Insulating and heat-tracing a temporary water treatment plant in Central Texas

Temporary and package water treatment plants go up fast. A modular plant arrives on skids to serve a new subdivision or utility district while the permanent plant is built, and most of its piping runs above ground in full sun. Central Texas does not freeze often, but when it does it can stay below freezing for days, as it did in February 2021 during Winter Storm Uri, the freeze a lot of Texans still call Snowpocalypse. A plant that freezes on a cold night stops serving the homes behind it.

In 2026 our crews worked on several of these plants in south Bexar County, Manor and New Braunfels. This post is what we learned, written for the plant vendors, general contractors and utility operators who have to get one ready before the first freeze.

What freezes first

On a package plant the big lines are rarely the problem while water is moving. What freezes is small, still water:

• Small lines, 2 inch and under: wash water, pressure-tank and pump lines. Small pipe holds little heat and loses it fast.
• Lines that sit idle: overflow and bypass lines, standby pumps, and anything that runs only during backwash or startup.
• Fittings and devices: valves, unions, hose bibs, flow meters and instrument taps have more exposed surface than straight pipe.
• Air and purge piping: we carry the insulation down to about a foot above the tank's water level.

The 3 and 4 inch influent and permeate lines need protection too, because flow drops at night and stops during maintenance. On the plants we have done, the specification called for heat trace either on every line 4 inch and smaller, or on 2 inch and smaller with insulation alone on the larger lines.

The build we install

1. Process pipe, usually 1 to 4 inch on a package plant.
2. Self-regulating heat-trace cable, run straight along the lower side of the pipe at the 4 or 8 o'clock position, where it is out of the way of feet and tools.
3. Fastening: glass-cloth tape about every foot. On plastic pipe, aluminum tape over the full length of the cable spreads the heat into the pipe wall.
4. Fiberglass pipe insulation, sized to fit over the pipe and the cable, at the thickness the plant specification and energy code call for.
5. UV-resistant PVC jacket, with the lap turned down so it sheds rain.

Insulation thickness is set by line size, fluid temperature and the insulation's R-value per inch, and the heat-trace cable is sized for that thickness. On the plants we did it was 1 inch. If anyone wants to change the thickness, tell whoever sized the cable first.

Why PVC and not aluminum: the owners of these plants asked for weather and UV protection that could be removed, and specifically not aluminum cladding. Package plants are serviced, leak-checked, modified and sometimes moved. A PVC jacket with self-sealing laps goes on without bands, comes off with a knife and goes back on after the repair.

On the smallest heat-traced lines and on tight fittings we sometimes switch to flexible elastomeric sheet, which wraps a congested tee more cleanly than preformed fiberglass. Elastomeric breaks down in sunlight unless it is coated, so every exposed piece gets a white water-based UV finish.

We coordinate the power side too. The plant vendor's electrician can make the connections, or we bring in an electrical contractor we have worked with for the last decade. We install the cable with its power connection and end-seal kits, and who makes each connection is settled before the quote. If the plant does not specify a controller, ask for an ambient-sensing thermostat so the cable is not running all summer.

How to keep the leak test from becoming a change order

Package plants are pressure-tested and leak-checked after the piping is set, and insulation is the first thing that comes off when someone is hunting a leak. On one plant this year the plant team cut the insulation away to find a leak, and our crew went back to re-insulate and re-jacket the section to match the original system. The right order of work avoids most of that:

1. Skid and equipment piping first. It is tested earliest and changes least.
2. Leave the yard and floor runs bare until the leak check is signed off, even if that means a return trip a few weeks later.
3. Stop at the flanges. We insulate valve bodies but leave flange bolts reachable, so a gasket can be tightened without cutting anything.
4. Walk the plant again before the final quote. On one Phase II plant, about 70 feet of pipe went in after our walkthrough. We price added footage by size, so it was a simple change order, but it is cheaper for everyone to catch it on the walk.

What drives schedule and price

• Footage by size. A plant with roughly 500 linear feet of 1 to 4 inch piping took us about two and a half weeks with a three-person crew, plus one six-person Saturday push.
• Congestion. Tight manifolds and stacked tees eat labor. Sixty feet of congested tees can take several people several days, and one plant ran about 60 percent over our labor estimate for that reason. When we price a plant, we look at the skid itself, not only the line list.
• Heat-trace lead time. On one job our crew waited several days for cable. Order the cable with the plant, not after the crew mobilizes.
• Who buys the cable. Some plant vendors supply the heat-trace cable themselves and need our quote split between labor and material. We do that routinely.

What to send for a quick quote

• The piping layout or P&ID with line sizes, or a marked-up drawing with lengths
• Which lines get heat trace, and the cable product if you are supplying it
• Whether the insulation must be removable, and any jacket requirement
• Where power is available, and whether you want us to bring the electrician
• The date the site is ready, and whether the plant will be moved later

Frequently asked questions

Does every line on a package plant need heat trace?

Not always. Small lines and lines that sit idle should be traced. Larger lines that run continuously sometimes get insulation only, but many owners trace everything 4 inch and smaller because a plant cannot afford a freeze during startup or maintenance. Follow the plant specification, and ask your insulation contractor to flag any line it leaves untraced.

Can the insulation be removed for maintenance and put back?

Yes, if it is built for it. We use preformed fiberglass that is not glued to the pipe, a PVC jacket that can be cut and replaced, and we stop the insulation at flanges. For valves or equipment that are opened often, removable insulation blankets are another option.

Does the insulation contractor handle the electrical for the heat trace?

We coordinate it. We install the cable with its connection and end-seal kits, and the power connections are made by the plant vendor's electrician or by an electrical contractor we have worked with for the last decade. Either way the split is settled before the quote, so nothing falls between trades.

Written by Chris Kelley from Bilt Rite Insulation's 2026 package-plant work. Field detail from Ruben Zamora, BRI superintendent, who ran the crews.