The tower crane industry is finally starting to gain traction after four years of the worst down market in history. Fleet utilization is steadily climbing after dropping below 25 percent, and backlogs for most companies continue to grow.
Tower crane sales are still very soft as the market continues to absorb the excess inventories still present with most crane owners. The failures of some larger companies also added to excess inventory issues between 2008 and 2011. Rental rates for tower cranes have slowly risen, but still remain depressed. The outlook for the second half of 2013 into 2014 is predicted to see a continual increase in monthly revenue.
As the utilization of tower cranes continues to grow, rental fleet and individual owners face another pressing issue – how to restore their fleets after so many cranes sat idled and stored.
Resurrecting a tower crane that has been mothballed requires large sums of money, time and due diligence to restore the crane to its original condition and stay in compliance with the manufacturer’s instructions, as well as state and federal regulations. In many cases this can amount to 50 percent or more of the anticipated rental income for the first job after refurbishing.
It’s not a matter of simply changing some oils and making sure the crane runs. To properly complete a thorough refurbishing requires a tear-down of all drives, inspection of the entire steel structure and replacement of many key electrical components, such as motor refurbishing.
First course of action is to assess the crane completely. Moving the crane to an open staging and inspection area makes the task easier and more complete.
Having a dedicated and written Quality Control/Quality Assurance program is important to ensure the evaluation meets the requirements your company has dictated to achieve the level of quality expected. For the first evaluation, assess the complete steel structure, looking for previous damage or damage that may have occurred during storage and handling. If the structure has severe corrosion, NDT testing of suspected areas may be required. An engineer with expertise in this area should be consulted. It is strongly suggested that all structural hardware is NDT tested. At Morrow, we inspect and NDT test all of our structural bolts on a rotating cycle.
Test the electrical motors. If the crane was stored outside, at a minimum the motors should be dipped and baked to ensure the insulation has not deteriorated causing premature failure once the crane has been put back into service. Key here is to use a quality motor shop that understands how your motors are wound.
Inspect all gear boxes. If they have been stored without being filled completely with oil, expect internal corrosion as the condensation over time will accumulate and the gears and bearings will rust. These repairs can be extensive as dismantling gear boxes and replacing corroded parts can be a lengthy process, especially if parts that are not normally stocked are required.
Inspect the slewing ring. This is very important for cranes that have been stored for a long period. If the seals are not perfect, moisture can collect internally and cause deterioration and corrosion. Having a pre-prescribed inspection program can alleviate a lot of the issues here by regularly inspecting the slewing ring. Lead times for replacement bearings can be as long as 24 weeks, so prompt action is needed if the crane will be used in the near future.
Inspect all ropes according to manufacturer’s instructions. Look for breaks, corrosion and any indication of damage. If the ropes were not lubricated prior to storage there is a good chance you will need to replace them.
Inspect all electrical components and cables. Look for splitting or dry rotted cables. Electrical components should be tested under power to ensure the controls function properly. If the crane has resistor banks, pay attention to them as they have a tendency to corrode internal over time.
After the evaluation, set forth a course of action. Having a developed overhaul program with pre-defined inspection criteria makes this process much easier.Don’t simply fix things. Develop a step-by-step inspection plan to ensure compliance with company policies and manufacturer’s inspection criteria. Document the work you do to prove you were diligent. If your inspection program is comprehensive, it will meet OSHA 1926.1412 requirements for annual inspections.
Refurbishing a tower crane that has been stored for a long period of time can be a very time-consuming and costly undertaking, and pre-planning is the key. Once all the inspections are completed, the crane has been tested, a fresh coat of paint has been applied, and it has passed your Quality Control/Quality Assurance process, you should be good to go.
Done properly, a refurbished crane will perform as good as a new one and ensure your equipment operates as designed, and give you many more years of life.