Steam hose safety
• Construction, application and coupling standards
• Effects of cold temperatures/temperature swings on steam hose
• Construction type and their effects on service based on handling irrespective of environmental temperature
Thank you for the opportunity to discuss steam hose safety issues. Please allow me to introduce our company so that you might better know who we are and why this issue is of interest to us.
Hose and Rubber Supply has been a wholesale distributor and manufacturer’s representative since 1959. As such, we represent and/or stock most of the major hose manufacturers and have had the opportunity to observe the performance characteristics of most hose products used in our industries and beyond. Of particular concern to us currently is the use of steam hose in the energy drilling, refining, and production markets, although these issues equally apply in food handling facilities.
This concern has been generated by the recent discovery of steam hoses being used that do not have the capability to withstand all the specific service, handling and environmental factors to which they can be exposed.
In order to establish a common vocabulary in dealing with these concerns I’d like to briefly outline the physical construction of hose and then take a more in-depth look at how each component involved can dramatically affect steam hose performance.
Hose involves three primary components; the tube, the reinforcement and the cover. Their respective functions are: the tube, to contain and convey the media; the reinforcement, to provide pressure and motion strength to the tube; the cover, to protect the reinforcement. We believe the choices available in steam hoses pertaining to all three of these components are critical to safety in the workplace with a product that can be extremely dangerous.
- Tube. Most tube stocks are typically made of somewhat similar compounding to resist steam and water exposure. However, specific compounding to provide low temperature service is not widely used as most steam hose is designed and produced for the large industrial markets in the middle and southern states. Service temperatures in those areas only require an operational temperature range of 0° to +450°F.
In cold climates tube stocks rated for a low temperature of 0°F tend to fail most often when the hose has been taken out of service, cooled to ambient temperature, and then handled – as in a rig move or when hanging in a steam rack outdoors. When the compounds in those tube stocks are taken below operating temperatures they become extremely stiff and even brittle, making them all the more susceptible to cracking or breaking. Cracks will allow a leak path or burst to occur when steam is reintroduced. Internal tube cracks cannot be found through standard visual inspections but normally only through dissection of the hose or the reintroduction of pressure.
Cold climate steam hose, with a -40° to +450°F operational temperature range, is readily available and protects against these cold weather service issues.
- Reinforcement. There are two primary types available, braided or spiral. Appropriate construction here becomes a particularly critical issue when dealing with sub-zero, rough service, and/or any dragging/pulling applications. If a crack and/or leak path has been established through the tube our experience has been that spiral construction will allow the steam to pass through the reinforcement more easily and rupture through the cover.
Most hoses built for the warmer climates tend to combine the O°F, or at best -20°F, service temperature with a spiral reinforcement construction. While in a few hose applications spiral reinforcement can offer an advantage, it is our experience that in most industrial steam applications it does not. Spiral reinforcement does not offer good resistance to pulling force or kinking and thus is not particularly well suited to regular handling or rough services.
Although there can be dramatic differences in the quality, robustness, and layering in braided reinforcement, as a design, braided reinforcement provides far more resistance to damage in steam applications – and thus more resistance to leak paths – than does spiral.
- Cover. In this component there are also two primary types that can be manufactured, oil resistant and non-oil resistant. We believe it to be very important in the hydrocarbon industries – and in locations where exposure to hydrocarbons in the forms of inverted mud (diesel based), lubricants, cleaners, etc., is likely – that the cover be an oil-resistant compound.
Non oil-resistant covers, when exposed to oils or many animal fats, can tend to soften and swell. There are some particular areas of compromise that can occur when non oil-resistant covered hoses are exposed to hydrocarbons as in the energy production environment.
- In a softened condition the cover can be torn from the hose easily and/or surrender the adhesion to the reinforcement. When cover damage occurs a hose loses its ability to protect the reinforcement from wear, abrasion and external influences. A damaged cover will allow exposure of the wire reinforcement to environmental factors, most predominately water and snow, initiating rust and corrosion and resulting in the removal of the hose’s capability to contain pressure. Hoses with compromised reinforcement wires can even be broken open by impact or pulling forces being exerted on the hose.
- An additional area of concern is the retention of the coupling, on any steam hose. The retention capability is in great part dependent upon specific outside diameters and compression factors. The interference fit changes when changes in the cover occur and attaching onto a softened and/or swollen cover will not meet appropriate retention specifications. A cover that has surrendered its adhesion to the reinforcement creates a high probability for failure. There are crimp couplings certified for steam hose but it is most decidedly a very technical application and should only be crimped by trained individuals with hose coupling and crimping knowledge.
Our deep concern in this issue of safety has been triggered by the recent observance of steam hoses in this region that not only have this dangerous combination of the three; O°F low-end, spiral reinforcement, and non oil-resistant cover, but the discovery of steam hose that also lacks any manufacturer branding or markings designating country of origin.
These unlabeled, ‘no name’ hoses can present serious dangers and liabilities in any type of hose application. This would be true whether dealing with air, hydraulic, or fuels, but in certain applications, such as steam, they can quickly turn deadly. Our long-term assessment of no name/no manufacturer hoses has unfortunately shown that they tend to build to the lowest possible standards and not the highest.
It is, therefore, our strongest recommendation that an extreme low temperature service where needed, braided wire reinforced, oil-resistant covered steam hose with the manufacturer’s identity clearly embossed be the standard in any industry for the safety and well-being of everyone involved.
Thank you for the opportunity to speak to this issue and to share our experience and history in this market. We, like so many, make our living in the world amongst friends and family and consider quality health and safety to be our common goal.
Should you have any further questions or would like specifications of steam hoses available to this market that meet the standards necessary to perform in the winter months, or would like to dialogue on this issue, please feel free to contact us at your convenience.