Technical complications ask for innovative approach

Xavier Rootsaert, project engineer for Fluxys explains the difficulties involved: “Seeing that it had been 25 years since we did this large scale maintenance of the flare, we didn’t have a fixed scenario. The height of the flare combined with the fact that it is built on a platform with limited size and supporting power, made it quite a technical challenge to provide safe access. On top of that, the strong sea wind created extra pressure on the narrow flare which was of course not designed to support a large scale scaffold being attached to it. A free standing scaffold could fall over.” 

Rotating top

An out of the box solution was necessary. “We considered getting the flare down or attach cables to it from the pier. Because none of those solutions were technically possible, we came up with the idea of the rotating top.”

More explanation we get from Rudy De Smedt, head of the scaffolding engineering department in Belgium and designer of the construction: “First, Technip calculated the strength of the flare. With that information we were able to calculate the maximum amount of scaffolding material we were allowed to use and to what extent we could attach the scaffold to the existing construction. The higher you build, the more wind pressure you get on the scaffold. Therefore, the weakest point is the top of the tower and we concluded that we couldn’t build a full scaffold around the top.
Accordingly, above the height of 34m we build only a third of the top. When the cleaning and painting was finished on one site, we got the this part down and built a new ‘third’ on the other side. This way, the top of the scaffold turned around the flare in 3 phases.”

Other challenges

But there were other challenges during the project. Rudy Desmedt: “The platform could carry a maximum weight of 100 tons. For that reason we had to change our design and minimize the number of floors. On the other hand, the wind forced us to minimize the number of railings. Too many railings would increase the vulnerability with regards to the side wind and might cause the tower to bend.”

 

'The Hertel team has delivered an excellent job taking into account safety, quality and communication.” 

Xavier Rootsaert, project engineer Fluxys

Xavier Rootsaert: “All these precautions ask a lot of flexibility of the building team. But the team of project manager Mario Styleman and team leader David Ysabie has delivered an excellent job, taking into account safety, quality and communication with other contractors on site.”