When maintaining a factory, there may not be space available to conduct construction since the equipment is occupying the space. On top of that, deadlines must be kept, since operations are paused for the duration of the construction. Let us talk about the time we set up a duct in a new chimney at a factory. The duct was huge, with a diameter of 4 meters. We needed a 160-ton crane to hang the duct, but limited space in the factory prevented the crane from going inside. With the deadline to complete the construction only 10 days away, what would you do?

Idea 1: Sever the old duct into small pieces for easy transportation and remove it. Install the new duct will in the reverse way, conveying small pieces into the factory, assembling, and installing them.

Idea 2: First, place the new duct on top of the old duct temporarily. Once the chimney stops operating, sever the old duct, pull it out, and pull down the duct placed on top to the correct position.

　Idea 1 would take too much time. Idea 2 would cost too much, and it was possible that the foundation would not be able to hold the weight of both ducts. The factory manager at the time was struggling with the issue. Then, an idea came to my mind while considering how to overcome this challenge. --- If a 160-ton crane cannot get closer, what about relaying the duct using two cranes: a 160-ton crane and one that is small enough to get close to the chimney? What if we built a temporary gantry to hold the duct above the existing equipment and use that as a relay point…
The idea is to use a 160-ton crane and a 50-ton crane while considering the size of the vehicle, pathway, available spaces to do work, working radius of cranes, and weight of cranes.

　Well, can this relay plan really work successfully? Will the dimensions perfectly match? We measured the dimensions of the area where the duct would be installed many times and conducted countless simulations. We considered where to temporarily hold the removed duct on paper by surveying at the area. However, concerns were unlimited. Complicated durability calculations were needed to set up the temporary gantry. We had to consider the locations of existing equipment, set up pillars, and maintain the durability of a gantry with a height of 8m and an area of 100㎡ to hold the new huge duct at the same time. Every day went by with calculations, calculations, and calculations. Finally, construction day came. How can it be possible to complete construction within 10 days? What can we do before the stop of operations? We had to plan the construction process perfectly. If we failed, we would not have time to start over, so we had no other choice but to make it successful.

　Finally, construction begins! Thanks to our diligent preparation, everything went according to the plan. The duct was light for its size, and the only change in plan was taking a day off due to wind hazards while operating the cranes.

　Water vapor went through the duct and was released from the chimney. After 30 minutes of tense observation, we concluded that the duct was operating perfectly. Then, we disassembled the scaffolding and temporary gantry. It was only after then that we could finally feel relieved. Many people, including our customers, my boss, my seniors, and partner companies, faced the challenge together, and it would have been impossible to achieve it alone. I would like to thank everyone who was involved in the project.