Nonmetallic duct bank with nonmetallic subducts
A duct bank for enclosing utility lines underground includes a first main duct formed from a nonmetallic material. The first main duct defines an interior volume therewithin and has a circular cross-sectional shape. The duct bank further includes a plurality of sub-ducts each formed from a nonmetallic material and being disposed in the interior volume of the first main duct. Each of the plurality of sub-ducts has a circular cross-sectional shape and is configured to carry one or more utility lines. The nonmetallic material of the first main duct includes one or more of: glass reinforced polyester (GRP), a hybrid fiber-reinforced epoxy-based laminate, or glass-reinforced vinyl ester. The nonmetallic material of each of the plurality of sub-ducts includes one or more of: GR, high-density polyethylene (HDPE), or polyvinyl chloride (PVC).
1 . A duct bank for enclosing utility lines underground, the duct bank comprising:
a first main duct formed from a nonmetallic material and defining an interior volume therewithin, the first main duct having a circular cross-sectional shape; and
a plurality of sub-ducts each formed from a nonmetallic material and being disposed in the interior volume of the first main duct;
each of the plurality of sub-ducts having a circular cross-sectional shape and being configured to carry one or more utility lines,
wherein the nonmetallic material of the first main duct includes one or more of: glass reinforced polyester (GRP), a hybrid fiber-reinforced epoxy-based laminate, or glass-reinforced vinyl ester,
wherein the nonmetallic material of each of the plurality of sub-ducts includes one or more of: GRP, high-density polyethylene (HDPE), or polyvinyl chloride (PVC);
a second main duct formed from the nonmetallic material of the first main duct and defining a second interior volume therewithin, the second main duct having a second circular cross-sectional shape;
the first and second main ducts each having an axial end; and
a coupler that interconnects the axial end of the first main duct and the axial end of the second main duct, wherein the coupler is formed from GRP,
wherein the coupler comprises a pair of elastomer or rubber bands that are embedded or mounted at an interior surface of the coupler and extend about a full circumference of the interior surface of the coupler.
2 . The duct bank of claim 1 , wherein each of the sub-ducts is configured to carry cables.
3 . The duct bank of claim 2 , wherein the sub-ducts are each formed from the same nonmetallic material.
4 . The duct bank of claim 3 , wherein:
one or more of the sub-ducts is configured to carry one or more power cables and one or more communication cables; and
the duct bank further includes a plurality of spacers disposed between neighboring ones of the sub-ducts.
5 . The duct bank of claim 4 , wherein:
the plurality of sub-ducts extend between the interior volume of the first main duct and the interior volume of the second main duct; and
the coupler is disposed radially outwardly of the first main duct and of the second main duct.
6 . The duct bank of claim 5 , wherein the coupler is a double-bell coupling.
7 . The duct bank of claim 1 , wherein the axial ends of each of the first and second main ducts are tapered.
8 . The duct bank of claim 7 , wherein the sub-ducts include a central sub-duct and a plurality of outer sub-ducts disposed at regular angular intervals about the central sub-duct.
9 . The duct bank of claim 8 , wherein the spacers extend between the central sub-duct and each of the outer sub-ducts.
10 . The duct bank of claim 9 , wherein the central sub-duct, outer sub-ducts and spacers form a single pre-assembled unit.
11 . The duct bank of claim 10 , wherein the spacers are formed from the same non-metallic material as the central sub-duct and outer sub-ducts.
12 . The duct bank of claim 1 , wherein the first main duct is formed from GRP.
13 . The duct bank of claim 12 , wherein the first main duct includes an outermost layer that includes carbon fiber.
14 . The duct bank of claim 13 , wherein the second main duct is formed from GRP.
15 . The duct bank of claim 1 , wherein the first main duct is formed from a hybrid fiber-reinforced epoxy-based laminate.
16 . The duct bank of claim 15 , wherein curing for the laminate is chosen based on prospective temperatures of the cables carried by the sub-ducts.
17 . The duct bank of claim 16 , wherein anhydride or amine curing for the laminate is chosen based on prospective temperatures of the cables carried by the sub-ducts.