Drum and Tank Heater

Heat the bottom third and let convection do the rest

Material in a drum only moves once it is liquid. A jacket wrapped around the lower part melts the material at the bottom first, and that liquid then rises and circulates, carrying heat up through the drum on its own. A jacket fitted around the middle or the top does the opposite: it makes a warm layer on top of a cold, solid plug that can take another day to shift.

On a drum that has set hard — wax, heavy oil, some resins, honey — plan on hours, and start low.

Slow and gentle beats fast and hot

Whatever is against the inside of the drum wall gets hottest. Push the power up to save time and that layer scorches, degrades, or bakes onto the wall while the core is still solid, and on a food or pharmaceutical product that ruins the batch. A jacket at the right watt density with the right insulation gets there in a reasonable time without ever letting the wall run hot.

Never heat a band of empty drum

The most common way to destroy a jacket is to power the whole wrap on a drum that is half empty. Behind the liquid there is something to carry the heat away. Behind the air there is nothing, and that band of the jacket climbs until the material fails. Either strap the jacket below the working level, or use a two-zone jacket where the upper zone can be switched off.

Plastic drums need a different jacket, not a lower setting

Steel spreads heat sideways and takes it away from the jacket quickly. Plastic does neither. A jacket sized for a steel drum, turned down, still puts too much power into one place on a polyethylene wall, and the drum softens where the jacket touches. A jacket for plastic is built at a much lower watt density from the start. Say what the drum is made of at the time of order — it is not a setting, it is a different product.

Straps, leads and the way a drum gets moved

The advantage of a jacket is that it comes off in a minute and goes on the next drum. That also means it gets handled a lot. Buckle the straps rather than knotting them, keep the lead running upward and clear of where the drum will be rolled or lifted, and never lift or drag a drum by the jacket. The lead entry is the part that fails, and it fails from being pulled.

Store it rolled and check it before each use

Between jobs a jacket ends up on a shelf, folded around something, or under something. Roll it. Before fitting, look over the inner face for scorch marks, cuts or hard spots, and check the lead entry. A jacket with a damaged face will be fitted against a drum full of product, which is the wrong moment to find out.