Hose Master

Chemical plants are one of the biggest industrial users of corrugated metal hose assemblies. Processes performed in the plants involve some of the most demanding environments:

• Temperatures ranging from extreme heat to cryogenics
• Mixing and transfer of hazardous compounds
• Equipment configurations that result in less-than-ideal piping situations

Metal hose can handle all of these factors and has some other inherent benefits over other hose types when it comes to the kind of applications seen in chemical plants. Let’s dig into some of the main areas of consideration and concern when dealing with chemical hoses.

Handling Considerations

Mishandling of hoses is one of the main contributors to premature failure. Because chemical plants have so many different inputs and outputs, hoses are often used to facilitate the transfer of chemicals from trucks, trains, or barges to the plant and even within the plant from one unit to another. Chemical blending manifolds are a great example of this, where a single hose assembly may be used for various connections at different times depending on what operations the plant is performing.

The need to easily connect and disconnect these hoses quickly and often makes cam and groove couplings a popular choice for chemical plants. When moving hoses from one outlet to another, it’s tempting for users to abuse the “arms” on the fitting and over-bend the hose or torque it into position. Always try and keep the hose as straight as possible, and avoid twisting it. Additionally, hoses are made to flex, but extremely tight bends (especially near the end fitting) can damage the hose and cause it to fail prematurely. Operators should keep this in mind to prevent deformation of the hose when making connections (guidance on using bend radius information can be found here).

Metal Hose Attributes

There are several intrinsic features of metal hose assemblies that make them well-suited for chemical plant service. Chiefly among them is that they are not susceptible to permeation. This is a huge benefit for both operator safety, and plant safety. The metal core is puncture-resistant, and in the event of a leak, the hose will typically develop a small crack or pin-hole and does not burst apart!

Metal hoses also have a more compact end fitting configuration. Because end fittings are welded onto the end of the hose instead of a barbed or crimped mechanical attachment they don’t take up as much of the hose’s flexible length. This results in more working live length compared to non-metallic assemblies, which further facilitates handling and easier installation by the operators. It also means that metal hose is easily customized without the need for adapters. Stainless steel fabrication techniques provide the ability to use a wide array of fitting configurations, and can be tailored to prevent media entrapment, resist end-pull, or to accommodate high system pressures.

Finally, one of the handling benefits of metal hose is its light weight. Calling metal hose lightweight might sound contradictory, but pound for pound, metal hoses generally offer higher working pressures than rubber or composite chemical transfer hoses. This gives metal hose a wide range of potential applications, and also translates into easier handling and installation by operators.

After personnel safety, avoiding unplanned downtime is the main priority for all industrial operations.  Plants typically keep an inventory of maintenance items like hoses on hand to swap out as needed to minimize lost production time.  Unfortunately, this inventory is not always stored or cared for properly.  I personally have visited power plants where they kept replacement hoses, pumps, gaskets, and flanges on the ground outside.  The end result of this kind of storage often defeats the purpose of having inventory parts because they can fail or lose significant service life before they’re ever even used.  While these storage concepts apply to all maintenance components, let’s discuss metal hose storage specifically.

External Considerations

The storing of hoses outside may come as a bit of a surprise (or may not) but it’s actually relatively common.  Rain or dust seem like insignificant elements to stainless steel but they can actually facilitate a great deal of damage, especially over time.  With rain, the phrase “evaporation equals concentration” helps to illustrate this point.  Everything that is picked up by the rainwater on its way down (including nearby plant gasses) is delivered in a diluted state, but as the water slowly dries up, it leaves behind a concentrated residue that can cause corrosion (especially if the hose is in a position to collect water that can then pool on the interior).

Dust and particulate matter can do this too, especially inside the plant.  Maintenance storage cribs and spare parts inventories can often be found near the equipment they’re meant to service.  Heavy dust and particulate matter from process equipment can pick up other chemicals and off gases that are present in the plant, and carry them down onto the outside of uncovered hoses.  This new mixture can cause unintentional chemical reactions that can corrode the exterior of the hose. I know of a specific instance in a coal-fired power plant where a baghouse collecting ash was improperly releasing a large amount of particulate…which then combined with lime dust and landed on nearby hose assemblies causing the exterior to become embrittled and fail. Even in cases where corrosion isn’t an issue, these fines can buildup on the outside of the hose in-between the corrugations and underneath the braid.  This can be difficult or impossible to clean out, and can affect the hose corrugation’s ability to flex, or can become entrapped in the braid causing increased wear.

Hose Options for Storage

Fortunately, there are simple remedies for most of these issues. It’s always up to the end-user how they want to properly address their plant processes: be it either with a modification of the hose itself, or by rearranging how they store the hoses in the plant. Let’s break down each one separately:

Addressing New Issues

Steel mill operators don’t like to have downtime problems, in fact they can’t afford to.  They want to run as much as possible, and as efficiently as possible.  Production equals dollars.  As problems pop up that cause unplanned downtime or upset production (and subsequently get addressed) over the years, they’ve driven the industry to continue to change and evolve as a whole.  So the mills of today don’t have the same issues that mills did in the past.  You can’t as easily say “Hey, we saw this exact same problem up the street on their furnace!” the way you may have been able to 50 years ago.

That doesn’t mean that mills still don’t run into issues, they just tend to be a bit more personalized. And when you have a unique issue, you tend to get a unique solution.  A mill will do its best to solve its own problems, yet each mill has their own idiosyncrasies.  When

"Which way do I measure this metal hose?"

A common question among some customers who use metal hoses is: "Which way do I measure this metal hose?" Well, there's a few different options.

1. The first method is to measure the overall length of the assembly.
2. Or, the live flexible length of the hose assembly can be measured.

Live Length vs Overall Length

Traditionally, the live length - or the amount of flexible hose between the fitting - is used to determine whether there is sufficient hose length to accommodate a certain

Metal hose applications can get tricky. Sometimes you can have problems or failures due to the surrounding piping system or because of the way the hose is installed.

Today we are going to discuss Part 2 of the do's and don'ts when it comes to installing metal hose assemblies in a metal piping system.

Hoses can take a great deal of damage when they are torqued. Twisting it stretches the corrugations and the fitting wells and can cause it to fail. To prevent torque, don't install the hose off-center.

When it tries to flex, the assembly will be torqued. Do install the hose in-line with itself; called in-plain. This prevents it from torquing when it flexes, and you should stick to one plain of movement. A quick test for in-plain could be done with either a sheet of paper or a flat surface like a table.

When handling long lengths or coils of hose, it's important to make

Gallagher Fluid Seals is a distributor of Hose Master corrugated metal hose and expansion joints.  With the largest in-house fabrication footprint in the U.S. of any metal hose manufacturer (350,000 square feet of manufacturing space) and 80+ ASME IX Certified welders on staff,  Hose Master delivers the highest quality products for the most demanding applications.

The following article can be found on Hose Master's Insights Blog.

Should I Install a PTFE Liner Inside a Corrugated Metal Hose?

by Frank Caprio, Dean of Hose Master University

We get various requests from our customers for non-traditional hose assembly constructions that they believe will help them solve tough application problems. Over the years, we’ve seen a lot of these, and some are pretty inventive, even if they’re not the best solution. Some other proposed solutions … not so good!

One especially challenging application that can drive people to consider specialized solutions is when the hose is exposed to corrosive media or environments. Typically, corrosion can be avoided simply by selecting an alloy that is resistant to chemical attack. However, certain refinery applications (such as those found in Cokers or FCCUs) entail operating conditions where some manufacturers recommend a special corrugated metal hose assembly which has been fitted with a liner made from smooth PTFE tubing. While this special construction sounds good in theory, it can create more problems than it solves. Let’s take a closer look at PTFE-lined corrugated hoses.