Unrestrained hydraulic tubing can emit sound as though it were a tuning fork. Fluid velocity, pressure (and their changes), and line size all contribute to the vibration, line shock, pressure surges, and sound, which are prevalent in many hydraulic machine operations. Shock, pressure surges, and vibration will flex metal tubing. This flexing can cold-work the tubing, particularly around connectors. In extreme cases, cracks in fluid lines can result.
Accordingly, components that hold hydraulic tubing, hose, and pipe in place have progressed from simple clamps to engineered support systems. A properly designed and installed tubing-support system can reduce noise, risk to property and personnel, and environmental damage caused by hydraulic fluid leaking from a damaged line.
Effects of vibration Tubing supports should control vibration and absorb shock. Pumps and valves are the greatest cause of vibration and shock because of the drastic pressure and fluid velocity changes that occur in these components during operation. Although intensive research has reduced pump- and valve-induced vibration, it is still considered a problem for the entire tubing system. Through pipe and tubing can also transmit and amplify vibration, shock, and related noise.
Excessive noise for plant personnel is only one negative effect. More importantly, if tubing, pipe, and hose are not properly supported, vibration may cause fittings and flanges to loosen. This can lead to increased safety risks for plant personnel, downtime, high maintenance costs, inefficiency of the system due to air causing cavitation in pumps and valves, and loss of hydraulic fluid. The economics of hydraulic leaks as a result of loose fittings and flanges can be quite revealing.
Resilient supports have been developed to damp the vibration in piping systems. Several types of supports are available that absorb shock and vibration to different degrees. These products use various materials — including rubber, metal, and thermoplastics — and designs to accomplish this task. The support systems generally fall into two categories: individual supports that hold single tubes, and multi-clamp assemblies to secure two or more lines. Multi-clamp assemblies may be the only choice if individual lines are too numerous for mounting side by side within allowable space. These systems position lines in rows, or tiers. Either system generally accommodate pipe and tube sizes from 316 to 24 in. They are secured in place with threaded fasteners or to a mounting rail or welded-on base.
Support material The simplest supports to hold tubing runs in place are metal, but they should not be used for hydraulic applications because repeated pressure cycles can cause a slight shift of tubing with every cycle. Over time, the metal tube rubbing against the metal support clamp can wear away enough material to cause a leak. Therefore, metal clamps should have a liner of soft material — such as rubber or plastic — to prevent abrading away tube surfaces. Clamps for hose may be made entirely of non-metallic materials.
Supports made from such thermoplastics as polypropylene or polyamid readily absorb shock and vibration. In addition, they are resistant to chemicals and abrasives, expand and contract with changing temperature, and, at the same time, exhibit relatively high strength. Finally, supports made from thermoplastics are inexpensive.