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Foamglas and cold service insulation for cryogenic gas processing

By Miriam Galindo, Owner & Manager · 6 min read

The Delaware Basin side of the Permian is full of cryogenic gas processing plants, the units that chill natural gas far enough to pull out the liquids. Those cold lines are a different problem than the hot work most crews around here do most of the time. On cold service the rules flip, and the part that usually gets underestimated, the vapor barrier, is the part that decides whether the system lasts. Here is how it works.

Cold service runs backward from hot service

On a hot line you hold heat in and moisture mostly bakes off. On a cold line you keep heat out, and moisture is the whole problem. The pipe is colder than the air around it, so water vapor is constantly driving inward toward the cold surface. If that vapor reaches the pipe it condenses, or on cryogenic service it freezes, right there inside the insulation. Now you have water or ice trapped against the pipe, wrecking the thermal performance and feeding corrosion, hidden under the jacket until it is bad. So cold service is built around stopping vapor, which drives both the material choice and, more than anything, the install quality.

The materials

Foamglas (cellular glass, ASTM C552)

The workhorse of serious cold and cryogenic service. Closed-cell glass that does not absorb water at all, and stays dimensionally stable down to very low temperatures. Where the service is coldest and a wet failure would be most expensive, Foamglas is the default for exactly these reasons.

Polyiso (ASTM C591)

Rigid polyiso covers a wide range and appears on some cold and dual-temperature service, always with a proper vapor barrier and jacket.

The vapor barrier is the system

On cold service, material selection matters, but the vapor barrier makes or breaks it. The barrier has to be continuous, with every seam, joint, and penetration sealed, and vapor stops placed so that any moisture that gets in cannot travel the length of the run. On cryogenic service, where the difference between pipe and air is extreme, the vapor drive is strong and constant, so the sealing has to be done right and checked. Multiple layers with staggered joints are common, so no single seam runs straight through to the cold pipe.

This is why cold service is unforgiving of rushed work. A hot line with a small gap in the jacket loses a little efficiency. A cold line with a gap in the vapor barrier pulls moisture in continuously and fails from the inside. The install is not where you save time on cryo work.

What that means for supply

A cold-service package is more than the insulation. It is the Foamglas or polyiso, the vapor barrier mastics and tapes, the sealants, the vapor stops, and the jacket, all specified to work together. Missing or substituting one piece of the vapor barrier undermines the rest. When you pull material for a cryo job, treat the vapor barrier components as core to the order, not accessories to add later.

Frequently asked questions

What insulation is used on cryogenic gas processing equipment?

Cold and cryogenic service uses closed-cell materials that resist moisture, mainly Foamglas (cellular glass, ASTM C552) and, on some service, polyiso (ASTM C591), plus a rigorous vapor barrier system. The colder and more moisture-critical the service, the more Foamglas tends to dominate, because it does not absorb water at all.

Why does cold service need such careful vapor barriers?

Because the pipe is colder than the surrounding air, water vapor constantly drives toward it. If vapor gets through the barrier it condenses, or freezes, inside the insulation against the cold pipe, destroying the thermal performance and starting corrosion. On cryogenic service the temperature difference is extreme, so the vapor barrier and sealed joints are the most important part of the system.

Why is Foamglas used for cryogenic service?

Because it is closed-cell glass that does not absorb water and stays dimensionally stable down to very low temperatures. On cold service the biggest risk is trapped moisture against the pipe, and a material that cannot take on water removes that risk at the source. That is why it is the default on the coldest and most critical runs.

Do you stock cold service and cryogenic insulation materials?

Yes. We carry Foamglas, polyiso, and the vapor barrier mastics, tapes, sealants, and jacketing that go with cold service, and we can direct-ship larger orders. Send the spec and takeoff for pricing.

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