The Metal Hose is the important connection component, which is composed of flexible hose, net cover and connections combine.
The use of braided metal connectors for applications such as pumps, compressors and other mechanical equipment will enhance the overall operation of a system. The optimum design provides a variety of advantages:
1. Greater flexure without fatigue
2. Longer service life
3. Greater capacity for pressure
4. Increased temperature capacity of media
5. Absorption of pump vibration and noise
6. Acceptance of thermal expansion
7. Reduction in pipe stress due to minor misalignment and pressure variations
8. Reduction of stress on pumps and compressor housings, reducing long term operation and maintenance costs.
The flexible metal hose used in the high pressure water descaling for the Rolling－ mill and its busted causes are described. It improved the ideas from the aspect of the structure of the flexible metal hose and the high-pressure water descaling, the feasible methods improving its reliability are put forward.
Construction
Corrugated Metal Hose Assemblies are usually made of stainless steel, bronze or other metals depending upon the environment in which it is being used. The corrugated hose is manufactured by forming a rolled strip into a cylindrical thin walled tube. The seams are joined by butt-welding and profile is impressed into the tube.
Types of Flexible Metal Hose
There are two bellows used by the flexible metal hose, one is annular corrugation, the other is helical corrugation.
Annular Corrugation Introduction
It has complete annular corrugation and high flexibility, not easily producing contorted stress under pressure. It can be installed with various types of fittings. The annular configuration is one in which the convolutions on a hose consist of a series of complete circles located at right angles to the longitudinal axis of the hose. This is sometimes referred to as a bellows. An annular hose is better suited for pump connections because it can better sustain tensional stress due to longitudinal expansion from rises in pressure.
Helical Corrugation Introduction
It has complete helical corrugation with little resistance occurring when the fluid is transmitted in the hose.
Braid
Metal wire braid on a hose assembly restrains against hose elongation under higher pressures and acts to dampen vibration. A second layer of braid may be used to increase pressure ratings. A heavy braid will also increase abrasion resistance. Optimal braid coverage will contain the core under pressure and reduce the possibility of squirm. Properly designed braid coverage will balance pressure capability with flexing requirements as well as minimize braid wear on the crown of the corrugation.
Hose Assembly
A welded hose assembly consists of several key components. The cover on a metal hose assembly protects the braid from external abrasion and can be made from many different materials including interlock casing, heat shrink covers or many types of heavy-duty elastomers.
Reinforced ends are recommended for applications where sharp bends or extreme flexure occurs near the end of the hose.
A liner is recommended when the substance being transferred is abrasive or the velocity of the media is above recommended levels. The liner will facilitate smooth flow while remaining flexible, however the inside diameter will be reduced.
Service Life Factors
The following factors will impact the service life of metal hose assemblies:
1. General corrosion
2. High velocity/ chemical abrasives
3. High Cycle/ Chemical media
4. Stress corrosion
5. Intergranular corrosion/ attack
6. Pitting corrosion
7. Fatigue
8. High flow velocity
9. Torsion
10. Vibration
11. Low pressure application
Reference：
''Application of the Flexible Metal Hose in the Descaling and Research
on its Bursted Causes''
Author: Ye Weiming (Mechanical Engineering Department of ECUM)
''River Bend Hose Metal Hose Assemblies''
From: River Bend Hose Specialty, Inc
http://www.riverbendhose.com/metalhose.html