Insulation materials: temperature limits, k-values and where each one fits

Where it is the right answer

Steam, condensate, hot water, hydronic loops and hot process lines anywhere under its ceiling. Sections come molded to the pipe size, so fit-up is fast and a long run goes on in a day.

Where it is not

Cold service behind anything less than a flawless vapor jacket — wet fiberglass on a chilled line loses most of its R and never dries out. Also not where the covering takes abuse: it crushes, and crushed insulation is a gap.

Where it is the right answer

High-temperature piping and equipment, fire-rated assemblies, and any hot run in a space where the covering gets leaned on, bumped and re-hung.

Where it is not

Cold lines — it is fibrous, so it fails the same way fiberglass does when moisture reaches it. On a 180°F line it also buys nothing fiberglass would not have done for less.

Where it is the right answer

Hot piping and equipment people climb on, stand on or lean ladders against, and large-bore high-temperature runs where a soft material would be crushed inside a year.

Where it is not

Anywhere R per inch is the constraint — its k is nearly double fiberglass, so the same inch insulates noticeably less. It also absorbs water, so it is not a cold-side material.

Where it is the right answer

Chilled, low-temperature and cryogenic lines, buried pipe, and outdoor cold runs — anywhere water getting in would end the system. It is its own vapor barrier, and it stays dry because there is nothing in it to wet.

Where it is not

An ordinary hot indoor run, where cheaper material does the same job. It is rigid, so complicated geometry takes fabrication time, and the price reflects both.

Where it is the right answer

Clearance problems. Two lines sharing one hanger gap, a wall or floor penetration with an inch to spare, a run boxed in by structure — places where the correct thickness in any other material simply will not fit.

Where it is not

An open pipe rack with room around it. On a line with clearance you can buy the same performance in more inches of fiberglass for a fraction of the price, and we will tell you so.

Where it is the right answer

Valves, flange pairs, manways, exchanger heads and autoclave doors — anything that has to be opened, inspected or serviced. A bare 6-inch gate valve loses about as much heat as four to five feet of bare pipe, and a hard cover means somebody cuts it off the first time it needs turning.

Where it is not

Straight runs. A blanket seals less perfectly than molded sections — figure about 85 percent of the loss recovered — and it costs several times more per foot than pipe sections would.