Glass Wool Pipe Insulation: Pre-formed Sections for Pipes

Glass Wool Pipe Insulation

Glass wool pipe insulation is supplied as pre-formed half-shells sized to the pipe outside diameter, from small tubes to large mains. DonFoil supplies it plain or faced with FSK or PSK foil laminate.

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Technical specifications

Property	Typical for glass wool	DonFoil grade data
Material	Glass fiber with thermosetting resin binder	By grade
Form	Pre-formed pipe sections (half-shells)	Half-shells
Density	Medium density that cuts cleanly	On request
Thermal conductivity (lambda)	About 0.030 to 0.040 W/(m*K)	On request
Pipe outside diameter	15 to 1000 mm typical	On request
Section length	Commonly 1 m	On request
Wall thickness	25 to 100 mm typical	On request
Fire classification	Non-combustible, Euroclass A1 / ASTM E84 Class A (fiber)	By grade
Facing options	FSK, PSK, or unfaced	All options

Figures marked typical reflect common glass wool values. DonFoil grade-specific density, lambda and dimension data is supplied on request or with the product data sheet.

What glass wool pipe insulation is

The pipe section is a half-shell molded to the pipe outside diameter so it slips over the line in one piece. Because it is pre-formed, it gives a uniform wall thickness that hand-applied insulation cannot match.

Where glass wool pipe insulation is used

It is used on HVAC chilled and hot water lines, plant rooms and district heating risers. By grade it is also applied to steam lines. The pre-formed shape keeps the insulation tight against the pipe so there are no voids at the metal surface.

Facing options

FSK facing and PSK facing are both used on pipe sections, with the foil acting as the vapor retarder and finish. Plain, unfaced sections are supplied when a separate jacket is specified. See FSK facing and PP scrim kraft facing for the laminate details.

Installation notes

Slip the half-shell over the pipe and close the longitudinal seam with FSK or PSK tape, then add a finish wrap where required. For chilled water add a vapor-tight facing and seal all seams to stop condensation. Segments longer than about 1 m need extra support so they do not sag.

Common mistakes

Picking the wrong outside diameter leaves a gap or forces the shell. Leaving the seam unsealed breaks the vapor barrier. Omitting a vapor-facing on chilled lines causes condensation on the outer surface. Under-supporting long runs lets the section sag, and mixing hot and cold grades on one system risks the wrong temperature rating.

Standards

Glass wool pipe insulation is supplied to ASTM C547, and to EN 13162 and BS 3958 for building applications.

Frequently asked questions

How do I size glass wool pipe sections?

Measure the pipe outside diameter and pick the matching section inside diameter. The section must not be forced onto a larger pipe.

What thickness do I need?

It depends on the pipe temperature and the target heat loss or condensation control. Confirm with your specification. DonFoil thickness data is on request.

How do I close the seam?

Butt the longitudinal edges and seal with FSK or PSK tape rated for the service, then add a finish wrap where required.

Can it be used on chilled water lines?

Yes, but add a vapor-tight facing and seal all seams to stop condensation on the outer surface.

What length are pipe sections supplied in?

Normally 1 m. Measure the run, divide by the section length and allow a small waste margin for cuts and fittings.

Related glass wool forms

Related: Glass Wool overview, Glass Wool Blanket, Glass Wool Board.