Talk:Boiler explosion

Early comments

Moved to article. --Dore chakravarty 07:55, 6 December 2005 (UTC)

Removed the phrase "particularly to locomotive boilers." Boiler explosions happen to boilers, not to a particular type of boiler.

"Explosions" section

This section states that lower pressure causes water to boil rapidly, which in turn raises the pressure, resulting in an explosion. This is not possible. If the pressure drops, some water will boil. This addition of gas will raise the pressure, preventing the rest of the water from boiling; thus, no explosion will occur. Furthermore, the boiling water undergoes an endothermic conversion, which will lower the temperature and check the pressure of the gas. Pcu123456789 03:10, 2 December 2006 (UTC)

Pcu123456789: Your explanation of the situation seems correct, and well explained. I'm going to rv the whole edit – I just wanted my doubts about it put into words! ––Old Moonraker 07:34, 2 December 2006 (UTC)

I endorse this; the original explanation was ingenious, but seems fallacious, and was not the root cause of most explosions. The idea may have some merit in explaining the large evolution of steam after a containment failure has already occurred. Strangely, Hewison noted that a similar incorrect theory circulated from the 1860's to the 1890's and was then finally disproved! Hyperman 42 00:43, 20 December 2006 (UTC)

My issue is with the statement that in a pressure vessel at 150 Celsius most of the water could flash into steam. I have just done the sums using Specific Heat capacity and Latent heat of evaporation and it looks to me like less than 10% of the mass of water could flash into steam from a 50 Kelvin over-temperature. That's still lot of steam though. Anyone care to check my sums? Specific heat capacity= 4.18 kJ/kgK. Latent heat of vaporisation = 2260 kJ/kg Gardnecd (talk) 17:03, 2 December 2009 (UTC)

I just edited the explosion section for better technical accuracy, and a more credible steam table for usage. 50 psi was not a realistic value for a large steam locomotive, neither was the 66% equivalent to TNT. I'm not sure where this information came from but it was obviously false. I wasn't sure if there should be a section on the fact that a steam explosion differs from a conventional explosion in the fact that it cannot exceed its initial pressure and it will never provide the equivalent impulse, even if it can have a massive energy discharge. I though perhaps I should leave that for an expert on the subject so for now i just edited the obvious technical fallacies out, and tried to clear up the explanation. Rawheas 22:11 March 28th 2012 (UTC)

50psi is admittedly low, but isn't too bad, because it's the pressure that boilers worked at during the period when explosions were more common. In the USA (where explosions were largely a problem for riverboats) the pressure was even lower. In the UK, the majority of explosions were in stationary boilers at fairly low pressures, not locomotives. The UK stationary explosions were so damaging because of their sheer scale - often one boiler in a battery exploded and the damage to adjacent boilers caused them to follow suit. There might be ten boilers involved, even though each was at a lower pressure than locomotives of the day.

I see the mention of high-pressure steam locomotives as misleading (as is the cited 350psi), because (AFAIK) none of these ever exploded. Even when Fury suffered its accident, that was a scalding accident from a relatively small leak, not an explosion. They're also, in the main, water-tube boilers with reduced water volumes. Andy Dingley (talk) 09:25, 29 March 2012 (UTC)

Sorry i was really acting uninformed on that edit. The previous link was to locomotives of very large capacity, such as 10,000kg, but these where the later more advanced high pressure type. In fact instead of changing the information i should have thrown that idea out all together because i never realized those boilers where not fire tube boilers at all. I'm really not an expert on old boilers and explosions, I just had to redo the article because of false thermodynamic information. If someone can provide more realistic information that would be great, otherwise I'll just go look up a good case example. Rawheas 15:59 March 29th 2012 (UTC)

Offhand I can't think when the last locomotive "boiler explosion" was, but that's probably our baseline accident - i.e. an accident where the whole locomotive boiler shell splits. Many of the later accidents were low-water accidents where the firebox crown failed. For the later, stronger boilers (another reason why simple pressure is misleading), the boiler shell often survived the accident. I'll take a look in Hewison and pick one, then try to find numbers for it. Andy Dingley (talk) 16:06, 29 March 2012 (UTC)

Steam engine invented by James Watt?

Would "low-pressure steam engine of the type developed by James Watt among others" be closer to the truth?Moletrouser (talk) 07:15, 19 October 2008 (UTC)

Possibly, but it doesn't really matter as none of what was written related to boilers or boiler explosions anyway. I've now removed the offending text... EdJogg (talk) 00:03, 20 October 2008 (UTC)

List of boiler explosions.

Should it be noted that this is not a complete or exhaustive list? --BenBurch (talk) 19:08, 2 March 2009 (UTC)

I've added {{incomplete list}}. EdJogg (talk) 01:51, 3 March 2009 (UTC)

Excellent. --BenBurch (talk) 01:04, 10 March 2009 (UTC)

I agree with the need to completely rewrite as discussed below. I can't do that, but I have tried to clean-up the list of boiler explosions by creating a new article that expands the list that was given here plus adds references and readings. Hope everyone finds this to be acceptable. If not, feel free to revert and best regards to all. JuniperisCommunis (talk) 14:21, 14 June 2009 (UTC)

Never add water when no water visible in the sight glass?

Another editor has said that the advice in fusible plug differs. The recent additions to this article seem very valuable and I'd like to see them stay, but perhaps this is a good example of why WP:NOTHOWTO. --CliffC (talk) 16:21, 13 April 2009 (UTC)

I've just been checking the sources over at fusible plug: they explain how the error came about and was eventually corrected. Let's wait to see the result of the {{citation needed}} request here. --Old Moonraker (talk) 16:28, 13 April 2009 (UTC)

Strangely enough (and speaking as someone who's around locomotive boilers quite a bit), I've been taught during the three years I've worked with them that the proper procedure, in any case of a very low water level, is to add water as rapidly as possible. A recent fusible plug failure with which I'm familiar was dealt with in precisely the same manner, with catastrophic explosion being averted; of course, the circumstances may be somewhat different, the failure in that case apparently being of the core of the plug, rather than a low water level. --Hippopotamus Aeronauticus (talk) 10:33, 27 April 2009 (UTC)

OK: prompted by User:Hippopotamus Aeronauticus I've removed the uncited and seemingly incorrect WP:NOTHOWTO. --Old Moonraker (talk) 11:15, 27 April 2009 (UTC)

This needs discussion in some detail, as it's historically significant (ref Hewison, at some length). An early theory of boiler explosions was that a low water level and an over-heated crown sheet (inner firebox top) could give rise to an overpressure and a burst boiler if water was added, by a process of flash steam boiling. Hewison discredits this, but it's a theory that obviously remains in circulation, as here.

It is possible that an overheated dry crown sheet could be encouraged to fail by adding water, in some cases, as it might cause distortion and thus local overloading of stays. That's more about "the exception that proves the rule" though, and general practice is that dry boilers should be filled ASAP (apart from anything else, injecting cold water drops the overall temperature and pressure, and use of a live steam injector to do so will also vent some pressure, all of which are helpful actions).

In the end, we ought to mention this as a discredited theory. Quickly though, we're better off without it. Andy Dingley (talk) 11:40, 27 April 2009 (UTC)

Check out the second case study at this link and then try to tell me that adding water to an over heated boiler can't possibly cause an explosion. It can and will if the conditions are right. In this case, the boiler’s water level was being maintained manually. The operator wasn’t paying attention and when he realized the boiler’s water was down, he switched on the feedwater pump. The result: he blew the end out of their facility and launching the boiler out of the building.

http://www.ais-forensic-engineering.com/casefiles.asp

--Proaudio55 (talk) 03:28, 6 May 2009 (UTC)

The important point to note here, methinks, is the use of the phrase, "if the conditions are right". My tuition has always been, if the water level is realised to be dangerously low (including by failure of the fusible plug), to bring both injectors into action as rapidly as possible. The objective is both to cool the boiler and to reduce the pressure within. I have also heard it opined, by colleagues, that the risk of thermal shock-induced failure, either of the stays or of the softened crown sheet, is too great to permit such an approach, and that the best policy is to, if possible, drop the fire and "run like the clappers".

Now, speaking as a man not trained in the arcane art of boiler design but able to discuss this question with those who have many, many years' experience of operating locomotive boilers, I would say that it was exceptionally irresponsible, given the variability of the conditions occurring in a low water level failure (steam pressure, temperature of the crown sheet, condition of the metal, durability of plates, and probably quite a few others that more specialised men than I could rattle off), for any advice whatsoever on "procedure" to be put forward by this article. I should sincerely hope that anyone in charge of a boiler would be appropriately trained for the job, and have been given not a few lectures on the preferable course of action to adopt in such a situation as this article describes; nonetheless, if someone reading this article were, in the heat of the moment, to remember its clearly-delivered didactic tones and make the wrong decision, lives could and would be endangered.

Incidentally, I trust you will note (when you have finished acting as though this were some sort of inane contest) that at no point did I suggest that the addition of feedwater to a boiler "can't possibly cause an explosion". I pointed out that, in my experience, the statement "never add water" is one not agreed with by those operating locomotive boilers. My view was, and remains, that expressed in the above paragraph: to administer advice, recommendations or (heaven forbid) actual instructions through this article is irresponsible, overly simplistic, and possibly downright dangerous. --Hippopotamus Aeronauticus (talk) 17:08, 12 May 2009 (UTC)

We could look at thermal shock. --Old Moonraker (talk) 06:05, 6 May 2009 (UTC)

Complete Rewrite Required?

This article has been tagged for re-write since 30 Aug 2007. Thought it was about time it was mentioned on the talk page! EdJogg (talk) 14:27, 8 May 2009 (UTC)

I think the problem is related to authors who’ve put this article together. It’s virtually 100% regarding obsolete locomotives/ hobby boilers and roughly 0% on current units. The article topic is “boiler explosions” not “choo-choo train accidents.”

Marine propulsion, heating, garbage incinerating, industrial process, power plant, and other types of boilers all have unique quirks and safety issues. However, there doesn’t seem to be any content regarding those. Talk about “fusible plugs” proves my point. I guess those are used on hobby boilers (?) but as far as I’m aware those aren’t acceptable primary safety devices on ASME or NBIC approved boilers. Ya’ll need to find some Chief A operators or “R” Stamp welders to kick in their 2 cents.

Proaudio55 (talk) 18:16, 10 May 2009 (UTC)

Therein lies one of the weaknesses of Wikipedia: subject coverage is dependent on people who are both interested/knowledgeable in the subject and willing to write about it. The types of boiler you mentioned are presumably not those that attract a hobbyist following? The bias is only present because people will only write what they know about.

I don't like your term "choo-choo train accidents" -- that shows shocking ignorance of the importance of the topic, and no consideration for those that have died, as does not realising that a fusible plug is a very simple (and fundamental) part of any (AFAIK) steam locomotive boiler (NB not 'hobby' boilers) and is far from obsolete technology.

However, as someone who is clearly knowledgeable of the subject, I am glad that you will be contributing positively to this article in the near future.

EdJogg (talk) 12:37, 12 May 2009 (UTC)

Ed's beaten me to commenting here (and one of the joys of replying to crassly ignorant comments like this is the waste of time that could be spent fixing stuff instead). My two'pennorth would be:

Yes, it's a poor article. So talk about fixing it.

Steam locomotives are hugely important in any analysis of boiler explosions. Boilers before this were low pressure, so tended to fail with spectacular leaks (and fatal scaldings, admittedly) rather than destructive explosions. Steam locomotives are, by their nature, lightweight and pushing the envelope of available technology in the period. They failed because they out-ran metallurgy, safe engineering and preceded the historical development of the management and government regulation that seeks to avoid further explosions (There's a great topic for an article waiting on the Manchester Steam Users' Association / British Engine Insurance Company, should anyone wish to contribute). They also used flued or fire-tube boilers rather than water-tube, and a large diameter pressure vessel is far more hazardous as an explosion risk than a small diameter water tube (please remind me that I'm an iggerant hobbyist who doesn't know that water tubes run at higher pressures...). Locomotive boilers also exploded more in the UK because we had more of them at the time, and we were keeping better records earlier on. In contrast the US had its boiler explosions earlier, on boats, at lower pressures, and with fatalities more likely by drowning than from the explosion.

So the peak of boiler explosion risk was the mid-late 19th century, in England, on railways. After they got dangerous, before they were made safe again.

The low risk from modern watertube boilers is to some extent illustrated by your own addition of a piece on combustion explosions in furnaces, not even on "boiler explosions" as such. You're probably right (I don't know the statistics) - modern boilers are themselves so safe that their biggest explosion risk is that from fuel combustion, not a steam explosion. That's a different sort of accident though, and only tenuously relevant here (worth mentioning, but needs clear labelling and separation).

As for the rest of your comments, then I'm not even going to reply - but "the family choo-choos" weigh several ton each, and I don't have an "R" stamp because my own welding qualifications came from the UK, not the USA. I do however know what a fusible plug is. Andy Dingley (talk) 15:08, 12 May 2009 (UTC)

It's also worth pointing out that a great many of these apparently irrelevant and obsolete pieces of equipment are not only still in existence but - gasp! - still working. Off the top of my head, I seem to remember that there are around two hundred preserved steam locomotives in the United Kingdom alone, of which somewhere between 50 and 100 are probably in service at any given point; this is, to forestall all nit-pickers and pundits who will point to largely irrelevant errors, just at a rough guesstimate. That's in one country. I would suggest that you then think about the number of traction engines, steamrollers, steam wagons, stationary steam boilers of the fire-tube variety - I know of at least one Lancashire boiler, not too distant from me, still in active service, which isn't a fire-tube boiler but which is an obsolete variety of non-water-tube boiler, and therefore is probably due the same contempt as "choo-choo train" boilers from the OP. That's just in the United Kingdom.

The fire-tube boiler, of riveted construction and with a copper firebox, is a far from irrelevant technology, despite its obsolescence, and is (as the above user has so eloquently described) the type seemingly most likely to suffer a boiler explosion, and an explosion with fairly terminal consequences for anyone nearby at that. The modern safety aids so prevalent in industrial boilers and steam-generators, almost universally of the far safer water-tube variety in any case, cannot be applied to a boiler whose water levels undergo a constant fluctuation during normal service anyway, simply owing to the angle of the ground. An automated feedwater pump fitted to a steam locomotive's boiler would have to be able to measure, very precisely, the water level throughout the boiler, the flow rate through the boiler, and the rate at which water was being lost due to steam generation (and then calculate a response based upon those variables), before it could be used. Otherwise, the simple and entirely innocuous act of going down a steep hill, which naturally results in "the tide going out" in the sight glass, would more than likely lead to an epidemic of priming, a lot of damaged engines, and a lot of very angry locomotive owners.--Hippopotamus Aeronauticus (talk) 23:47, 12 May 2009 (UTC)

200 preserved (to what extent?) / 50-100 operational - steam locos, seems a little low, though it's a good enough ballpark figure.

I know there are in the region of 2000 traction engines / steam rollers / steam wagons preserved in the UK, and you can see upwards of 200 of them in steam at the Great Dorset Steam Fair each year. That's a lot of boilers.

VERY good point about giving advice. What we CAN put in here (once referenced) is the potential effects of adding water in such conditions (ie, depending on various factors, could make the situation safe or else induce catastrophic failure!!)

Incidentally, it may be worth mentioning the vertical boiler at this point, since that type is less prone to the issues suffered by locomotive boilers on hills, (eg Light steam launches, logging engines and Sentinel Steam wagons).

EdJogg (talk) 00:40, 13 May 2009 (UTC)

Yes, it was a pretty rough figure. I figured it better to be too conservative with my numbers and be accused of inaccuracy, than too liberal and be accused of hyperbole ;) Hippopotamus Aeronauticus (talk) 16:42, 13 May 2009 (UTC)

++Ear to ear grin++ Gee, did I get under somebody’s skin? :-) 66.173.87.242 (talk) 13:32, 16 May 2009 (UTC)

Duplication

Material relating to locomotive fireboxes is duplicated in "Fireboxes" and "Locomotive boiler explosions in the UK". Suggest a trim, but as there is a possibility that my instinct for tidiness may, once again, be mistaken for deletionist (☺!) a consultation here first. Views? --Old Moonraker (talk) 06:52, 13 September 2011 (UTC)

Afterthought: given the gradual improvements to the article we might then be at the point where we remove the two-year-old {{cleanup}} tag. --Old Moonraker (talk) 10:47, 13 September 2011 (UTC)

Awkward

Reading this article is awkward. Many sentences are too short or too long with commas that throw off the speed of reading. It should be rewritten in a language that is more consistent and concise.

24.246.40.139 (talk) 18:33, 8 May 2012 (UTC)

Edits to "Principles" section 2012.06.06

Hi all, I am trying my best to help this article in good faith. I have added reference quotations ("causes of boiler explosions" section) carefully transcribed from the original hard copy in my possession. I also made several other edits/rearrangements for grammatical clarity and technical accuracy. I rewrote a statement regarding the specific dangers inherent in "locomotive-type" boilers that is technically accurate.

I removed the statement "particularly to locomotive boilers" (again) A. Because many explosions occurred to traction, marine, and stationary boilers as well, and B. Because the statement does not have a citation to support it. This statement should not be added back without a proper citation.

I have removed the "bleve" interpretation and link from the "principles" section (again): A. Because it is not correct from a physics/thermodynamics point of view. B. It is not a legitimate reference by wikipedia standards. My previous"citation needed" challenge tags (added months ago) were removed by others, but no proper citations were added, so I have removed the reference in accordance with wikipedia guidelines. This statement has been removed before, and should not be added back without a proper citation.

Some of the original article appeared/still appears to be the result of "original research" and can be removed on those grounds. It is the right/duty of all wikipedia editors to comply with the guidelines of wikipedia itself, and since many statements previously made in the article do/did not comply with wikipedia standards for verifiability, they may be removed as well. Tomtroszak (talk) 20:00, 6 June 2012 (UTC)

Suggestions for further improvement 2012.06.06

I appears to me that the original article was written by a British steam locomotive enthusiast, and all due respect is given to their interest in the topic and effort expended in creating the article. However, some of the statements originally presented were not properly supported by reference to published sources, so they have been removed in accordance with wikipedia standards for verifiability. Many of the details of boiler construction, etc. still remaining in the article are more applicable to a discussion of British locomotive design than the topic of "boiler explosions" in general. For the purpose of clarity I propose that the extraneous material be removed to a separate (or another existing) article on British locomotive design where it is more applicable; rather than offending the original author/editor by deleting material which is not necessarily incorrect, but not of material importance to this particular article. Tomtroszak (talk) 20:49, 6 June 2012 (UTC)

The point about "British steam locomotive enthusiast[s]" (plural) is valid, and other perspectives may well be needed. However, a remedy of including a large-scale WP:NPS from a U.S. source isn't the answer. RV. --Old Moonraker (talk) 21:28, 6 June 2012 (UTC)

Hi Moonraker! Thanks for the heads up on quoting. I made my original edits to the page many months ago saying basically the same thing, but in my own words. You deleted those edits as well. You seem unhappy that your "pet" article does not stand up to any scrutiny, and seem unwilling to accept that the original article does not meet wikipedia standards. I tried re-writing it once, but that went away pretty quickly as well. I thought perhaps this time the article could be "adjusted" politely, bit by bit, by removing the few "offensive" bits of unverifiable material as per wikipedia guidelines and leaving the rest intact. The wikipedia standards invite me to challenge and remove unverifiable material, and that is what I have done, and will continue to do. Please post only encyclopedic information that can be verified by external sources. Please maintain a neutral, unbiased point of view. Encyclopedic content must be verifiable.Tomtroszak (talk) 23:43, 6 June 2012 (UTC)

Dear oldmoonraker, P.S. Please chill out a bit. You have always deleted my edits within hours of posting, before anyone else has had a chance to read the results of my edit. I don't think anyone is going to die as a result of having read a few paragraphs of technically correct, verifiable material. Try letting it stand for 24 hours if you can manage. I am trying to play nice here. Thanks!Tomtroszak (talk) 00:05, 7 June 2012 (UTC)

Sorry: I had initially thought the extracts were from a copyright work and that would warrant swift action. The point applies to equally to WP:NPS: "Avoid including … lengthy quotations." and the outcome would be the same. Many other editors have changed "your" work here; after a quick check of the page history, I seem to have done so only once before, two years ago. --Old Moonraker (talk) 06:40, 7 June 2012 (UTC)

Some apparent progress! 2012.06.07

Dear oldmoonraker, Thanks very much for the reply, and for allowing my recent edits to stay, at least for a while! I did not thoroughly review who changed what or when, apologies for that. I appreciate you taking the time to engage here, my main issue is lack of time needed to study wikipedia policy, much less actually make the edits that were so badly needed. Please note that the majority of my edits did not actually change the intent or meaning of the existing words, merely arranged them for clarity and neutrality. I'm OC, I can't help it. You could have simply "trimmed" down the "excessive" quotes yourself, and left the rest stand as an improvement of the article as a whole. The outcome would have been very different if you had taken as much time to review all aspects of my edits as I spent trying to "work" some clarity into the (entire) existing text without offending previous editors. I tried replacing the entire article before, that didn't work either. Click. Gone. When you or others reflexively keep hitting the "revert" button, it effectively destroys the process of "editing" as I understand it. It is more helpful to provide guidance on particular issues. So, here are some points I would like to make:

• There does seem to be some consensus in the discussion that the article needs improvement. Yay, consensus. I agree. Thats what I'm trying to do.
• It is logically impossible to improve the article by hitting the "revert" button. Everyone think about it this for a minute, please.
• Let's all try to improve the article without the use of the "revert" feature, twinkle(ing) or whatever. Try actually editing. It's fun. Right up to the point where someone else "reverts" away all of your trouble.
• There is a lot of discussion logged above, but very little of it has anything to do with improving the article in terms of meeting wikipedia standards. Let's focus on issues relating to the content of the article, one at a time, make the edits, and improve the article one bit at a time.
• If anyone has a "problem", question, comment, or criticism of my edits, please bring it to my attention here instead of "revert"ing them away. I'm very happy to debate, discuss, educate, and or learn from others.
• If anyone reading this has something constructive to add to the article, please do so. If not, please leave the !@#$% article alone.
• Please remember that all of our personal opinions are actually irrelevant, the bottom line for wikepedia is verifiabilty, not "truth". I know it is possible to have both, but it will take some work to "prove" this from my resources. My edits may have stylistic "errors" but their intent and content is more in line with the purpose of wikipedia than the original text. Help me out here.

So, a little about me: I have more than 35 years of hands-on experience in the repair, maintenance, and operation of boilers, including VFT, locomotive, traction, Roberts, package, and power plant (B&W sinuous header). I have designed and constructed both mini and full sized VFT, Roberts, and Locomotive type boilers from scratch, including forging (flanging) the throat sheet, backhead and tube sheets by hand and hot riveting the joints. I have rebuilt, fired, driven, and operated many locomotive, traction engines, and all of these types of boilers in actual service. I have been fortunate enough to have worked extensively with several "mentors"; who were career "steam men" starting from the late 'teens of the previous century. I am also knowledgeable in the fields of physics and chemistry, and taught both subjects for a few years at the 12th grade (U.S.) and college levels. In the field of railway preservation I am a published author, and have worked for/with dozens of museums on several continents to preserve, restore, and operate historic machines of many types. I have also designed and constructed many custom machines, including a very specialized furnace that I created for the U.S. Navy, which was designed by me for use in studying the effects of corrosion on ferrous alloys at high temperatures (gas turbines), and is now on its way to a former NASA scientist to study ceramics at high temperatures (aerospace applications). Yep, I was born in the U.S. So sue me.

All of the above is completely irrelevant in this forum. What is relevant is that in my reference library I posses more than 600 volumes of primary source material (old books) pertaining to the technology, chemistry, physics and general science of the industrial revolution, dating from the 1840s - present. I have read at least some parts of every one, many all the way through. They contain a lot of information. A lot. Actually, nearly every book ever written contains some factual or technical errors, but more than 99 percent of the info is both in common to all and consistent with "Newtonian Physics". My real-life experience simply allows me to know what published information make sense and what doesn't. All of my edits are based upon my study of this material, not my personal opinion. I can and will provide citations for everything that I write, either immediately, or as time allows, as I stated in my original letter (see my "talk" page). If anyone has issue with what I write, post it here, we discuss, we fix. I think it could work.

@Andy Dingley

(cur | prev) 19:52, 5 September 2011‎ Andy Dingley (talk | contribs)‎ . . (13,394 bytes) (-366)‎ . . (Rust and fatigue have specific meanings, neither of which are significant causes of boiler explosions. Undid revision 448613240 by Tomtroszak (talk)) (undo)

Hi, Andy. Thanks very much for putting your comments along with your edits, which allows me to respond: My previous edit had been removed as being "too technical", so I was trying to be more chatty and vernacular... how about this?

Stress corrosion can induce an extreme degradation of strength in highly localized areas of the pressure vessel; i.e., necking at the ends of crown stays, cracks in the the knuckles of the tube and side sheets, grooving along the inside of lap seams, etc. which can result in weakening the boiler until it is no longer capable of withstanding normal working pressure. This degradation is the result of unequal forces acting through the stays between the firebox and boiler shell during repeated thermal cycling, or the bending forces acting upon offset plates due to constant changes in pressure; and is greatly accelerated by poor water quality including dissolved oxygen, and the presence of minerals which can cause the ferrous alloy to form salts in the boiler water, thereby thinning the plates until they fail.

Is that better? I can go either way.

According to The Hartford Steam Boiler and Insurance Company statistics for the early 1900s, boilers that failed inspection and were considered dangerous due to accumulations of scale, rust, soot, and crapped-out flues outnumbered stuck safety valves and the like by a factor of ten or more. A new boiler was usually designed to withstand a pressure of at least 3-5 times normal working pressure before bursting and so can easily survive a stuck safety valve for decades if it is not over-fired and then left unattended... And many, many reports of "bagging" crown sheets indicate that most locomotive or marine (flat top) fireboxes can withstand a significant amount of overheating without catastrophe (usually caused by scale, or overfiring, or both), at least when they are relatively new...

So in fact, the vast majority of boiler explosions have taken place at normal working pressure. Therefore... (long drum roll) in terms of raw statistics, the number one killers really are... (cymbal crash): Rust and Fatigue.

If you compare information from various sources you can see a coherent trend:

• New boilers can be seriously mistreated and still survive.
• Old, thin, cracked, crappy boilers can be operated carefully for decades.
• Old, thin, cracked, crappy boilers that suffer a low water event along with a stuck safety valve (at the same time) are probably going to blow.

Boiler explosions really don't "just happen", the great majority seem to have been caused by gross, criminal, aggravated, unjustified neglect combined with a serious operator error.

(cur | prev) 09:35, 6 September 2011‎ Andy Dingley (talk | contribs)‎ . . (13,394 bytes) (-393)‎ . . (rv - uncited claims. "Rust" is _hugely_ misleading here. If you have evidence for rust, in the sense of atmospheric oxidation of iron, then show it.) (undo)

Hi, Andy. One of my previous edits had been removed as being "too technical", so I was trying to be more chatty and vernacular by using the greatly oversimplified but commonly understood word "rust", instead of the all-encompassing but highly complex word "corrosion". IMHO, not hugely misleading, merely oversimplified. My verification for the use of the oversimplified term comes from this well-respected published source, and throughout the chapter the words rust and corrosion are used interchangeably:

Q. What is corrosion? Ans. Chemical action which causes destruction of the surface of a metal by oxidation, rusting. ^ Graham, Frank D. (1945) "Audel's Power Plant Engineers guide" New York, Ny: Theo Audel and Co. (p.333)

You or anyone could have simply inserted the better word "corrosion" in place of the simple word "rust" into my text, the meaning would have been the same. — Preceding unsigned comment added by Tomtroszak (talk • contribs) 19:21, 7 June 2012 (UTC)

Hi Tomtroszak, thanks for the comments.

This is a difficult article. It's covering 200+ years of history, during which boilers have changed an awful lot and the reasons for their explosions have changed too.

First of all, I'd agree that grooving (in its very specific term as applied to boilers) is a crucial cause of boiler explosions. However it was also a fairly short time for which it was a major cause of explosions - locomotive boilers at increasing pressures, before the importance of a lap strip, rather than lapped plates, was realised. The boilers failed because of grooving, the grooves developed because of stress corrosion - with an emphasis on stress here. Since the edit we're discussing, a section specifically on grooving has been added. "simply inserting the better word "corrosion" in place of the simple word "rust" ", alone would not have been an adequate change.

I still don't consider that "rust and fatigue" are acceptable terms here. Rust implies simple atmospheric rusting, as a generalised process around the entire boiler. Whilst it has surely been the cause of some accidents in some unmaintained boilers, the point about why grooving was so dangerous is that it was an exceptionally damaging form of corrosion that took place for unexpected reasons. Any competent owner or operator won't use a rusty boiler, it's obvious that it's dangerous and very few operators were ever so careless. Grooving caused explosions because it was unexpected and caught out conscientious operators too - at least until its cause was recognised. Nor is 'fatigue' appropriate. Yes, boilers probably suffered from fatigue too - yet a failure by fatigue has a specific meaning, contrary to that of grooving (grooved boilers fail because they're locally thin, fatigued would be a local weakness in full-thickness plates). I don't see fatigue failures as being the specific cause of significant numbers of explosions, in the way that grooving was. Grooving is caused by stress corrosion specifically. "Rust" is wrong. Where fatigue was a cause, it was almost always in firebox sling stays, not plates, and not even in firebox bolt stays.

Presenting a simple historical list of reasons for boiler explosions is of course over-simplified. Yet if we had to, I think this would come down to three phases: over-pressure (either weak designs or tied-down safety valves), unexpected wear mechanisms like grooving (new powerful boilers developed unexpectedly rapid failure modes), then lack of water accidents (usually leading to crownsheet failures). Failures due to lack of maintenance (either over-use of worn-out boilers, or failures caused by poor washout and localised overheating) have been something of a constant throughout. Andy Dingley (talk) 11:45, 10 June 2012 (UTC)

note on rust

Andy Dingley wrote: I still don't consider that "rust and fatigue" are acceptable terms here. Rust implies simple atmospheric rusting, as a generalised process around the entire boiler.

Hi Andy! To most folks the term "atmosphere" perhaps implies only pure, dry air, and "rust" implies only a generalized thinning of metal plates by simple oxidation, due to the presence of oxygen in the atmosphere surrounding the plate. However, if ferrous metals are placed in an actual atmosphere of pure, dry air "rusting" (oxidation) occurs very slowly, or not at all. In an atmosphere of damp air, "rusting" (oxidation) proceeds more quickly as the moisture in the air acts as an electrolyte on the surface of the metal, and tiny charged "cells" form in each and every crevice of the surface of the material. In an atmosphere of liquid water, "rusting" (oxidation) is increased exponentially. The conductivity of the water allows any oxygen present in the water to couple with the iron in each "cell" in the plate, molecule by molecule, forming rust via simple oxidation. All you need is iron, water, and air. Every boiler that receives untreated water from any source has plenty of all three. Minerals in the water increase the conductivity and could also form salts with the iron and so contribute to either thinning or pitting, but they are not necessary for severe damage to occur, and not necessarily applicable to all boilers in all circumstances. To be sure, "fancy" forms of rust do help out, but simple oxidation is still king in terms of the tonnage of iron dissolved, and number boilers ruined in the last two centuries. Whether it be shallow or deep, localized or widespread, inside, or out... Rust is Rust. Mr. Graham is correct enough, and the citation makes the usage good enough for WP.

In all cases, if the surfaces of the plate and the level of exposure to moisture are both relatively uniform, the oxidation process removes iron from the entire surface more or less evenly. If the surface is rough, or some particular area collects moisture preferentially (like under a jacket, between studs and brackets, etc.) then "pitting" or highly localized oxidation occurs. Surface cracks from any cause such as stress, or any other crevices also form electrolytic "cells" which greatly increase oxidation corrosion in those specific areas whether inside or out, inherent in the design, or the result of previous corrosion. Some types of iron oxide also attract and retain water, so rust often begets more rust. Little pits collect moisture which begets bigger pits. Soot can make the moisture more acidic (more conductive) which speeds things up as well.

Hmmph. After I wrote all that I found these quotes for you:

''Qualitatively we describe corrosion as the deterioration of medals by a product-favored oxidation reaction. The corrosion of iron for example converts iron metal to red brown of rust which is hydrated iron (III) oxide Fe2 03 + H2O. The process requires both air and water and it is enhanced if the water contains dissolved Ions and if the metal is stressed (dents, cuts and scrapes on the surface) The corrosion process occurs in what is essentially a small electrochemical cell. There is an anode and a cathode, an electrical connection between the two (the metal itself), and an electrolyte with which both anode and cathode are in contact. When a metal corrodes there are anodic areas of the metal surface where the metal is oxidized and cathodic areas where electrons are consumed by several possible half reactions. With iron the rate of the corrosion process is controlled by the rate of the cathodic process."

"Of the three possible cathodic reactions, the one that Is fastest Is determined by acidity and the amount of oxygen present."

"If both water and O2 are present the corrosion reaction is about 100 times faster than without oxygen."

Chemistry and Chemical Reactivity, Fifth Edition. Copyright 2003 Thomson Learning Inc. Tomtroszak (talk) 14:02, 12 June 2012 (UTC)

notes on grooving

Andy Dingley wrote:

"Grooving caused explosions because it was unexpected and caught out conscientious operators too - at least until its cause was recognised. Nor is 'fatigue' appropriate. Yes, boilers probably suffered from fatigue too - yet a failure by fatigue has a specific meaning, contrary to that of grooving (grooved boilers fail because they're locally thin, fatigued would be a local weakness in full-thickness plates). I don't see fatigue failures as being the specific cause of significant numbers of explosions, in the way that grooving was. Grooving is caused by stress corrosion specifically. "Rust" is wrong. Where fatigue was a cause, it was almost always in firebox sling stays, not plates, and not even in firebox bolt stays."

Hi Andy! I think we can sort this out. The term "stress corrosion" refers to corrosion that occurs only in specific areas, due to microscopic cracks on the surface, caused by stress. The specific mechanism of "grooving" is stress cracking, followed by deep, localized corrosion of the cracks, in a self-reinforcing cycle:

• The grooving process begins as the constantly fluctuating shape of the boiler shell (due to changes in pressure and temperature) causes minute longitudinal stress cracks (fatigue) in the surface of the metal immediately on either side of the overlap.
• The minute cracks on the inside become anodic "crevices" in contact with the boiler water and form corrosion "cells" which then greatly accelerate the corrosion or enlargement of the original cracks.
• As the cracks deepen and enlarge, the original load stress is now being concentrated at the root of the ever-deepening groove
• The constant cycling of the now-concentrated stress induces progressively greater fatigue on the little bit of metal that remains.
• The end result is extreme, localized fatigue of the plate next to the lap, on the inside, where it is not easy to spot.

Remember that the stress which is causing the initial minute fatigue-induced cracks caused is the same on both sides of the seam. These would be invisible to the naked eye at first, because the actual stress is relatively low. The microscopic cracks on the outside progress very slowly because it is relatively dry. The development of a deep, sharp groove in an otherwise sound plate progresses most rapidly under the water, less so in contact with steam, and hardly at all on the outside. So, the lap-seam "grooving" phenomenon is not so much caused by stress corrosion but rather, it is a specific example of it.

notes on fatigue

One definition of fatigue (used as a verb) is "to crack or break (a material or part) by inducing fluctuating stresses in it, or (of a metal or part) to become weakened or fail as a result of fluctuating stresses". So, as we see above, a lap-seam failure due to "grooving" is a specific type of fatigue failure that occurs in an otherwise full thickness of plate due to the fluctuating forces and the ever increasing concentration of stress caused by localized corrosion.

Fatigue due to thermal stress cycling, which is caused by the unequal thermal expansion and contraction of the firebox plates, the firebox stays, the tube sheets relative to the outer shell of the boiler, is a root cause of failure of those parts:

• Heating of the firebox, tubesheets, and tubes causes a difference in temperature between the heated components and the rest of the boiler.
• The more rapid the heating, the greater the differential in temperature between the heated and non-heated components.
• The greater the differential in temperature between the components, the greater the stress on the components.
• Whenever a previously hot component is rapidly cooled, the stresses are reversed.
• The more often (or rapid) the change in temperature, the greater the fatigue.

Stress corrosion can further increase the stress (and fatigue) on any component, by weakening it at the point of greatest stress. Fatigue compounded by stress corrosion is the exact same mechanism that causes "necking" at the ends of firebox stays. In addition, the minute cracks that form from fatigue near the ends of firebox stays can also act as "tooth" or a roughening of the surface which provides a better "anchor" for hard scale to attach, and the cracks hidden under a thick layer of scale then become "anodic", etc., etc.. Unless the boiler design itself is defective, the stress on any component caused by the working pressure of the steam is small by comparison to the stress caused by thermal shock. Tomtroszak (talk) 16:14, 12 June 2012 (UTC)

@EdJogg

(cur | prev) 01:03, 8 December 2010‎ EdJogg (talk | contribs)‎ . . (12,353 bytes) (-313)‎ . . (excessive use of templates -- assumed vandalism -- Undid revision 401142600 by 75.216.108.158 (talk)) (undo)

Dear EdJogg, That was me attempting to "challenge" the content of the article that I found questionable from both a scientific and verifiable source perspective. I hadn't logged in properly, my apologies. The excessive use of templates was based on the excessive quantity of content in the article that I found objectionable. However, regardless of the origin of the templates that were inserted into the text, instead of rising to the "challenge" to provide citations to prove that the material in question was verifiable by a published source, you simply removed the templates. Seems rather unsporting, don't you think?

2012.06.12 verification of my edits to "principles" section (finally)

I wrote my original description in my original edits to the article from memory, but I finally today (years later) found one of several descriptions of the "water hammer" explanation from a verifiable source:

"the following experiment made by the United states inspectors: A cylindrical boiler was tested and withstood a steam pressure of 300 pounds without injury." " When the [discharge] valve was suddenly opened at a pressure of 235 pounds the boiler gave way, the iron being twisted and torn into fragments and thrown in all directions. The reason for this was that the sudden rush of steam from the boiler into the discharge pipe reduced the pressure in the boiler very rapidly. This reduction of pressure caused the sudden formation of a great quantity of steam within the water, and the heavy mass of water being thrown with great violence toward the opening whence the steam was being withdrawn, struck the portions of the boiler near that opening and caused the fracture." The Colliery Engineers Company (1900) Locomotive Boilers (I.C.S. Reference Library #59) Stationer's Hall, London: International Textbook Company (Sec.12-p.76)

woop-woop. I knew I had it somewhere. Turns out it was in one of the books that I have been using already for other references, which was lying out on the floor all this time. No wonder I couldn't find it.Tomtroszak (talk) 16:55, 12 June 2012 (UTC)

Anglo Bias and lack of regulation

I came here from Technischer Überwachungsverein ( English ) and the initial comment:

The TÜVs originated in Germany in the late 1800s during the Industrial Revolution, following the explosion of a steam boiler at a brewery in Mannheim in 1865. This led a group of engineers to found the first Dampfkessel Überwachungsverein (DÜV, Steam Boiler Inspection Association) and soon similar associations were created in other German cities and these came together in an association in 1873.

So I was interested in when each country started regulation; nothing here mentions how or when each began, or influenced other countries' regulation, nor how severe different countries were in applying such.

This article and the corresponding List of Boiler Explosions are almost entirely American and to a lesser extent British concentrated. I know for a fact that 19th century France had some bad accidents, and I would imagine boiler explosions happened from China to Peru.

A ( induced ) boiler explosion is a plot point in Thomas Armstrong's King Cotton set in the 1860s ( decided upon as a teachable moment for an employer willing to ignore regulations ). Claverhouse (talk) 19:21, 30 October 2017 (UTC)

The history of boiler explosions is quite different in each country. In the UK, steam was widely used from the earliest, so explosions were encountered through stationary boilers. This became an economic problem, leading to the setting up of mutual insurance companies, such as the Manchester Steam Users Association, who then imposed construction, maintenance and operation standards in order to reduce the number of explosions to an affordable level.

In the US, most explosions were on riverboats, which led to regulation for the crew of such boats (and eventually the naphtha launch). In much of Europe, the problems were first encountered through railway locomotives.

The bibliography here has the two main books, but McEwen's other books are good too and Hill's Power from Steam is important too. Andy Dingley (talk) 20:10, 30 October 2017 (UTC)

That doesn't explain why only American and British boilers and explosions are covered in this article. Nor the lack of mention of regulations.

Countries may have had different explosions; but the same boiler will blow up anywhere it is installed --- so what regulations apply to a British-made boiler will affect the same boiler in Argentina: you wouldn't expect a carmaker to vary running advice according to where sold. Every maker learns from every other country's innovations, particularly in the 19th century. Claverhouse (talk) 23:00, 30 October 2017 (UTC)

Welcome to Wikipedia. Articles here, and the sections of content within them, exist because someone wrote them. The bits that aren't there probably aren't there simply because no-one has written them. As this is the English language Wikipedia, then it is likely that UK & US topics get covered first. This isn't anti-European bias, it's just covering what's nearest first.

So what would you like to see added here?

Also it was a recognised problem that workable boilers often failed when mis-used outside their maker's control. Poor feedwater supplies, and a lack of regular washouts, were a common problem. Andy Dingley (talk) 22:48, 31 October 2017 (UTC)