Toddington Standard Locomotive Limited has issued an update on the progress in overhauling the boiler of Standard Class 4 2-6-0 No. 76077.

Among the latest findings are the boiler contains lamination in the steel platework, additional repair work is required to ensure its long-term life.

However, a Non-Destructive Testing (NDT) examination revealed unexpected problems.

The boiler is being overhauled by Leaky Finders Ltd. in Devon. After arrival, work started on removal of the front tube plate, which is to be replaced, with the front parallel ring of the barrel also due to be replaced. To enable the ring to be removed, the boiler need to be inverted.

Most of the foundation ring rivets were removed, and part of the corroded firebox throat plate cut out. A Non-Destructive Testing (NDT) examination of the boiler revealed that there were laminations present that could cause problems in places that need welding, such as when carrying out patch repairs.

Laminations occur when impurities such as small deposits of slag can end up as linear pockets within the steel when it is being rolled.

Also identified during the Non-Destructive Testing were many of the original Monel metal stays in the upper part of the firebox were broken or flawed and needed replacing, as well as a few rows of crown stays due to excessive wastage of their heads in the firebox.

In January, Toddington Standard Locomotive Limited chairman Chris Irving, and its engineering director Andrew Meredith met the NDT specialists and the boiler inspector at Leaky Finders to agree a way forward.

They agreed that while the lamination issues are not by themselves a show-stopper, work needed to return the boiler to working order will be much more extensive than Toddington Standard Locomotive Limited Leaky Finders originally thought.

Although the laminations by themselves are not a major issue, since the boiler performed perfectly well throughout its BR career, they become a significant problem when patches need to be welded in to replace corroded material.

Cracks can form when welding is carried out near a lamination, which results in weakening of the metal. Unfortunately, when the boiler was built at Darlington in 1952, the quality of the steel was sometimes poor, and at that time, the technology needed to identify any laminations was not available.

Discovery of the laminations means that much more of the firebox steelwork will have to be removed than originally planned, which also means that over 400 perfectly serviceable copper stays will need to be sacrificed.

Once the overhaul of 76077 has been completed, it will be coupled to a new BR2A tender which is the type that it was coupled to before withdrawal by British Railways.