Hose safety

Hydraulic hose — general safety guidelines
Maintenance technicians, fabricators, end-users and installers need to be aware of the potential safety hazards when handling or even when in proximity to hydraulic hose assemblies. The following conditions, provided in part by Goodyear, can lead to personal injury and property damage.

1) Always use hose in well-ventilated areas; some fluids may permeate the hose cover and create fume and/or fire hazards.

2) Hydraulic systems typically operate at very high pressures. Any leak of pressurized fluid can penetrate the skin, causing severe tissue damage and burns. One good approach is to use guards or shields around the hose assembly to reduce the risk of injury.

3) Whipping – under high operating pressures, the hose and/or fitting can come loose or blow, causing the end of the hose to whip with great force. Again, the hose assembly should be shielded, guarded and, whenever possible, secured to avoid injury or damage from whipping.

4) Hydraulic fluids are flammable and can explode with a source of ignition. To avoid possible injury or property damage, care should be taken to eliminate ignition sources and to properly route the hose assembly to minimize the chance of combustion.

5) Most hose is conductive. Some applications require use of non-conductive hose to avoid electrocution.

6) When hydraulic hose assemblies fail, the equipment it powers will fail, too, sometimes abruptly and without warning. Never work directly beneath hydraulically powered booms, shovels or other large, heavy pieces of equipment.

7) When air or gaseous materials are being conveyed, the correct hose should be used. A pin-perforated cover may be required. Perforations in the cover will prevent permeated gases from accumulating and blistering the cover. Check with your supplier for the correct hose specification.

8) Extreme care should be used when operating hand-held hydraulic tools where the operator is in proximity to the hydraulic hose assembly. The following steps should be taken to avoid injury:
a. Use strain relievers on each end of the hose to prevent kinking, excessive bending or stress on the hose at the coupling.
b. Never use the hose assembly to pull or carry the tool.
c. Exposed hose near the operator should be guarded in case hose assembly fails to prevent injury from high pressure or high temperature fluid.
d. Operators should be protected with the required safety clothing for the job and fluids being used.
e. The hose should be protected against any external damage.

9) Hose assemblies should be properly routed to avoid strain and the possibility of the hose bursting. Proper routing will also protect the assembly against flex fatigue, excessive heat or abrasion.

10) When selecting a hose style and assembly, check for hose compliance to all relevant government, industry, and safety standards or regulations.

High-pressure injection hazards
High-pressure injection injuries, also known as grease gun injuries, are caused by the accidental injection of a foreign material, such as grease, oil, or solvent under pressure, through the skin and into the underlying tissue. This is analogous to medical techniques used to administer immunization shots without a needle.

A grease gun injury can cause serious delayed soft tissue damage and should be treated as a surgical emergency. Any person sustaining an injury of this sort should seek immediate medical attention, regardless of the appearance of the wound or its size.

Accidents involving injection injuries can occur when using any type of pressurized equipment. Two common cases in which petroleum products may be involved are accidents with pressurized grease guns or with hydraulic systems.

Pressurized grease guns are commonly used in service stations, garages and industrial plants. Typically, most service stations have grease guns operating at 621-1,034 kPa (90-150 psi) air pressure. Most modern industrial hydraulic systems operate in the range of 13,790 to 34,475 kPa (2,000 to 5,000 psi). A stream of oil ejected from a nozzle or leak under pressure of this magnitude has a velocity comparable to the muzzle velocity of a rifle bullet.

The most common sites of injury are the fingers or hand. However, any part of the body can be involved. With grease guns, especially, accidents usually occur when the injured person wipes the tip of the nozzle with his finger or the nozzle slips off the grease fitting while being held in place.

Grease may also be injected into the body from a leak in the grease line. In hydraulic system accidents, a leak in a hydraulic line can emit a high-velocity stream of oil and cause injury if it strikes a person. Workers are commonly injured when they try to stop the leak by covering it with their hand or finger.

Chemical irritation is not a major problem with most petroleum products because hydraulic oils and greases are generally non-irritating and low toxicity to skin. However, the resulting bacterial infection can be a problem because of the damaged tissue and circulation in the wound, even though it has been surgically opened and the foreign material removed. One of the dangers from this type of injury is that it is not recognized quickly by the injured person as being serious. Often the initial wound may be very small and essentially painless. The injured person may even continue working. However, in every case in which a person receives this type of injury, he or she should stop work and get immediate medical treatment.

The following are some basic rules that must be observed:
DON’T
► Play around with or use a grease gun for practical jokes.
► Touch the end of a grease gun.
► Use any part of the body to test a grease gun for grease flow.
► Use any part of the body to stop a leak in a hydraulic line.

DO
► Routinely check all hoses for wear and possible weak spots.
► Handle a grease gun with respect for its power.
► Take special care when starting up a new hydraulic system to be sure that every part of the system can withstand the operating pressure.

IN CASE OF A GREASE GUN ACCIDENT, SEEK IMMEDIATE MEDICAL TREATMENT. Identify the grease or oil involved in the accident. Contact the supplier or the manufacturer to obtain the product’s Material Safety Data Sheet (MSDS) about possible toxicity if a physician or hospital needs more information.

Hydraulic hose and electrocution
Although it is a mercifully infrequent occurrence, workers have been burned or electrocuted when using metal-reinforced hoses on aerial bucket trucks near energized power lines. Hydraulic hose, fluid and power lines are a deadly combination. Electrical contact between two power line phases through a metal-reinforced hydraulic hose can generate sufficient heat to rupture the hose and cause a fire. In addition, an electrocution hazard can be created if a metal-reinforced hose on the boom of a truck contacts an energized power line and allows current to flow through the truck chassis. Either scenario can quickly result in serious injury or death.

OSHA standards require that all hydraulic tools used on or near energized power lines or equipment be supplied with non-conducting hoses with sufficient strength for normal operating pressures. NIOSH recommends that the following precautions be taken to control the hazards associated with hydraulic hoses used on aerial bucket trucks:
  • Employers should not install metal-reinforced hydraulic hoses on any part of the boom, aerial bucket or hydraulic attachments of aerial bucket trucks used near energized power lines [29 CFR 1926.951(f)(3)].
  • Employers should remove any metal-reinforced hoses currently installed on any part of the boom, aerial bucket or hydraulic attachments of aerial bucket trucks used to work near energized power lines.
  • Before work begins, employers should require a competent person [29 CFR 1926.32(f)] to conduct an initial and daily job site survey and inspect all equipment to identify hazards and implement appropriate controls.
  • Employers should stress the importance of adherence to established safe work procedures. These include covering energized power lines in the immediate work area with insulating hoses or blankets, or de-energizing and grounding the lines before work begins. Workers should test
de-energized power lines to verify that they have actually been de-energized.
  • Employers should provide all workers with task-specific training that shows how each step controls the identified hazard.
  • Employers should install all hydraulic hoses used in aerial buckets so that the flow of hydraulic fluid can be stopped immediately by the worker in the bucket.
This objective can be achieved by incorporating a control valve into the hydraulic system in the aerial bucket.
  • Manufacturers should continue research into the development of hydraulic fluids that are non-flammable and non-conducting.
  • Employers should encourage equipment and tool manufacturers to design an independent coupling system to prevent the use of unsuitable hydraulic hoses on booms, aerial buckets or aerial bucket attachments. Labeling or color coding hoses may also help workers who service this equipment.

Material for this article was supplied by Goodyear,
Exxon Mobil and NIOSH. For more information, visit
Goodyear at www.hydraulics.goodyear.com;
Exxon Mobil at www.exxonmobil.com; and
NIOSH at www.cdc.gov/niosh/homepage.html.

This article appeared in the August/September 2006 issue of MRO Today magazine. Copyright 2006.

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