Category Archives: Metal Hose

PTFE Liner for Corrugated Metal Hose

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
Corrugated Metal Hose
See the hose peeking out between the collars? Me neither.

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.

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Assembly Components and Value: Corrugated Metal Hose

If no special options or accessories are needed, there are four basic components to a corrugated metal hose: The tube (or hose itself), the braid, the braid collars, and the fittings. There may be times where an unbraided hose will work, but most applications require an assembly containing these four components. Let’s look at each of these components and their function as part of the total assembly, and how they all work together to provide value.

Metal Hose Components

Fittings
Corrugated metal hose assemblies are able to incorporate virtually any fitting that is able to be welded to the hose ends. Because of this, it is critical that the end fittings selected are appropriate for the intended application. Make sure the fittings are the right size, alloy, and pressure (designated by pipe schedule, tube gauge, pressure class, etc.) for the application, including any piping standards or specifications that must be met.

Braid Collars
Braid collars are used to join the inner corrugated hose and the braid together during the cap welding process, where a TIG weld joins the hose, braid, and braid collar into the cap weld bead. A good cap   weld becomes the base for the subsequent attachment weld. Additionally, the braid collar serves to isolate the last few corrugations from movement, as their cycle life may be compromised by the heat required to properly weld fittings to the hose. It is critical that the braid collars are sized properly in order to facilitate welding and to protect the last few corrugations from movement.

Continue reading Assembly Components and Value: Corrugated Metal Hose