Comprehensive Guide to Composite Hoses - Structure, Standards, and Applications

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In the classification of hoses, there is a special type of low-pressure hose that is similar to rubber hoses but has essential differences. This type of product is widely used worldwide, and it is the composite hose.

In this chapter, we will introduce the product knowledge of composite hoses to help you understand and master the structure and characteristics of composite hoses. First, let's take a look at the definition and standards of composite hoses. Composite Hose, as its name suggests, is a flexible pipe formed by winding multiple layers of high molecular polymer materials and reinforced by internal and external spiral steel wires. Its structure is slightly different from the industrial hose structure we have previously understood; although it can also be divided into three-layer structures, its inner and outer layers are both spiral steel wires. The spiral steel wires provide the skeleton support for the hose, and the middle layer is made of multiple resin materials, including a high barrier inner layer, a reinforcement layer, and an anti-aging outer layer.

Composite hoses have gradually evolved to today's structure and appearance. The earliest composite hoses were mainly made of metal materials such as tin, lead, and aluminum. These materials, although having good barrier properties and corrosion resistance, also had the disadvantages of being non-corrosion-resistant and heavy in weight. With the advancement of technology, in 1950, Switzerland invented plastic hoses made of LDPE (low-density polyethylene). However, single plastic hoses were weak in anti-penetration ability and not suitable for packaging contents that require high air tightness. To overcome these limitations, in the mid-1960s, composite hoses made of various materials began to appear worldwide. This composite hose combines the advantages of metal and plastic, offering better barrier properties and corrosion resistance. The invention of composite hoses was to address the shortcomings of single plastic hoses in anti-penetration ability. By combining multiple materials, their performance was significantly improved, eventually forming the high-performance composite hoses we use today.

There are unified standard specifications for composite hoses in the industry, including production standard specifications: BS5842, BS EN13765, BS EN13766. BS5842 is an old British standard but is still referred to by some manufacturers. BS EN13765 and BS EN13766: These standards provide the basic quality standards that industrial composite hose products must follow, and these standards are also widely used in the design, manufacturing, and testing of composite hoses. Interested friends can refer to the standards for detailed content.

Next, let's understand the naming method of composite hoses: The inner and outer spiral skeleton layers can usually choose galvanized steel wire, polypropylene (PP) covered steel wire, aluminum alloy, stainless steel (SS304L and SS316L).

Middle layer: The inner layer material uses polypropylene (PP) or polytetrafluoroethylene (PTFE) with good corrosion resistance, and the outer layer uses anti-aging polyvinyl chloride (PVC), with polypropylene (PP) as the reinforcement layer.

After understanding the main materials for making composite hoses, we focus on the naming rules of composite hoses. The naming rules for composite hoses are unified in the industry. As long as the code is given, everyone will know the structural features of the product. The general naming of composite hoses consists of three letters:

The first letter = the type of inner spiral steel wire

The second letter = the type of outer spiral steel wire

The third letter = the inner layer of the hose

So, how are the three letters identified? This uses the materials mentioned earlier, and each letter represents different materials:

E or P means Polypropylene

G means Galvanized Steel

S means Stainless Steel

T means PTFE (Teflon)

A means Aluminium

Composite hoses have minor structural differences, so is there a quick way to identify hoses? The world has color-coded different types of composite hoses in appearance. However, it is not mandatory. For example, common oil hoses use black color, general chemical hoses use gray, and Teflon chemical hoses use red, etc.

Finally, let's briefly introduce the advantages and disadvantages of composite hoses. Its advantages are obvious, and its disadvantages are also obvious.

Let's talk about the advantages of composite hoses first:

1. Composite hoses have good corrosion resistance because the inner layer of the composite hose is made of plastic materials, which can easily transport different materials and meet the transportation needs of gasoline, diesel, crude oil, and various chemical liquids.

2. Composite hoses have a multi-material multi-layered sealing structure, which still has good anti-burst and anti-leakage properties in the worst environments and will not burst suddenly, even in cold weather, they can still maintain high flexibility.

3. The hose body is soft, flexible, and anti-aging. The complete radius is smaller than that of rubber hoses, especially for large-sized hoses, so they have reliable electrostatic dissipation performance because both the inner and outer layers are conductive steel supports (or other conductive materials).

Of course, as mentioned earlier, the disadvantages of composite hoses are also obvious:

1. Unable to transport gases, because there is no adhesion between the plastic films of each layer, relying only on multi-layer winding and steel wire fixing, so there are small gaps between the layers, and gases can easily escape, so they cannot be used to transport compressed gases. This point must be noted, and many people have caused structural damage to the hose when testing composite pipes with air pressure tests.

2. The inner wall is not clean enough, which we can see from the pictures. Whether it is the inner spiral steel wire or the multi-layered middle layer, it is determined that the inner wall of the composite hose cannot be as smooth as the rubber hose. It is easy to retain the medium and hide dirt, and it cannot reach the food grade. The interchangeability of the fitting is poor.

3. Composite fittings are usually matched to specific brands of hose, and the unique inner helix steel wire structure requires a corresponding helix end to work with the hose.

In summary, today's course focused on three aspects of composite hose product knowledge: first, we introduced the definition and standards of composite hoses, second, we talked about the naming methods and common types of composite hoses, and finally, we briefly introduced the advantages and disadvantages of composite hoses.