Material Strength of Fusible PVC® Pipe Energizes Difficult, Bundled Electrical Conduit Crossing

Difficult projects, such as a bank of electrical conduit installed beneath the Hackensack River in May of 2012, require ingenuity and detailed coordination of engineers, owners, contractors, and manufacturers.

The challenging project called for fifteen individual conduits, composed of ten 6-inch and five 5-inch diameter Fusible PVC® pipes, to be slipped into a 36-inch steel casing that had been installed under the Hackensack River via horizontal directional drilling. The 6-inch conduits will be used immediately after installation for a 69 kV high voltage power feed under the river. The final five 5-inch conduits are intended for future 26/13/4kV crossings.

J. Fletcher Creamer & Son, Inc. (JFC&S) contracted with Underground Solutions, Inc. (UGSI) to provide Fusible PVC® pipe (conduit) and fusion services. A key element of the project was protecting the power lines from the excessive heat that would be generated during operation. Heat is commonly associated with reduction of cable life and ultimately can result in premature cable failure. Therefore, it was imperative to provide proper heat transfer through the use of thermal grouting. Fusible PVC® conduit was chosen as the conduit material for this application due to its high tensile strength and its resistance to the external loading created by the thermal grouting process. This tensile strength allows for a thinner pipe wall for the Fusible PVC® conduit compared to other thermoplastics, while still maintaining the required buckling resistance. There were significant advantages for the Fusible PVC® conduit in terms of reduced casing size, thermal grout volume, and lighter installation weight.

The complicated orchestration of fusion and internal de-beading required four UGSI fusion technicians and three fusion machines. Space restrictions limited the crew to only 1,800 LF of pipe fused per shift (15 sections of 120 LF each). The UGSI fusion crew alternated shifts with the JFC&S crew that bundled the pipe using specially designed casing spacers. Since the Fusible PVC® pipe would be used as a conduit for the large kV cables, the entire internal bead formed during the fusion process had to be removed to prevent damage to the cables. A mandrel device was passed inside each joint confirming bead removal.

Pipeline Details and Project Summary
Project: Hackensack River Bundled Conduit Crossing
Location: Carlstadt, NJ
Length: 22,500 LF of Pipe (1,500 LF Crossing)
Pipe Size: 6" Schedule 80 and 5" DR17
Owner: PSE&G
Contractors: J. Fletcher Creamer & Son, Inc. & inTerra Innovation, Inc. (Grouting)
UGSI Contact: Matt Boeh (412) 418-3201

Fusion Begins

Coordinated Fusion Assembly

Bundling of Pipe

Pipe Entry

Successful Crossing

Thermal Grouting