Maximum overhaul: How outages are planned and executed

10 July 2023

Stanwell Power Station Outage Superintendent Chris Jensen loves it when a plan comes together – so he’s in his element as the station prepares for its next maintenance overhaul.

Like any machine, power stations require proper care and maintenance in order to keep running safely and efficiently. That’s why every generating unit in every power station in the National Electricity Market (NEM) is required by law to undergo a regular, scheduled maintenance overhaul to achieve statutory compliance.

These planned outages are carefully coordinated with the Australian Energy Market Operator (AEMO) ahead of time, in order to minimise their impact on the market.

Outside of these overhauls, an ongoing regime of maintenance is required to keep each of Stanwell’s power stations running optimally throughout the year. This ensures that the energy grid continues to operate securely and reliably – and we can continue to provide the spark for a bright future.

From 15 July to 4 September this year, it’ll be time for Unit 1 at Stanwell Power Station (SPS) to be put under the microscope – but Chris’ work starts well before that.

“We started preparing for this overhaul in October last year,” Chris says. “That’s how early you have to start to allow for the scoping, planning and procurement of the parts and resources that are required for a project like this.”

How does a unit overhaul work?

Scaffolders are currently on site, completing the thousands of hours of scaffolding work that are required to make the unit accessible for its overhaul.

From 15 July, the unit will be temporarily removed from service. The overhaul will include inspecting the plant to determine its condition and the need for further repairs, and then completing the repairs, projects and scheduled work activities required.

“These scheduled activities are based on statutory inspection requirements,” explains Chris. “What needs to be done for each part of the unit will depend on its inspection cycle – you have five-year inspections, ten-year inspections, fifteen-year inspections, twenty-year inspections and mid-life inspection intervals.

“This overhaul includes a mid-life refurbishment of the generator transformer. That’s a major project – we would always do maintenance on the generator transformer, of course, but the maintenance activities we’re doing this year are even more comprehensive than what we would usually do, due to a more thorough inspection.

“Other major projects as part of this overhaul include a dip seal / drag link replacement, a 50 per cent inspection of the hot reheat pipe, and a fire system upgrade. It’s about ensuring that the unit will operate safely and meet its reliability targets until the next scheduled overhaul.”

Workers will be on-site around the clock throughout the overhaul, with a paramedic on-site for the duration. Sundays will be the quietest days, as radiography and isolation activities are completed with minimal crew on-site; but throughout the rest of the week, the station will be a hive of activity.

“On a normal day outside of an overhaul period, there’d be approximately 130 people on-site at SPS,” says Chris. “But during an overhaul, that number peaks at approximately 600 people.

“That means that more than 400 extra workers need to be brought on-site for the overhaul, in addition to the station’s permanent workforce. These are project support staff, fitters, riggers, boilermakers, pressure welders, electricians, blasters, industrial cleaners, general labourers, and so on. The majority of these additional workers are subcontractors from Queensland and New South Wales, but we also bring people in from overseas to do more specialised work.”

All of these additional workers are required to do online training and inductions before they arrive. They’re then given staggered start dates and arrival times, to avoid a logjam at the front gate while their credentials are verified.

This influx of workers has a significant economic impact on the local community, benefiting the hospitality, accommodation, tourism and transport sectors.

All told, each overhaul is a major operation – and as the Outage Superintendent, it’s Chris’ role to ensure that it all runs smoothly.

“I enjoy the challenge,” he says. “It’s all about problem solving, and I enjoy that. We put an extremely detailed schedule together to eliminate as many problems as we can in advance, and to make sure that we don’t have teams working on top of each other at the same time. And then it’s about maintaining focus on our critical paths to ensure that they stay on schedule and on target.

“At the end of the day, it’s about delivering the unit back online safely by the date that’s been arranged with AEMO. Everything we do is working towards that goal.”

What happens next?

Once the required inspection, maintenance, refurbishment and replacement of plant and equipment has been completed, the unit will be recommissioned and returned to service. 

The units at Stanwell Power Station have been on a four-year maintenance cycle, but are gradually being moved to a five-year overhaul cycle.

“This means that, after this overhaul cycle, the plant will be safe to return to service for the next five years,” Chris explains. “So during this outage, we’re performing some additional work to get this unit up to that five-year standard. We’ve already done that for Units 3 and 4, and we’ll be bringing Unit 2 up to that standard next.”

Typically, each generating unit at a power station is overhauled individually. This helps to ensure that there’s still enough energy to meet demand at any given moment, and means that the same workers can go from one overhaul to the next.

“When Unit 1 is returned to service, I’ll initially be focused on project close-out,” says Chris, “which includes sitting down with the contractors we worked with on this project to see if there are any lessons that have been learned that we can carry on to the next project.

“But then it’s straight into planning the next overhaul, which is scheduled for Unit 2. That’s how it works – if you’re not in the middle of an overhaul, you’re getting ready for the next one.”