For an experienced erection team on a regular job, assembling a Potain MCT 58 city crane is a straightforward task that can be completed with a mobile assist crane in just four hours. But this was not a regular job.
When your jobsite sits at the top of a hydroelectric dam; which itself sits at the foot of a volcano; there’s no access for vehicles bigger than a small car; and you’re on a remote island in the middle of the Indian Ocean, you know you’re going to need to think differently about placing your crane on the project.
Yet this was the challenge faced by Manitowoc and local dealer GLI (Grues Levages Investissements) when tasked by energy company EDF (Électricité de France) to replace an old Potain 427 E maintenance crane at its Sainte-Rose power station on the French overseas department of La Réunion.
“We love difficult briefs,” said Christophe Chappaz, technical director for GLI. “And this was a tough brief. We knew that cranes from other brands were not feasible because of the load capacity limit of 1 t on the helicopter. We collaborated closely with Manitowoc to adjust the capacity, technology, warranty and erection plan to meet EDF’s needs for this MCT 58 and combined with our experience, we were able to assure the client we could complete the task safely.”
Another reason GLI felt confident with the job was that the company had installed the original crane at the EDF site by helicopter 30 years ago. In fact, several of the staff responsible for that project were still employed at the company, so could advise on its disassembly and replacement. This experience gave GLI the edge when tendering for the project.
GLI was also able to match the capacity of the 427 E with a new MCT 58, which is conveniently manufactured in sections weighing less than the maximum payload of a commercial helicopter. In addition, when it comes to assembly, the MCT 58 is among the quickest and simplest to put together.
Christophe Chappaz maintains a strong relationship with Manitowoc, having worked for the company in a variety of technical support, aftermarket and Lift Solutions roles before moving to La Réunion to join GLI in 2012.
For this project, he liaised closely with the Manitowoc Lift Solutions team, to ensure every section of the MCT 58 came in at less than 1 t and that the slinging points were optimally positioned for the helicopter lifts. Corrosion-resistant paint and stainless-steel casing for the electrical components were also specified to provide maximum durability in the damp environment on top of the dam.
Practice makes perfect
After manufacturing, the crane was shipped to the GLI yard on La Réunion, where the erection team practised assembling and disassembling prior to installing it, to be sure of the weight, slinging points and work plan. On the day of the erection, the components were transported by road and arranged in a field five minutes by helicopter from the job site.
The erection of the new MCT 58 was completed in 26 flights, each lasting approximately 15 minutes. Total erection time was around six and a half hours, which GLI spread over two days. The vertical and rotating elements went up on the first day, with the horizontal parts and finishing wrapped up on the second.
“The rotor blades on the helicopter induce a swirling wind, which is difficult to manage, so it was important we took things slowly and steadily. You cannot rush a project like this when safety is critical,” Chappaz said.
The four GLI technicians on the project communicated constantly with the helicopter pilot by radio to ensure the process went exactly to plan. The social distancing required as a result of COVID-19 restrictions posed an additional challenge, but the team adapted to complete the job safely and professionally.
The crane was secured using static fixing angles and erected at a height of 19.7 m with 30 m of jib. The maximum load is 3 t at 20.7 m and 1.96 t at 30 m. EDF will operate the crane by radio remote control to help dismantle the old 427 E crane, carry out general maintenance on the 3 t cofferdams and 1 t water intake grid, and support a dam reinforcement project.
“I am very proud of what the GLI and Manitowoc teams managed with this challenging task. The crane is working well and EDF is happy with the result. Good project organisation and close collaboration and communication were the key to success!” Chappaz concluded.