The Ffestiniog & Welsh Highland Railways has used an update on an overhaul of the boiler of the Double Fairlie locomotive Merddin Emrys.

The overhaul coincided with the locomotive’s scheduled ten-year boiler inspection, and took place between November 2025 and mid-March 2026.

A regular boiler inspection ensures the locomotive can continue operating in accordance with stringent standards imposed on heritage railways to ensure their locomotives continue to operate safely and reliably, and to their expected performance.

During its overhaul, Merddin Emrys’ boiler was subjected to Non-Destructive Testing (NDT), which enabled its condition to be assessed in detail without the need to damage its structure.

There followed extensive refurbishment, which included a complete re-tubing of the boiler and the replacement of superheater tubes, which are vital for improving the locomotive’s efficiency and performance.

Other work on Merddin Emrys included fitting a new foundation ring, which is an essential structural component at the base of the firebox.

Twenty-eight screwed and weld-sealed stays were also replaced with new ones; these are vitally important as they maintain the strength and integrity of the firebox when it is under pressure.

The final work was to confirm the boiler’s ability to operate safely under working conditions by subjecting it to a rigorous hydraulic test at 240 psi.

The complete boiler overhaul was a major engineering effort, and was a significant investment by the railways to ensure Merddin Emrys is fit for the foreseeable future, so it can continue operating services for many years to come.

Merddin Emrys was one of the locomotives that took part in last year’s ‘Railway 200 – FR Platinum Jubilee Weekend’, which ran for four days and marked 70 years of passenger trains on the Ffestiniog Railway, and for which it received a new green livery, as worn in the 1950s and 1960s by sister locomotive Taliesin.