Capital Equipment News

Genrec Engineering demonstrated the depth and extent of its skills and capabilities in steel fabrication and engineering when it successfully repaired a damaged dragline excavator boom in record time for one of South Africa’s leading coal mines.

Importantly, the project also marks yet another important milestone in the company’s drive to diversify into specialist and niche markets since it was acquired by the Southern Palace Group (SPG) in 2016.

Genrec repairs damaged dragline excavator boom in record time

Genrec Engineering successfully completed this technically complex and demanding project in as little as 10 weeks to assist a leading colliery in the Mpumalanga coalfields mitigate downtime.

Producing coal for domestic thermal energy production and for export to global markets, the dragline excavator is an essential component of the mine’s open-cut strip mining method. It is used in combination with drilling and blasting and dozers to expose the seam before wheel loaders and dump trucks are deployed in extensive load and haul operations.

Genrec Engineering’s involvement in the project commenced with a full-scale investigation into the damaged boom structure at the mine site in August 2017. Managing director of CMTI Consulting, Dr. Danie Burger, was part of the team that participated in the investigation with various insurance companies.

Why Genrec?

Burger says that a decision to award the contract to repair the boom to Genrec Engineering was based on the company’s long legacy in the South African and international steel engineering and fabrication industry.

“There is no other steel fabricator and engineering company in South Africa with the necessary infrastructure, as well as capacities and technical competence to take on such a complex project. Had the boom been sent to the original equipment manufacturer’s (OEM) premises in Australia for repairs, it would have taken up to four times longer to return the dragline excavator back to service with obvious negative ramifications on the mine’s production,” says Dr. Burger.

Representatives of the mine’s management team visited Genrec Engineering’s factory in Wadeville, Gauteng, a week ahead of the commencement of the repairs. Mark Prince, divisional director of Genrec Engineering, says that they were very impressed with the state-of-the-art facility and, just as importantly, the skills and experience of the Genrec Engineering management and engineering team.

“The depth of experience and expertise of our team have allowed us to constantly innovate, which is a strategic differentiator in this industry and a trait that we proudly demonstrated on this complex design and build project,” Prince says.

“My team of professionals had to be able to think out of the box and on its feet to overcome a myriad of challenges to ensure the timely and quality completion of the project in an extremely short timeframe. The fact that we were able to complete this project in such a short timeframe speaks volumes of the capabilities housed here in Wadeville that have placed us firmly on our next growth path.”

Job at hand

The boom comprises a 37-t mid-section, which is 30 m in length and 13 m in width, and the 43-t 32 m long and 13 m wide front portion, and both have a transportation height of 3,5 m. It was completely remodelled by Genrec Engineering’s design team with assistance from CMTI Shared Services, in a process that took about a week-and-a-half to complete.

The original drawings of the Bucyrus dragline excavator were more than 30 years old and updated versions were later received from Caterpillar.  They were used to generate models to develop the manufacturing drawings and upgrades to the boom, in addition to the manufacturing sequence, work procedures and transport sections.

The project also involved careful and complex logistical planning, considering that Genrec Engineering had to locate and source up to 34 t of chord material from various Australian mines to supplement insufficient supplies of the required specification.

This material was then transported to a central point for collection before being airfreighted to South Africa’s O.R. Tambo International Airport by Qantus Airways.  Importantly, a comprehensive analysis was undertaken of all available material sources to ensure quality and, importantly, traceability in line with the stringent requirements of the OEM.

The chords were buttered up and machined to specification and all lacing laser cut to fit assembly. It took about three weeks of round-the-clock operations to complete the complex laser cutting by approved specialists located in Vanderbijlpark, with Genrec Engineering team members located permanently on site to advise, as well as monitor progress and quality.

They were delivered to the plant in the correct assembly sequence and welding was then undertaken to the OEM’s exacting standards and procedures in a 2 200 m² bay that was converted for specialised manufacturing projects.

Process commences

“The process commenced with pre-heating and the roots undertaken with tungsten-inert gas (TIG) welding and CO2 used as a filler. Non-destructive testing (NDT) was done using magnetic-particle, phased array ultrasonic, radiographic and ultrasonic testing. Personnel from NJM Heat Treatment & NDE Services, as well as NDT specialists were stationed permanently on site to ensure that we were able to maintain sound productivity rates and adhere to exacting quality standards,” explains Burger.

A total of 2,3 t of weld material and eight weld feeders were also sourced from Australia to supplement available resources for this project.

Due attention was also given to the quality of the more than 20 welding machines deployed on the project. Importantly, they had to provide a consistent current at the correct frequency to ensure a high quality weld.

One of the complexities of the welding operations was the varying diameters and positioning of the larger chords and smaller lacing.  A total of 129 welders were tested by Genrec Engineering and 52 metal inert gas (MIG), or gas metal arc, and tungsten inert gas (TIG) welders employed to work on this project, together with 18 boiler makers and assistants.

They were designated to the various teams that would work in the three shifts to ensure an uninterrupted 24/7 operation. Ranks were bolstered with five specialist boom welders, as well as an expert boom weld engineer and project co-ordinator from Australia.

They also assisted in undertaking the four successful Procedure Qualification Records ahead of welding activities. Further demonstrating the extent of the skills of capabilities of the Genrec Engineering team are the rotators that were designed and developed especially for this project.

These complement the large investment already made by the company and SPG in acquiring the capital equipment needed to diversify into niche and specialist markets. Among these are the computer-numerically controlled machines housed on the factory floor that have been fully integrated into the SolidWorks engineering program to ensure high levels of precision and productivity.

These, alone, represent about a R50-million investment that is also being supported by continued skills development and training as Genrec Engineering builds up its skills base to cater to the high demand for its specialist services.

Further scope

As part of the project, Genrec Engineering was also tasked with upgrading the dragline excavator’s boom-point box.

A special furnace was designed and developed around the boom-point box and soaked at 600 degrees Celsius for six hours and then cooled down to 37 degrees Celsius for five days. The furnace was heated with gas at a rate of 37 degrees Celsius an hour to 600 degrees Celsius.

A canopy was also designed to allow sand blasting to continue apace in the workshop while welding progressed according to plan to maintain high productivity rates. The components were transported to the mine site by Mammoet using a 13-wheel Nicolas trailer and resting on 11 t cradles that were specially designed and manufactured by Genrec Engineering.

It took three days to transport the two loads to site as part of the last phase of the project. Impressively, this is said to be the largest abnormal load to have ever travelled on the Gauteng road network, and Genrec Engineering was also involved in the extensive road survey, in addition to obtaining all necessary road permits from the Gauteng Department: Roads & Transport.

The mid-section of the dragline excavator boom was dispatched to site at the end of November and the front end in early December.

It was successfully assembled by Caterpillar’s southern African dealer, Barloworld Equipment, on site in December over a period of four weeks.

Prince concludes that he is proud of his team’s involvement in yet another successful project that has again demonstrated the important role that the local steel industry plays as an employer, as well as driver of critical skills development in line with government’s re-industrialisation strategy.

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