Engineers with Drones Engineers with Drones logo
Let's Talk
  • Home
  • Asset inspections
  • Services
  • Sectors
  • Resources
  • About
  • Contact
Inside the fully drained penstock at Ardnacrusha Power Station, looking up along the riveted steel walls towards the daylight opening at the top

Penstock inspection at Ardnacrusha

A fully drained penstock at Ireland’s oldest hydro power station, flown from the spiral casing to the upper gates as the eyes of the ESB NDT (Non-Destructive Testing) team.
Overview

The Job at a Glance

A confined space drone inspection inside a fully drained penstock at Ardnacrusha Power Station during a generating-unit shutdown. The drone was launched from inside the spiral casing and flown up through the penstock, allowing the ESB NDT team to examine the flexible diaphragm, the penstock walls and the gates at the top without scaffolding out the entire structure.

Ardnacrusha Power Station

One of the oldest power stations in Ireland, and the oldest hydro power station in the country, inspected during a large shutdown.

A fully drained penstock

The penstock and spiral casing were drained down, dam beams were put in place, and the whole structure was opened up for repairs.

Expansion joint targeted

An expansion joint about halfway down the penstock, where the site’s history showed mud builds up and causes deeper corrosion, and at times freezing.

4K imagery record

A complete deliverable set of 4K imagery, alongside Engineers With Drones on site as the ESB NDT team’s eyes in the hardest-to-reach areas.

Background

Ireland’s oldest hydro power station, drained down for repairs

Engineers With Drones were brought in for a large shutdown. One of the generating units had been drained down: the penstock was fully drained, so was the spiral casing, dam beams were put in place, and the entire structure was opened up for repairs.

The internal steel structure of the drained penstock at Ardnacrusha Power Station, showing the riveted plate work and lattice bracing
Inside the penstock at Ardnacrusha Power Station, drained down during a shutdown so the structure could be opened up for inspection and repair.
The challenge

The alternative was scaffolding the entire penstock

Reaching everything inside a penstock is difficult. At Ardnacrusha they run roughly 4 metres in diameter, and under normal circumstances inspecting the full interior would have meant scaffolding out the entire structure.

The site’s long history told the inspection team where to concentrate. One example is an expansion joint about halfway down the penstock, fitted to compensate for differences in heat and expansion. Mud is known to build up inside it, and that can cause deeper corrosion, cause issues, and at times even freezing.

It is not a place that is easily accessed. As Bob Foley puts it, "it was a very rare occasion to be into that place."

The expansion joint partway down the drained penstock at Ardnacrusha, showing riveted steel plate
The expansion joint partway down the penstock, a known accumulation point where mud builds up and can lead to deeper corrosion inside the joint.
Methodology

Flown from the spiral casing, up through the penstock

The team stayed down inside the spiral casing and set up all their gear there, then flew the confined space drone up through the penstock. Working that way meant the structure did not have to be scaffolded out.

Engineers With Drones were on site to support the ESB NDT team, who carry out this class of inspection routinely and know these structures well. The role was to act as their eyes in the areas that were extremely difficult to access.

The flight covered the flexible diaphragm, the walls of the penstock, and the gates at the top: the full extent of the infrastructure the team needed to examine.

The riveted gate structure and bracing at the top of the drained penstock, lit by the drone
The gate structure at the top of the penstock, captured by the confined space drone as it flew the length of the drained structure.
Deliverables

A set of eyes, and a 4K imagery record

The primary deliverable on this job was being the eyes of the ESB NDT team during the shutdown. Everything was also recorded and presented to them as a full deliverable set of 4K imagery, so any part of the structure could be reviewed again later.

On site as the ESB NDT team’s eyes

Covering the areas of the penstock that were extremely difficult to access, during a live shutdown at the station.

Full set of 4K imagery

Everything captured was recorded and handed over as a complete 4K imagery set, so the team could review it again at a later date.

Inspection footage

Penstock inspection video

Inspection footage from the confined space drone flight up through the drained penstock at Ardnacrusha Power Station, showing the internal condition of the steel structure.

Confined space drone footage from the inspection of the fully drained penstock at Ardnacrusha Power Station, covering the flexible diaphragm, walls, expansion joint and gate structures.
Comparative methodology

Why they chose us

The alternative was scaffolding out the entire penstock to reach everything inside it. Flying it instead let the ESB NDT team see the full interior while remaining down in the spiral casing.

Access
One flight from the spiral casing vs scaffolding out the entire penstock

Instead of scaffolding the whole structure, the team set up inside the spiral casing and flew the drone up through the penstock.

Coverage
Diaphragm, walls and upper gates vs reaching them by scaffold

The flight covered the flexible diaphragm, the penstock walls and the gates at the top of the structure.

Deliverable
Full 4K imagery set vs the inspection visit alone

Everything captured was recorded and handed over as a 4K imagery set, so the client could review the structure again later.

Efficient option Our method

Using a drone

A confined space drone flown up through the drained penstock from inside the spiral casing, with the crew set up outside the structure.

  • No scaffolding required The team set up inside the spiral casing and flew the drone up through the penstock, so the entire structure did not have to be scaffolded out.
  • Diaphragm, walls and upper gates covered The flight examined the flexible diaphragm, the walls of the penstock, and the gates at the top.
  • Support to the ESB NDT team Engineers With Drones were on site as their eyes in the areas of the penstock that were extremely difficult to access.
  • 4K imagery record handed over Everything captured was presented as a full deliverable set of 4K imagery for later review.
Project status Completed — 4K imagery set delivered
Manned approach Traditional method

Without a drone

Under normal circumstances, reaching everything inside the penstock would have meant scaffolding out the entire structure.

  • Scaffolding out the entire penstock Conventional access to everything inside would have required the whole penstock to be scaffolded.
  • The expansion joint sits halfway down The targeted expansion joint is about halfway along the penstock, well inside the structure.
  • The gates sit at the top The gates are at the top of the penstock, at the far end of the structure from the access point.
  • A confined space inside a drained pipe The inspection work takes place inside the drained penstock itself, roughly 3 to 4 metres across.
Access method Scaffolding out the entire penstock
Let's talk

Speak to an engineer about your project

Complex surveys and inspections require more than just a pilot. Our engineers can help you scope your requirements and indentify the right approach.

Talk to an engineer

+353 (0)21 202 8281

Quickest for technical scoping

Email your brief

info@engineerswithdrones.ie

Best for sending detailed specs

Next steps

Where to find out more

You can find out more about our confined space drone inspections, or read about the culvert inspection at Ardnacrusha and the Parteen Weir underwater ROV inspection, both at the same hydroelectric scheme. Alternatively, you can contact us here.

Last updated: