Selecting the Correct Metal Hose for Your Application
As a Hose Master Factory Authorized Fabricating Distributor, we fabricate our Flexible Metal Hose Assemblies to the standards set forth by both NAHAD and the Hose Master Factory. Our fabrication department and techniques are state of the art and all of our fabricators have been trained, tested and approved to fabricate assemblies by the Hose Master factory.
Gather all the information you need to select the proper hose assembly for the application.
- Size – What are the diameters of the hose required? Diameter of the end fittings?
- Temperature – As temperature increases, pressure containing capabilities of the hose assembly decreases. The internal and external temperatures, minimum, maximum and operating all need to be taken in to consideration.
- Application – How is the how going to be installed and what is its purpose? This includes the overall assembly length and what kind of movement is expected of the hose. Need this information to select proper length and flexibility of the hose assembly.
- Media – Identify the all the fluids/chemicals that are exposed to the internal and external surfaces of the hose assembly. The purchaser must make certain that all components are compatible with media and the environment in which the hose is installed.
- Pressure – Identify the maximum internal pressure that hose assembly must handle. Also, identify if the pressure cycles, surges or spikes. This information must be considered, since hose pressure ratings are reduced when these conditions are present.
- Ends - Specify the end fittings required for installation. Materials and pressure ratings must meet the requirements of the application.
- Dynamics - Identify the velocity of the fluid moving through the hose assembly. Since corrugated metal hose does not have a smooth interior, high velocities may cause resonant frequency vibration, causing early failure of the hose assembly.
Material – Utilize resources, such as National Association of Corrosion Engineers (NACE) and the Compass Corrosion Guides to make your material selection or call our customer service, for their assistance.
Pressure – You must make sure that the hose selected with have a maximum pressure rating that meets the requirements of your application. The stated maximum pressure rating is reduced based on each the following circumstances
- Temperature – As temperature increases, hose pressure capabilities decreases. Use the Temperature Derating Table to determine the factor to multiply the hose working pressure by to obtain the temperature derated working pressure.
- Dynamic Pressures – Pulsating, surge and shock pressures can damage a hose assembly. If the application has pulsating or surging pressure, the working pressure of the hose needs to be derated to ½ of its original value. If the hose is exposed to shock pressures, the working pressure must be derated to 1/6 of its original value.
Consider an industrial water application at 100 psi/70°F and a 2” line size.
2” Annuflex hose with a single braid is rated to 449 psi and is suitable for up to 449 psi with no pressure surges or shock. Same hose with surging pressure is derated to ½ or 224.5 psi. Same hose exposed to shock pressure is derated to 1/6 or 74.8 psi.
Contact us when your application has rapid pressure fluctuations.
Flexibility – Make certain that the minimum bend radius of the hose is less than the bend radius required by your application. See the vibration chart, to determine if the assembly will be exposed to normal vibration levels. If you have an application that involves excessive vibration, contact our customer service department for recommendations.
Fittings – End fittings are selected based on the mating fittings and the chemical compatibility with your application. You must also make certain that the end fitting pressure ratings, as well as those of the hose, exceed the required pressure rating of the application. Because applications vary widely, various end fittings can be welded together to make combinations to meet virtually any application needs. Contact us for these customer applications.
Length – How to select the proper length of a metal hose assembly
- Properly design the application, don’t pipe it first and buy a hose to fit.
- Never Torque a Hose or Bend it in more than one plane
- Never bend the hose tighter than its published bend radius
- Never Compress the hose from end to end
- Install it correctly using these guidelines
- Use this information to select the proper length
- We fabricate our assemblies to NAHAD standard tolerances. If your application requires tighter tolerances, contact our customer service.
We fabricate our assemblies to Industry Standards. If your application requires a smoother interior transition, we offer Half-Corrugation prepped assemblies and/or Argon purging. We offer armor casing and spring guards for external protection and lined assemblies for high velocity and abrasive services. For high vibration we can provide a fiberglass buffer between the hose and braid or a bronze buffer braid between the hose and braid. Silicone impregnated fiberglass fire sleeve can be installed on the outside of the assembly to protect personnel from burns or protect the hose in from flame and slag. Additional covering options and tagging are available on request.
While our hoses are inherently clean and free of oil and other contaminants, we also have the capability of furnishing hoses cleaned for oxygen service.
- Standard testing for all metal hose assemblies is done using compressed air under water, and is sufficient for nearly all applications
- Hydro-testing is optional at additional charge. Pressure and duration depend on customer requirements
- High Pressure Gas, Helium Mass Spectrometer, and Dye Penetrant testing can also be furnished on request at additional charge