Hello All,

Hoping everyone has a Good New Year.............!!!!

Thought we might examine these two pictures showing the results of corrosion at the base of the stay bolt where it enters the sheet....

Inspections can be rather deceiving sometimes without some exploration.

You thoughts, please...................

Take care................

Dave

In the lower picture, I have worked on boilers like that in the distant past.
It would be interesting to have the stay bolt pitch, ultrasound of plate thicknesses, etc..
We had a similar situation, probably about the same appearance of necked stays. After examining other parameters, the Inspector requested some stays be renewed. We replaced the worst using threaded stays and opening the holes one size.
I am not sure now what the necking allowances are, but sometimes those things look worse than what they are. Certainly one or two there look to be necked badly.
A lot more work is required on the boiler before one needs to worry about the stays.

Water treatment and layup procedures.

I certainly wouldn't claim to be an authority on boilers, but I'd have to say that looks pretty nasty. You won't really know what you've got until you can get all the crud off everything. One method is needle scaling, but how are you going to get inside there with a needle scaler ?? I've heard of using a diluted solution of carbolic acid and water to remove heavy scale buildup, of course you would need to wash the boiler extra good afterwards, and you should be advised that this will most likely open up everything which is loose and leak prone. Some old timer boilermakers say that a bit of scale seals up your boiler, just like some old mechanics will tell you that old, worn out motors run better if they have a bit of sludge in the crankcase. Clean it out, and you'll see what's really wrong... just be careful what you wish for. (And best of luck to you.)

Crevice corrosion at the base of stays in the water space is something that is frequently hidden by scale, and it doesn't take much scale to cover it up. It's also a common find, particularly with some threaded stays or welded stays with improper root penetration. A trained and experienced eye is critical for an internal inspection, or inspection of any kind. This type of deterioration next the the staybolt is also why you'll see many UT measurements taken inside the firebox up against the staybolt to look for this. In my experience, right next to the staybolt is often where the thinnest measurement is found, even if there isn't severe crevice corrosion like is seen here. I've seen inexperienced individuals attempt UTs, where readings were exclusively taken in the area between staybolts, missing thin spots next to staybolts, or missing thin spots in other areas prone to crevice corrosion, pitting, or grooving- such as at the bottom of the firebox sheets at the mudring. Thoroughness is a virtue of boiler inspections.

Obviously this is particularly concerning to find in a boiler when severe, as the loss of material as seen here not only reduces the sheet thickness, but also reduces the amount of engagement between staybolt and firebox sheet. Lose enough engagement on enough stays, and there won't be adequate structural support for the sheet.

-Sam

Photo provided by a friend.
Cross section of a CASE steam traction engine with a leak in the crown sheet. Upon inspection and replacement of the sheet, this bolt and portion of the sheet was cut in cross section. This was not the worst area of the sheet. The boiler had been operating at 140psi (I think).

I don't have anything like that scary photo of the Case engine, BUT, trust me on this: When we took the firebrick out of my Porter saddletanker, the inner side sheets were potato chip thin. They were only held in place by the brickwork, so far as I can tell !! She was a 180 pound engine, last operated at the Thompson Winery (for events open to the public) at 160 psi. This was better than 40 years ago, and all I can say is I'm just glad that nobody was killed fooling around with her. With present day licensing standards, trying to repair the old boiler was definitely out of the question. Even if it might have been possible, it would have been very far from cost effective.

You never know, maybe all that scale and rust and mud is covering up brand new, store bought looking, shiny, solid, steam tight metal. But I'd say it's not likely. Either way, you have to make certain of what you're dealing with, no two ways about THAT.

THAT is a very scary and sobering photo. Maybe 2 threads engaged, if that?

Reminds me of cut-out sections of a crownsheet I saw 20 or so years ago, with 1-1/2 threads left (bolts were out of the sheet). The locomotive had been operating 10 years prior to that time, and passed the traditional hydrostatic tests, which did not reveal sheet thinning like this.

Howard P.

Why wouldn't it be possible to repair an inner side sheet?
It is absolutely possible. May not be affordable for everyone but it is possible.

It certainly WOULD be possible to replace an inner side sheet and all the staybolts, or anything else that was wrong with my engine's old boiler. However that might make sense if only a small part of the boiler needed repair or replacement, but it doesn't make sense when you're talking both side sheets, 400 staybolts, a belly patch, replacement of the bottom third of the front tube sheet, holes rusted through the wrapper every place that had a stud for the cab supports, rearranging the throttle linkage because it was hitting one of the crown stays, replacement of at least that one staybolt, but most likely there are more defects that we didn't find because we were just wasting time looking further at the old boiler.

So the choice was either buy a new, welded, modern boiler, or spend at least as much (but most likely several times as much) to repair the old boiler. You have a choice, you COULD have an old, rusty, patched up hulk if that's what you really want for your locomotive.

When I worked at Texas State RR, we had three engines with pretty decent old boilers that had been repaired in accordance with all applicable codes, and were maintained religiously. At every monthly washout of those engines there was a five gallon bucket of rust and mud and scale when we were done. When I was firing them, I used to wonder where all that rust had come from.

On the other hand, we had one engine with a brand new welded boiler, and it got the same maintenance as the others. When we were done with our washout, there was about half a handfull of soap suds left.

So if you crunch those numbers, it isn't much of a choice. Expensive ?? EVERYTHING about restoring an old engine is expensive, and that's why I've been careful not to throw good money after bad.

Well said Sammy. While most boilers are repairable I think it is to the point where as time goes on a new boiler will be the route to go. Railroads often either scrapped or built new boilers depending on a few different perspectives. Of course we do not want to scrap these big artifacts but in many cases in the future I think new boilers might be the answer. This topic is not a new one. Unfortunately there were many failures in new built boilers but it is working more and more as the industry finds its sea legs in locomotive boiler making.

Mid Continents #1385 got a new boiler for this same reason as Sammy gave. Of course it is not running yet but hopefully it will pass FRA inspections. Speaking of #1385 and thin sheets. In the early 1970s there was a concentrated effort to get #1385 running again after sitting for 9-10 years. Our resident boiler welder at the time was building up the front corners of the firebox with weld. I was working with him or nearby. He took his hand chipping hammer and it went through the corner he was going to build up. I crawled in by invitation to look and see what he had found. Being a stayed surface it was probably not going to blow up, but that just gave us an indication of the condition we were dealing with. Front corners are often a problem area, they were replaced. I do not think ultra sound readings were being done yet on state certified boilers at that time. 30+ years later after a number of examinations and evals it was decided to start over. Firebox repairs are one thing but when both the barrel and firebox are bad and redesigned super heat additions all point to why you have to decide where and what to repair or replace. The devil is in the details which way and how to proceed. Lot of failed new boilers and repairs in the past so one must proceed with caution.

The Polson #2 received some heavy boiler repairs and it was cost effective to do them. #1385s boiler could of been repaired but was decided to replace the whole works. We shall see soon enough what that decision brings. So some deep thought goes into these decisions. Actually the decision is much easier {I think?} when the boiler is complete junk. It is when the boiler is at the tipping point where the decision to repair or replace is more difficult. It all costs a lot of money.
Regards, John.

I have found this sort corrosion to be more prevalent in sidesheets. Though occasionally have seen it across the first 1.5ft of a crown. The thickness around bolts is consistently about .015-.030 less than readings taken in the middle field. This is why the NBIC calls for paying close attention to thickness of sheets at the joint with the bolt... though 95% of people don't take readings there as is evidenced by social media posts regarding ranging from 4-8-4's to narrow gauge 2-8-2's.

This very thing is what led me to condemning the sidesheets formerly in the Reading 2100.

Cheers.