There are several important factors to note when designing a metal hose assembly: alloy, fittings, media, pressure, and so on. One of the most crucial factors that is often taken for granted in industrial applications is hose length. Utilizing the incorrect length in an assembly can be detrimental to its cycle life and potentially result in failure in an assembly. If an assembly is too short, there is potential for the corrugation geometry to be deformed as the assembly is stretched between the connecting points. Conversely, if an assembly is too long, it risks being over-bent as the hose tries to move out of its own way. To avoid these unnecessary failures, let’s review the steps to properly measure metal hose assemblies.
How to Measure Metal Hose Assemblies
To calculate the proper length of an assembly, it is first necessary to verify that the existing installation was properly designed. Indication of improper design are factors such as torsion, over-bending, or compression of the assembly, which can lead to premature failure.
Next, you will need to measure the overall length of the assembly. The overall length is the total length of the assembly from end-to-end. When measuring for overall length, it is important to be aware that the points from which measurement should be taken vary between fitting types. Measuring for overall length from an incorrect point on a fitting would result in an inaccurate measurement. How to measure various fitting types are as follows:
- JIC/SAE Fittings: Measure from the seat of the fitting
- Elbows: Measure to the center line of the fitting
- Fixed Flanges: Measure to the face of the flange
- Floating Flanges: Measure to the face of the stub end
- Threaded Fittings: Measure to the end of the fitting
Finally, make sure that there is enough live length in the assembly to accommodate the required movements during service. The live length is the portion of the assembly that is “active,” or has the ability to flex while in service. There are various formulas available to help calculate these length requirements. If it is determined that the existing live length is insufficient to accommodate the required movements, then Gallagher’s engineering team can provide expertise in appropriately adjusting the overall length of the design.
Utilizing these guidelines when measuring metal hose assemblies will help to ensure that an assembly is designed to sufficiently support the intended application.
Meeting the Tightest Tolerances
After proper measurement and design, it is important for a metal hose assembly to meet certain tolerance requirements as well. NAHAD sets guidelines for metal hose manufacturers in regards to the length tolerances to which a finished hose assembly must conform. Hose Master’s metal hoses are able to hold to those tolerances, as well as tighter specifications when the application requires. Adhering to strict tolerances in a completed assembly not only allows for solutions to the most stringent of applications, but also aids in providing maximum reliability, longevity, and safety.
For More Difficult Measurements
Taking measurements in the field can be difficult, especially if the installed assembly contains bends. For more difficult measurements, Gallagher can help.
The original article was written by Abby Svitana, Market Analyst at Hose Master.
For more information about measuring metal hose or for general inquiries about metal hose products, contact Gallagher Fluid Seals today.