Work Assessment

Since November deciding in requirement to replace all 22 flues and 102 boiler tubes, a reasonable amount of physical work has been undertaken and seemingly an equivalent amount of time spent on measurements and calculations to determine the exact state of the firebox and smokebox tubeplates, both 50 years old having been fitted as part of the last general boiler overhaul by the SAR in 1959. The main activities were;

• all flues (5 1/2 ins. diam) were removed first and this has never been an easy task. First the welded flue ends were tediously ground from the firebox tubeplate then the expanded flue ends in the smokebox slit with an oxy torch and partially collapsed to release that joint. This was followed by the hardest part, slogging the firebox end of the flue with a sledge hammer while cramped in the firebox until that expanded joint released itself and the flue moved forward about 100 mm.
  
  
• with the each flue released, a shackle was attached to the smokebox end of the flue and the hydraulics of the Leyland truck used to drag the flue from the boiler. It was then a task for at least 3 chaps to transfer the flue to the tray of the Leyland - the flues are that heavy.
  
  
• the removal of the 102 tubes (2 1/4 ins. diam) required the same process, except the hydraulics, and was easier due to their much smaller size.
  
  
• the condition of all flues and tubes was fairly good corrosion wise but together with their by now relatively thin walls and age , the boiler inspector considered their use by date was up.
  
  
• with all flues and tubes out, it was time to clean the scale from the interior surfaces of the boiler including the barrel sides, tubeplates, feed water tray, palm stays, internal pipes etc. Although the interior was considered to be reasonably clean, a number of buckets of scale resulting from many years of water boiling, were removed. What was very heartening was the effective layer of iron tannate deposited on all surfaces from the tannin treatment to the boiler water. The tannin also assists in removing scale and sludge via the blowdown valve.
  
  Ian's photo caught young volunteer Oliver Lukins hard at work descaling the boiler.
  
  
• a few weeks was then spent grinding excess weld from the tubeplates, cleaning and deburring all flue and tube holes and cleaning the water side of both tubeplates (required needlegunning as well) - all these tasks being pretty dirty affairs.
  
  
• at this stage the "bible" of pressure vessels, Australian Standard 1210, was being consulted and calculations started to determine how the tubeplates measured up against the AS with regards to the specified pitch of all holes, minimum ligament widths between holes, maximum permitted hole diameters and tubeplate thickness.
  
  
• a number of sets of AS based calculations were carried out to see how the tubeplates compared with their original drawings, tolerances permitted by the AS, the current tubeplate thickness and hole diameters and finally the repair options proposed by ourselves.
  
  
  
  Fitter
  Ron Williams
  accurately
  measuring the
  smokebox
  tubeplate
  
  Photo:
  Ian Johnston
  
  
  
• the calculations showed the condition of the firebox tubeplate was such that it could probably be used without any major work required on the plate itself but that the diameters of the swaged ends of both the flues and tubes would need to be increased to allow for the increased diameter of all holes.
  
  
• the same calculations applied to the smokebox tubeplate showed that the plate required some major work or even partial replacement. The main deficiencies were related to oversize and oval flue holes resulting in undersize ligaments plus oversize tube holes although the ligament widths were still acceptable. After much discussion, our final proposal was to reform the flue holes by welding followed by machining back to drawing size and to "bell" out the ends of the tubes to more closely match their respective holes. This is much more preferable than over expanding tubes out to the oversize holes. The AS allows holes to be no more than 0.100 ins. larger than its corresponding flue or tube and that is one of the limits we have to work within.
  
  
• a meeting was held at Mt Barker on 14/01/09 with our boiler inspector, Bernie Dickinson, and SteamRanger's Ron Williams, Ian Johnston, Bob Sexton and a number of interested volunteers to discuss all aspects, calculations, current corrosion wastage of tubeplates (minimal at about 0.060 ins.) and our proposed repair methods. Bernie confirmed our calculations and interpretations of AS 1210 to be correct and endorsed the welding repairs to the smokebox flue holes. The holes will be machined after making mods to our magnetic based drill to adapt it to use more as a borer.
  
  
• however before any of this takes place, there are two more critical and major determinations to be carried out on both tubeplates - magnetic particle tests for cracks in holes and ligaments on both sides and ultra sonic testing of the thickness of the entire plates to ensure their compliance with the AS. Until the plates pass these tests we cannot conclusively say that either plate is still suitable for use. So for the next week or two, the outside faces of each tubeplate need to be cleaned back to bare metal followed by the crack testing of both sides of both plates then if no major issues arise from that, ultrasonic thickness testing of both plates. If at this stage both plates can be used, albeit with a fair bit of welding and machining on the smokebox plate, new flues and tubes can be ordered with some hunting around for someone to swage and bell the ends of both as required.
  
  

Latest News - 7th February 2009

• Ron Williams spent a few days undertaking the magnetic particle crack testing of both sides of both tubeplates including the flue and tube seats in each hole. Both tubeplates showed minor but fixable cracks, the most significant being a "shower" of surface cracks on the water side radius between the very bottom tube hole of the smokebox tubeplate and the barrel. It is intended to grind the cracks until they have completely disappeared (as indicated by MP testing) then build up the plate with pad welding - a slow process to prevent any undue heat stresses being set up. A few tube holes in both plates have small radial cracks which will be similarly ground out and welded.
  
  
• Boiler Inspector Bernie Dickinson has kindly loaned us his ultra sonic thickness meter to measure the tubeplates' thicknesses at dozens of spots. The probe requires perfectly flat and smooth surfaces to yield accurate results so many spots were prepared on both plates and these correspond to the numbers seen on this photo. While there is some thickness wastage of both plates, a bit more than we had theorised, Bernie considers that there is still adequate thickness in both plates.
  
  
  
  
  
  
• Some time has been spent in developing and perfecting techniques to weld all smokebox tubeplate flue holes due to their being oval in shape and oversize, plus four tube holes with the same problems. As a means of providing a full and clean weld edge on the back (water side) of the tubeplates, a number of firebrick "pavers", as used in slow combustion heaters, were purchased. These will be clamped to the water side of the tubeplate with the welding rod being run against the paver from the smokebox side. A "flue hole" was cut into a vertically mounted steel plate on the bench and our magnetic base drill was adapted to run a cutting tool to machine the hole, before and after a welding run had been applied. After some fine tuning by Ron Williams, this technique has worked a treat and provides a very easy and cheap way of reforming the holes.
  
  
• As well as the above hole repairs, two tube holes in the firebox tubeplate and ten in the smokebox tubeplate have ovalities exceeding 0.040" - one at 0.086". The higher the ovality, the more difficult it becomes to expand a round tube into an oval hole using a circular expander. Previous experience in SR and elsewhere has shown the holes with ovalities over 0.040" can be leakers on the first (and subsequent!) hydros. The two firebox tube holes have already been bored using the magnetic base drill set up as a borer.
  
  
• All the holes (22 flue, 10 tube) to be welded have been "centred" and "circled" so that when the cutting tool is set up to machine the welded holes, the scribed circle, based on plotting the hole centre, around each hole is used to centralise the cutting tool. Don't need a newly machined hole to be offset from its centre.
  
  
• Calculations and measurements showed that most tubeplate minimum ligament widths satisfied AS 1210 except for a few around the flue holes in the smokebox tubeplate. However the repair work on those holes effectively makes them smaller thus increasing the ligaments to acceptable widths.
  
  
• The question of swaging and belling of the new flues and tubes as required is being actively pursued but not with a lot of luck at this stage. Ideally it would be nice if this work could be done in Adelaide but a number of firms we have approached either are not set up to do it or don't want to do it. There are firms capable of the work interstate but it will be a costly exercise to transport flues and tubes across the border and back. The firebox end of the flues and tubes need to be swaged down in diameter while the smokebox end of the tubes need to be belled up in diameter - all to non standard sizes because of the necessity to have all flues and tubes as close as possible to their respective existing hole diameters.
  
  
• A 16 page report has been drafted covering all aspects so far; what we found, what was considered to be why, options of replacement or repair, loads of calculations as required by AS 1210, final repair proposals and why, and the boiler inspector's endorsement of everything being proposed.
  
  
• So far so good for the existing tubeplates but the writing is certainly on the wall that both plates will more than likely need to be renewed at the next major internal inspection, maybe 10 years time.
  
  January 2011 Update

  In early January David Groves completed tack welding the two halves of 621's new combustion chamber plates into position ready for the full welding process. Once fitted, our contractors RCR can access the firebox to start their work in early February including machining the flue holes in the smokebox tubeplate then fitting the new tubes and flues . After their work, over 100 flexible stays will need to be machined and fitted - an awesome sounding task.

  Here's a photo of David's handy work so far. The shots show the entire section that is being replaced. The plate is being installed in two sections due to the size and weight of the plate and poor access for the plate in one section.

  David has cut the old (original 1936) wasted section out using an angle grinder as opposed to oxy making it a rather neat cut. The view shows the entire section made up of two separate sections that will obviously meet with a weld in the middle. Installation of the first section was a rather straight forward task given the size of the hole it is fitted into. The second section proved a little more difficult as the pate is being installed from the inner side of the radius rather than from the outer, thus requiring a fair bit of grinding in order for the plate to fit into its hole but without relieving the gap to much and making the plate too small. All sounds easy however in practice it required a number of hours to get it correct first time.

  Added to the difficulties of installing the new plate is the many corners of previously replaced sections from the SAR days. It does not appear they were quite so fussy with ensuring the sections of plate were flush with the section it was being butted to. This required much dogging and manipulation of the new and old plate to create the best match. AS can be seen the plates are currently tacked in place ready for David to spend a number or hours preheating and welding the sections in. This being a rather delicate task as the combustion chamber section removed gives support to the firebox tube plate. David has provided a number of makeshift longitudinal stays between the firebox and smoke box tube plates to ensure the firebox tube plate does not move at all throughout the process. These stay were made up from some of the old tubes that were removed. Yet to be removed is another smaller section of plate immediately to the rear and centre of the current sections being replaced and taking in the replacement of another 7 flexible stays.

  The ship carrying our container of flues and tubes for 621 and Rx224 arrived in Adelaide in mid January with our cargo delivered to Mt Barker soon after. Cleaning and annealing the ends of the 200 tubes and 22 flues will be carried out by SteamRanger personnel with RCR Energy Services scheduled to start work on boring the smoke box tube plate holes in the first week of February. This task is expected to take six or seven days. After this time installation of the flues and tubes will also be carried by RCR with appropriate hydrostatic boiler tests to take place once the boiler is ready.

April 2010

An important series of firebox thickness measurements has just been completed and the results are not quite what we wanted. These measurements were started last year but did not progress very far due to the loco being "mothballed", then the 15 year old borrowed thickness meter went on the blink which resulted in a 3 month repair job including new parts having to be sourced from the UK. Prior to this the meter did perform faultlessly measuring the thicknesses of both of 621's tubeplates. After the repair work the meter was "borrowed back" and was used on the firebox of the paddlesteamer "Marion" and from all accounts they obtained satisfactory results. However shortly after when we again restarted work on 621, the meter would calibrate OK but would stay locked on that reading and not take any measurements so it is now back with the repairer. It would be nice to have our own meter, and one day perhaps we should, but they are not cheap at a couple of thousand $s a piece. Not wanting to lose another 3 months, last week we were fortunate to be able to borrow another more modern meter. Ultra sonic meters such as these depend on clean, polished and flat test spots and none of these normally exist in a firebox. This meant almost 500 spots had to be prepared using a polishing disc - a tedious, dirty and time consuming task, more so when there is a fair degree of surface pitting. Some of these prepared spots can be seen in Ian's photo.

Earlier measurements along the firebox side plates indicated some expected wastage in the plate thicknesses but not enough to be an issue. However measurements taken in late April in the combustion chamber (CC) indicated the plate thickness along the bottom of the CC (at 6 o'clock) was down to condemning level. The CC forms the forward section of the firebox and can be seen in the photos as the chalked section just behind the tubeplate. The chalk lines indicate the welded plates of the CC but it is only the lower one third of the CC which is in question (roughly corresponding to the hatched section). Whether we replace the whole chalked section or only part of it has yet to be decided with our boiler inspector. We need to determine whether we need to replace the hatched section of the inner throatplate which also has some wastage. The brick arch is normally located at the edge of the hatched section back towards the camera.

While we have replated fireboxes in the past, notably Rx 207's, we have not carried a repair of this size. The cutting, rolling and welding of new plates is fairly routine but the lining up, drilling and tapping of around 100 stay holes will be a challenge. With the current lead time on the acquisition of new tubes and flues, unless some more unknown nasties pop up, it is not expected that this repair work will seriously delay overall progress on 621.

Why is it then that only the bottom of the CC is currently a problem and the rest of the firebox, based on the measurements taken, is acceptable? Probably a couple of reasons. The first is found in the boiler's records which show 621's boiler was overhauled in 1941, 1948 and 1959. In the first two overhauls a number of repairs and patches were applied to all firebox plates except the CC which appears to have survived without giving much trouble (being protected by the brick arch from spiky thermal stresses, cold air etc would be one reason). In 1959 both the tubeplate and crown sheet were completely renewed so the records suggest that the CC is original from 1936 - not bad going. The second reason is that it is a well known fact that the underside surfaces of any part of a boiler, including tubes and flues, suffer from more corrosion due to many friendly bubbles of air being trapped on those surfaces, particularly when a boiler cools down and what is worse, the bubbles can stay there. So the combined presence of steel, air bubbles and water is a great scenario for corrosion.

September 2010

There has been a lot of investigative work carried out of this loco in order to provide a scope of work required to return the loco to service. This has also included 4 months of negotiations with tube suppliers and a possible private donor to fund the boiler works. It is with great pleasure that I can now report to the membership that negotiations with a private donor have been successful in obtaining the funds for the boiler work in order to return 621 back to active service. The donor has provided funding for the purchase of flues and tubes to order immediately ex Willingale Tube Manipulation and Fabrication U.K., Britain's largest boiler tube supplier.

Tubes are being manufactured in Germany and manipulation (swaging and belling of the ends) carried out by Wilingale then shipped to Adelaide. Further funding by the donor is being provided to outsource the boiler works (boring of tube plate and tube installation) to RCR Energy Services (AKA Tomlinson Boilers). Supply and shipping of all materials for this work will take 6 months and is expected to land in Adelaide sometime in December. You may recall the comparison of cost from a local supply in Australia as opposed to overseas supply was a saving of almost half the cost including shipping.

On a private trip to the UK Ian Johnston took the opportunity on 9th September to visit Willingales in Suffolk, UK, who are the suppliers of flues and tubes for 621 and 224. They have a large setup for doing all sorts of things to all sorts of tubes and are one of the last firms in the UK to be able to handle any sort of task. The swaging and belling of 621 boiler tubes has been completed. The internals of their hydraulically powered swager is shown in this photo (such a machine would be very handy at MB). 621's flues and 224's odd 1 7/8" diameter tubes had at that stage not been delivered from Germany. Still amazing that all this procurement, swaging, belling and transport can be undertaken from the UK much cheaper than through Aussie suppliers. However by comparison there is quite a large market in the UK and Europe and Willingales export all over the world. To them ours is quite a small order.

Back at Mt Barker separate work has been performed throughout the firebox with extensive thickness testing being carried out of all surfaces showing up some areas requiring minor repairs to the side plates. A not so good area is the lower radius section of the firebox combustion chamber showing thickness has reached it condemning level. Repairs will require a reasonably large section of the combustion chamber to be cut out and renewed also requiring the replacement of somewhere near 100 flexible ball stays. This task is not beyond the capabilities of our own volunteers and is not expected to delay the project as this repair can be carried out concurrently with other boiler work.

Previously reported activities

• Boiler     It is with great pleasure that we can now report that negotiations with a private donor have been successful in obtaining the funds for the boiler work. This has allowed orders for purchase of flues and tubes from Willingale Tube Manipulation and Fabrication U.K. Tubes have been manufactured in Germany and swaging and belling of the ends will be carried out by Willingale. Further funding by the donor is being provided to outsource the boiler works (boring of tube plate and tube installation) to RCR Energy Services (AKA Tomlinson Boilers) in SA.

  Supply and shipping of all materials for this work is taking some 6 months and delivery is expected in Adelaide sometime in December 2010. You may recall the comparison of cost from a local supply in Australia as opposed to overseas supply was a saving of almost half the cost including shipping.
  
  

  SHR volunteers will be aware that longserving mechanical services "guru" Ian Johnston has recently been on holiday in the "Old Dart", during which he took the opportunity to visit Wellingales in Suffolk, who are the suppliers of flues and tubes for 621 and 224.

  They have a large setup for doing all sorts of things to all sorts of tubes and are one of the last firms in the UK to be able to handle any sort of task. The swaging and belling of 621 boiler tubes have been completed and are seen as 5 bundles in this photo. 621's flues and 224's tubes had not been delivered from Germany when Ian visited.

  
  
  
  

• Firebox     Separate work has been performed throughout the firebox with extensive thickness testing being carried out of all surfaces showing up some areas requiring minor repairs to the side plates. A not so good area is the lower radius section of the firebox combustion chamber showing thickness has reached it condemning level. Repairs will require a reasonably large section of the combustion chamber to be cut out and renewed also requiring the replacement of somewhere near 100 flexible ball stays. This task is not beyond the capabilities of our own volunteers and is not expected to delay the project as this repair can be carried out concurrently with other boiler work.

  And here is a selection of Ian Johnston and Andrew Gramp's photos of some of the work in progress in early November
  
  

         
     
  

Negotiations with 621's donor have been successful in obtaining funding for the purchase of a complete set of 1 7/8 inch fire tubes for Rx224 of which will be manufactured and shipped with materials for 621. 1 7/8 inch tubes are no longer able to be procured in Australia.

January 2011

In early January David Groves completed tack welding the two halves of 621's new combustion chamber plates into position ready for the full welding process. Once fitted, our contractors RCR can access the firebox to start their work in early February including machining the flue holes in the smokebox tubeplate then fitting the new tubes and flues . After their work, over 100 flexible stays will need to be machined and fitted - an awesome sounding task.

Here's a photo of David's handy work so far. The shots show the entire section that is being replaced. The plate is being installed in two sections due to the size and weight of the plate and poor access for the plate in one section.

David has cut the old (original 1936) wasted section out using an angle grinder as opposed to oxy making it a rather neat cut. The view shows the entire section made up of two separate sections that will obviously meet with a weld in the middle. Installation of the first section was a rather straight forward task given the size of the hole it is fitted into. The second section proved a little more difficult as the pate is being installed from the inner side of the radius rather than from the outer, thus requiring a fair bit of grinding in order for the plate to fit into its hole but without relieving the gap to much and making the plate too small. All sounds easy however in practice it required a number of hours to get it correct first time.

Added to the difficulties of installing the new plate is the many corners of previously replaced sections from the SAR days. It does not appear they were quite so fussy with ensuring the sections of plate were flush with the section it was being butted to. This required much dogging and manipulation of the new and old plate to create the best match. AS can be seen the plates are currently tacked in place ready for David to spend a number or hours preheating and welding the sections in. This being a rather delicate task as the combustion chamber section removed gives support to the firebox tube plate. David has provided a number of makeshift longitudinal stays between the firebox and smoke box tube plates to ensure the firebox tube plate does not move at all throughout the process. These stay were made up from some of the old tubes that were removed. Yet to be removed is another smaller section of plate immediately to the rear and centre of the current sections being replaced and taking in the replacement of another 7 flexible stays.

The ship carrying our container of flues and tubes for 621 and Rx224 arrived in Adelaide in mid January with our cargo delivered to Mt Barker soon after. Cleaning and annealing the ends of the 200 tubes and 22 flues will be carried out by SteamRanger personnel with RCR Energy Services scheduled to start work on boring the smoke box tube plate holes in the first week of February. This task is expected to take six or seven days. After this time installation of the flues and tubes will also be carried by RCR with appropriate hydrostatic boiler tests to take place once the boiler is ready. The final step in 621's restoration was a test run to Goolwa depot and return on Sunday August 21st hauling steel car 710 and DE loco 958. The trip was a success with the boiler steaming excellently, as would be expected with an all new heating surface of tubes and flues. With the exception of one oil feed pipe to the driver’s side piston rod coming loose and the fireman’s side trailing truck axle box running rather warm all else ran like a Swiss watch. Tied in with some very crisp stack talk produced by the baker valve gear, there were smiles as far as the eye could see.

621 has subsequently hauled the regularly scheduled Southern Encounter and Highlander commencing on Sunday August 28th and will continue as train loco right through to the end of November, fire restrictions permitting.

For the record, final workshop milestones were:

• Work on loco 621 previously went very much to schedule in July and August. The majority of the few remaining tasks were completed with little or no trouble or delay and as a result of a couple of marathon Saturdays where work went late into the evenings. We thank key players Craig Dunstan, David Groves and Shaun Cassidy for their assistance supported by other members of our volunteer mechnical services team. Installation of all 108 flexible stays and three flexible stay cups as manufactured by Dinki Di Engineering. The photo at the end of this report shows David inside the firebox combustion chamber seal welding the stays on the fire side.
  
  
• On Saturday July 2 the first cold water boiler hydro test to 100 psi marked the first filling of the boiler since November 2008. With all flues and tubes holding pressure at 100psi and with the boiler then drained, welding of all flues and tubes in the fire box and appropriate stay tubes in the smoke box was performed as per current day standards. This task required approximately seven full days welding to complete. Once the welding was complete a further 100psi hydro test ensured any tubes upset during the welding process were “nipped up” by post welding expanding as required.
  
  
• On Saturday 30th July, again another long day by many, the boiler barrel was washed out in preparation for a hot water hydro test to 250psi, being 1¼ times normal operating pressure and at a temperature of 60ºC. A number of tasks are required to set up the boiler for the hot water hydro testing. These include the addition of some external “bush” plumbing to connect the circulating pump to move water around from the rear of the boiler to the front to obtain the correct temperature mix throughout the entire boiler, along with plumbing for the hydro test pump to raise the required pressure.
  
  
• In late July the first fire was lit in 621’s firebox in three years (top photo) marking a memorable moment for the monumental task undertaken and in mid August the fireman’s side conrod that was bent during the accident in 2008 and repaired by contractors HeavyMech, looking much straighter now, will be installed with the remaining rods. The boiler was then scheduled to undergo a full steam test with a test run to follow a week or so later.
  
  

March 2011

In early March contractors RCR started the boring process of machining a total of 14 tube holes and the 22 flue holes in 621's smokebox tubeplate, good timing having just dispatched 207 to GD. The setting up and boring of the first tube hole has been an all day task due to RCR's chaps (Clinton and Patrick) coming to grips with this sort of task and the boring machine they have hired for the job. The machine does a good job but has some limitations due to its size (see photo) with difficult access to the hole being bored, mainly to take diameter measurements to keep tabs on the bore. However once a couple of holes have been completed, it is hoped a technique can be developed to speed the process up a bit. The flue holes won't be so difficult due to their larger diameter - 142 mm compared to 61 mm. Have to talk metric to the RCR lads as that is all they work with. We had to obtain a DCMB/CFS permit to operate our mini forge to anneal both ends of all tubes and flues before expanding into the tubeplates. Just like Phil N has found out down south, getting these permits nowadays is like extracting teeth from intractable boffins.

Another one of those milestones we like to see, this time all of 621's 102 boiler tubes are in their respective holes in the boiler tubeplates although not fully expanded as yet. A few week's work beforehand was undertaken to anneal both ends of each tube by using our purpose built forge to heat the ends to cherry red then clean and polish the ends back to bare metal. (Our first photo below shows new volunteer Chris Lings cutting his teeth on the forge with the draught being supplied by 621's lightup blower). As usual there have been some hic cups which can be summarised as follows;

• in an endeavour to save a fair amount of money, the firebox end of all tubes were swaged to a diameter which just fitted the smallest diameter tube hole in the firebox tubeplate. One of the big drawbacks of retubing a boiler with old tubeplates is that tube and flue hole diameters are all over the place due to wear and tear of a number of previous retube jobs. As our tube holes are now oversize (but most not excessively) and non standard, special swaging dies had to be made at close to $2000 a set - just for one diameter, so that's why there is only the one swage diameter.. One of the issues with 621's tubeplates has been the many varied diameters of the holes and as most would recall, the smokebox flue holes being excessively oversize, had to be welded up and machined to drawing diameter.
  
  
• at the firebox end it was found too many new tubes were protruding into the firebox too far, around 15 mm instead of about 8 mm due to too many of the holes being too large. The result of this was too much of the swaged tube protruding into the firebox and too little protruding into the smokebox. This effect was predicted but not to the extent it has happened and it has resulted in the tubes bottoming out on the water side of the tubeplate at the top of the swage radius instead of near the bottom of that radius. The consequence of this was that those tubes cannot be properly anchored onto the tubeplate by the radius and the tube expansion/fillet seal weld between the tube and tubeplate on the fire side.
  
  
• as this was predicted but not quite on the scale it has occurred, the fall back plan was to prosser roll the tubes after their initial expansion into the tubeplate. Prosser rolling is undertaken with specially shaped rollers (bit like a small dumbbell) so that the larger diameter ends of these rollers slightly flare the open end of the tube in the firebox and slightly expand the tube a couple of mm past the tubeplate on the water side resulting in a slight bulge which acts to anchor the tube to the tubeplate on the water side. In effect this bulge replaces what should have been a healthy swage radius and is an acceptable boiler practice. Hope all that makes sense!
  
  
• A trial fitting of two tubes was undertaken on Monday 4/04/11 with a normal expansion followed by the prosser rolling and both procedures worked like a charm. So a lot of physical work saw all remaining 100 tubes slotted into the boiler. The RCR Energy chaps are now in the process of a two stage expansion procedure of all tubes in the firebox followed by the prosser rolling. Two stages are best as the first stage to about half expansion provides support for the tubeplate ligaments between all holes before the tubeplate is subject to heavier forces during the final expansion - prevents any possible distortion of the now well used tubeplates. Then the tubes will require the same two stage expansion in the smokebox but not the prosser rolling.
  
  
• In the meantime, work has also been undertaken on the 22 new flues. As received these were covered by a tenuous protective coating which has taken some elbow grease and kero followed by steam cleaning to remove it - not the sort of stuff we need in a boiler trying to make clean steam. The task took longer than it should have with a dysfunctional steam cleaner having long moments of laying down and only providing cold water - no steam!! There could be some difficulties with the fitting of the flues into the rebored holes in the smokebox tubeplate which are now to drawing size. So are the new flues meaning there is not much clearance between the tubes and holes. But it has only just been discovered that for some reason some flues are oval by 0.040" or 1 mm - not much but enough to make them a tight squeeze across the wide diameter. The cleaned flues are currently being annealed then the ends will need the same cleaning and polishing as the tubes.

   

In early March contractors RCR started the boring process of machining a total of 14 tube holes and the 22 flue holes in 621's smokebox tubeplate, good timing having just dispatched 207 to GD. The setting up and boring of the first tube hole has been an all day task due to RCR's chaps (Clinton and Patrick) coming to grips with this sort of task and the boring machine they have hired for the job. The machine does a good job but has some limitations due to its size (see photo) with difficult access to the hole being bored, mainly to take diameter measurements to keep tabs on the bore. However once a couple of holes have been completed, it is hoped a technique can be developed to speed the process up a bit. The flue holes won't be so difficult due to their larger diameter - 142 mm compared to 61 mm. Have to talk metric to the RCR lads as that is all they work with. We had to obtain a DCMB/CFS permit to operate our mini forge to anneal both ends of all tubes and flues before expanding into the tubeplates. Just like Phil N has found out down south, getting these permits nowadays is like extracting teeth from intractable boffins.

Another one of those milestones we like to see, this time all of 621's 102 boiler tubes are in their respective holes in the boiler tubeplates although not fully expanded as yet. A few week's work beforehand was undertaken to anneal both ends of each tube by using our purpose built forge to heat the ends to cherry red then clean and polish the ends back to bare metal. (Our first photo below shows new volunteer Chris Lings cutting his teeth on the forge with the draught being supplied by 621's lightup blower). As usual there have been some hic cups which can be summarised as follows;

• in an endeavour to save a fair amount of money, the firebox end of all tubes were swaged to a diameter which just fitted the smallest diameter tube hole in the firebox tubeplate. One of the big drawbacks of retubing a boiler with old tubeplates is that tube and flue hole diameters are all over the place due to wear and tear of a number of previous retube jobs. As our tube holes are now oversize (but most not excessively) and non standard, special swaging dies had to be made at close to $2000 a set - just for one diameter, so that's why there is only the one swage diameter.. One of the issues with 621's tubeplates has been the many varied diameters of the holes and as most would recall, the smokebox flue holes being excessively oversize, had to be welded up and machined to drawing diameter.
  
  
• at the firebox end it was found too many new tubes were protruding into the firebox too far, around 15 mm instead of about 8 mm due to too many of the holes being too large. The result of this was too much of the swaged tube protruding into the firebox and too little protruding into the smokebox. This effect was predicted but not to the extent it has happened and it has resulted in the tubes bottoming out on the water side of the tubeplate at the top of the swage radius instead of near the bottom of that radius. The consequence of this was that those tubes cannot be properly anchored onto the tubeplate by the radius and the tube expansion/fillet seal weld between the tube and tubeplate on the fire side.
  
  
• as this was predicted but not quite on the scale it has occurred, the fall back plan was to prosser roll the tubes after their initial expansion into the tubeplate. Prosser rolling is undertaken with specially shaped rollers (bit like a small dumbbell) so that the larger diameter ends of these rollers slightly flare the open end of the tube in the firebox and slightly expand the tube a couple of mm past the tubeplate on the water side resulting in a slight bulge which acts to anchor the tube to the tubeplate on the water side. In effect this bulge replaces what should have been a healthy swage radius and is an acceptable boiler practice. Hope all that makes sense!
  
  
• A trial fitting of two tubes was undertaken on Monday 4/04/11 with a normal expansion followed by the prosser rolling and both procedures worked like a charm. So a lot of physical work saw all remaining 100 tubes slotted into the boiler. The RCR Energy chaps are now in the process of a two stage expansion procedure of all tubes in the firebox followed by the prosser rolling. Two stages are best as the first stage to about half expansion provides support for the tubeplate ligaments between all holes before the tubeplate is subject to heavier forces during the final expansion - prevents any possible distortion of the now well used tubeplates. Then the tubes will require the same two stage expansion in the smokebox but not the prosser rolling.
  
  
• In the meantime, work has also been undertaken on the 22 new flues. As received these were covered by a tenuous protective coating which has taken some elbow grease and kero followed by steam cleaning to remove it - not the sort of stuff we need in a boiler trying to make clean steam. The task took longer than it should have with a dysfunctional steam cleaner having long moments of laying down and only providing cold water - no steam!! There could be some difficulties with the fitting of the flues into the rebored holes in the smokebox tubeplate which are now to drawing size. So are the new flues meaning there is not much clearance between the tubes and holes. But it has only just been discovered that for some reason some flues are oval by 0.040" or 1 mm - not much but enough to make them a tight squeeze across the wide diameter. The cleaned flues are currently being annealed then the ends will need the same cleaning and polishing as the tubes.

   

April and May 2011

The boiler re-tubing was progressed, however not without the usual hiccups that are encountered along the way. Trial fitting of the superheater flues proved not to be as straight forward as would be expected, when attempts to insert a flue into the fireman’s side lower row came to a halt with the flue only travelling about 2 feet into the hole and nipping up on the tube plate. Investigations found an appearance of ovality between the flue and flue hole. Removal of the flue for a closer inspection and measurements of both the flue and the flue hole revealed some ovality in the recently rebred hole and a considerable amount of oversize ovality in the flue. Added to the hole ovality was the fact that the ovality in the hole put the finished OD of the hole at its smallest diameter 5.552” as opposed to drawing size of 5.562”. The flue used for the trial fitting as it turned out, was the worst of all the flues for ovality with measurement of approximately 5.545” obviously making it an extremely tight fit with the slightly rough surface finish. Subsequently all holes were measured to determine the extent of which the boring machine had introduced ovality. The flues holes varied somewhat with several holes being within tolerances and several exceeding. Those flue holes exceeding the minimum size, required some reworking of which RCR promptly attended too, reworking all holes to the required dimensions. All flues were also inspected and reworked by means of linishing the flues to a maximum OD of 5.540” using a template to gauge the flues. The second fitting attempt proved successful with all flues being inserted along with the remaining tubes between the flues without further inserting difficulties. Flue and remaining tube expansion has been performed and completed in its initial phase with prosser rolling of the tubes as required to set the desired tube protrusion from the tube plates along with four of the top row of flues to accommodate for the uneven smoke box tube plate. All tubes and flues have been ground back to the required final lengths. Upon successful completion of boiler hydrostatic tests the firebox end and required smoke box tube ends will be seal welded, as likewise will the flues.

Fabrication and welding installation of the replacement combustion chamber plates is complete. The three separate sections were individually trimmed to size and inserted and tacked into place. The two large sections were fitted and fully welded into place prior to the installation of the boiler tubes and flues as a number of old tubes had been reworked and installed as longitudinal stays in order to ensure the fire box tube plate remained firmly anchored during the removal and replacement of plates in the combustion chamber. The remaining third section of plate has been removed and new plate installed since the tube installation. All 108 stay holes have been bored and tapped into the new plates ready for installing stays. Shaun Cassidy and Oliver Lukins spend many hours using a manufactured jig, boring and tapping holes for the precise fit of the new stays. All stays, stay cups, stay cup caps and copper sealing rings have been manufactured by Dinki Di engineering and supplied. Stay installation has begun, expecting to take approximately two days to insert and set up the new stays and replacement cups. David Groves will seal weld the stays and stay cups once installation is complete. All 108 stays require seal welding on the fire box side.

Shaun, Oliver and Ron Norell have spent two weeks working on the loco over the pit to replace a worn engine trailing truck centre pivot pin and lower bush. The worn pin and bush were indentified in the 2008 work and were given a limited life. Both pin and bush (hardened) have been installed to the trailing truck pivot. The pit work has also comprised of repairs to the rear tender coupler dampening package mounting cradle. The cradle has required some extensive pad welding and grinding to restore the worn rubbing surfaces that had subsequently worn away. This work has required a fair bit of building up and dressing back in order to restore squareness to the cradle mounting. A template has been made to provide and accurate fit for the somewhat heavy dampening package that will now be reinstalled in its mounting cradle. The rear tender draw gear will then be refitted to the tender.

   

Several hours have already been spent inspecting and cleaning up components that make up the regulator, superheater elements, element hole blanks, and other smoke box fittings in readiness for hydrostatic testing and steam testing. The regulator valve spindles and seats have been cleaned up or recut as required ready for installation. The superheater elements have been tap tested and cleaned ready for hydro testing to 1000psi prior to installation into the boiler. Upon successful completion of hydro tests there is many hours of welding required to the tube ends in the firebox and required ends in the smoke box.

The boiler re-tubing was progressed, however not without the usual hiccups that are encountered along the way. Trial fitting of the superheater flues proved not to be as straight forward as would be expected, when attempts to insert a flue into the fireman’s side lower row came to a halt with the flue only travelling about 2 feet into the hole and nipping up on the tube plate. Investigations found an appearance of ovality between the flue and flue hole. Removal of the flue for a closer inspection and measurements of both the flue and the flue hole revealed some ovality in the recently rebred hole and a considerable amount of oversize ovality in the flue. Added to the hole ovality was the fact that the ovality in the hole put the finished OD of the hole at its smallest diameter 5.552” as opposed to drawing size of 5.562”. The flue used for the trial fitting as it turned out, was the worst of all the flues for ovality with measurement of approximately 5.545” obviously making it an extremely tight fit with the slightly rough surface finish. Subsequently all holes were measured to determine the extent of which the boring machine had introduced ovality. The flues holes varied somewhat with several holes being within tolerances and several exceeding. Those flue holes exceeding the minimum size, required some reworking of which RCR promptly attended too, reworking all holes to the required dimensions. All flues were also inspected and reworked by means of linishing the flues to a maximum OD of 5.540” using a template to gauge the flues. The second fitting attempt proved successful with all flues being inserted along with the remaining tubes between the flues without further inserting difficulties. Flue and remaining tube expansion has been performed and completed in its initial phase with prosser rolling of the tubes as required to set the desired tube protrusion from the tube plates along with four of the top row of flues to accommodate for the uneven smoke box tube plate. All tubes and flues have been ground back to the required final lengths. Upon successful completion of boiler hydrostatic tests the firebox end and required smoke box tube ends will be seal welded, as likewise will the flues.

Fabrication and welding installation of the replacement combustion chamber plates is complete. The three separate sections were individually trimmed to size and inserted and tacked into place. The two large sections were fitted and fully welded into place prior to the installation of the boiler tubes and flues as a number of old tubes had been reworked and installed as longitudinal stays in order to ensure the fire box tube plate remained firmly anchored during the removal and replacement of plates in the combustion chamber. The remaining third section of plate has been removed and new plate installed since the tube installation. All 108 stay holes have been bored and tapped into the new plates ready for installing stays. Shaun Cassidy and Oliver Lukins spend many hours using a manufactured jig, boring and tapping holes for the precise fit of the new stays. All stays, stay cups, stay cup caps and copper sealing rings have been manufactured by Dinki Di engineering and supplied. Stay installation has begun, expecting to take approximately two days to insert and set up the new stays and replacement cups. David Groves will seal weld the stays and stay cups once installation is complete. All 108 stays require seal welding on the fire box side.

Shaun, Oliver and Ron Norell have spent two weeks working on the loco over the pit to replace a worn engine trailing truck centre pivot pin and lower bush. The worn pin and bush were indentified in the 2008 work and were given a limited life. Both pin and bush (hardened) have been installed to the trailing truck pivot. The pit work has also comprised of repairs to the rear tender coupler dampening package mounting cradle. The cradle has required some extensive pad welding and grinding to restore the worn rubbing surfaces that had subsequently worn away. This work has required a fair bit of building up and dressing back in order to restore squareness to the cradle mounting. A template has been made to provide and accurate fit for the somewhat heavy dampening package that will now be reinstalled in its mounting cradle. The rear tender draw gear will then be refitted to the tender.

   

Several hours have already been spent inspecting and cleaning up components that make up the regulator, superheater elements, element hole blanks, and other smoke box fittings in readiness for hydrostatic testing and steam testing. The regulator valve spindles and seats have been cleaned up or recut as required ready for installation. The superheater elements have been tap tested and cleaned ready for hydro testing to 1000psi prior to installation into the boiler. Upon successful completion of hydro tests there is many hours of welding required to the tube ends in the firebox and required ends in the smoke box.

June and July 2011

On Saturday 30th July, again another long day by many, the boiler barrel was washed out in preparation for a hot water hydro test to 250psi, being 1¼ times normal operating pressure and at a temperature of 60ºC. A number of tasks are required to set up the boiler for the hot water hydro testing. These include the addition of some external “bush” plumbing to connect the circulating pump to move water around from the rear of the boiler to the front to obtain the correct temperature mix throughout the entire boiler, along with plumbing for the hydro test pump to raise the required pressure.

After several hours of work, the first fire was lit in 621’s firebox in three years thus creating a memorable moment for the monumental task undertaken. Maintaining a small fire to warm the boiler to the required temperature over a period of around 2 hours or so gave the required boiler temperature to adequately undertake the high pressure hydro test. Upon removing the hot ashes from the fire grates, the required pressure was soon achieved with very pleasing results. No sign of any leaks from either firebox or smoke box tube plates or the renewed combustion chamber plates or stays. The only unfortunate leak came about from one of the flexible ball stays close to the renewed sections of plate on the fireman’s side near the radius of the crown sheet. With the hot hydro test being a success the boiler was drained whilst warm and dried in order to carry out the stay replacement.

   

Spare stays already manufactured by Dinki Di during the combustion chamber replacement work were of a suitable length for the required replacement however required machining down to the required diameter. Shaun and Ron have undertaken the task of removal and replacement of the affected stay.

The troublesome fireman’s side blow down valve has been overhauled by reboring the valve spindle housing and replacement of the valve spindle bush along with machining of the valve seat. The blow down valve has been reinstated along with the original blow down muffler once again enabling boiler blow downs from both sides of the boiler.

Superheater element installation has now been completed along with many of the smoke box fittings and baffles. When the con rod, bent by a errant motorist in 2008, returns from straightening by HeavyMech all rods will be refitted. A further cold water hydro of the replaced stay and superheater elements will be performed along with a number of servicing tasks in readiness for steam testing.

August 2011

Most recently all the loco’s brake cylinders habe been inspected, nearly 20 years since the last inspection, and it was found that one of the engines brake pistons has some cracking. Interestingly enough the cracking appears to have ben caused by sand inclusion during its original casting process. This was found by attempting to dig the crack out in order to stop its progression however the inclusion was soon located as the crack got deeper. Interesting how these things take so many years to come out. The crack was actually visible with the naked eye.

Work on 621 over the past weeks has gone very much to schedule. This is mostly due to the majority of tasks falling into place with little or no trouble or delay and as a result of a couple of marathon Saturdays where work went late into the evenings. Thanks to David Groves and Shaun Cassidy for their assistance in duties over and above on these days, along with the other volunteer input.

Recent tasks have seen the installation of all 108 flexible stays and three flexible stay cups as manufactured by Dinki Di Engineering. The cup threads retaining the cup caps on three cups had significant wastage in their threads requiring them to be replaced with new cups. The photos below show David applying pre-heat to the outer boiler barrel prior to welding the cups in place and inside the firebox combustion chamber seal welding the stays on the fire side.

Much preparation work had been performed leading up to Saturday July 2, wíth the boiler's first cold water hydro test to 100 psi - the first filling of the boiler since November 2008. Installation of “blanks” (fitted into the water side of the regulator header) in place of the normal superheater elements, permitted just the boiler itself to be hydro tested. The superheater elements had already been hydro tested to 1000psi. These blanks posed a problem during the cold water hydro due to a split retaining collar. This collar is used to apply pressure against the socket for sealing in the regulator header. During the 100psi test, water streamed from several places in the smoke box tube plate including the header blank. This required removal of all superheater blanks to insert the flue expander to further expand the flues to take up all leaks. It was at this time we noted the fractured collar. A number of days were spent in both the fire box and smoke box expanding tubes and flues until the boiler remained water tight and held pressure for several hours without leaks. This is certainly not the best time of the year for getting wet during these tasks.

With all flues and tubes holding pressure at 100psi and with the boiler then drained, welding of all flues and tubes in the fire box and appropriate stay tubes in the smoke box was performed as per current day standards. This task required approximately seven full days welding to complete. Once the welding was complete a further 100psi hydro test ensured any tubes upset during the welding process were “nipped up” by post welding expanding as required.

   

Steam loco 621 restoration complete!

621 has subsequently hauled the regularly scheduled Southern Encounter and Highlander commencing on Sunday August 28th and will continue as train loco right through to the end of November, fire restrictions permitting.

For the record, final workshop milestones were:

• Work on loco 621 previously went very much to schedule in July and August. The majority of the few remaining tasks were completed with little or no trouble or delay and as a result of a couple of marathon Saturdays where work went late into the evenings. We thank key players Craig Dunstan, David Groves and Shaun Cassidy for their assistance supported by other members of our volunteer mechnical services team. Installation of all 108 flexible stays and three flexible stay cups as manufactured by Dinki Di Engineering. The photo at the end of this report shows David inside the firebox combustion chamber seal welding the stays on the fire side.
  
  
• On Saturday July 2 the first cold water boiler hydro test to 100 psi marked the first filling of the boiler since November 2008. With all flues and tubes holding pressure at 100psi and with the boiler then drained, welding of all flues and tubes in the fire box and appropriate stay tubes in the smoke box was performed as per current day standards. This task required approximately seven full days welding to complete. Once the welding was complete a further 100psi hydro test ensured any tubes upset during the welding process were “nipped up” by post welding expanding as required.
  
  
• On Saturday 30th July, again another long day by many, the boiler barrel was washed out in preparation for a hot water hydro test to 250psi, being 1¼ times normal operating pressure and at a temperature of 60ºC. A number of tasks are required to set up the boiler for the hot water hydro testing. These include the addition of some external “bush” plumbing to connect the circulating pump to move water around from the rear of the boiler to the front to obtain the correct temperature mix throughout the entire boiler, along with plumbing for the hydro test pump to raise the required pressure.
  
  
• In late July the first fire was lit in 621’s firebox in three years (top photo) marking a memorable moment for the monumental task undertaken and in mid August the fireman’s side conrod that was bent during the accident in 2008 and repaired by contractors HeavyMech, looking much straighter now, will be installed with the remaining rods. The boiler was then scheduled to undergo a full steam test with a test run to follow a week or so later.