When selecting the components of a metal hose assembly, it's crucial to understand the relationship between temperature and pressure. This understanding is key to correctly matching each component to the intended working pressure of the application. Given that corrugated metal hoses can handle extreme temperatures better than other hose types, it's especially important to grasp how these temperatures (internal or external) affect the working pressure of a corrugated metal hose assembly.

Here’s a quick reminder of how to select hose and fittings that will handle the combined pressure and temperature. As the temperature increases, the maximum allowable pressure rating of the assembly decreases. The percentage of this decrease depends on the alloy of the components and the temperature to which they will be exposed. The NAHAD Hose Safety Institute Handbook lists the guidelines for derating the working pressure of hose and braid when used at elevated temperatures.

Just as a chain is only as strong as its weakest link, a corrugated assembly is only as strong as its weakest component. Once the maximum temperature to which the assembly will be exposed is determined, the hose and fittings must then be selected to accommodate this pressure/temperature combination.

Using the derating chart, match the alloy(s) of the hose and braid to the maximum temperature to which they will be exposed in order to obtain the proper derating factor. Then, multiply the hose’s Maximum Working Pressure by the most limiting derating factor (i.e., the lowest multiplier of the hose and braid alloys) to obtain the reduced working pressure. This procedure should also be followed for the other components of the assembly (fittings, accessories, etc.), as per the manufacturers’ recommendations for their products.

To calculate a working pressure derated for elevated temperature, multiply the hose working pressure shown in the catalog by the appropriate derating factor below.

Note: The working pressure of an assembly at elevated temperatures may be affected by fitting type, material, and attachment method.

If a hose is being used for extremely low temperatures, such as cryogenics, corrugated metal hose is again the best choice. Stainless steel retains its strength at low temperatures without a marked increase in brittleness. Certain alloys, such as carbon steel, are not recommended for low-temperature applications. Other factors, such as the fitting attachment technique or dynamic pressure changes, may limit an assembly's working pressure. The HSI Handbook addresses some of these considerations, or you can contact the manufacturer for additional assistance.

Proper installation and maintenance are also crucial for ensuring the longevity and safety of a hose assembly. The HSI Handbook provides detailed guidelines for correct installation procedures, including proper alignment, routing, and anchoring of the hose. It is essential to regularly inspect the assembly for potential leaks or damage and promptly replace any worn or damaged components.

In addition to following manufacturer recommendations and guidelines, it is also important to consider the specific application and conditions in which the hose assembly will be used. Factors such as temperature, pressure, chemical compatibility, and environmental factors can all impact the performance of a hose assembly. Consulting with an experienced engineer or technician can help determine the best hose material and construction for your particular needs. At Hose Master, we pride ourselves on our engineered-driven and customer-focused culture.  Reach out to us directly or connect with one of our authorized distributors today to discover the Hose Master difference and experience first-hand how we contribute to keeping industry flowing.