Keeping vital process cranes well maintained can reduce, and even eliminate, production risks by ensuring efficient operation. Whether it is a process crane or maintenance crane, having reliable equipment is vital to achieving successful production results every day. Working with unreliable or outdated equipment can make the workday feel like it is one step forward, then two steps back.
It was an all too familiar problem for Weyerhaeuser paper mill in Savannah, GA. Its outdated wet end house crane was breaking down on a regular basis. Though used primarily for maintenance operation, the crane is vital, according to Will Tallevast, electrical and instrumentation superintendent at the Georgia facility, and proper functioning is necessary for safe and efficient shutdowns.
Rather than provide reliable efficiency as a vital maintenance crane should, it had become an expected expense for Weyerhaeuser. The company has 12 scheduled annual maintenance shutdowns. The unreliable crane was increasing the time spent during scheduled shutdowns by as much as 25%. Weyerhaeuser was forced to contract full-time maintenance crews to be on-site 24 hours a day during the maintenance shutdowns. The added costs of the unreliable crane were mounting, says Tallevast.
The mill did not shut down production during the crane modernization project
What didn't work
Installed during the initial construction of the mill in 1990, the crane was used during regularly scheduled maintenance intervals to move the heavy press rolls, which range in weight from from 40 tons to 70 tons each. During maintenance, the rolls need to be replaced.
"We have an annual shutdown every year lasting seven days. We change out the heavy rolls," says Tallevast. "We change some smaller rolls and occasionally change the bearings. The crane is used to hold the roll while we are changing the bearings."
The 40-ton crane, with three 25-ton lifting assemblies, lifts and deposits the rolls in a lower-level maintenance facility, then lifts new rolls into place. "In between the annual changes, every six weeks we have felt changes, when the crane is used to pull the felts out; it is light-duty work, but it does require a crane," Tallevast explains. "Once a month, we use the crane quite extensively for up to eight hours. The major maintenance is done just a few times a year."
Operators confirm that moisture was a constant issue within the room beginning with the installation of the crane in 1990. While industrial cranes are generally considered viable for 30 or more years, the humidity inside the mill was rough on equipment. When Weyerhaeuser acquired the facility in 2000, the cost of keeping maintenance crews on hand during the shutdowns exceeded $100,000/yr, not including the cost of parts and lost production during those periods.
"As soon as we arrived in 2000, the crane caused a lot of downtime. The unit was very rusty. Most of the control cabinets had rust holes," says Tallevast.
Operating temperatures in the facility often exceed 100°F, with a constant humidity hovering near saturation. According to Tallevast, it was common to have trouble with contactors and limit switches in the mill. Safety was also a paramount issue. Moving heavy loads presents specific safety concerns, particularly when the machinery moving the rolls becomes unreliable.
"Any time you are making a lift and the crane quits, it is certainly a safety issue," Tallevast says. "We had to do something."
Roll weights range from 40 to 70 tons
Modernizing the crane's components
In 2005, Jack Nix, the Savannah representative of Konecranes, Inc., was initially contracted by Weyerhaeuser to provide on-site maintenance and inspection services as a result of this crane.
"For the first on-site shutdown, we provided two technicians that were standing by in case of a breakdown. The crane would break down regularly," says Nix.
By 2007, as a provider of both overhead lifting equipment and service, Konecranes recommended that Weyerhaeuser consider a modernization to reduce lost time, increase efficiency, and minimize costs. Tallevast agreed; overall efficiency could be maximized with proactive measures. The time had come to stop bandaging the crane and solve the underlying problem.
The engineers at Konecranes needed a solution that could replace the current maintenance equipment and withstand the demanding environment. In addition, the three industrial hoist and trolley packages had to be phased out, as to not disrupt the maintenance schedule.
Nix began the modernization process by conducting on-site research on the crane, reviewing maintenance and breakdown records, and estimating the cost. The solution was to replace all three hoist and trolley packages with brand-new SM hoists, a heavy-duty industrial hoist and trolley package manufactured by Konecranes.
"Fortunately, Konecranes has experience in paper mills," says Tallevast. "They knew the environment. I relied on them to specify what was needed."
The replacement hoist and trolley packages were engineered and manufactured specifically for the Weyerhaeuser crane. Konecranes engineers worked efficiently using the specifications of the original crane. The entire engineering process of the replacement parts was complete within 30 days and ready for the next regular shutdown, which occurs roughly every four weeks.
Except for the steel structure and bridge wheels, all components were modernized. In addition to the hoist and trolley packages, the modernization included all-new control panels, motors, gear boxes, stainless steel festoon systems, and electrical systems. Konecranes also replaced the bridge drive system that allows for the positioning of the crane.
The crane lifts and deposits roll in a lower level maintenance facility, then lifts new rolls into place
The vital logistics
To address the demanding timeline, replacement parts were manufactured in Finland, Konecranes global headquarters, and shipped directly to the Port of Savannah. The proactive logistics of Konecranes saved up to two weeks of possible customs delays in other ports and shipping from another location.
As if the challenges of replacing such a large portion of a heavy overhead crane were not daunting enough, Weyerhaeuser could not shut down production during the modernization project and realized the crane may be needed during the project. As part of the contract for the project, Konecranes was required to have the crane available for Weyerhaeuser within four hours of request. Konecranes agreed to plan the replacement of hoist and trolleys, motors, control equipment, and electrical facilities so that at any given point during the process two of the three hoists could be operational within a matter of hours.
"At any given time we could tell them we need the crane and within four hours, they could provide two of the trolleys," says Tallevast.
"We did all this while the paper machine was still running," says Nix. "It was very hot and humid. It is very unusual to do the work that we did and have that on-demand service guarantee built into the purchase order."
Despite the difficult working conditions, Konecranes technicians were able to complete the entire installation in 15 days. The complete modernization, from engineering, manufacturing, shipping, and installation, was completed in sixteen weeks.
Many steps forward, no steps back
Both Tallevast and Nix agree that maintenance operations at Weyerhaeuser have dramatically improved. With the exception of only a few minor crane-related issues, Nix is happy to report that there have been no process-hindering crane failures since the modernization project in mid-2007. The crane no longer causes extended maintenance shutdowns, nor does it require the constant maintenance that cost the company hundreds of thousands of dollars in additional costs and lost production. Further, Weyerhaeuser also addressed the air control issues that had long plagued the equipment.
"We perform monthly inspections at the facility," Nix says. "We stay on top of everything."
Weyerhaeuser is pleased with the work Konecranes did and the work the company continues to do providing inspection services for the facility. In total, the $400,000-project was designed and completed in roughly six months, saving Weyerhaeuser untold dollars in lost revenue and maintenance costs, and reducing the potential for maintenance downtime and safety threats.