Prevention of Water Jetting Injuries
The high pressures can cause injuries similar to gunshot wounds but have the added health hazard of involving contaminated water.
- By W. David Yates, Ph.D., CSP, CHMM
- Oct 01, 2007
ONE of the most rapidly emerging service industries is that of industrial maintenance, and more specifically, water jetting or water blasting. As with any new or growing industry, specific standards and regulations are non-existent, and the industry is left to regulate itself. Fortunately for the water jetting industry, most of the companies providing this service are professionally oriented and strive to take every precaution necessary to protect the interests of employees and clients.
While most people think of water blasting as the home version of the pressure washer, where pressures can reach as high as 1,500 psi, industrial versions operate at pressures up to 40,000 psi. The pressures arising from this equipment are powerful enough to cut through steel, so one can imagine what the stream could do to human flesh. Other hazards associated with this industry include those common to the construction industry, such as confined space entry, fall hazards, trip hazards, eye and respiratory hazards, electric shock hazards, and potential chemical exposure. Of particular interest to the industrial cleaning industry is the potential for water jetting or water blasting injuries.
To properly understand the potential hazards associated with water jetting, it is first necessary to gain a basic understanding of the type of work being performed and the terminology used. Water jetting or water blasting is a process whereby a stream of pressurized water is aimed at undesirable materials adhering to a substrate, such as the inside of a metal tank or paint on steel, concrete, or other material. The water stream is set at the minimum pressure to remove the unwanted material while at the same time prohibit damage to the substrate material.
There are two options to water jetting. The first is to use a high volume of water at lower pressures, and the second is to use a low volume of water at higher pressures. Both have their particular functions and benefits.
The water jet stream is directed through the use of nozzles with various orifice sizes attached to a "shotgun or "lance." "Shotgunning" is a hand-held application with an assembly of a lance and a nozzle that can be manually manipulated in virtually all planes of operation.
"Lancing" is used in two forms: flexible and rigid. "Rigid Lancing" is an application where a lance or jetting gun extension is fitted with a nozzle, nozzle assembly, or nozzle manifold. The lance is inserted into and retracted from the interior of a tube, tank, or vessel. "Flexible Lancing" is using a flexible hose section that carries water to the nozzle, which is normally located between the trigger or control valve and the nozzle. Under normal conditions, flexible lancing has additional hazards to be concerned with, which include the flexible hose turning back toward the operator during insertion into the tube being cleaned. It is extremely important that the lance portion (a rigid section of the hose) be at least as long as the diameter of the tube being cleaned. This will prevent "turning back" of the water blasting hose.
As with any type of industry, the first step to be taken prior to water blasting is to perform a thorough Job Hazard Analysis (JHA). This step is critical to preventing workplace injuries and should not become routine. The JHA forms the basis of the project safety mindset and should be conducted with the assistance and participation of affected employees. The old adage "two sets of eyes are better than one" definitely applies to performing the JHA. Once it has been completed, it should be discussed in detail with each employee working on the project prior to beginning the operation.
Safety hazards specific to the water jetting or water blasting industry include noise, heat/cold injuries, slips/trips/falls, confined space entry, lockout/tagout, eye injuries, cuts, head injuries, and water blasting injuries. While volumes can be written on each of these subjects, a brief discussion on each topic follows below.
Noise hazards in the water blasting industry are commonplace. The equipment used to supply and pressurize the water can exceed 85 dBA. Other sources of noise potentially exceeding the 85 dBA threshold include plant or facility noises from generators, boilers, evaporators, compressors, etc. These noises tend to be continuous and therefore require the use of hearing protection appropriate to the noise levels.
A good baseline audiogram along with annual evaluations is not only required by OSHA for employees included in a Hearing Conservation Program but also extremely important in preventing or reducing noise-related injuries.
One particular note: The environment in which the work is being performed is often dirty and wet. Experience has shown that an adequate supply of disposable, moisture-resistant ear plugs should be maintained. This enhances the frequent changing of ear plugs by employees and reduces the potential for ear infections.
Eye and Face Protection
As mentioned previously, during water blasting, a stream of pressurized water is aimed at unwanted materials adhering to a substrate for the purpose of removing it. When the stream of water impacts the material, it becomes loosened from the substrate. It is necessary to protect workers' faces and eyes from this flying debris by the use of both safety glasses/goggles and a faceshield that are properly fitted and maintained.
A large majority of water blasting operations is performed in areas that require the use of head protection in order to prevent employees from hitting their heads on piping systems and to protect against falling objects or debris. The selected hard hat should be adequate for the environment and the type of work being performed. Hard hat selection should be done in accordance with ANSI Z89.1-1997.
The cut hazards from working in an industrial environment are endless. Therefore, it is necessary to purchase and utilize cut-resistant gloves, such as Kevlar-reinforced gloves, for this work.
Environmental Factors (Heat/Cold)
Industrial maintenance often presents harsh work environments, including cold and hot temperatures. While water blasting in extremely hot temperatures, you have the added factors of moisture/humidity, personal protective equipment, and sometimes radiant heat from the surrounding areas or equipment. It is important to follow the basic principles of heat injury prevention through acclimatization, hydration, physical fitness, and rotation of employees at frequent intervals.
During the winter months, water from water blasting operations can freeze almost immediately, thereby creating additional slip hazards. Slip hazards can be reduced through the use of drainage systems (PVC piping and polyethylene sheeting) to prevent pooling of water, and you can spread rock salt to keep the water from freezing. Proper attire, including slip-resistant safety boots to prevent slips and layered clothing and gloves to prevent cold injuries, is highly recommended. It is often overlooked that persons working in cold environments can become dehydrated and suffer heat-related injuries.
Confined spaces pose their own particular hazards. A good confined space program that adheres to the requirements established in 29 CFR 1910.146 is crucial to ensuring the safety of employees entering a confined space.
Adherence to 29 CFR 1910.147 is particularly important in the industrial environment because most operations involve multiple contractors, all with their own programs. It is especially important to know, understand, and communicate the host employer's lockout/tagout program to all employees. A prudent project supervisor always conduct a thorough lockout/tagout inspection with the host employer. This reduces the likelihood an energy source will be left activated.
Water Blasting Injuries
Water blasting operations involve streams of water under pressure. It is the high pressures that can cause injuries similar to gunshot wounds but have the added health hazard of involving contaminated water.
The WaterJet Technology Association has developed a wallet card that should be carried by all water blasting employees. The card provides information to physicians on how to treat water jetting injuries.
Significant accomplishments have been made in developing safeguards for water blasting employees. These include the development of Kevlar-plated protective suits, metatarsal boots, and various "lance or nozzle arrest" systems. The Dunn Guard System™ (patent pending) is designed to capture the nozzle end of the lance to prevent whipping of the lance if it is accidentally pulled out of the condenser tube too far. The weight of the guard system is heavy enough to prevent the whipping action but light enough to be easily moved from tube to tube. Use of nozzle arrest systems has greatly reduced the incidence of water jetting-related injuries.
In summary, the hazards associated with this industry are numerous. With proper employee education, however, along with thorough JHAs, providing the correct personal protective equipment, and creating a safety-conscious culture, these hazards can be mitigated, if not eliminated.
This article originally appeared in the October 2007 issue of Occupational Health & Safety.