If you’ve invested in a high-quality heat transfer fluid (we’d suggest Duratherm, of course), the last thing you want to deal with is a leaky system. Leaks not only waste fluid and money, but they also create safety hazards—from slippery floors to potential fire risks.

Here are a few practical tips for resolving some of the most common and easily fixed causes of leaks:

The repeated heating and cooling of thermal oils—sometimes from ambient temperature up to 600°F—causes pipes and fittings to expand and contract significantly. Systems that are started up and shut down daily are especially prone to this, and fittings often begin to leak as a result.

The solution is to make fittings leak-free using thread seal tape (such as Teflon tape) or a thread-sealing compound. If a standard grade isn’t enough, a thick, high-density Teflon tape—readily available from most industrial suppliers—is a better option. Its greater expansion and contraction provide a stronger, longer-lasting seal.

For the most robust seal, consider X-Pando. This sealing compound withstands temperatures up to 1000°F and is resistant to nearly everything. The only drawback is that once joints are sealed with it, they can be very difficult to take apart.

Compression Fittings

When working with compression fittings, avoid over-tightening. Too much torque can deform the internal components and cause the seal to fail. Start by tightening the nut by hand and check for leaks. If the fitting shows signs of weeping, carefully tighten further with a wrench until the leak stops.

Quick-Connect Hose Fittings

A common issue with quick-connects occurs when oil finds its way inside. Over time, exposure to air and high heat causes the oil to oxidize, forming sludge. This buildup clogs the fitting and prevents a proper seal.

Fortunately, it’s a simple fix. Cleaning the fitting with a solvent will remove the sludge, restore the connection, and help prevent further leaking.

Seals/O-Rings/Mechanical Gaskets/Elastomers

For seals, the most critical factor is compatibility—both with the fluid and the operating temperatures. If you’re uncertain, your fluid supplier should be able to advise you.

We typically recommend Buna-N or Viton seals, as both perform reliably at higher temperatures and are compatible with most Duratherm fluids. Using the right seal material is key to preventing leaks.

By following these basic steps, most leaks can be resolved. Still need guidance? Don’t hesitate to give us a call—we’re always here to help.