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GWR No 2 overhaul http://bdca.org.uk/forumtwo/viewtopic.php?f=2&t=94 |
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Author: | Roger Cooke [ 11 Oct 2011, 14:49 ] |
Post subject: | Re: GWR No 2 overhaul |
It's been a long time since I last posted an installment of this story, although work has been continuing throughout the year. In the last but one post I said that we were weighing up the pros and cons of removing the firebox from the outer wrapper, or leaving it in situ. Once all the plain tubes had been removed, it became very apparent that it was essential to replace all the stay tubes due to their poor condition. We think that they were the original tubes (there is no evidence whatsoever that they have been replaced before) and if so were some 70 years old, so haven't done badly (lest the idea of a set of tubes lasting over 70 years seems ridiculous, remember that the stay tubes are very much thicker than the plain tubes). So, the firebox had to come out! In essence, this should be a fairly straightforward job with a boiler of this type. It is necessary for the rivets securing the uptake to the out wrapper, the foundation ring rivets, and the door ring rivets to be removed, then in theory the inner firebox complete with stay tubes will drop out downwards. That is the theory! So, the uptake rivets were burned out:- Attachment: And the foundation and door ring rivets were similarly burned out. Since the skirt was to be replaced anyway, the skirt was also cut off just below the foundation ring. The first attempt was then made to move the inner firebox out from the outer wrapper, with hydralic jacks in the steam space. Nothing, no movement at all! Close inspection then revealed that the foundation ring has been welded to the inner firebox on the water side and the out wrapper on the ashpan side, and the door ring had also been welded to both the inner firebox and the outer wrapper. So, out with the grinder to cut some welds. To be continued.... |
Author: | Roger Cooke [ 11 Oct 2011, 15:15 ] |
Post subject: | Re: GWR No 2 overhaul |
After the welds had been ground out, we decided to take the boiler outside and stand it the right way up for the next attempt to extract the firebox. So, with the help of the Iron Fairy, the boiler was uprighted and the out wrapper was lifted a couple of inches. With the help of a matched pair of 100 ton Enerpac hydraulic rams, the firebox and uptake slowly emerged at last:- Attachment: (Note that by the time the photo was taken the hydraulic rams had been removed). Finally the firebox was out. Notice the old repair to the uptake - there is a band welded round the uptake reinforcing it at the height of the normal water level in the boiler, where pitting could reasonably be expected. There is no evidence of any defect under the sleeve, fortunately; this area has been throughly NDT-ed to make sure. Attachment: With the firebox out it was possible to needlegun and clean the outside of the firebox and the inside of the outer wrapper within an inch of their lives, ready for inspection and NDT testing. The remaining stay tubes were also removed. Finally, it was possible for John Glaze, the boiler inspector, to carry out his next inspection of the cleaned and stripped boiler. Attachment: This photo of the inner firebox and uptake clearly shows the characteristics of the remarkable Spencer-Hopwood design which made it so successful. The firehole is facing the camera, and the location of the water tubes, running between the two flattened areas, one on each side, can be seen. The tubes are inclined upwards from left to right, so that there is excellent thermal flow through them. The two large access panels in the outer wrapper, known (for obvious reasons) as the tube doors, are in line with the ends of the tubes (although each door only covers half of the tube nest) so that it is possible to access all the tubes from at least one end for descaling and cleaning. It is also, at least in theory, possible to replace the plain tubes (but not the stay tubes) through the tube doors without disturbing the firebox. One disadvantage of the Howood design, however, is that there are several joint in the boiler which are impossible to caulk with the boiler assembled, for example the joint between the bottom of the uptake and the top of the firebox (the tubes are in the way). For this reason it is essential that this join is perfect before the boiler is assembled; woe betide if it leaks when the boiler is filled. For this reason, it is even more important that usual that the services of a very highlly skilled boiler smith are available. |
Author: | Roger Cooke [ 25 May 2012, 10:02 ] |
Post subject: | Re: GWR No 2 overhaul |
Once again a long time has passed since the last instalment, but in the meantime work has continued steadily. Over the winter season work on the boiler took something of a backseat since the railway's priority (for obvious reasons) has to be the closed-season maintenance of the loco fleet, however progress on the boiler has been good. Once the inner firebox and outer wrapper were separated, all the remaining tubes were removed and both inner and outer parts thoroughly cleaned by needlescaling. Plate thicknesses were ultrasonically checked and any areas of pitting or concern (very few, fortunately) were built up. A lot of hours went into ensuring that the three large doors in the boiler, the two tube doors mentioned previously and the manhole door (which gives access into the waterspace and provides, inter alia, access to the fusible plug which on these boilers is screwed in from the waterside since the tubes are in the way on the fireside), fitted properly. For many years the crane from which this boiler was taken, DS1560/ADRR95209 was stored out of use at Swindon in the company of its sister crane DS1561/ADRR95210. When the cranes were evicted from Swindon in about 2004, 1560 was taken to Tyseley for storage and 1561 to Southall for restoration. At that time, either accidentally or deliberately (it's not clear which) the two sets of doors becames swapped over. The result of this is that when 1561's boiler was overhauled at Ropley on the Mid-Hants Railway for the Southall team, a lot of work was needed on the doors to make them fit properly. Later on, when I realised what had happened and suggested to the Southall team that we swap back, they were quite naturally reluctant, since by then their boiler was in steam, and of course the doors had been adapted to fit so wouldn't fit my boiler anyway. So the only sensible course of action was to rework the doors from 1561's boiler to fit the apertures in 1560's boiler. After hours of careful work and a lot of 'engineer's blue', the doors are now a perfect fit! The mudhole doors were also missing from the 'new' boiler, and we had thought that it would be necessary to buy a new set (quite feasible since they are standard items). However it turned out that the mudhole apertures are the same size as those on the earlier Swindon-built VFT boiler, and the doors from that boiler are actually in surprisingly good condition, so these have been refurbished and fitted (and every cost saving, however small, is welcome)! Also of course all the tube holes in the tubeplates have been cleaned up and reamered to a suitable minimal oversize, and a new set of both stay tubes and plain tubes procured. Obtaining the tubes was not without some problems, since the stay tubes in particular are an unusual size (and also have 1/4" wall thickness) and only one supplier could be found. This supplier was unable to swell the ends as required, and the only firm who could do this task was a competitor supplier who unfortunately could not supply the tubes! In the end the tubes went from one to the other and finally arrived at Cranmore. They have now been fitted, welded, and NDT'd, and it is indeed good to see tubes going back in at last. The plain tubes have also been delivered but their installation is waiting on the delivery of a tube expander of the correct size. Hopefully they will be installed within the next fortnight. During the time that the boiler has been in the workshop the majority of fittings have also been overhauled ready to go back on. Although the progress is at last highly visible and it is obvious that reassembly has begun, which is great psychologically, there is still much work to be done before the boiler can be steamed and work continues. I will post more photos showing shiny new things soon! In the meantime we have all learned a lot from the overhaul of this unusual boiler. If there are any other operators of Hopwood boilers reading this who need their boiler overhauled (even if not as thoroughly as this) please feel free to get in touch; we can easily offer advice and guidance, and if so desired the ESR would be happy to quote for a complete overhaul to very high standards. And finally, speaking of DS1561/ADRR95210, this crane was recently moved (as mentioned elsewhere on this site) from Southall to a new home on the Swanage Railway where its overhaul nears completion, and it is looking very good indeed. Although not quite complete, it is in working order and has steamed since arrival, and is a credit to the people at both Southall and Swanage who have achieved so much. |
Author: | Roger Cooke [ 16 Oct 2012, 15:41 ] |
Post subject: | Re: GWR No 2 overhaul |
Next the plain tubes were fitted:- Attachment: Plain tubes fitted and expanded into place:- Attachment: Firehole ring tack-welded to the firebox ready for reassembly:- Attachment: Finally the inner firebox assembly is ready for replacing in the outer shell:- Attachment:
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Author: | Roger Cooke [ 16 Oct 2012, 15:51 ] |
Post subject: | Re: GWR No 2 overhaul |
On 9th June 2012, a rare sunny and dry day, a landmark was reached with the reinsertion of the inner firebox into the outer shell. It hadn't been easy to extract on some 14 months earlier, and it wasn't easy to get back in! In the end however, with a bit of gentle (and some not so gentle) persuasion, it was in. Attachment: Attachment: Foundation ring, door ring, and uptake bolted ready for rivetting:- Attachment: Attachment:
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Author: | Roger Cooke [ 16 Oct 2012, 16:11 ] |
Post subject: | Re: GWR No 2 overhaul |
Finally, some two years and five months after the boiler escaped from the scrap man and arrived at Cranmore, the day came for the formal tests. Under hydraulic test at 160psi:- Attachment: Later the same day being prepared for the steam test:- Attachment: And in steam. Steve Masters, the ESR's CME on the left, and John Glaze, the boiler examiner on the right. Attachment: As expected there were no problems of any kind during the testing. John was able to issue the appropriate certification without hesitation. So another first class overhaul by the Cranmore workshop team under Steve's expert leadership! Fantastic job! Now all I need to do is get the crane ready to receive the boiler! As usual, comments and feedback are welcomed. |
Author: | Ian Kingdon [ 12 Feb 2013, 12:49 ] |
Post subject: | Re: GWR No 2 overhaul |
Roger, a highly interesting narrative of the problems in restoration of the real thing.From a complete laymans viewpoint, how was the grate inserted/cleaned of clinker etc unless it was in pieces, and was it inserted through stoke hole or from the bottom? Where did the ash end up for ultimate clearance? I presume on the later models which had a water tank underneath there must have been a provision for ash clearance above wagon top somehow, or directly under boiler like a domestic stove? |
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