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OVERHAUL 2015 - 2022


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In April 2022 Sir Nigel Gresley returned from an overhaul which took more than six years and cost about £750,000. If you would like to make a donation towards the cost of this overhaul please click on the donate button.


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Notes from information supplied by Darrin Crone, Locomotive Engineer.

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From July 2022.

13th July

The superheater has now been moved forward in the smokebox so that the front tubeplate and steam pipe end can be accessed and examined. To support the superheater in its forward position angles were welded in place, in line with the supports the superheater header normally sits on. Additional packing pieces were used to adjust the height of the header as it was moved forward.

With the supports in place the last header to tubeplate joint nut was removed. Jacks were put between the tubeplate and back of the header. The jacks moved the superheater forward very slowly, but move it did. As it moved forward we decided to remove the centre cover section as this would increase the allowable forward travel of the header.

When we could access the space between the header and the tubeplate we could see an obvious step in the pipe, about three inches in and on the centre bottom. We cleaned the pipe out and tried to determine if this was either a crack or perhaps a mark from the expanders from when the pipe was originally expanded in to the tubeplate. Though we were confident that it was a crack, as it tied in with what we had seen in the boiler when we pressure tested the pipe and applied soapy water. However, using dye penetrant crack detection we could get no evidence. Not believing our eyes we tried it again, four times and still no crack detected.

Membership

So then the area around the "crack" was ground flush and magnetic particle crack detection tried, and straight away a very positive result was obtained. This gave us the confidence to remove the front section of pipe and have it replaced. The sealing weld between the end of the pipe and the tubeplate flange was then carefully ground out. The front of the pipe was then heated to release the expansion fit in the front tubeplate. When cooled the pipe was pulled out with a winch from the tubeplate end, while the pipe was lifted at the rear inside the boiler. It was pulled forward about a foot and the crack was clearly visible on the outside of the pipe.

With the pipe exposed the end was cut off just behind where welded to the main length of the pipe making sure the cut was straight and square to make the welding of the new section as easy as possible. The removed pipe end was then cut longitudinally and the crack could be clearly seen going through the pipe wall.

The main length of the steam pipe was then moved back into the boiler so that the tubeplate hole could be cleaned and measured so that the new swaged pipe end dimensions can be specified. A drawing has now been done of the end we need using the hole dimensions and the shape from the LNER/BR drawing. The drawing has been sent with a purchase order for a swaged end and a plain section to renew the regulator end.

The steam pipe flange on the smokebox tubeplate has been inspected by LNWRh, who will be welding the new section of pipe into the tubeplate. They are satisfied with its condition and finish and require no further work to it.

Finding the new pipe we need to end the existing steam pipe took some tracking down. Our usual pipe sources didn't stock the size and when we did find a supplier they would not sell less than 10metres! We need a couple of feet. The original suppliers of the pipe and the formed end were unable to help. Eventually a supplier was tracked down who can supply the pipe of the correct size and produce the formed end. Meanwhile, as a back up plan we obtained some quotes for thick wall round section that we could machine as a formed section. Both manufacturing methods and materials being acceptable to our boiler inspector. Our preference is to reproduce the original LNER/BR arrangement with a formed swaged end and this is what we are now progressing.

At the regulator end the steel cone that seals against the regulator is to be replaced by a bronze end as the original design. The bronze has been ordered and is now on site at Crewe awaiting the new section of steam pipe to which it will be brazed.

At the other end of the loco work progressed on freeing the cab for removal. There are the bolts all along the bottom edge of the cab, but also the TPWS enclosure is fastened to the cab side. The water handles for the injectors are connected to the cab sides, as is the gravity sands mechanism mounted on a large bracket that bridges between the cab side and the reverser stand. The shut off handle for the manifold is fasted to a bracket in the cab roof. All these have had to be removed and their fasteners cleaned and stored for reuse.

The front cab front windows were removed to avoid any possible damage to them when the cab is removed.

The OTMR unit is on a large mounting bracket fastened to the cab side and floor. The bolting was removed and the enclosure moved away from the cab side and stood on wooden blocks so that the electrical connections were not disturbed.

To get the cab off needs the vacuum ejector to be removed as it projects through the cab front. It is an awkward and heavy item and can't be slung in position so has to be man-draulically removed. This was done with not one finger lost. To get it out, the steam supply pipe had to be removed and to allow this the ejector steam supply valve at the manifold had to be removed.

To separate the sides of the cab a jack was made up from an old boiler tube with screws welded to the ends. A supporting strut was made to go across the top of the cab sides to support the cab when lifted with slings through the side windows.

TOP

The cab was then lifted off without a hitch. With the cab on the ground the firebox side cladding in the cab and the first section in front of the cab was removed to access the firebox crown for examination. The insulation being removed and bagged for disposal. It was decided that the next cladding sheet to the front of the left firebox side should also be removed. To clear the firebox crown in this area it was decided to remove the crinoline section on the left side of the firebox.

Before removing this section of crinoline, we decided to straighten up the crinoline spine over the firebox as this had led to a crease in the cladding. Clamps and packing were used to get it as straight as possible. The crinoline in this area has seen some modification in the past, probably to lower the height of the engine, and could do with a thorough re-jig, however changing the crinoline profile in this area would have the knock on effect of changing the cladding shape in the area of the cab front, and we don't want to have to make any changes to the cab front at this stage.

It is planned to examine and caulk around the foundation ring, so the cladding below the footplate was removed, again with the insulation removed and bagged.

To access the inside of the foundation ring the grate has had to be removed. The firebars were passed out of the firebox then the front side and trailing grate bearers were also removed. The bearer supports in the firebox corners were removed, all having to be cut and ground out as they had stuck fast. New supports will have to be made.

The ashpan sprinkler pipes and supports have also had to be removed to access the foundation ring corners. As these had to be removed we plan to improve the sprinkler system when refitted.

While out of traffic we have taken the opportunity to improve certain aspects of the loco. The spark arrestor much improved at this overhaul has seen further improvement with a new arrangement of stainless steel screws and brackets securing the upper spark tray. This makes the tray more secure, a better seal against the chimney and should make it easier to remove.

The smokebox steam pipe lens ring faces and the lens rings were cleaned, carefully keeping track of which ring goes with which pipe end. They are now ready for re-lapping.

The ejector exhaust pipe in the smokebox and the bronze smokebox side elbow were cleaned and are now ready for refitting. The chimney flange that fastens to the smokebox top has also been cleaned ready for refitting.

With the cab removed the ejector has been remounted in position to allow the vacuum chamber pipe put in by LNWRh to be re-routed improving its appearance and allowing the chamber and train pipes to run together to the vacuum duplex gauge as they did before modification.

Mugs

The fire iron bracket near the battery box only extends a couple of inches and the irons have to be carefully arranged to fit. If not they are left unsecured and foul the battery box front. So it was decided to extend the bracket. This has now been done retaining the shape of the original bracket.

The Kylchap cowls have been dismantled for de-carboning. It was noticed when first installed that the trailing set are not correctly aligned so they will be adjusted.

While at the SVR we found that the speedo conduit had been contacting a steam pipe and the outer sheath had melted exposing the steel sleeve. At the time the conduit was repositioned and wrapped. As the speedo has had to be removed to allow the cab to be removed, it was decided to replace the damaged conduit. This has been done. While examining the speedo on the bench it was found that there was a mix of screws in the rear electrical connection housing and that they were corroded and difficult to remove. So these have all now been replaced by a common size of stainless steel screw.

The blower stub pipe that is fitted behind the superheater elements appears to be leaking at the joint with the front tubeplate so this was removed so that the joint can be remade. The sealing face on the tubeplate has been dressed so that it is flat. Now when blued against the stub pipe there is contact all round the face. A new joint was made and the pipe has now been refitted.

The snifter valve mounting studs have been die-nutted and the securing nuts run freely. The snifter is ready for refitting. The mating flange on the superheater header has also been cleaned off, removing the old gasket material.

The copper gasket between the superheater header and tubeplate has been cleaned and just needs annealing before fitting.

The removed smokebox top section cut out during the previous report has had all its tapped holes cleaned out. All the smokebox steam pipe bolts have been die nutted, with 1 being condemned as damaged and another requiring replacement as it had to be cut out when removing the pipes.

The superheater header moved just off the studs on the front tubeplate. 22 Jun 2022
Photograph: Darrin Crone

The superheater header

With the header as far forward as we can get it we can now see in to the front of the steam pipe. 22 Jun 2022
Photograph: Richard Swales/p>

The front of the steam pipe

Using magnetic particle inspection to examine the pipe for defects on 23 Jun 2022.
Photograph: Richard Swales/p>

Magnetic particle inspection

The loco looks small inside the boiler shop at Crewe. 23 Jun 2022
Photograph: Darrin Crone

Inside the boiler shop

The cab is lifted off so we can access the firebox outer wrapper crown. 29 Jun 2022
Photograph: Darrin Crone

The cab is lifted off

The insulation being removed after the cab and cladding on 30 Jun 2022.
Photograph: Richard Swales

Insulation being removed

The crown exposed for examination of the outer crown stays. 7 Jul 2022
Photograph: Richard Swales

The crown exposed

The fire iron bracket in grey near the battery box has been extended. 8 Jul 2022
Photograph: Darrin Crone

The fire iron bracket

The speedo has been fitted with new waterproof flexible conduit and new stainless steel screws. 8 Jul 2022
Photograph: Darrin Crone

The speedo conduit
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