Low-Temperature Applications: Can I Use a Metal Hose?

It comes as no surprise that metal corrugated hose is the preferred choice for high-temperature applications. But what about low-temperature applications? This is a question we frequently see from our customers. The simple answer is yes- metal hose is a great option for low-temperature applications. However, there are important factors that should be considered before making a recommendation.

Service Conditions

Before recommending a particular hose for a low-temperature application, we first need to identify the conditions that the hose will experience while in service. For example, what are the minimum and maximum temperatures of the application? If the assembly is going to be exposed to wide temperature variances, it is important to determine how frequently and rapidly the temperature will change. Metals expand and contract as they heat and cool, and at different rates depending on the alloy. Severe fluctuations in operating temperature can apply stress on welded joints as the base materials expand and contract, which may cause cracks to form.

A traced assembly can be used to regulate media temperature.

One way to verify that an assembly will be able to accommodate these stresses safely is by conducting a cold shock test. Cold shock (or “thermal shock”) testing is performed by plunging an assembly into a cryogenic bath, then allowing it to return to room temperature (or to the highest temperature to which it will be exposed), followed by various testing and inspection. This ensures that the welds will not crack when exposed to similar temperature extremes while in service.

Another service condition to identify is whether the temperature extremes will be present inside the hose (the media temperature) or outside the hose (the external environment). Will the hose be buried in ice? Will it have cryogenic liquids flowing through it? Is there a chance the media could freeze and change into a solid? Is it possible for frost to build-up on the hose exterior? These are all potentially damaging conditions that can be mitigated by selecting the correct assembly for the job. For example, an application in which the hose may surrounded by a cold exterior environment may be best served by utilizing a traced assembly. We recommend using the STAMPED acronym to assist you in identifying the service conditions for any hose application!

Standards and Certifications

“The simple answer is yes – metal hose is a great option for low-temperature applications.”

Along with service conditions, it is important to also identify any standards that must be met in an application. This can be a challenge because there are different standards that may apply depending on the alloy, the forming process (cast, forged, drawn, etc.) and the finished product (hose, pipe, flanges, etc.). Hose Master uses the low temperature ratings in the ASME Process Piping Code B31.3, as well as other internationally recognized standards. Identifying the applicable standard is important because different standards may have different low temperature ratings for the same alloy.

When identifying standards, it is also important to note that a particular alloy may have multiple certifications, meaning it complies with two (or more) standards, each of which may offer different ratings for a given alloy. For example, many of our alloys comply with both ASTM and EN (European) specifications. In these instances, the standard specified by the customer dictates the minimum allowable temperature rating.

Finally, the method of fabrication may affect the allowable low temperature limits. Many standards include or make reference to various welding requirements, many of which require the welders to achieve and maintain compliance to those standards through thorough education, testing, and audits. These standards may dictate the allowable low-temperature limits for a welder’s certification, superseding the low-temperature limits of the materials being joined.

Selecting a Metal Hose for Your Low-Temperature Application

In summary, there is no one answer to “how low you can go” in regard to operating temperatures for metal hose. Finding out as much as possible about the intended application, including any applicable standards, ensures not only that the materials of the assembly will be able to handle the application, but also that the assembly will conform to any required specifications. If you have any questions regarding the conditions and standards involved in your low-temperature applications, please contact us and we would be happy to help you!

Article from:

 

Eaton Synflex Optimum hose and fittings now available!

Eaton introduces the Synflex Optimum thermoplastic hydraulic hose and fitting product line empowering OEMs to reimagine design without limitation. Our system engineered portfolio offers streamlined product configurations for simplified selling across numerous applications with improved hydraulic system performance to your customers while optimizing your inventory!

Benefits of new 3TR Synflex Optimum Hose:

  • Nonstick cover reduces routing force requirements
  • Reformulated cover improves abrasion resistance
  • Innovative tube compound improves chemical resistance
  • Innovative tube compound improves cold temp flexibility
  • Better adhesion level improves kink resistance
  • Twin-line (multi-line) bonding capability
  • Thermoforming for low cost, leak free and quick drop-in assembly

Benefits of new 4TA Synflex Optimum Fittings:

  • Reduced insertion force to push fitting onto hose
  • Leverages existing crimp machines and tooling
  • Single piece design eliminates brazing failure risks
  • Captive nut evenly distributes force during assembly
  • Leverages 1A nipple to unlock 500+ terminal end connections
  • Smaller profile for improved routing capability
  • Part number marking for easy identification
  • Dura-KoteTM plating for extended corrosion protection
  • Works with all Synflex Optimum hose series

Contact FB Wright for price and availability.

Change Gasket

Originally developed by Flexitallic in direct response to customers’ long-term heat exchanger sealing problems. Change™ is a highly-resilient metal-wound gasket, designed to deliver the most dynamic static sealing technology ever. Manufactured using proprietary equipment, Change™ has a proven track-record showing it outperforms conventional gasket technology in challenging environments, especially in applications with mechanical and thermal cycling conditions. It has also achieved independent industry accreditation from TA Luft for its ability to deliver the tightness of a Kammprofile with the recovery of a Spiral Wound Gasket. This is achieved through the application of a unique metal spiral profile, which is more advanced than those found in standard gaskets. This profile, combined with a laser welding process, facilitates the construction of a robust and dynamic seal.

Spiral Wound vs. Braided Hose

What is the difference between wire braid and spiral hydraulic hose?

The fluid power industry takes common knowledge for granted, but we often forget every single individual in the industry was once a beginner, not knowing of the basics. The quest for knowledge starts with the basics, and what is more basic than knowing the difference between two fundamental hydraulic hose construction types.

What is the difference between wire braid and spiral wound hydraulic hose?  This is a common and fair question. Both wire braid and spiral wound wire perform the same task.  However, there are slight variations.

A wire braided hose consists of crossing and woven high tensile steel wires overlapping one another to reinforce the tube below. Wire braiding machines perform a complex task of winding the wire intricately around the tube, like dancers around a horizontal maypole. The overlapping nature of braided wire not only increases burst resistance to the tube but also allows flexibility between the braids. The crisscrossing braided wire has more tensile play than a spiral hose, resulting in tighter bend radius and overall flexibility.

A spiral wound hose consists of two or more sets of helically wrapped high-tensile wire that exhibits excellent strength, making the hose very strong and very rigid. The resistance to pressure spikes is remarkably high, especially when compared to a braided hose. However, the bend radius suffers, and spiral wound hose is highly resistant to bending. This effect is especially evident with 4- or 6-wire hoses, which are required from many large diameter, high-pressure applications.

ICE Champion

Which to choose will depend on your application.  Although technology advances are improving the strength of braided hose, other technological advancements are improving the flexibility of spiral wound hose. The hose industry is highly competitive and ever changing, so you can expect improvements in both construction types as materials and manufacturing.

Article courtesy of hoseassemblytips.com