Field Notes: Grouting electrical conduit in NYC

Our technical services staff is back from a quick trip to New York City to do on-site training with one of our customers there, who is doing a project for the Metro Transit Authority of New York City.

The project is to seal the annular space around 25 or so electrical conduits inside am MTA utility vault in the Bronx because ground water was leaking through the conduit into the vault. The Prime Resins technical services manager did on-site training of the contractor’s crew on how to properly use the activated oakum technique. This technique involves saturating oil-free oakum (jute fiber rope) with a hydrophilic polyurethane resin—our Prime Flex 900 XLV—and pushing it into the gap to be filled. This can be used for gaps, joints, wide cracks and gushing leaks.

The crew used about 4.5 gallons of 900 XLV and 30 feet of oakum for the training and approval phase of the work, which sealed approximately 25 4-inch conduits. Wood dowels were used to push the oakum into the conduit since live electricity was involved. The crew sealed from 6-10 inches back into the duct.

The product performed as expected and the water flow was sealed. The MTA will observe the test sections for several weeks to ensure there are no subsequent leaks. Then the remainder of the project will be completed along with three additional vaults.

This slideshow requires JavaScript.

Leave a Reply

Translate »