Published with permission from Honeywell
Technicians working in wind towers must be aware of, and armed against, confined space hazards that include unsafe oxygen levels, and toxic and flammable gases.
Wind towers reap the power of wind to generate electricity. How ironic, then, that wind towers can take the wind out of those who must repair, maintain or inspect equipment there.
According to one published account, three wind tower technicians were installing bolts in a turbine in a wind tower in Minnesota when their work ignited a fire. The tower quickly became engulfed in flames. One worker fell more than 200 feet and died; the other two escaped with injuries.
The event provoked discussion about the industry-wide need to educate workers on safe practices required for confined space entry in wind towers. The trainees identified include wind energy technicians as well as municipal workers, county inspectors and others.
The problem is, wind towers contain several potentially hazardous compartments. OSHA has identified the turbine area as a permit-required confined space. Other permit-required spaces depend on wind tower design, and these may include the basement electrical room or telecom vault, and trenches or excavation pits dug in the construction phase. Other areas, such as the hub, or nose cone, and turbine blades, are classified as non-permit required confined space, but may be re-classified as permit required confined space if some substance or operation (e.g. arc welding) was performed there. The point is, all compartments must be evaluated for risk.
Oxygen depletion is always a concern when working in confined spaces. Toxic fumes can arise from heat or electrical sparks igniting solvent-based resins or other volatile organic compounds used to lubricate turbines, blades and electrical apparatus.
Workers who must crawl into the narrow, culvert-like spaces of a blade to inspect lightning protection equipment, or repair the blades or fiberglass skin can be subjected to off-gassing from battery acids or VOCs (volatile organic compounds). The decomposition of dead birds or rodents that may have found their way into the confined space may suck enough oxygen from the environment to cause unsafe oxygen levels.
The American Wind Energy Association, OSHA and other regulatory agencies have posted notices on confined space hazards posed by wind towers, and have pointed to the need for confined space training.
The smart technician will make it a habit to perform air samples prior to entering a confined space. In following best practices, the technician should carry a portable gas monitor in their toolkit and practice due diligence in its operation and maintenance.
Multi-Gas Monitoring Is an Essential Requirement of Confined Space Entry
A portable multi-gas detector is the instrument of choice for wind tower technicians because it can warn of the multiple threats posed by confined space entry, detecting toxic gases in parts per million levels and flammable gases at the lower explosive limit (LEL). A standard four-gas detector will include sensors for monitoring oxygen, hydrogen, carbon monoxide and hydrogen sulfide. These four gases deserve special mention in confined space work.
Hydrogen sulfide, also called sewer gas, is heavier than air and can accumulate in electrical vaults, basements and other areas underneath the tower. The characteristic rotten egg smell can be detected by smell at lower levels and for short duration; at higher levels, the gas can cause dizziness leading to unconsciousness.
Methane, the primary component of natural gases, is a combustible gas found often in confined spaces. Produced by leaks in pipelines, methane, along with propane and other flammable gases, must be monitored with a combustible gas sensor that gives an alert at the lower explosive limit (LEL). A standard four gas portable monitor is equipped with a flammable gas sensor.
Carbon monoxide, the product of incomplete combustion of hydrocarbon compounds, can be found where any gas-powered equipment is used, e.g. propane heater.
Oxygen levels must be determined prior to entry of a confined space as well. The threat of suffocation is present from low oxygen levels. Oxygen can be consumed by oxidation from rusting equipment, bacteria growth, displacement by another gas, or rotting vegetation. The decomposition of a dead bird or rodent in a turbine, for example, may be all thats needed to suck enough oxygen from the confined space to create unsafe breathing conditions. Oxygen sensors are also included in a standard four gas monitor.
Thankfully, these gas threats can be averted by following due diligence in regard to OSHA and NIOSH confined space requirements and by gaining a working knowledge of a confined space portable gas detector.
What to Look for in a Quality Gas Detector
Most portable gas detectors are designed for ease-of-use, single-button operation. Premium models may offer additional details including large backlit displays & oversized, heavy-duty buttons. These features help the user operate and view gas readings in foggy, dark or wet conditions. Check to see if the unit logs standard data as well as event and calibration data that can be loaded onto a computer program in case the data needs to be retrieved. If any of your crew has a limited understanding of English, check to see if the portable unit offers multi-lingual display or voice-assisted operation.
The unit should also convey alarm annunciation in multisensory ways, audibly (through a distinctive loud sound), visually (through strobe) and tactilely (through vibration). In this way, workers will be alerted to emergency alarms, quickly and without fail.
Manufacturers have introduced a new generation of multi-gas detectors that are easy to operate, with simple interfaces being common. Durable, lightweight enclosures are typically constructed of polycarbonate or other materials that withstand impact, water and dust ingress.
Training in the use of a portable gas detector should include the following commandments:
Always test the atmosphere before entering a confined space.
The technician should arrive at the site with a confined space carrying kit that includes gas detector, spare sensors, bump test station and accessories such as sampling probe. All safety managers should follow a routine that goes something like this: Insert the probe through the vent of the confined space area (if possible), then open the entranceway and test more thoroughly from the outside.
Always test for oxygen levels.
If oxygen display does not read 20.9, or if gases or vapors are detected, ventilate and retest.
Perform a bump (functional) test; and learn how to calibrate your instrument properly or obtain professional assistance on how to do so.
Performing a bump (functional) test means subjecting the instrument to a known concentration of gas to ensure that the sensors (and the unit itself) is operational. Some bump test/calibration kits require little or no training on the operators part and can be carried out by pressing a single button. The entire testing and calibration sequence can be carried out in two minutes or less, with a simple Pass or Fail notification displayed and more detailed results logged for later download.
Instruction on the operation and maintenance of portable gas monitoring instrumentation is provided by some manufacturers; one such program is offered through Honeywells Honeywell Analytics University.
Perform continuous testing for flammable and toxic gases upon entering the space (having completed pre-entry checks).
It is important to remember that toxic or flammable substances may be disturbed due to work performed earlier, so the potential for hazards exists every time a confined space is entered. Unrecognized atmospheric hazards are the number one cause of fatalities in confined spaces. Whats more, changes in atmospheric conditions can occur at any time. Regretfully, complacency is all too common.
Make certain that all your crews portable gas detectors are in good working order.
Gas detectors should be tested regularly to ensure correct operation. Inspect equipment thoroughly before use. Follow the manufacturers guidelines for verification/bump tests and calibration. Use only certified calibration gases and the correct/recommended calibration equipment.
Use fully serviceable equipment.
Any equipment defects should be reported to the project lead or supervisor. Quality equipment means longer battery and sensor life, protection against dust and water ingress and availability of spare parts and service. No one should ever wear or use defective equipment.
Consider time- and money-saving premium features
A powerful sampling pump in a gas detector not only ensures accurate readings of remote samplings, but longer unit life. Further, are the batteries rechargeable? Are the sensors themselves durable and resistant to poisons that may affect performance or shorten cell life? Performance issues like these may be difficult to assess, but in some cases, sensors designed for longevity are also designed for easy replacement. If your crew, for example, monitors multiple gases, you may receive better value through the unique built-in sensor/cartridge design available today. When one sensor fails, the whole sensor set can be swapped out, ensuring the safety manager of a fresh set of sensors. Due to the economies of sensor manufacture, this multi-sensor cartridge design enables a multi-sensor exchange to be carried out at about the same cost as replacing a single sensor.
Make sure the unit is built rugged
Manufacturers now build rugged, concussion-proof technology into portable gas detectors. However, you should check to see if the unit is IP67 rated, which gives the user a high degree of protection against dust and water ingress, so that the unit will function under the most adverse conditions.
Be Safe, Not Sorry
The wind energy industry is the fastest growing segment of renewable energy production. In the next few years, hundreds of technicians will enter the field. And as the nations inventory of wind towers age, it is inevitable that repairs will increase, along with more frequent confined space entries. The time for learning best practices and carrying out due diligence in confined space work is Now.
With a little preparation, you can maximize the short- and long-term value of your companys investment in portable gas detection instrumentation. You can track evidence of safety and compliance, and protect people, equipment and environment, and increase company profitability. Learn how to use a portable gas detector and you will have taken one step further on the way to a long, rewarding career in a dynamic industry.
OSHA definitions of Confined Space
- Limited entrance and exit by design
- Unfavorable natural ventilation that could contain or produce dangerous air contaminants
- Not intended for continuous occupancy
NIOSH definitions of Confined Space
- An enclosed or partially enclosed work space
- Limited entrance and exit by design
- Subject to accumulation of toxic, flammable contaminants
- May develop oxygen deficiency
- Not intended for continuous occupancy
