installation of valves.
Flanges shall be of the weld neck type to match
wall thickness of pipe.
3.7
PIPE JOINTS
Pipe joints shall be designed and installed to effectively sustain the
longitudinal pullout forces caused by the contraction of piping or
superimposed loads.
3.7.1
Threaded Steel Joints
Threaded joints in steel pipe shall have tapered threads evenly cut and
shall be made with UL approved graphite joint sealing compound for gas
service or polytetrafluoroethylene tape applied to the male threads only.
Caulking of threaded joints to stop or prevent leaks will not be permitted.
3.7.2
Welded Steel Joints
Gas pipe weldments shall be as indicated. Changes in direction of piping
shall be made with welding fittings only; mitering or notching pipe to form
elbows and tees or other similar type construction will not be permitted.
Branch connection may be made with either welding tees or forged branch
outlet fittings. Branch outlet fittings shall be forged, flared for
improvement of flow where attached to the run, and reinforced against
external strains. Beveling, alignment, heat treatment, and inspection of
weld shall conform to ASME B31.8. Weld defects shall be removed and
repairs made to the weld, or the weld joints shall be entirely removed and
rewelded. After filler metal has been removed from its original package,
it shall be protected or stored so that its characteristics or welding
properties are not affected adversely. Electrodes that have been wetted or
have lost any of their coating shall not be used.
3.7.3
Polyethylene and Fiberglass Pipe Jointing Procedures
Jointing procedures shall conform to AGA XR0104. Indiscriminate heat
fusion joining of plastic pipe or fittings made from different polyethylene
resins by classification or by manufacturer shall be avoided if other
alternative joining procedures are available. If heat fusion joining of
dissimilar polyethylenes is required, special procedures are required. The
method of heat fusion joining dissimilar polyethylene resins shall be
tested in accordance with paragraph TESTS, subparagraph Destructive Tests
of Plastic Pipe Joints.
3.7.4
Connections Between Metallic and Plastic Piping
Connections shall be made only outside, underground, and with approved
transition fittings.
3.8
VALVE BOXES
Valve boxes of cast iron not less than 4.7 mm (3/16 inch) 3/16 inch thick
shall be installed at each underground valve except where concrete or other
type of housing is indicated. Valve boxes shall be provided with locking
covers that require a special wrench for removal. Wrench shall be
furnished for each box. The word "gas" shall be cast in the box cover.
When the valve is located in a roadway, the valve box shall be protected by
a suitable concrete slab at least 1 square meter. 3 square feet. When in a
sidewalk, the top of the box shall be in a concrete slab 600 mm 2 feet
square and set flush with the sidewalk. Boxes shall be adjustable
SECTION 02556A
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