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A row of pale vertical storage tanks on a UK industrial site under a soft grey-white sky, their cylindrical shells catching low daylight, pipework at their bases.

Application

Tanks and vessels, insulated in place: the shell followed, the heat kept where it belongs, the foam protected.

Cylindrical, spherical or irregular, steel, GRP or plastic: closed-cell foam is sprayed onto the outside of the shell and takes its shape without cutting or fitting, then a protective coating goes over the foam so the weather never touches it.

Start a project brief What it costs: the cost guide
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01The build-up

The shell stays in service. The jacket goes on around it.

A bare tank does two things it should not: it loses or gains heat through every square metre of shell, and when its contents are colder than the air, it sweats. Switch the drawing between the bare vessel and the jacketed vessel.

Two states. Switch between them; the marks and the reading follow.

Swipe across to see the whole section.

BARE SHELL · HEAT OUT, CONDENSATION ONSection, schematic, not to scale. Three marks in each state; the cards beneath read them.

Cold shell · below the dew pointThe dew point · water formsAbove the dew point · dry

1The shell

Thin, conductive, and the whole surface is exposed.

A steel or GRP shell has almost no thermal resistance. Heated contents lose heat through all of it, all the time; chilled contents gain it. The energy bill is the shell area.

2Condensation on the shell

A cold vessel sweats.

When the contents are colder than the air, the shell sits below the dew point and water forms on it, runs down and pools at the base. Corrosion starts under the drips. Cladding with open joints does nothing about the air behind it.

3The fittings

Nozzles, manways, legs and ladders.

Every fitting is a break in any pre-formed insulation and a path for heat and moisture. Fitting boards or sections around them is slow, and the joints are where the failures start.

The short version: a vessel is a shape, and spray foam is the one insulation that takes the shape of what it is sprayed on. Jacket, then coat, then cut back and finish at the fittings: the sequence is the page.

02Project record

The sequence, on a real vessel.

Installation footage from HOLVEM's own projects. This item is a project record, played on request; nothing on this page that is not real footage carries that label.

Project recordSilo, cut back and finished
Silo insulation cut back and finished. Closed cell, externally, the fittings closed.

Cut back and finished, at the fittings.

The jacket is trimmed cleanly where it meets the vessel's fittings and edges, and the edge is closed before the coating goes over it. What you see is the detail that decides whether a jacket lasts.

All project records

03The order of work

Five steps, on the outside of the vessel.

The work is done externally, normally with the vessel in service and the site working around it. Each step is checked before the next begins.

  1. Shell condition

    The shell is inspected: material, corrosion, coatings, leaks at seams and fittings, and the operating temperature of the contents. A leaking vessel is repaired first, by someone else. Closed-cell foam is not a repair.

    HOLVEM checksSound shell, no leaks; operating temperature recorded.

  2. Preparation and protection

    Loose coating, corrosion product, oil and contamination come off the shell. Fittings, gauges, ladders and the ground around the vessel are masked and protected. Access is set up around the vessel.

    HOLVEM checksClean, dry, keyed shell; every fitting protected.

  3. Passes and depth

    Closed-cell foam is sprayed onto the shell in passes, following its curvature, to the specified depth. The top of a vertical vessel is sprayed too, so the jacket is continuous.

    HOLVEM checksApplied thickness measured and recorded around the vessel.

  4. Protective coating

    Once the foam has cured, a protective elastomeric coating is applied over the whole jacket, to the specified thickness and in the specified colour. This is not optional on an external vessel: the coating protects the foam from UV and weather.

    HOLVEM checksCoverage and film thickness logged.

  5. Cut back and finish

    The jacket is cut back cleanly around nozzles, manways, legs, supports and the base, the edges closed and the coating carried over them. Anything that needs future access is left accessible.

    HOLVEM checksEvery fitting closed and finished.

A close detail of a bare steel tank shell with a flanged nozzle, faded paint, rust streaks running down from the flange bolts and a tide line of condensation.
BeforeThe bare shell
The substrate as it is inspected: the shell, its coating, its fittings and the marks that say what the contents do to it.

Every step is checked before the next. Thickness measured, coverage logged, compiled into a QA record at completion.

04Preparation

Before the first pass: what the vessel has to be.

Vessels are working plant, not empty buildings. Three things HOLVEM establishes first.

Sound and sealed

No leaks at seams or fittings.

Foam over a weeping seam traps the product and hides the fault. Leaks are repaired first; the jacket goes on a shell that is doing its job.

Clean and dry

Adhesion on steel, GRP or plastic.

Old coatings that are failing come off; sound coatings are checked for compatibility. The shell is dry at the time of application, and its temperature is within the range the foam can be applied to.

Planned around the plant

Fittings, access and the site.

What stays accessible, where the jacket stops, how the site works around the vessel while the foam and coating cure: agreed and drawn before the first pass.

Survey, or photographs?How HOLVEM works: we understand your project before we price it

05Thickness and objective

The depth is set by what the vessel has to do.

Three objectives, three directions for the depth, each confirmed for your vessel and its contents. What it costs is on the cost guide, not here.

25 mmCondensation control

Stop a cold vessel sweating.

Enough on most chilled or cold-water vessels to put the outer face above the dew point of the surrounding air, so the shell stays dry and corrosion under the drips stops.

50 mmHeat retention

Keep the contents at temperature.

Cuts the heat lost from heated contents or gained by chilled contents, so the plant that holds the temperature works less. The depth is calculated from the temperature of the contents and the loss you want to cut.

75 mm and aboveA specified heat loss

A figure to meet, for the process.

Set by the heat-loss or hold-time figure the process needs, calculated for the vessel, its contents and the site conditions. Specified per project and confirmed by the calculation.

A vertical storage tank with a smooth, continuous cream closed-cell jacket finished in a pale protective coating, cut back neatly around a flanged nozzle and the legs.
AfterThe jacket, coated and cut back
The finished face: a continuous jacket, the coating over it, the fittings cut back and closed.

Thickness and objectiveWhat it costs: the cost guide

06Where it suits

Where the vessels are.

Tanks and vessels stand on farms, in factories and in process plant across the UK. Three building pages where this application is common.

Building

Grain stores and silos

Steel silos and bins where condensation on the inner face spoils the grain, jacketed and coated from outside.

Read the building page

Building

Industrial units and factories

Process and storage vessels on working sites, insulated in place without stopping the line.

Read the building page

Building

Agricultural buildings

Water, feed and slurry tanks on farms, insulated to hold temperature and to stop sweating.

Read the building page

Every building type HOLVEM works on

07What HOLVEM checks

Three things checked before anyone talks about depth.

HOLVEM does not quote a depth from a photograph. The vessel is understood first: what its contents do to the shell, what the coating has to withstand, and what heat loss the process can accept.

Condensation risk analysis

Will the outer face stay above the dew point?

For a cold vessel, the operating temperature of the contents and the humidity of the site set the dew point the jacket has to clear. HOLVEM calculates the depth that clears it, rather than assuming one.

The coating

What the weather and the site will do to it.

UV, rain, temperature cycling, and anything the site throws at the vessel: the protective coating system is chosen for it and its film thickness specified. Exposed foam is never left as the finished face.

Heat loss

What the process can accept.

For a heated or chilled vessel, the heat lost through the jacket at the specified depth is calculated for the shell area and the site conditions, so the depth is a number the process can check, not a guess.

Condensation risk analysisU-values and Approved Document LFire performance and coatings

08Straight answers

Ask us the hard ones.

The questions people with a tank or vessel actually ask on the call, answered the way the specialist answers them.

Does the tank have to come out of service?
Normally no. The jacket is applied externally with the vessel in use, and the site works around it while the foam and coating cure. Where a vessel runs very hot or very cold, the operating temperature is part of the specification.
Why does the foam need a coating?
Exposed closed-cell foam degrades under UV. On an external vessel a protective elastomeric coating over the whole jacket is part of the system, not an extra: it is the weatherproof, inspectable face.
Will it stop my cold-water tank dripping?
Yes, if the jacket is deep enough to keep its outer face above the dew point of the surrounding air. That depth is calculated from the contents' temperature and the site humidity, not guessed.
What shapes and materials can you do?
Cylindrical, spherical, conical and irregular; steel, GRP and plastic. Spray foam takes the shape of what it is sprayed on, so there is no cutting or fitting and no joints.
How do you prove it was done properly?
Applied thickness is measured and recorded around the vessel, coating coverage is logged, and the evidence is compiled into a QA record handed over at completion.

The next step

Your vessel.
Your brief.
A specialist.

If you already know the thickness or U-value you need, we price to it and confirm it is right; if not, we work it out with you. Tell us what the vessel holds, at what temperature, and what the site is like around it. Photographs of the shell and its fittings are the most useful thing you can send.

Start a project brief Send photographs first

Or call . Enquiries received before 3pm on a working day are contacted the same day. After 3pm, the next working day. We understand your project before we price it.