Metal or Rubber, That is the Question!

The material selection for hoses is of vital importance to the successful conveyance of media from one location to another. To mitigate the risk of failure, the acronym S.TA.M.P.E.D. is frequently used to determine which type of hose is best suited to the application at hand. When considering the material selection of a hose, the first five criteria of S.T.A.M.P.E.D. can be applied to aid with selection.

By KCI Editorial

The two most common materials used for hoses are metal and rubber, both of which come with their benefits and restrictions. Rubber hoses are particularly common and often readily available.³ However, there are times when an alternate material, such as metal, may be more appropriate for the process. When choosing which type of hose will best benefit a project, using S.T.A.M.P.E.D. to examine the size, temperature, application, media, and pressure is particularly useful.

Size

If a hose is required to navigate a lengthy terrain, rubber is often a favorable material. Rubber is often made invarious lengths and diameter, making it particularly useful for applications that must reach long distances. Not only is the material lighter, making it more suitable for transportation, but it has a greater range of flexibility. If the length of the hose requires navigation that does not follow a straight path, rubber is able to bend and curve to make necessary accommodations. This is useful when running the hose outdoors.²  Metal hoses may be better in shorter distances, as they are more rigid than rubber. They may be more appropriate when maneuvering a smaller distance within a facility.¹ 

Temperature

Both the internal and external temperature are considered when choosing a material for a hose. Although the atmosphere a hose is subjected to is not integral in the decision-making process, it is important to consider what environmental elements the hose will be subject to. Rubber hoses are therefore ideal for a variety of temperatures, ranging from both hot to cold. Specific rubber compounds can be better suited for hoses subject to very high or very low temperatures.² Metal hoses are however considered better for a wide variety of extreme temperatures. Their material can withstand the intensity of an extreme temperature and remain intact, proving their durability. Extreme temperatures can be traced to corrosion of materials. With metal, corrosion is less likely, and they are often more resistant to abbrasion.¹

Application
When considering the application, it is best to evaluate where the hose will perform its function – what will it be used for? Rubber hoses are used in a wide variety of industrial sectors, including agriculture, chemical, and oil & gas. This includes any application that requires that the hose be flexible or is susceptible to vibration. Metal hoses are more often used in chemical and petrochemical processes, mainly due to their strength against corrosive materials. If the application requires a particularly corrosive chemical, metal is usually guaranteed to be the best option, as it will last far longer and require maintenance or a replacement infrequently.¹ Another thought to be considered in application is whether this hose is a replacement. Rubber hoses are replaced and repaired more frequently than a metal hose, due to their material durability.

Media

The type of media conveyed through a hose should be considered when determining the hose’s material. Rubber hoses are commonly used in many facilities for liquids such as water and wastewater. They are also used with chemicals of lower corrosion levels. Metal is far less likely to be permeated, and therefore typically used for applications that convey gaseous media. As gaseous vapors have the potential to harm both people as well as the environment, the use of a metal hoses which can adequately withstand corrosion reduces the risk of leaks. If the media is cohesive or sticky, special consideration needs taken into account to avoid the risk of media clinging to the walls of the hose.¹

Pressure

Every hose, whether rubber or metal, is rated with a pressure rating. Based on the method of construction, rubber hoses carry a wide variety of pressure ratings, and can be made to withstand up to 10 000 psi.3 Metal hoses typically have higher pressure rating. Under full vacuum, metal hoses also maintain their shape. The corrugations in a metal hose give it excellent hoop strength, which gives it the ability to handle a full vacuum. Non-metallic hoses must use helix wires to improve their vacuum rating, but collapse is still possible.¹

Final Thoughts

Using the S.T.A.M.P.E.D. method to determining whether a rubber or metal hose is the most suitable material for an application is a great practice to ensure the successful conveyance of media. Not only does it mitigate the risk of failure, but it also provides a reliable set of criteria on which to select the safest option.