I have learned that 611 has transverse circulators instead of arch tubes in her firebox. can any of you give me any details on how these work? I believe the only major mechanical problem 611 suffered during her excursion career involved these circulators, when they cracked loose (?). This occurred in the summer of 1983, and there was an issue at the time with broken staybolts, though I am not certain how this was related. I do know 611 was pulled out of service because of this for repairs late in 1983, and had more repairs during the winter of 1983-4, which resulted in the replacement of a good many staybolts.
lois

The primary reason for the firebox problems from 1982-1984 were due to operating procedures rather than design issues. Repairs and personnel changes were made, there were no further major issues after that.

Lois- transverse circulator tubes (as used by the N&W), arch tubes, "Security" circulators, and Nicholson thermic syphons were all devices for increasing the circulation of water in the boiler. They also added heat transfer area in the firebox, where it did the most good. These factors increased the boiler's ability to generate steam. They also provided support for the brick arch.

They work on the principal of natural convection. One end is higher than the other, so that when water enters and is heated, it becomes less dense and rises, exiting at the high end of the device.

All of these devices (with the exception of standard arch tubes) provided some protection for the firebox crown sheet in the event of low water by keeping some water flowing across the crown sheet even if the boiler water level was actually lower than the crown sheet.

Perhaps Gary would tell us more about what operational problems led to what mechanical difficulties and what repairs and changes were required to solve them. Names need not be mentioned, but the technical information could save others from having the same failure down the line.

dave

Dave, It was not an operating problem, rather an operating procedure based on inexperience with larger locomotives. Too short a thermal cycle for the size of the boiler, something that has been discussed in many places including here. In other words, she was being heated up too fast....

OK, fast fireup stressed the welds and stays? Repairs were the usual patches and caulking followed by taking more time in firing up?

If that's the case, nothing new to be learned here. Thanks, Gary.

dave

Patches & caulking on the road followed by new sidesheets in the shop....then new operating procedures...

One of the first lessons drilled into my head when I first started hostling cold iron was "slow to steam, slow to leak". It was expected to take the better part of a day to fire up when completely cold, and it had better! Once I had made engineer I had a hostler go from 30 LBS to 200 LBS in two hours...I was not happy and told him so, and also made management aware of it. A week later, the engine was out of service on account seven staybolts had let go due to this treatment. The hostler was treated with a goodbye.

In late 1982, I saw 611 go from dead cold no fire, to pops lifting in 5 hrs.....

OUCH!!!!! I would have thought Mr. Purdie would have ripped the hide off of whoever did that....or was he retired by then?

An older gentlemen here in Charleston told me he and his wife once rode the Powhatan Arrow into Roanoke around 1958 behind leased ACL E3 diesels which barely made it into town because of problems. A J was pulled out of the dead line to substitute for the E3's and force-fired to operating pressure in something like an hour. Being a steam enthusiast, he got as close as he could to watch despite the fact he was wearing a white linen suit. It didn't fare very well in the ensuing cinder storm.

Yes, but Mr. Purdie's son, Bill Purdie, Jr. stayed on with the steam program for some years afterward.

I was working for the N&W when the 611 pulled into Portsmouth, OH in 1983 on the Independence Limited. They dropped the fire just as soon as they got the train off the main and asked us (the Maintenance Shop) if we had a decent welder. It turned out we had a middle aged pipefitter who was a certified welder and who enthusiastically agreed to go into the hot firebox to fix a cracked weld on one of the transverse arch tubes. Our pipefitter wanted to grind the crack out and weld it up properly, but Mr. Purdie (Jr.) told him to just weld over the crack with no grinding. I don't know if Purdie was skeptical of this guy's abilities or perhaps he was just worried grinding the crack out might reveal worse problems.

IIRC, it took our guy less than an hour to do the welding and they immediately started a new fire and began bringing the engine back up to pressure. I have no idea how well that repair held up.

Given all the abuse steam locomotives suffered in revenue service, I'm left to wonder about the relative fragility of these circulators. N&W was among the best in terms of availability - their lubritoriums and recharging boilers with preheated water and piped in steam for lighting up after washouts surely helped - but it would be interesting to know just how much trouble the circulators were in service. There's a reason boilermaker crews worked 24 hours a day.

dave

If it helps any: My recommendation in welded practice is to use a transition 'fillet' between plate and tube; I think these could be pressings rather than forgings, but design how you want. These transition from the sheet around a fairly liberal radius to be inline with the tube proper, and this ought to take considerable thermal cycling without stress raising at the normal 'corner' where the tube goes to the sheet.

I already mentioned to Lois that the 'top' of the circulator arch, where the vertical 'upgoer' rises to the crown, should have a transition streamlining, to give what is essentially the effect of two 'half-arches' with flow streamlining siamesed into one.

The issue would then come down to whether the tubes themselves, and the plate adjacent to them, could be so overheated during "improper firing" that DNB became established inside them at some point (now not the transitions!) which would cause spot overheating and metal failure. One immediate "perhaps" solution would be to center small jets from a Cunningham circulator setup in the bell mouths leading to each circulator tube, to give better directed mass flow, and ensure directed flow away from the circulator exit above the crown. THAT ought to hold up at least as well as the sheets...

GCR 4960 has the same set up of fire box circulators and I do not remember a problem with their performance in either operation aspect or maintenance. I do fell that if you spend your time on set up and alignment it pays off for you in the long term. I know Mr. Franzen paid a lot of attention to the set up and alignment.

On firing rates. You would be surprised just how fast a locomotive can be raised to an operating pressure. If you go back and reread the posts by M Austin on Niagara’s you see they lit off only 1 hour before the train was called. Having preheated water to evenly heat the boiler made this possible. Using hot water to get above the ductile/brittle transition temp and evenly warm the boiler does a lot. The other key here is after the initial pressure from the shop they built pressure while moving in the yard completing other task. This light loading of the boiler helps to promote circulation of the boiler water helping to eliminate potential temperature differentials.

A story from my experience on pressure building. One day I brought 4960 up to pressure at a rate just below 2 psi per minute. The right front mud ring plug dribbled but only around 150 psi. The next day we cut the firing rate down to ½ psi per minute but we had the same temporary leak. Sometimes leaks are not formed by firing rates but by other issues.

Finally if you look in an SP firing manual you will find an emergency fire up procedure that pushes a boiler pretty hard. I have seen this procedure used and while it works, on a 2-8-0 boiler it only took 21/2 hours to go from cold to full pressure. While now knowing more the procedure dangers it will not be used again but I will say a well constructed and maintained boiler can go through a lot that we do not give them credit for..

Robby Peartree