Buy the Right Hose - Corrugated Metal Hose

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Hydroformed Corrugation Process:

A. Tube

The manufacturing process of corrugated metal hose starts with stainless steel strip that is rolled and the edges welded together to form a thin-walled, gas-tight tube. Hose Master offers:

B. Hose

After the tube has been welded, corrugations are formed into the tube to make it flexible. There are two corrugation profiles, annular and helical.

Corrugations are formed into the tube either mechanically or hydraulically ("Hydroforming").

Hydroforming:

• Enhances flexibility and cycle life.
  • Maintains wall thickness.
  • Reduces concentrated residual stress.
  • Minimizes work hardening.
• Is a clean process.
  • Hydroforming uses water to form the hose while most other processes require lubrication.

Corrugated Strip Process (Extraflex/Hydraflex):

In addition to our line of annular, corrugated hose, Hose Master offers two helical hoses specially designed to maximize performance without the drawbacks of traditional, mechanically-formed, helical hose. Rather than welding a tube and mechanically forming the corrugation, these products are made from stainless steel strip that is formed before welding. Because it is not mechanically formed from a tube, it is extremely flexible and does not contain all the residual stresses like traditional mechanically-formed helical hose.

Both Extraflex and Hydraflex are made by pre-forming the stainless steel strip, overlapping the material, and then continuously resistance welding the seam together. While Extraflex is made with one ply of stainless steel, Hydraflex is made with two plies for higher pressure ratings.

Braiding Process:

To give corrugated hose the ability to withstand pressure, stainless steel wire is braided over the hose. Hose may be single braided (one layer of braid) or double braided (two layers of braid) to achieve even greater working pressures. Braided braid is used on large diameter hose.

Designing the proper braid for each type of corrugated hose requires sophisticated engineering to maintain the proper balance between the braid strength and the hose flexibility. Hose Master's braid packages offer several advantages:

1. High Percentage Braid Coverage - Hose Master has a high percentage of braid coverage yielding better cycle life and protection against damage to the hose.
2. Machine Braided Hose - Hose Master weaves the braid directly onto the hose ensuring that the braid fits tightly against the hose, preventing potential hose deformation or squirm.

Selecting a Hose:

When selecting a hose, you must consider three variables: pressure carrying capability, flexibility, and chemical compatibility.

• Pressure Carrying Capability - The hose must be strong enough to handle the pressures to which it will be exposed. To determine hose pressure capability, refer to the "Maximum Working Pressure" stated for the hose. The Maximum Working Pressure must be reduced for each of the following circumstances:
  
  
  • Temperature - As temperature increases, hose working pressure decreases. After you have determined the proper alloy (see "Chemical Compatibility" below) go to the "Temperature Derating" table and match the alloy of the hose and braid with the highest temperature to which they will be exposed (either internally or externally) to obtain the proper derating factors. Then multiply the hose's Maximum Working Pressure by the most limiting temperature derating factor.
  • Dynamic Pressure - Pulsating, surge, or shock pressures, like those encountered with quick opening or closing valves, can inflict severe damage on a hose. If your application entails pulsating pressures, the working pressure should be derated by 1/2. If your application entails shock pressures, derate the stated working pressure to 1/6 of its value.

Example: 1" Annuflex hose - T321 Stainless steel hose and T304 stainless steel braid @ 500°F with shock pressures.

Catalog Maximum Working Pressue = 718psi.
Temperature Derating Factor at 500°F = 0.88; and the Pressure Derating Factor = 1/6.
Maximum Application Working Pressure = 718 psi x 0.86 x 1/6 = 105.31 psi.

• Flexibility - Confirm that the hose's minimum bend radius is less than the bend radius required. Keep in mind that the hose's minimum bend radius will change with pressure. To determine the minimum bend radius, go to the charts for the type of hose being used and match the line for the hose's I.D. with your application's pressure requirements. The chart will show you the recommended minimum bend radius. Care should also be taken for applications with vibration (see chart).
• Chemical Compatibility - You must choose a material for the hose and braid that is compatible with the media being conveyed through the hose as well as the environment in which the hose is installed. When determining chemical compatibility it is important to know the temperature and concentration of the chemical(s). Although there are many resources to confirm chemical compatibility, two of the industry standards that you may use are the National Association of Corrosion Engineers (NACE) and the Compass Corrosion Guides. You may also contact our Customer Service Department which can check these sources for you.

Now that you know more about the options, browse our online selection of corrugated metal hoses.