Tag Archives: MARTHINUSEN & COUTTS (PTY) LTD

QUICK REPAIR PUTS ARCELORMITTAL TURBINE GENERATOR BACK TO WORK

A 40 MW turbine generator from ArcelorMittal’s Vanderbijlpark works was repaired on a fast track schedule by ACTOM Turbo Machines.

The emergency repairs were required after the generator broke down in October 2018, with damage including failed bearings on the generator train. ACTOM Turbo Machines, a division of ACTOM (Pty) Ltd, undertook to complete the work and have the generator back in operation by mid-December 2018.

Demonstrating its high level of expertise as a mechanical repairer, ACTOM Turbo Machines first diagnosed all the elements that would require attention during the repair. All four bearings – as well as the rotor sealing elements – were found to be damaged. Other damage, which was unrelated to the October failure, was also discovered.

“The damage involved a crack on the high-pressure (HP) gland section of the main steam casing, while a second unforeseen irregularity was a malfunction in the starting or auxiliary oil pump,” Danie Bloem, ACTOM Turbo Machines’ project manager on the contract, says.

Other irregularities were an incorrect bolt clearance on one of the HP palms, probably due to faulty installation.

“In addition to repairing the damaged bearings, we also had to recondition a spare set of bearings that ArcelorMittal had in reserve,” Bloem says. “The sealing segments were replaced with new ones manufactured at our Sasolburg works.”

He notes that the process of repairing the crack in the main steam casing took the team five days, working around the clock.

“A high level of welding expertise was required here, as the casing is made of a special material,” he adds.

The repair of the starting oil pump was also performed in only two days. This required the manufacture of a new shaft, and also the reconditioning of the mechanical seals.

Once the generator resumed operation, vibration testing confirmed that its performance had improved significantly, Bloem points out.

SASOL AWARD FOR ACTOM TURBO MACHINES

Petrochemical giant Sasol has recognised ACTOM Turbo Machines with one of its top 2019 awards for exceptional service in repair, refurbishment and ongoing maintenance.

The award in the ‘Top Performing Service Supplier’ : Large Enterprises category was recently made by Grace Nndwammbi, Sasol’s senior vice-president supply chain to ACTOM Turbo Machines’ managing director Chris Bezuidenhout at Sasol’s head office in Sandton.

A division of ACTOM (Pty) Ltd, ACTOM Turbo Machines is the only large non-OEM business in its service category to win the award to date. Since its inception six years ago, it has become the largest non-OEM turbo-machinery and high-speed rotating equipment service provider in sub-Saharan Africa.

Sasol is very OEM-reliant in terms of service backup and parts supply, according to Anton Hamman, Sasol’s principal specialist sourcing mechanical equipment. Nonetheless, ACTOM Turbo Machines has proved itself in service provision for turbo machines, where critical and complex skills are required.

“We view turbo machines as the heart of our operations, so it is absolutely essential that the service provider has all the critical skills needed to ensure that the equipment is maintained to OEM specification,” Hamman says. “If you use a non-OEM company for this work, you must be certain they have the required skills and competencies to perform this work to the correct standard every time and understand the associated risks.”

He highlights that safety awareness was a critical aspect of this service. The 36 MW machines in Sasol’s oxygen plant, for instance, are extremely large and heavy. This makes them difficult and potentially dangerous to work on.

“ACTOM Turbo Machines has demonstrated its awareness of the hazards involved and rigorously applies all the procedures necessary to ensure that no one gets injured and that the work gets done as per agreed schedules,” he says “On turbo machines, we look for the best skills in the country and globally, and this is what ACTOM Turbo Machines offers.”

Bezuidenhout says ACTOM Turbo Machines was honoured to have received the award.

“It signifies recognition of the highest order, which we greatly value and cherish,” he says. “It marks an important milestone for us in our ongoing drive to provide the best possible service to industry.”

He commends the company’s maintenance and refurbishment teams on the achievement. ACTOM Turbo Machines has a long-term service agreement with the Sasol group, including Sasol Secunda, Sasol Sasolburg, Sasol Mining and Natref.

The agreement is to provide maintenance on a periodic basis at all these sites. At Sasol Secunda’s oxygen plant, the company has a permanent presence of 40 personnel to attend to all 16 of the plant’s oxygen trains.

MARTHINUSEN & COUTTS INVESTS TO UPGRADE ITS ZAMBIA FACILITY

A new 435 m² machine shop workshop and transformer department at Marthinusen & Coutts’ facility in Kitwe, Zambia will further improve the quality and turnaround time of its offerings in the region.

According to Marthinusen & Coutts Zambia general manager Eugene Lottering, the commissioning of the machine shop workshop in January this year created significant space in the 1700 m² main workshop, allowing for the investment in a transformer department.

“We now have a dedicated factory for machining work-pieces for the main shop,” says Lottering. “The Marthinusen & Coutts head office in Johannesburg makes a vital contribution by sending their machine shop foreman to provide training. This upgrades the local Zambian machining skills on a continual basis.”

The division’s machine shop facility boasts five machining lathes, two milling machines, and a submerged arc welding machine. It also has a 50 tonne horizontal press and rotor binding machine. All equipment operates under two 6,3 tonne jib cranes.

“Our transformer department has allowed us to enter the market in transformer repairs. The facility is equipped with a 20 tonne overhead crane to lift larger transformers,” he says.

The new department is equipped with a new coil machine, ratio tester, an oil purification machine and a dedicated oven.

Marthinusen & Coutts, a division of ACTOM (Pty) Ltd has already successfully overhauled transformers for a number of opencast mines. This included a 10 MVA unit, two 5 MVA units and a 3 MVA unit. Working in collaboration with M&C Johannesburg has ensured quality is maintained, while local transformer repair skills are also being developed.

“We have also established a Level 3 maintenance site services team to provide on-site electro-mechanical assistance to customers,” says Lottering. “This includes on-site repairs, maintenance and testing.”

Significant previous investments in the division’s Kitwe workshop have included a 12 tonne balancing machine, a vacuum pressure impregnation (VPI) plant, burn-off and curing ovens, and a fan test column. There is also an AC and DC test facility, equipped with power analyser, surge comparison tester, core flux tester and high voltage pressure tester.

“Our continuous investment in the region allows us to provide customers with a one-stop electro-mechanical repair facility for alternators, generators, motors and transformers, as well as mechanical equipment,” he says. “This means shorter lead times and less transportation risk, while also benefitting the Zambian economy.”

M&C’S REWIND OF 36MW COMPRESSOR MOTOR STATOR YIELDS ‘BEST EVER’ TEST RESULTS

Marthinusen & Coutts recently provided a solution to an irregularity that occurred in the stator of a large 36MW compressor motor deployed at Sasol’s Secunda plant.

The results of final tests, conducted by H.V. Test Filed Services on the stator after M&C had completed all the necessary repairs on it, were found to be the best among many such tests conducted on similar equipment over a period of several decades.

Initially a Sasol maintenance team discovered during a routine inspection in January 2018 that the flux shield mountings on the stator were faulty, whereupon Sasol awarded M&C a contract to identify the cause of the irregularity and offer a remedy.

“We tested the stator winding, which we found to be fine, but confirmed that there was a defect in the flux shield and recommended that it be repaired, as there was a risk of it damaging the winding if left to continue operating in its existing condition. To repair the flux shield meant also having to remove the winding and perform a rewind on the stator,” said Rob Melaia, M&C’s engineering and technical executive.

Sasol accepted M&C’s recommendation and in August last year assigned it to perform the required repairs. “In addition to replacing the old bars with new bars purchased from a reputable coil manufacturer in the US, we did a very specific modification to repair the flux shield to prevent a recurrence of the defect in the future,” Melaia stated.

“On investigating the defect we found that the electrical current, instead of flowing only in the flux shield as it ought to have done to prevent the core from overheating, had started flowing in the mounting bolts, so causing wear by electrical arcing in the mounting holes and the mounting studs,” he explained.

The solution M&C’s repair team provided was to fit copper braid straps from several points on the flux shield to the stator body to reroute the current in such a way as to prevent a repeat of the damage as witnessed. To confirm the effectiveness of the solution M&C arranged to have the refurbished stator tested by local independent test authority H.V. Test Field Services.

Partial discharge and Tan Delta tests were conducted, being the recognised tests for determining the integrity and efficiency of medium voltage windings. The results were:

  • A maximum partial discharge of below 250 PicoCoulombs (pC) at 120% of phase voltage.
  • In the Tan Delta tests the dielectric dissipation factor was found to be 65 x 10-4 at 20% of phase voltage and 105 x 10-4 at 100% of phase voltage.

“These test results were the best ever to be achieved among the numerous machines on which HV Test has conducted tests of this kind!” Melaia pointed out.

“We have every reason to be proud of this outcome as it says volumes about M&C’s expertise in this field, both in terms of correctly diagnosing and repairing faults in a wide range of large rotating equipment, as well as providing the appropriate and most effective solutions for them,” he concluded.

MOTOR REHABILITATION IN ZAMBIA KEEPS MINE PUMPING

Marthinusen & Coutts’ Cleveland Engineering Services Division, a division of ACTOM (Pty) Ltd, recently teamed up with the Marthinusen & Coutts Kitwe facility in Zambia to rehabilitate medium voltage pump motors in one of the wettest mines in Africa.

A pump OEM had approached Marthinusen & Coutts, the largest after-market service provider of electrical and mechanical rotating machines in Africa, to assess several underground pump motors. There was an urgency to the situation due to the risk of flooding should there be any undue interruptions in pumping operations.

Investigations revealed that the motors driving the pumps were in a poor condition, with this severely affecting the availability and the performance of the pump chambers. This required the initiation of a detailed refurbishment programme, involving the procurement of spare parts, the setting up of an on-site bearing store, and taking the lead in returning the motors to full service.

Where possible, the motors were repaired in situ – thus avoiding any possible crisis of underground flooding – while others were removed for full refurbishment. The highest level of engineering practices where followed during repairs, re-installation and commissioning. Ongoing support is also being provided, including the training of mine maintenance staff, the development of installation and commissioning specifications, conducting of regular site inspections, management of spares, and continual engagement with mine engineering management.

Marthinusen & Coutts operates six state-of-the-art repair and manufacturing facilities – in Johannesburg, Benoni, Sasolburg, Rustenburg, Harare and Kitwe. Supported by a network of technically equipped partners throughout Africa, it provides services not only in Africa but globally.