Steam Department Update 08-10-2013

The reason for the delay is frustratingly simple.  As reported two weeks back, the unexpected issue found in the first pressure testing was leakage from the sockets of two flexible stays.  This necessitated the removal and replacement of the stays and their sockets.  While we have some spares on it site, it turned out that we had in stock only one suitable blank, from which to make the new stays.  Tom managed to locate a source that could supply more from stock but these only arrived this week.  (The available from stock is rather critical as they can be made but the lead time for this is 6 weeks plus !).

So the second of the stays is still being machined and ................. it is sort of difficult to pressure the boiler to test all the other defect correction when you have a 1 inch hole in it where the stay should be !.

During the last two weeks a lot has been done on 1630:

·         Over the last two Saturdays all the tube ends, that were identified as having leakage, have been re-rolled.  This included both super heater and small tubes at both ends.

·         The old stay sockets were ground flush and removed from the backhead .

Backhead with old socket removed

·         On Thursday evening Dennis welded the new stay sockets into the backhead.  This requires that the socket be accurately positioned using a special tool seen below.  The socket is positioned on the tapered holder and the tapered thread is then screwed into the hole in the inner firebox.

Socket fitting tool

The end can then be slid along the shaft until the socket is tight against the backhead.  It is held by the rod in the correct orientation to align exactly as the stay will do.

Socket positioned for welding

Held in this way the socket can be tack welded into place.  The tool is then removed and the socket welded into place.

Dennis welding the socket into place

The purpose of the weld is not to hold the socket against pressure (the stay and the fact that the socket is far larger than the hole in the backhead will do that) but to ensure that the seal to the backhead is steam tight.

By the end of the evening both sockets were in place and ready for their new stays.

New sockets ready for the stays

·         Dennis also made good a small area of the caulking between the inner firebox sheet and the mud ring that had shown some seepage under pressure;

·         Mike, Jim and Jerry used the special taps to enlarge and thread the stay holes in the inner firebox sheet ready to receive the new stays, while Mike prepared the copper rings that seal the cap into the socket.

·         Aside from investing a lot of time locating the spares, Tom has been machining the replacement stays.  One is now threaded and just about ready to fit while the other is getting under way.  A significant amount of work is required to turn each blank into a stay ready for fitting.  This shows a blank alongside one of the old stays.

Stay blank compared to old stay

Each one requires:

o   Slotting the head of the ball (to allow the stay to be screwed into the firebox);

o   Polishing any ridges off the ball;

o   Drilling the tell tale hole along the length of the stay;

Tell tale drilled in new stay

o   Reducing the diameter to the exact size required for threading.  (Each time that a stay is replaced the size is increased by 1/32nd as the new thread is cut into the inner firebox).  Just to ensure life is not simple, the two being replaced prove to be marginally different in size.

Cutting stay to correct diameter

o   Finally cutting the thread on the stay.

o   Only once this is done can the stay be screwed into the firebox and hammered over.  After all the preparatory work, the final fitting is relatively quick.

o   The current plan is that the machining and fitting will be done Sunday and during the coming week.

·         The fireman's side water gauge was removed and refitted to correct a leak detected under pressure;

·         The engineer's side water glass was fitted so that it can be part of the next pressure test;

·         The unions to both check valves were split and remade.  It was found that the copper sealing ring on the engineer's side was missing.  This could explain why this was leaking under pressure.  A new ring was annealed and the union remade so we believe that this should be much improved.

·         With all the defects that were noted under pressure corrected, but being unable to test this work, we moved on to other tasks:

o   Jason worked on examination and cleaning of the air brake valves;

o   Mike and Phil started preparing the air compressor for operation.  The valves in the compressor all need to be opened, cleaned, lapped where necessary, and lubricated so that it is ready for testing as part of the steam test.  Once the cleaning is done we will plan to test it initially using compressed air;

o   The cab was cleaned up and the first major group of back head fittings was reinstalled.  This includes the flange and hydrostatic lubricators.  These were fitted first as they are needed to allow the air pump supply line to be pressurized.  It is good to see the cab starting to take shape again !.

Lubricators back in place

So, in the next week, everything rests on the progress of Tom and the team can make in machining and fitting the stays.  If they can complete this during the week, we will plan to test the tightness of the boiler and fittings again next weekend.

Nigel