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BOLTING & FASTENINGS


FEATURE SPONSOR


TORQUEING WITH TRACEABILITY


Torqueing, in this context, is essentially the measured application of rotational force to a threaded fastener.


When the torque is either under or over the manufacturer’s specification, it can cause considerable damage to the turbine structure. Guarding against this risk must be a priority in order to safeguard the health and safety of operatives, and the life expectancy of the turbine.


UNDERLYING COSTS AND FAILURES


The extent of the damage has the potential to vary considerably. One key technical implication of over or under torque however, is the potential for vibrations in the turbine… which presents a real risk of catastrophic failure.


TOOLS REQUIREMENT – A PROBLEM


In many windfarms maintenance operatives have to use a variety of tools to complete the job. For example, in the turbine tower; an operative may need one tool to run down the bolts plus a hydraulic wrench to achieve final torque. Using these two tools could present a number of complications, particularly regarding ease of operation and manoeuvrability. Subsequently health and safety is a significant concern. Thus being able to record the torque data from tightened joints for audit purposes would be a distinct benefit. Furthermore, when triggering electric multipliers on pre-tightened bolts, a dangerous over-torque can occur due to the slow response time of controllers, high motor start currents and high motor inertias. In some instances, this over-torque can be in the region of 100 percent. When triggered multiple times in this type of condition, there is an extreme danger that the application may fail due to the overstress of the joint.


SOLUTION


So, a tool that will tighten bolts accurately to the required torque, audit pre-tightened bolts, and can then record this data is required.


A single tool solution does exist. Norbar’s EvoTorque2, enables users to torque bolts accurately and reliably and generate a record to confirm the fact, providing complete traceability for Operations & Maintenance teams and their clients.


When performing a retightening test, the EvoTorque2 also demonstrated a clear advantage whereby, when triggered 18 consecutive times on an already tightened bolt, it achieved total accumulated over-torque of around 15- 20 percent of the set torque; depending on the hardness of the joint.


So many consecutive applications using traditional electric tools would almost certainly result in failure of either the tool or bolt. EvoTorque2 can provide more reliable torque results than conventional tools and negates the need for final torqueing with a hydraulic wrench.


The output of most electric motors


reduces as the motor temperature increases with use, resulting in less accurate torque values. EvoTorque2 accuracy will not change as a result of ambient temperature or motor temperature, thus enabling numerous joints to be tightened successively with trusted results assured.


GUARDING AGAINST THIS


RISK MUST BE A PRIORITY IN ORDER TO SAFEGUARD THE HEALTH AND SAFETY OF OPERATIVES....


Power on windfarm sites is usually


provided by small generators with long cable runs, this raises concerns about the quality of the power supply. The implication is that most electric tools either will not run or their torque output becomes erratic. EvoTorque2 tools are largely immune from the effects of voltage fluctuation due to its motor controller technology; the tool will either run accurately or indicate that the voltage is outside of tolerance.


In response to customer feedback from many industries Norbar has designed and launched EvoTorque2 a product which adds data memory and transfer capabilities, and audit mode to the features and benefits of the original EvoTorque tool. EvoTorque2 is capable of incredible


control in tough conditions – where bolts have not previously been tightened it will deliver torque values with an accuracy of ±3 percent. Where torque is re-applied to a pre-tightened bolt results are within ±5 percent of set torque.


NEW TRACEABILITY AND CONTROL BENEFITS


Every torque and angle value that EvoTorque2 applies can be recorded with a corresponding date and time stamp. Up to 3,000 such readings can be stored in the tool’s memory. These can be downloaded to a PC either by USB cable or transferred wirelessly via Bluetooth Smart for later analysis. Modes of operation include Torque,


Torque & Angle, and Audit. The first two enable users to select torque only or a combined torque & angle target


26


www.windenergynetwork.co.uk


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