Also known as carbon steel, mild steel is the most common form of steel for all applications and hose clips are no different. It is also one of the broadest grades of steel covering a wide range of mechanical properties. This means that understanding and specifying the correct grades can have a significant impact on the performance of a finished product. For example, the stresses and requirements for a sheet of steel forming a body panel on a car would be completely different than those for the material for the band of a hose clamp. Indeed the ideal hose clamp material specification is not even the same for the housing as for the band. This is why material selection is taken very seriously at Jubilee®.
One disadvantage of mild steel is that it has a very low natural resistance to corrosion. This is overcome by applying a coating, most commonly of zinc. Variances in coating methods and standards mean that corrosion resistance can be an area of extreme difference between hose clips. The British Standard for hose clips requires a 48 hour resistance from significant red rust in a 5% neutral salt spray test and many non-kitemarked products cannot reach this. At Jubilee our internal tests have revealed some products on the market, not of our manufacture, showing significant red rust within the first 15 hours of the test. Our clips all reach a minimum 72 hours and our Original, Light and Multiband ranges are all capable of surviving 240 hours in the neutral salt spray test.
Stainless steel is in many respects a more complex subject than Mild Steel and even more so where hose clips are concerned, due to the common practice among cost motivated manufacturers for mixing different material grades to supply products with low manufacturing costs and reduced performance.
Ferritic stainless steels are used by many hose clamp manufacturers as a substitute for mild steel or as a low price alternative to austenitic grades of stainless steel. Ferritic steels (used in specifications W2 and W3 and falling in the 400 grade series) do not require any additional process to improve corrosion resistance due to the presence of chromium in the alloy. However the absence or low quantities of nickel in this steel mean that the performance is below that of the austenitic grades of stainless steel in many respects.
Austenitic stainless steels offer the highest levels of corrosion resistance against all forms of corrosion including acid and the broadest range of operating temperatures as well as being non-magnetic. At Jubilee® we produce stainless steel clips in 304 and 316 grades only; both of these are acceptable for marine use and Lloyds register approval, whereas ferritic grades are not. These grades are also acceptable for use in the food and beverage industry where acids such as acetic, citric, malic, lactic and tartaric may not permit the use of ferritic steels.
As mentioned above some manufacturers will mix stainless and carbon steels when manufacturing hose clamps.
Historically this was done to circumvent the need to electroplate the band and housing before the insertion of the screw, which created issues in automation of production procedures. It was therefore common practice to choose a material that was as close in price as possible to mild steel and so the most commonly seen specification is a 430 grade ferritic stainless steel. As the screw is introduced separately the same issue does not apply and so the most cost conscious option remained a mild steel plated screw and the result of this has been the proliferation of the mixed material hose clamp specification.
As most people will know, dissimilar metals can react when brought together and the result in a corrosive environment is that one is sacrificed to the benefit of the other. This means that mixed material clamps can experience a cathodic reaction between the two metals and will rust faster than clamps made all from one material specification.
At Jubilee®, we select only the best materials for manufacturing our products and our engineers embrace technical challenges without cutting corners so that you know that you have a hose clip you can rely on.