Kiln shell section replacement – Tanga Cement Tanzania

When a client has an urgent breakdown this is when Robtek performs at its best. Tanga Cement is a long-standing customer of Robtek’s and we were only happy to assist when the client's kiln shell ripped apart for 3/4 quarters of its circumference and the plant was immediately stopped end of March 2021.??

On a breakdown basis, 60mm steel plate had to be sourced, procured, prepped and rolled. Due to abnormal road transport constraints through to Tanzania, the shell sections had to be fabricated in SA in 2 halves.?

While this was being done we packed and prepped our tool and equipment containers. They were loaded onto the first available truck and set off on the long trip up to Tanzania.??

Once the kiln shell was fabricated it was set up for machining, this needed to be done on both sides of the kiln shell section.????

Chair plates which fit between the shell and riding ring tyre were also required for the replacement. These plates required machining to the correct thickness and to be rolled and cut to size, followed by drilling and tapping.?

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Once the kiln shell sections were completed, they were loaded onto a 2nd truck for transport. Crates containing kiln chairs, retainers, blocks, erection steel and consumables were also loaded on the truck and made their way up to Tanzania.??

Whilst the trucks were making their way to the site. A 250T crane required for the lift was arranged and began making its way to the site for establishment.??

On the 30th of April 2021, Robtek dispatched our first kiln installation team to commence the stripping and removal work to gain access to the kiln shell.??

Our team got to work on a kiln support tower and stripping where possible. When the first truck carrying our tools and equipment arrived on the 6th of May, the team got to work, removing the old part of the shell that needed replacing.??

We were then also able to remove the old shell piece from the tyre.

Truck 2 carrying the shell section reached Tanga cement on the 11th of May, and the team got right to work to commence joining the section halves which entailed bracing and aligning in preparation for submerge arc welding.??

The section halves were welded at the longitudinal splits on the outside, back gouged, ground, weld tested with dye pen and then welded on the inside as well.??

With the newly completed section, the existing tyre could be positioned onto the new shell. The complete assembly was then rigged into position.??

Erection steel is installed inside new and old sections so that the seams could be temporarily joined and aligned. The remaining chair plates were then installed, and the first set of alignment runouts could be taken.

Shell seam measurements were recorded, runouts calculated and adjusted accordingly.?

Once the runouts met the specification and were accepted for welding the manual root welding could commence.

Post the root welding being complete, the submerge arc machine could be set up on the first joint seam. Preheating of the seam commenced and submerge arc welding was underway.?

When both external seams were complete, the internal erection steel could then be removed and internal weld preparations could commence. This entailed gouging and grinding a weld prep for internal welding. cracking tests were complete. After dye pen cracking tests were complete, sub-arc welding completion could then be done from the inside.

3rd Party NDT testing was then Robtek’s great team proudly a carried out achieved and 100% pass. The kiln could now be handed over back to the plant for refractory installation. Final fit up of chairs and shimming was completed and discharge seals were refitted. All temporary supports and scaffolding were then removed, cleaned up and site de-establishment could commence.???

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