While it is critically important to provide a safe, reliable assembly that will resist high temperatures and corrosive conditions, certain applications where the hose is routinely moved around by the operators may necessitate special options or accessories to increase assembly service life.
Specialty chemicals are typically proprietary blends of ingredients, which must be precisely measured in order to ensure product consistency. This blending operation may require a battery of hoses, each conveying the various ingredients to the mixing station. Additional hoses provide media used for cleaning, purging, and inerting operations. The hoses used in this area may be rubber, composite, or corrugated metal, and each hose type offers certain advantages along with certain limitations.
Handle With Care
Blending hoses are subjected to frequent (and sometimes rough) handling by the operators, which can increase the likelihood of damaging the hose. We have seen countless applications where the service life of blending station assemblies can be improved simply by training the operators in proper hose handling, inspection, and storage practices. The operator must be vigilant to ensure hoses don’t become tangled, overbent, twisted, or crushed. Often, wear-resistant covers are used on blending hoses to protect them from external damage. While these covers offer a degree of protection, most of them do not prevent the hose from being bent beyond its design. In fact, when these sleeves pull back from the hose ends, it should be brought to the customer’s attention in order to illustrate the need for a better way to protect these hose assemblies from damage.
There are things the customer can do to optimize the piping system as well. Note how the upper bank of connections in the photo are oriented at a 45-degree angle downward. This allows hoses to gently slope down to the ground when connected to these ports. However, the lower connections are horizontally oriented, which can cause hoses to sag and overbend. In these installations, a more robust cover may be needed to prevent overbending the assembly.
Corrugated metal hose assemblies with interlocking metal armor guard are ideally suited for these mixing applications, for many reasons. Corrugated metal hoses are fire-resistant and highly flexible. They do not experience permeation issues like non-metallic hoses, which is especially important for compressed gas lines used for purging and inerting operations. Also, the end fitting configuration is more compact than other hose types, so the hose assembly is easier to move around and connect to the system. The interlocked armor guard serves to protect the hose from external damage while also preventing the hose from being overbent, which is a common mode of failure in chemical blending operations. Most other covers provide only limited protection from impact damage and do not act as a bend restrictor. When using an interlocked metal armor guard for protection, it should fit snugly over the inner hose in order to provide superior protection and ease of handling.
When inspecting hoses in these blending and mixing stations, look for signs of overbending, external damage, twisted or kinked assemblies, or covers that have pulled back from the hose ends. Is there a hose inspection, testing, and replacement program in place? Is the correct hose alloy being used? Conducting a hose inspection or a plant wide survey of hose installations is a great way to identify areas where improvements are needed. Working with a qualified vendor ensures there are no “mixed” messages when it comes to chemical blending!
