How to insulate pipes with fiberglass insulation

Written by robert sylvus
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How to insulate pipes with fiberglass insulation
Wrapping pipes with fibreglass pipe insulation creates an energy-efficient barrier. (Jupiterimages/ Images)

Insulating pipes with fibreglass pipe insulation lessens a water heater's workload, saving energy and money. Pipes with fibreglass insulation hold heat longer, deliver hot water faster and keep the water a degree or two higher than pipes without insulation. High-temperature pipes, like those that carry steam, can use fibreglass insulation -- foam insulation does not have a high enough temperature rating. Never expose fibreglass pipe insulation to weather; it must remain dry before, during and after installation.

Skill level:
Moderately Easy

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Things you need

  • Serrated knife
  • Tape measure
  • Fibreglass pipe insulation tape
  • Plastic squeegee

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  1. 1

    Open the fibreglass pipe insulation. Fibreglass pipe insulation contains two fibreglass shells and a foil-backed paper covering. Gluing on the foil holds the two shells in place. One end of the paper covering extends past one of the fibreglass shells and forms a flap. The flap has a protective covering on it.

  2. 2

    Peel the protective covering off the flap. Place the half of the pipe insulation without the flap on a straight section of pipe. Fold the half with the flap around the pipe. Press the centre of the flap against the outside of the first half. Press the flap onto the insulation's paper covering, starting in the centre and working to the ends of the insulation.

  3. 3

    Insulate all straight sections of pipe. Butt the ends of each piece of insulation together. Stop the insulation between 1 and 2 feet from each bend in the pipe. Cut the fibreglass pipe insulation to length with a serrated knife.

  4. 4

    Measure from the butt end of a piece of insulation to the outside edge of a bend in the pipe with a tape measure. Add the thickness of the shell to this measurement. Transfer the total to a piece of fibreglass pipe insulation and cut the insulation at a 45 degree with the serrated knife. Repeat this for the second side of the bend.

  5. 5

    Install the cut pieces of fibreglass pipe insulation over the pipe bends. Adjust each piece to eliminate any gaps between the butt ends.

  6. 6

    Cover each butt joint, including the butt joints on the pipe bends, with fibreglass pipe insulation tape. This type of tape has threads embedded in the covering.

  7. 7

    Press the fibreglass pipe insulation's flaps and the tape against the pipe insulation with a plastic squeegee. Work the squeegee back and forth to remove all bubbles and folds in each joint.

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