It is currently 28 Mar 2024, 15:04

All times are UTC [ DST ]




Post new topic Reply to topic  [ 21 posts ]  Go to page Previous  1, 2, 3  Next
Author Message
 Post subject: Re: GWR No 2 overhaul
PostPosted: 11 Oct 2011, 14:49 
Online

Joined: 23 Dec 2010, 00:07
Posts: 384
Location: Poole, Dorset
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:
File comment: Uptake rivets being removed.
P4011094_r1.JPG
P4011094_r1.JPG [ 161.41 KiB | Viewed 21922 times ]


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....


Top
 Profile  
 
 Post subject: Re: GWR No 2 overhaul
PostPosted: 11 Oct 2011, 15:15 
Online

Joined: 23 Dec 2010, 00:07
Posts: 384
Location: Poole, Dorset
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:
P4161119_r1.JPG
P4161119_r1.JPG [ 171.32 KiB | Viewed 21922 times ]


(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:
P4161121_r1.JPG
P4161121_r1.JPG [ 171.68 KiB | Viewed 21922 times ]


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:
P4161129_r1.JPG
P4161129_r1.JPG [ 193.44 KiB | Viewed 21922 times ]


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.


Top
 Profile  
 
 Post subject: Re: GWR No 2 overhaul
PostPosted: 11 Oct 2011, 16:32 
Online

Joined: 23 Dec 2010, 00:07
Posts: 384
Location: Poole, Dorset
In due course John Glaze came to inspect the cleaned and stripped boiler, together with the boiler fittings, and the results were excellent. Some remedial work is needed to both the wrapper and firebox (hardly surprising after 70 years' use) but nothing untoward or unexpected was found. The skirt, as mentioned before, needs to be replaced, but the skirt is not technically part of the pressure vessel which simplifies the repair scheme somewhat. All the tubes,including the stay tubes, need to be renewed.

With the plain tubes there is no particular problem, since they are fitted in exactly the same way as locomotive tubes, i.e., expanded in position in the tubeplates. With the firebox out of the boiler, this is very straightforward.

The stay tubes, of which there are ten strategically distributed across the tube nest, are a little more tricky. The purpose of the stay tubes is to reinforce the firebox and prevent the boiler pressure from collapsing the tubeplates towards each other; they are under compression when the boiler is in steam. To provide the necessary strength, they are significantly thicker-walled than the plain tubes, and originally were also screwed into both tubeplates, then seam welded on the outside of the tubeplate. In order to be screwed in, it is of course necessary for the thread in one tubeplate to be perfectly aligned with the thread in the other - in effect a continuous single thread. One end of the tube is of course larger in diameter than the other, so to cut the thread correctly a gigantic, specially made tap-come-reamer is needed. This has to be long enough to engage both tubeplates at the same time, and has to have the correct thread machined on it to cut the single continuous truncated thread. For this boiler a "first oversize" cutter and tap is also needed, since the threads need to be enlarged.

Our enquiries to date suggest that no-one has such a thing any more, and we have been unable to find anyone who has made a replacement inner firebox of any kind for a Hopwood boiler in the last 30 years. The tool would therefore have to be specially made (technically quite possible and there are several well-known firms who would be delighted to do this), but the cost would be very considerable.

Because of this, we had a head-scratching session with the boiler inspector (who legally has to sign off any repair scheme) to see if we could come up with an alternative. Eventually, after analysing the loading on the tubes, firebox, and boiler, and the dimensions of the tubeplates, we agreed on a scheme involving a weld-only installation which does not require the threads to be cut - a "J-prep" weld will hold the tubes securely in the tubeplate. This greatly simplifies the repair and should give a substantially stronger finished join that the thread/seam weld original. It will also in the end result in a stronger tubeplate ligament than threading oversize would have produced.

Whilst this work has been going on, work has also been in hand on the boiler fittings.

The boiler fittings have presented some concerns. The original VFT boiler which was fitted to the crane when it was sold by BR in the 1970's had a safety valve assembly on one port, a manifold and main steam valve on a second port, and a single feedwater delivery port to which was bolted a "Y"-shaped manifold and two clack valves. In early days one clack was fed via an injector, and the other by a 'banjo' feed pump. The feed pump appears to have been removed quite early in the crane's life (probably in GWR days) since which time the unused clack was left in situ but simply capped off. The crane therefore spent most of its working life with a single boiler feed, a somewhat unsatisfactory (and probably illegal) situation.

When the crane was at the DVLR, the unused clack and "Y"-piece were removed and subsequently mislaid, so by the time the crane came to Cranmore it had only a single clack. All the remaining fittings from the VFT boiler were however located amongst the parts at Cranmore.

When I bought the "new" boiler ex-DS1560 from Simms Metal Management of Halesowen, the deal and price included the boiler, all its fittings, and the banjo feed pump. At the time of the sale, the crane was still at Tyseley awaiting movement to Simms's yard. Unfortunately, and to my very great annoyance, during the few hours of the morning when the crane was being prepared for movement by road (i.e., the jib was being cut off and the jib and runner and crane itself were being loaded onto road transport) the feed pump and all the boiler fittings (manifold, safety valves, clacks, clack adaptor and blowdown valve) were removed by means of oxy-acetylene and made off with. They have not been seen - at least, not by me - since. Extensive enquiries made subsequently have also not resulted in their return. Since most of the fittings will only fit this or an identical boiler - of which there are only four in the UK - (since only the two clack valves and some of the manifold valves are standard Great Western fittings) this is a completely pointless and irritating theft!

[Update to the above paragraph: Subsequent enquiries have resulted in me speaking to two separate and independent eyewitnesses to the removal of these parts, and I now know beyond reasonable doubt who removed them and where they were removed to. My polite requests for the return of the parts resulted in a flat denial of possession, and due to the complexities associated with establishing who actually owned the parts at the time of their removal it is, sadly, unlikely that there are any steps which can be take to effect their return. Given that the UK railway preservation scene is small and generally co-operative, it is sad that factions exist within it who will behave in this way. Should the person or people in question happen to read this and feel moved to return the boiler fittings and feed pump, I would be delighted (and will happily edit these comments to something more upbeat).]

The new boiler also had a different arrangement of fittings to the old, namely the safety valves and the manifold were a single casting on one port, the main steam valve was on a second port, and the clacks were a similar arrangement to the VFT boiler with two clacks on a "Y"-shaped manifold. The stolen feed pump was probably identical to the one originally fitted to the crane in 1908.

On examination once the boiler had arrived at Cranmore, it became apparent that it should be possible to adapt the fittings from the VFT boiler to replace the stolen fittings on the Hopwood. The VFT safety valve casting will fit directly onto the Hopwood safety valve/manifold pad without any modification, also the safety valves will need resetting to the higher pressure. The VFT manifold/main steam valve casting will not, however, fit the Hopwood main steam valve pad since the mounting studs are on a different pitch circle diameter. It should though be possible to fabricate an adaptor to allow it to fit (this will obviously require the services of a coded welder, and need full testing and certification since it is part of the pressure vessel). So far so good.

However that still left the problem of the clacks - the "Y"-piece from the VFT boiler was lost together with the second clack, and both clacks and the "Y"-piece from the Hopwood boiler had been stolen. At this moment, however, one of those rare pieces of good fortune occured, and the original "Y"-piece and second clack, removed at least 35-years ago at Buckfastleigh, turned up at the South Devon Railway, and a deal was struck to reunite both items with the crane! After the disappointment of having all the new boiler's fittings stolen, it was a wonderful reversal of fortune. Thank you, SDR!

The one remaining item still outstanding for a complete set was therefore the banjo feed pump. The one stolen at Tyseley was a Truslove No 2 pump (and I do have a record of its serial number in the unlikely event that any reader is offered it for sale). Truslove did not exist in 1908 when the crane was build, and it is likely that the original feed pump would have been a Mumford of similar size (Truslove eventually bought the manufacturing rights to Mumford banjo pumps after the death of A G Mumford in 1933). In another of those rare moments of good fortune, a Mumford No 2 pump was found for sale in Scunthorpe, originally taken from a Humber ferry. A deal was done, and the pump was acquired.

So, despite the setback from the despicable lightfingered brigade, a complete set of fittings has now been assembled.

Here are two photos showing the stolen Truslove feed pump:

Attachment:
File comment: Truslove No 2 banjo pump on DS1560
Swindon Cranes 044.jpg
Swindon Cranes 044.jpg [ 42.17 KiB | Viewed 21922 times ]


Attachment:
File comment: Truslove No 2 banjo pump on DS1560
Swindon Cranes 045.jpg
Swindon Cranes 045.jpg [ 45.22 KiB | Viewed 21922 times ]


The stolen clack valves; the "Y"-piece is not really visible in the photo but fits between the clacks and the boiler.

Attachment:
File comment: DS1560 clacks and injector
Swindon Cranes 046.jpg
Swindon Cranes 046.jpg [ 42.28 KiB | Viewed 21922 times ]


Finally, the stolen manifold which is also the safety valve casting:-

Attachment:
File comment: DS1560 manifold and safety valves
Swindon Cranes 047.jpg
Swindon Cranes 047.jpg [ 32.52 KiB | Viewed 21922 times ]


As stated above, these parts are of very little use to anyone else; the clacks are standard GWR backhead clacks and will fit certain locos, the injector steam valve is standard. Virtually all the rest however is non-standard and is useless to anyone other than a crane operator (and there are very few of those). If the person who took them is reading this and would like to return them to me, I would be very grateful and no further questions will be asked.



Story to be continued...


Top
 Profile  
 
 Post subject: Re: GWR No 2 overhaul
PostPosted: 25 May 2012, 10:02 
Online

Joined: 23 Dec 2010, 00:07
Posts: 384
Location: Poole, Dorset
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.


Top
 Profile  
 
 Post subject: Re: GWR No 2 overhaul
PostPosted: 16 Oct 2012, 15:36 
Online

Joined: 23 Dec 2010, 00:07
Posts: 384
Location: Poole, Dorset
Since I posted the last instalment above, a lot more has happened.

The two large tube doors, the one large manhole door, and all the mudhole doors were refurbished and dressed so that they were a perfect fit and seal.

Attachment:
File comment: Lower tube door.
P5121234.JPG
P5121234.JPG [ 157.41 KiB | Viewed 21539 times ]


Attachment:
File comment: One of several mudhole doors.
P5121236.JPG
P5121236.JPG [ 164.82 KiB | Viewed 21539 times ]


On the inner firebox, the tube holes were all reamered out until clean, then the new stay tubes were fitted. The stay tubes were welded and the welds NDTed, the rest of the inner firebox also having been NTDed (hence the white in the photos).

Attachment:
File comment: The new stay tubes fitted.
IMG_3444.JPG
IMG_3444.JPG [ 177.56 KiB | Viewed 21539 times ]


Attachment:
File comment: The new stay tubes. Note the one plain tube in place but not expanded (on the right of the photo) showing clearly how much thicker the stay tubes are.
IMG_3446.JPG
IMG_3446.JPG [ 186.92 KiB | Viewed 21539 times ]


Attachment:
File comment: The new stay tubes.
P5121232.JPG
P5121232.JPG [ 152.21 KiB | Viewed 21539 times ]


Top
 Profile  
 
 Post subject: Re: GWR No 2 overhaul
PostPosted: 16 Oct 2012, 15:41 
Online

Joined: 23 Dec 2010, 00:07
Posts: 384
Location: Poole, Dorset
Next the plain tubes were fitted:-

Attachment:
File comment: A stack of lovely new tubes!
P5121241.JPG
P5121241.JPG [ 160.34 KiB | Viewed 21539 times ]


Plain tubes fitted and expanded into place:-

Attachment:
P6091244.JPG
P6091244.JPG [ 171.22 KiB | Viewed 21539 times ]


Firehole ring tack-welded to the firebox ready for reassembly:-

Attachment:
P6091245.JPG
P6091245.JPG [ 154.34 KiB | Viewed 21539 times ]


Finally the inner firebox assembly is ready for replacing in the outer shell:-

Attachment:
P6091250_r1.JPG
P6091250_r1.JPG [ 169.23 KiB | Viewed 21539 times ]


Top
 Profile  
 
 Post subject: Re: GWR No 2 overhaul
PostPosted: 16 Oct 2012, 15:51 
Online

Joined: 23 Dec 2010, 00:07
Posts: 384
Location: Poole, Dorset
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:
P6091251_v1.JPG
P6091251_v1.JPG [ 161.84 KiB | Viewed 21539 times ]


Attachment:
P6091252_v1.JPG
P6091252_v1.JPG [ 171.67 KiB | Viewed 21539 times ]


Foundation ring, door ring, and uptake bolted ready for rivetting:-

Attachment:
P6161253.JPG
P6161253.JPG [ 158.97 KiB | Viewed 21539 times ]


Attachment:
P6161255.JPG
P6161255.JPG [ 148.07 KiB | Viewed 21539 times ]


Top
 Profile  
 
 Post subject: Re: GWR No 2 overhaul
PostPosted: 16 Oct 2012, 16:01 
Online

Joined: 23 Dec 2010, 00:07
Posts: 384
Location: Poole, Dorset
Over the next few weeks, the boiler was rivetted up, and the pads for the boiler fittings were dressed and re-studded. During the course of this it was necessary to turn the boiler over a number of times in the workshop, and there really isn't much room for manoeuvering the Iron Fairy in the workshop.

Watch out for the roof!

Attachment:
P7071261_vr1.JPG
P7071261_vr1.JPG [ 165.92 KiB | Viewed 21539 times ]


Paul adds a sense of scale to the boiler:-

Attachment:
P7071262_v1.JPG
P7071262_v1.JPG [ 218.62 KiB | Viewed 21539 times ]


After the foundation ring was rivetted, a new skirt was welded on (originally on these boilers the skirt is integral with the outer wrapper) and the angle ring rivetted to the bottom of the skirt. The new ashpan door/damper assembly was then fitted to the skirt.

Finally, when everything else was taken care of, the boiler was given a coat of black paint and the fittings were replaced. A preliminary hydraulic test was undertaken, and a very small number of rivets attended to. Then the boiler was taken outside and loaded onto a suitable wagon so it could be moved into the running shed for steam tests, and the formal hydraulic and steam tests and exams by the boiler examiner.

Attachment:
File comment: Photo courtesy Tom Dalton. All rights reserved.
20120929_001.JPG
20120929_001.JPG [ 135.23 KiB | Viewed 21539 times ]


At last it even looks like a boiler!


Last edited by Roger Cooke on 16 Oct 2012, 16:23, edited 3 times in total.

Top
 Profile  
 
 Post subject: Re: GWR No 2 overhaul
PostPosted: 16 Oct 2012, 16:11 
Online

Joined: 23 Dec 2010, 00:07
Posts: 384
Location: Poole, Dorset
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:
PA081272_r1.JPG
PA081272_r1.JPG [ 189.57 KiB | Viewed 21539 times ]


Later the same day being prepared for the steam test:-

Attachment:
PA081275_r1.JPG
PA081275_r1.JPG [ 166.35 KiB | Viewed 21539 times ]


And in steam. Steve Masters, the ESR's CME on the left, and John Glaze, the boiler examiner on the right.

Attachment:
PA081280_r1.JPG
PA081280_r1.JPG [ 155.79 KiB | Viewed 21539 times ]


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.


Top
 Profile  
 
 Post subject: Re: GWR No 2 overhaul
PostPosted: 12 Feb 2013, 12:49 
Offline
Registered User

Joined: 28 Jan 2013, 21:13
Posts: 5
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?


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 21 posts ]  Go to page Previous  1, 2, 3  Next

All times are UTC [ DST ]


Who is online

Users browsing this forum: No registered users and 10 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group