Flex Hose Wear-Hard/Soft Materials

[Vanlabs]

New to the forum, looks like a great source. Glad I found it !!!!!

I have a failed flex hose from a steam system. (Very high pressure and vibration) THe construction is a corrugated tube (625 inco)on the inside, wrapped by 304 braided weave, and over both of these is a strain relief spring appling compressive force, it is also 304. The inner corrugated tube got severly worn and the pattern on it is from the braid, the failure was it wore right through under the strain relief.

So...why did the 36C (tube) inco material get worn from the 95B (braid) SS material? The outer strain relief hardly got worn also. Is the inconel more susceptable to wear? All three components would be "sliding" due to flexing and vibration. The main mechanical force is vibration though.

Here are the materials.

Stain relief---43.7 C on the outside
Braid---94.8 B in between
Corrugate tube--36.5 C wearing on the inside

 

[btrueblood]

I'll take a stab at the question.

For the convoluted tube, the wear is focused on a single area of contact (outside radius of convolution). Since pressure is internal, all of the motion starts with this part.

For the next layer, the wear from the moving convolution radius is spread over some lateral distance, and many fibers from which the braid is formed. The wires can both flex and rub against one another, adding energy dissipation modes not available to the homogenous tube.

The outer spring likely moves the least, and suffers the least contact of the three pieces.

The wear issue would be analogous to running a block of aluminum back and forth along a 10 foot run of nylon carpet. Eventually, significant wear would appear on the aluminum, and only slight degradation of the carpet (considered as whole) would be noted.