A.
Casing Pipe.
Uncontaminated used welded steel pipe may be used for casing as long as it meets the minimum thickness and no indentations exceed 1/2". The inside surface of the casing shall be free from burrs or other projections which could damage the carrier pipe. Field cut casing pipe ends shall be ground smooth. Encasement pipe shall be welded steel pipe with the wall thickness as shown on the plans. If a minimum wall thickness is not shown on the plans, casing shall comply with the following:
MINIMUM WALL THICKNESS | DIAMETER OF CASING PIPE |
|---|---|
1/4" (0.2500") | 12" or less |
5/16" (0.3125") | over 12" - 18" |
3/8" (0.3750") | over 18" - 22" |
7/16" (0.4375") | over 22" - 28" |
1/2" (0.5000") | over 28" - 34" |
9/16" (0.5625") | over 34" - 42" |
5/8" (0.6250") | over 42" - 48" |
1.
The criteria for casing shown in the above table are intended to be minimum requirements only and shall be applicable unless more stringent requirements are designated on the plans or on the Bid Form. The Contractor shall be responsible for insuring that the casing materials are of sufficient strength for the installation method he chooses and for the soil conditions encountered. Casing shall be clean inside and outside with exception of minor rust and scale.
2.
In railroad right-of-ways, encasement pipe shall be ASTM A36 steel (minimum yield strength of 36,000 psi), unless specifically stated otherwise in the permit issued by the Railroad Company.
B.
Casing Spacers/Insulators.
Casing spacers shall provide electrical insulation between the carrier pipe and casing. They shall be made of high density polyethylene or other approved material. The casing spacers shall be “RACI” as manufactured by Public Works Marketing, Inc., or approved equal. The spacer shall be sized such that the bell of the carrier pipe will be held a minimum of one-fourth (1/4) of an inch from the bottom of the casing, and the spacer O.D. shall not be less than the casing I.D. minus three-fourths (3/4) of an inch. The design and type of spacer shall be suitable for the type, size, and weight of the carrier pipe and its contents. Insulators shall dielectrically insulate the carrier pipe in the casing pipe and shall adequately support the pipe under all working installation conditions.
C.
Casing Seals:
Casing seals shall be manufactured rubber seals for the size of casing specified and shall be configured so they can be fastened to the casing and carrier pipe with stainless steel bands.
D.
Cathodic Protection:
When required by railroad or TxDOT permit, steel pipes and/or casings shall be protected from corrosion by cathodic protection. This shall include a buried 32-pound packaged magnesium anode, #12 lead wire, a Fink test station, and a test station marker.
(Ordinance 2007-106, App. B, adopted 3/20/07)