industrial plants, oil & gas projects
The repairs to Sasol’s 160-metre high cooling tower for Sasol Synfuels includes the repair and coating of the tower to extend its life by an additional ten years. The project commenced in February 2017 and is due for completion in May 2019. It includes the demolition of delaminated concrete, surface preparation to parent concrete, reinstatement of reinforcement bars and the reinstatement of the concrete using various materials and applications. The access system includes the use of two Alimak Scando construction hoists, a purpose-designed monorail and sixty-six temporary suspended platforms.
The Koeberg Nuclear Power Station repairs was completed in March 2019. The scope of this concrete rehabilitation project included the evaluation of the structural integrity and repair to safety related nuclear structures. Stefanutti Stocks performed hammer testing, chloride testing, reinforcement cover readings and Schmidt hammer tests. Reinforced concrete rehabilitation was undertaken to the Unit 1 and Unit 2 containment and fuel buildings, with safe access to the external faces of these buildings achieved through the erection of scaffold towers. Repairs were also undertaken to the structural cracks on the reactor building dome roofs. The scope also entailed critical reinforced concrete repairs to the SEC Pits seawater intake basin during the March 2018 outage.
The Arnot Chimney Repair was completed for Eskom in June 2015 and entailed the repair and protection of both 196-metre high chimneys at the Arnot Power Station. The scope of work included the installation of permanent platforms and cat ladders cumulatively weighting thirteen tons, as well as the installation of two Alimak SE600 hoists to give future access to Eskom. The repair scope included the removal of existing cast iron capping and refractory bricks, as well as the installation of new stainless-steel capping. The top twenty-metres of the chimney was repaired and coated with protective coating.
The refurbishment of two 165-metre high smoke stacks at Hendrina for Eskom was completed in February 2015. The project included the installation of permanent platforms around the top level of the chimney; the repair of the refractory brick lining; removal and replacement of damaged lightning arrestors; and installation of temporary suspended platforms to access the top thirty-metres of the chimneys. The damaged and spalled concrete was repaired, and the surface prepared for concrete using high-pressure washing. Skimming mortar/pore leveller as well as a Polybron coating was applied to the concrete substrate and aircraft warning lights were installed at the top of the smoke stacks.
In 2014 Stefanutti Stocks Civils undertook the access, repair and protection of cooling towers at Sasol Synfuels in Secunda. The top rim of the cooling tower had been struck by lightning causing the concrete to spall. In order to enable access an Alimak Hoist was installed, as well as a platform around the circumference of the tower. Twelve suspended platforms were installed in order to inspect and repair the inside of the tower. During the repair process representative samples of the concrete was taken to diagnostically test for chlorides and sulphide percentages to determine the rate of carbonation within the structure, which would inform the long-term maintenance strategies for the cooling towers.
The flue cleaning and maintenance of Sasol Secunda’s Flue Stack entailed the installation of temporary platforms and rigging reticulation to a flue on the east chimney. The scope of work included the cleaning of ash residue from the refractory lining and a total of 450 tons of material was removed over twelve shifts under shut down conditions.
An acid proofing project at the Rustenburg Base Metal Refinery for Anglo American Platinum Limited was undertaken between January 2014 and May 2015. The high-acidic content of the projects in the Leaching and Purification Plant at the refinery affects the concrete’s integrity and approximately 5 580m2 of acid proofing project was installed and reinforced. Other quantities included the removal of 4 675m2 old acid proofing; 5 579m2 structural grout skin; 396m2 of acid resistant bricks and 4 464 metres of joint sealing.