Rope access specialist Skyriders and plant care engineering consulting expert Carab Tekniva completed the inspection of a 210-m-high smokestack and various boiler pressure components at the Paiton coal-fired power station in East Java, Indonesia.
The two South Africa-based compa- nies undertook inspection work at independent power producer Paiton Energy’s power station through a joint venture and completed the latest project on the smoke stack and the 700 MW Unit 7 boiler within ten days in May.
“Unit 7 or 8 of the Paiton power station is shut down for planned maintenance once a year. The Unit 7 shutdown took place from April 20 to June 20 this year. “During the outage, all the critical power plant components were inspected and scheduled repairs on malfunctioning and damaged components were performed,” says Carab Tekniva boiler engineer Jan-Hendrik Fourie.
He adds that the company worked on two projects simultaneously – the boiler inspections with Skyriders and a full high-pressure-piping elevation survey of the mainsteam, hot reheat, cold reheat and feedwater systems.
“The boiler inspections are scheduled to be performed at the start of every outage. This is done as soon as the boiler shuts down so that enough time remains during the outage to perform repairs identified during inspections.
“The hot-piping elevation survey was performed because there was some con- cern regarding the mainsteam piping which, during operation, started to expand into the support structures,” Fourie says.
There is a database for each boiler unit and each outage and all the inspection data is captured using Carab Tekniva’s software, he explains.
Fourie, who acted as project manager for the duration of the inspection process, indicates that the company’s Boiler Health Care Programme software solution was used to monitor the condition of the boiler components and proactively monitor the condition of the plant using trend analysis to implement maintenance strategies.
“This enables a Carab Tekniva engineer to do trending of the boiler wear and accurately identify areas of high wear rates, which should be monitored during future outages,” he says.
“The wear to which Indonesian boilers are subjected is mostly caused by the rubbing or fretting of tubes, as a result of retaining lugs or support plates that have broken loose and caused the pressure parts to fret during operation. “Compared with South African coal- fired boilers, where fly ash erosion and sootblower erosion are large contributors to tube failures, the coal used by the Paiton power station has a far lower fly ash content compared with South African coal.
“Therefore, less sootblowing is required on the superheater, economiser and reheater elements, which decreased tube material loss rates considerably, owing to less sootblowing. “The calorific value of the Indonesian coal is higher than that of South African coal and, as a result, the Paiton power station uses less coal,” says Fourie.
He notes that routine maintenance on these large boiler units significantly reduces downtime caused by unplanned tube failures, which, typically, occur as a result of fly ash erosion, sootblower erosion and thermal fatigue.
A thorough boiler inspection by Skyriders ensured that damaged or eroded tubes were identified and repaired in advance. The costs related to unplanned outages are high and the technical know-how is not always available at times when an unplanned tube leak occurs, Fourie points out.
“When all the inspections were complete, the results were presented to Paiton’s engineering manager, outage manager and system engineer. I explained the general state of the boiler, the areas of concern and which components needed repair,” Fourie states.
Skyriders marketing manager Mike Zinn adds that Skyriders and Carab Tekniva continue to be the preferred companies to undertake inspection work on international projects, such as Paiton, as both offer a great service at competitive prices.
“Although similar services could be provided by companies based in Europe, North America and Australia, Skyriders and Carab Tekniva provide the same internationally recognised and accredited offering at a rate that is substantially lower than the rates offered by international competitors, without compromising on safety or quality,” he explains
Zinn notes that a team of six rope-access technicians and boiler inspectors from Skyriders worked with a boiler engineer and engineering technician from Carab Tekniva to inspect the wall blowers, water wall tubes, superheaters, reheater tubes and screen tubes, in addition to the other mechanical components located inside the boiler and the smokestack.
“This was a highly demanding project that had to be completed within ten days. Skyriders was responsible for all physical inspection work, while Carab Tekniva captured and analysed the data before advising the client on areas of concern, potential scope of work and a maintenance strategy. “The project was successfully completed within the specified timeframe,” he says, attributing its successful completion to a strong working relationship and mutual understanding between the two companies.
The humid climate and close proximity of the Paiton power station to the ocean proved to be challenging for the inspection team, notes Skyriders rope access team leader Progress Malang.
The high humidity was physically draining and the rope access technicians had to deal with fatigue and uncomfortable work conditions. These challenges were, however, overcome, owing to the experience and commitment of the entire team,” he states.
Although the language barrier also impacted on effective communication, Malang points out that a translator, in addition to two Indonesian inspection assistants, was used to deal with this challenge.