Steam Department Update 3-31-2012

A rather limited turn out at the shop this Saturday with several people helping at the book store to catalog and prepare a large collection of model locomotives recently received thru a donation.

However the key target on 1630 was achieved.  The sand blasting of the boiler interior is now complete and a few of us were able to start removing all the ply that sealed the boiler and cleaning the dust and sand from the locomotive.  Despite all the sealing the process creates a vast amount of dust and some escape of the abrasive.  We now need to remove as much as possible of this from areas close to bearings etc. before we can move her outside to sand blast the back head.  At that time we will aim to give her a thorough cleaning.

The interior of the boiler shows the progress that has been made and also provides some unusual views of the inside of a locomotive boiler.

Here you can see the top and part of the side seam of the firebox.  The many long vertical and shorter horizontal stays hold the inner and outer fireboxes together.  In use the inner firebox must always be completely covered by water but most of the height above the firebox crown would be steam.  The water and steam are all at a pressure of 180 psi.  The extensive stay system is required to hold the inner and outer firebox together against that pressure.  On the left you can see one of the super heater flues and two of the smaller fire tubes that have been left in place.  On the right are the holes from which other flues and fire tubes were removed to allow access to the boiler for cleaning and inspection.  In this picture they are still blocked by the ply sheet used to contain the blasting abrasive but soon they will again be open to the fire space.

Looking back to firebox

In this shot we are looking forward toward the front tube sheet.  Here you can clearly see where the majority of the tubes had to be removed to allow access to the sides and bottom of the boiler and only a few remain in the center.  At this point the holes were still blocked by ply sheets but, by end of day, they were again open to the smoke box.  Above you can see the long braces that secure the top section of the tube sheet to the boiler barrel.  Again the whole structure is built to resist a pressure of 180 psi.  The tubes themselves brace the lower part of the tube sheet but above the level of the tubes (an area that would be full of steam, when in operation) the braces are required to prevent the tube sheet being pushed forward by the pressure.

Looking forward to front tube sheet

This view shows the top of the front tube sheet more closely.  Here you can see the heavy attachment of the braces to the tube sheet.  To understand why they are so heavy do a quick calculation.  At 180psi the load on an area about 10 inches square is around one ton!!.   In the center can be seen the dry pipe.  This carries steam from the throttle (high in the dome) forward to the super heater header (in the smoke box on the other side of the tube sheet) and then on to the cylinders.  It is called the dry pipe as the steam that it carries is now separated from the water in the main space of the boiler.  This view also shows the work still to be done in removing the abrasive that still sits on top of the tubes and other surfaces within the boiler.

Dry pipe and front tube sheet braces

Meanwhile Paul made good progress on needle chipping and wire brushing the truck of the Shay.  With the thick crud removed it can now be taken down to clean metal for final inspection and then repainting.  The bolster now looks pristine after Paul's efforts.

Clean at last

This makes an interesting comparison to the shot of the same part 11/26 last year.

Where we have come from

Nigel