.I.G shall only be permitted
to utilize welded pipes and fittings when:
1. The inspector has performed a visual inspection as to the quality of the weld; and
2. The test pressure used during an Inspection complies with the following:
a. Systems with a maximum operating pressure of ten P.S.I.G. or less, shall be
tested to a minimum of three P.S.I.G. or ten times the operating pressure, whichever
is greater.
b. Systems with an operating pressure greater than ten P.S.I.G. and less than or
equal to 70 P.S.I.G. shall be tested at 100 P.S.I.G.
c. The test duration shall be one hour for every 100 feet of pipe, or fraction thereof.
The minimum test duration shall be one hour and the maximum test duration shall
be 24 hours, irrespective of system design.
(c) Gas piping systems with pressures over 70 P.S.I.G. may only utilize welded pipes and
fittings when:
1. All welds are of full penetration; and
2. The welds are subjected to the following tests:
a. All welds are subjected to a 100% X-ray or 100% Ultrasonic Examination (UT)
test unless they are socket welded;
b. All socket welded type joints must be subjected to a magnetic particle test or
other non-destructive test;
c. The gas piping system shall be pressure tested to a minimum of 1.25 times the gas
piping systems working pressure. However, the test duration must be a minimum of
one hour and the test must be witnessed by the Inspector; and,
d. Any testing company or field agent that provides a (UT) field examination must
meet the requirements of 248 CMR 3.04(6). A copy of the testing certification shall
be submitted to the Inspector.
3. Repairs that are made to welded joints that fail the X-Ray or (UT) test shall be
re-tested and re-certified. For future reference; the failed welded joint that is re-tested
shall be identified by stenciling ½ inch high white lettering at the weld location the date
of the re-test.
4. The Inspector shall require an affidavit signed by the individual who performed the
X-ray or (UT) examination for the testing agency. The affidavit shall state that all welds
meet the requirements of the applicable specifications and tests.
(7) Add a new sub-section 5.6.2.7 as follows:
5.6.2.7 Galvanized. Galvanized pipe shall not be used.
(8) Replace sub-section 5.6.3.4 with the following:
5.6.3.4 Corrugated Stainless Steel.
(a) CSST Fittings. All fittings and accessories used in the installation of CSST piping
systems shall be approved by the CSST manufacturer for use with their system and shall only
be installed by licensees who have completed manufacturer training/certification acceptable
to the Board.
(b) CSST Concealed Fittings.
1. Where gas piping is to be concealed:
a. connections shall only be made with CSST fittings listed for use in concealed
spaces; and
b. connections shall be produced by the manufacturer of the CSST piping system.
2. Malleable fittings shall be permitted in concealed locations when used in
combination with CSST fittings.
3. For each malleable fitting there shall only be a single CSST connection.
(c) Repairs to Concealed CSST Piping.
1. Repairs required in a CSST system which is concealed, or otherwise not readily
accessible, shall be repaired with a fitting listed for the CSST system being used.
2. Installation of an access panel shall be required at the repair site.
(d) Interior Meter Connections. Interior meter connections may be directly connected to the
CSST system as long as the meter is securely affixed to the building, and the CSST is
secured to the building structure when 24 inches or more of tubing is exposed.
(e) Exterior Meter Connections.
1. No CSST shall be connected to an exterior meter.
2. The tubing shall terminate at the foundation wall with a termination fitting, and the
meter shall be rigidly connected with steel piping to the building structure.
(f) Sleeved Gas CSST.
1. CSST shall be sleeved when passing through a metal or concrete deck to protect the
integrity of the tubing. Licensees should be aware that the tubing may be required to be
fire stopped/rated per 780 CMR: Massachusetts Amendments to the International
Building Code 2009. If applicable, this requirement will be regulated/ enforced by the
Building Inspector, not the Inspector as defined in 248 CMR 3.01: Definitions.
2. The sleeve shall be Schedule 40 black or galvanized pipe and shall extend a
minimum six inches from the top of the finished floor and the underside of the deck.
(g) Only manifolds for CSST systems supplied and listed by the CSST manufacturer may
be concealed.
1. Assembled manifolds shall be installed in an accessible location.
2. Assembled manifold is a piping combination made up of close nipples and malleable
tees.
(h) Fireplace Log Installations.
1. CSST shall terminate with a termination fitting at the entrance to the masonry fire
box.
2. The workmanship shall be performed and completed in such a manner so that the
termination will not be exposed to any adverse effects.
(i) Fixed Appliance Connection Using CSST. CSST may be directly connected to a fixed
appliance when the following conditions are met.
1. The tubing is securely attached to the building structure or other means of solid
support.
2. Tubing shall not run exposed for a distance greater than or equal to 30 inches without
being physically attached to the building structure or other means of solid support.
3. CSST terminates with a proper fitting and gas cock.
(j) CSST Used Underground.
1. When in contact with the earth or other material that could corrode the piping, the
CSST shall be installed within a sleeve designed to withstand the superimposed loads.
2. Except for pre-engineered sleeves that are Product-accepted by the Board, the sleeve
shall allow free movement of the CSST.
3. All sleeve ends shall be sealed liquid tight.
4. An acceptable tape marking system shall be in place no more than six inches from
the top of the grade indicating that a gas line is below.
5. The minimum depth for buried gas piping as describe herein is 18 inches from the top
of grade.
(k) CSST Used as an Appliance Connection. CSST shall not be used as a flexible appliance
connector downstream of the appliance shutoff device.
(l) Sizing CSST Systems. CSST systems shall be sized and installed with a maximum 14
inch water column (0.5 P.S.I.G.) gas pressure.
(m) CSST Installation and Modifications. Installation of CSST in the Commonwealth of
Massachusetts shall be in strict compliance with the manufacturer's instructions and the
Massachusetts State Plumbing and Gas Code 248 CMR 3.00: General Provisions Governing
the Conduct of Plumbing and Gas Fitting Work Performed in the Commonwealth through
7.00: Large Gas Utilization Equipment.
(n) Testing Requirements for CSST Systems.
1. Before any piping is covered, when CSST piping systems are installed in new
construction or remodeling, the system shall be tested as part of the Inspection as
prescribed under Section 7.1 as modified under 248 CMR 5.05.
2. Before piping is connected to any appliance the licensed plumber or gas fitter shall
do a second test of the system.
3. A tag shall be:
a. affixed to the meter or service manifold acknowledging this test; and
b. signed and dated by the licensed plumber or gas fitter.
(o) Liquid Leak Detector. No corrosive liquids shall be used in the testing of the CSST
system. Some household soaps and detergents may be corrosive to gas and plumbing
products.
(p) Exposed CSST Tubing. When CSST is installed outdoors or is subject to corrosive
chemicals, exposed stainless CSST tubing (where the jacket has been removed) shall be
recovered with tape as specified by the CSST manufacturer. Said re-covering of CSST shall
occur following the testing.
(q) CSST Piping Installed on Roofs. CSST shall be installed for roof top equipment only
when it is supported by one of the following methods:
1. The CSST tubing with a UV stabilized jacket is supported the full length of the CSST
run.
a. The tubing shall be affixed to a wooden plank or a steel channel that is securely
attached by an appropriate method every six feet to the roof structure.
b. The tubing shall be attached directly to the support every six feet.
2. The CSST tubing is installed within a metal or plastic conduit that is securely
attached by an appropriate method every six feet to the roof structure. Where the piping
system requires a tee to be installed within the line, the sleeve shall terminate no more
than 12 inches from the tee on both runs and the branch line.
3. For CSST tubing having sizes of 1.5 and two inches and having a UV stabilized
jacket, the following requirements shall be satisfied:
a. the CSST shall be supported on blocks which are spaced not more than 48 inches
apart.
b. The blocks shall be constructed of materials appropriate for outdoor conditions
and shall be securely attached by an appropriate method to the roof structure, and:
c. The method used to attach the CSST to the block shall not damage the plastic
coating.
d. The maximum length of tubing not supported by any method listed shall not
exceed 30 inches when connected to a gas fired roof top unit or similar gas
equipment.
(9) Replace subsection 5.6.8.4(1) with the following:
Pipe and Fittings in excess of four inches in diameter shall be welded.
(10) Amend subsection 5.6.8.4(2) by deleting "or cast iron"
(11) Replace subsection 5.6.8.4(5) with the following:
Cast iron is only permitted for flanges, valves, strainers, and filters.
(12) Add a new subsection 5.6.8.5 as follows:
5.6.8.5 Other Fittings. Notwithstanding the provisions of this section, metallic piping joints and
fittings which do not otherwise meet the requirements of this section may be utilized if approved
by the Board or otherwise have met the product acceptance requirements of 248 CMR
3.04(1): Board Required Product-acceptance.
(13) Add a new subsection 5.7.6 as follows:
5.7.6 Limitation. The provisions of this section shall only apply to premises owned gas meters,
which are comprised of a secondary meter and meter assembly installed on the downstream
portion of the gas piping system of a serving gas supplier's meter.
(14) Replace section 5.12 with the following:
5.12 Manual Shutoff Valves.
Acceptable Shutoff Devices: Gas Cocks and Ball Valves installed for use shall be listed. The
Valves shall:
(a) Have clearly indicated open and closed positions and rigidly secured stops to limit both
extremes of rotation;
(b) shall be marked in a conspicuous place with the manufacturer's name or registered
trademark; and
(c) Where in contact with material or atmosphere exterting a corrosive action, a corrosion
resistant handle shall be utilized.