High pressure "hobby" boiler question

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Hey guys, its me again, One of the engineers at my work is really into (read: one track mind, no pun intended) scale steam trains, like just big enough that you can ride them around and do whatever it is you do when you pretend to deliver cargoanywho, he brought in his engine, there was a large crack/ hole from the firebox into the water reservoir (picture the big tube on the old time steam engines)I dont think I can reweld it, the hole sits right next to one of the copper exhaust tubes, and its very pitted and corroded. Also, I dont think I mentioned this, buts its also running at 100lb of steam when functioning correctly. If I were to weld it, as soon as I ran near the copper tube it would mix with the puddle and contaminate it.so he asked me and my supervisor if we wouldn't mind building him a new one. Does anyone here have any experience with stay-bolts? any knowledge would be helpful, and also, maybe if someone here is into the same thing, some upgrades we can do over the old model hahathanks a ton guys!Miller Spoolmate 200 w/t S-52 WirefeederMM 211'09 Miller Trailblazer 302
Reply:You might look at some of the steam engine groups for examples of what is in store for you.  Keep in mind that a steam boiler is a pressure vessel in the extreme and unless the boiler is extremely small is subject to steam boiler codes.  That means the building and repair of the boiler must follow code and be inspected by the local steam boiler authority.  Otherwise you open yourself up to all kinds of liability.   The copper tubes in a steel boiler sets up galvanic corrosion.  Likely part of the failure you are looking at is from corrosion rather than stress.   There are people online that contract to build scale model boilers and they have all the paperwork to back them up so that you conform to code.    Yes you could make another pressure vessel but have you ever swaged copper tubes into the shell plate of a boiler?  It takes a bit of practice to get it right.  If you expand the copper tube ends too much you get a weak joint.  if you don't swage enough you get leaks.   From your description you will need proper pressure certified pipe as well as certified plate.  You will need to layout, drill and ream to size all the holes for your water tubes then weld the assembly together partially before installing your copper tubes.  The copper tubing also is likely no regular water tubing bought at the local hardware.  Likely it is a specific wall thickness.   I looked at these problems myself and decided to just move on.... any model steam engines I make. (they are definitely amateur), run on compressed air.
Reply:You may want to take a look at the California live steamers website. They have links to forums on building steam locomotives. Most of what they have our 1/8 scale. I used to take my kids there to ride the trains. It is a really cool place.
Reply:I was going to ask a dumb question; is there a reason that these are not silver soldered together?     But when I looked at the galvanic table silver was way at one end, so would probably have bad problems with galvanic corrosion.    The liability seems pretty extreme, I would not touch it with a ten foot pole.Sculptures in copper and other metalshttp://www.fergusonsculpture.comSyncrowave 200 Millermatic 211Readywelder spoolgunHypertherm 600 plasma cutterThermal Arc GMS300 Victor OA torchHomemade Blacksmith propane forge
Reply:Let me add that stay bolts aren't really bolts any more but solid round bars  usually same dia as tubes ,that is welded on both ends to the tube sheet, some have weep  or telltale holes center drilled  in them so you can tell if they are broken. A few years ago a guy wanted me to weld on his small boiler , I told him I could but I couldn't put an R or S stamp on it as I wasn't Licensed for that.
Reply:Well let me clear up a few things,The boiler being the size that it is falls under what is known as a "hobby boiler"https://malegislature.gov/Laws/Gener...er146/Section7And from my understanding, the 100PSI limitation doesnt apply if the grating area is smaller than whatever the law says. So no worries, also, my supervisor who is along with this project is a pipewelder by trade, and from a long career of welding process piping and gas pipe welding. No lack of skill on our end anyways.@lotechman The gap was definitely caused by corrosion, 25 years worth I was told. There was no feasible/safe way of making the repair, hence opting to build a new one. I have a background in HVAC as well so no problems swageing the copper tubing. @gxbxc Is that so! I had found a diagram on the internet of staybolts and i was wondering what that center hole was for! wouldnt those create a weak point though? The diagram I looked at it looked like both ends of the rod were threaded into the plates and then plug welded. Does that sound correct?Miller Spoolmate 200 w/t S-52 WirefeederMM 211'09 Miller Trailblazer 302
Reply:Not threaded just welded  Also that exception you quoted is for annual inspection of boilers ,requires for insurance, not the manufacture But it may vary from state to state .Last edited by gxbxc; 11-14-2014 at 05:15 PM.
Reply:Originally Posted by gxbxcNot threaded just welded  Also that exception you quoted is for annual inspection of boilers ,requires for insurance, not the manufacture But it may vary from state to state .
Reply:I stand corrected on the threaded stay bolts .
Reply:Originally Posted by gxbxcI stand corrected on the threaded stay bolts .
Reply:Originally Posted by Ian Duffinbecause these are so small, and are exempt from inspection, I "legally" can build them without adding the stamp (The law page that I quoted seemed pretty limited in its explanation, I'll do some more research on the subject but I feel reasonably safe working on something like this)
Reply:I'm a former commissioned boiler inspector and have investigated several bloody boiler failures of all sizes.It simply doesn't matter IF your project falls under certain local codes based on size or pressure because the consequences of failure are the same-someone gets hurt or dies and usually there are huge monetary damages too.Please keep this in mind....We folks are masters at creating working "toys" of steam engines and even jet planes, but those toys often possess the same destructive potential of the real thang.I do NOT doubt your ability to make a sound weld repair to this vessel, and commend you for pausing to ask before you attempt it, but I suggest you keep asking and learning before you attempt it. There are better forums than this for your questions.  Find them and post pics and enjoy what you learn there.Stay bolts take many shapes and are attached in many different fashions. Some are hollow to provide visual evidence that they have corroded tru and will leak at their ends. Stay bolts are found even on modern boilers and pressure vessels. They are used to "stay" mainly flat surfaces subjected to internal pressure. On a firetube boiler like you are dealing with, the tubes provide the required support except for the area above the tube sheets where they are required. You will also find them in the "water legs" that drop down and surround the furnace and flat crown sheet above the furnace. Sound stay bolts are absolutely critical to pressure vessel integrity and must be properly installed and NOT reduced by corrosion.Tubes are usually "rolled" in place, but often then seal welded especially in really hot areas like where they join rear tube sheet of first pass. IAW the NBIC and ASME Code, repairing a tube does not require special stamps or certifications, but good sense and fear of your life should urge you to take extra care there.To help you keep safety in perspective I'll offer this...Water, when heated to the boiling point, will expand INSTANTLY 1608 times in volume when pressure is released to atmospheric pressure. Water/steam expands at same rate as TNT when above boiling point and suddenly released, no matter if it is at 100 PSI or 1200 PSI.
Reply:Originally Posted by wornoutoldwelderI'm a former commissioned boiler inspector and have investigated several bloody boiler failures of all sizes.It simply doesn't matter IF your project falls under certain local codes based on size or pressure because the consequences of failure are the same-someone gets hurt or dies and usually there are huge monetary damages too.Please keep this in mind....We folks are masters at creating working "toys" of steam engines and even jet planes, but those toys often possess the same destructive potential of the real thang.I do NOT doubt your ability to make a sound weld repair to this vessel, and commend you for pausing to ask before you attempt it, but I suggest you keep asking and learning before you attempt it. There are better forums than this for your questions.  Find them and post pics and enjoy what you learn there.Stay bolts take many shapes and are attached in many different fashions. Some are hollow to provide visual evidence that they have corroded tru and will leak at their ends. Stay bolts are found even on modern boilers and pressure vessels. They are used to "stay" mainly flat surfaces subjected to internal pressure. On a firetube boiler like you are dealing with, the tubes provide the required support except for the area above the tube sheets where they are required. You will also find them in the "water legs" that drop down and surround the furnace and flat crown sheet above the furnace. Sound stay bolts are absolutely critical to pressure vessel integrity and must be properly installed and NOT reduced by corrosion.Tubes are usually "rolled" in place, but often then seal welded especially in really hot areas like where they join rear tube sheet of first pass. IAW the NBIC and ASME Code, repairing a tube does not require special stamps or certifications, but good sense and fear of your life should urge you to take extra care there.To help you keep safety in perspective I'll offer this...Water, when heated to the boiling point, will expand INSTANTLY 1608 times in volume when pressure is released to atmospheric pressure. Water/steam expands at same rate as TNT when above boiling point and suddenly released, no matter if it is at 100 PSI or 1200 PSI.
Reply:Originally Posted by KelvinDo what you want, but I wouldn't take too much comfort in the fact that you can "legally" do it. Lawyers make their living by suing people and you don't need to have broken any law for someone to sue you and win a big judgment ... or put you in the poor house from the legal fees of defending yourself, even if they don't win. People sue each other for looking at each other cross-eyed nowadays, and when somebody gets hurt, juries are inclined to feel sorry for them and side against the defendant even if they did nothing really wrong...personally, I wouldn't touch it even if I did feel qualified. 100 psi steam is 337°F
Reply:After you primed my couriosity  about stay bolts. I did some searching around the web  and found a reprint of a 1902 story about boiler making and metal trades scholarships for you men and boys to learn the trade , It seems that in 1902 they had a shortage of skilled metal workers much like we have today.
Reply:Originally Posted by Ian DuffinThank you for the explanation, and believe me, my boss has pounded the destructive potential of steam into my head a million times!
Reply:Originally Posted by gxbxcAfter you primed my couriosity  about stay bolts. I did some searching around the web  and found a reprint of a 1902 story about boiler making and metal trades scholarships for you men and boys to learn the trade , It seems that in 1902 they had a shortage of skilled metal workers much like we have today.
Reply:http://www.smokstak.com/forum/forumdisplay.php?f=7This forum is for traction steam but the boilers are the same. Someone there may be able to recommend a rail road site.  DanManipulator Of Metal
Reply:Go read this:http://newsok.com/star-elementary-20...rticle/2779122This happens in our houses on regular basis...Simple water heaters explode routinely....Usually they blow up thru the roof and make huge mess but only make local news for just one day.They are usually NOT firery gas explosions, but instead steam explosions due to overheating and over pressurization from faulty pressure/temp controls. A simple 40 gallon electric water heater can totally destroy average size house and does so on routine basis.
Reply:I'm a licensed power engineer myself. I'm also a certified welder. My advise to you is to wash your hands of this project. I wouldn't touch it.JasonLincoln Idealarc 250 stick/tigThermal Dynamics Cutmaster 52Miller Bobcat 250Torchmate CNC tableThermal Arc Hefty 2Ironworkers Local 720
Reply:Hi pressure steam  @ 1,000 psi is like 550 degrees  and will not condense for about 10 or more feet , when we ran the super heaters   on are plant you could hear a leak even with the plant noise . operators used a broom to wave in front of them when they were looking for a leak, It would catch fire when the steam hit it. .
Reply:I grew up in Navy destroyer engine and boiler rooms. We ran 1320 PSI superheated steam right off the superheater and experienced many leaks. Those leaks were super small but deafening and intensely hot. We could lite our cigs off the root steam piping once we drilled small hole in the insulation.I'm glad you appeared here and asked about welded repairs to steam boilers. It's becoming a lost art and guys like you are needed to keep it alive safely. Please read all you can on it and don't hesitate to attempt to help your friend once you get some knowledge.Remember this....Modern boilers are now built to ASME Code or it's equilivent all over the world. That volumous code is totally written in human blood....It's a difficult read and we in the industry say ASME stands for "always, sometimes. maybe and except", but it totally Rules where if used it factors in 5 X overkill....Yet even then boilers still expode.Go for it and enjoy the experience. you will appreciate it all the more once you understand fully that your efforts and cautions allowed you to safely make that sucker run again.
Reply:Originally Posted by wornoutoldwelderYup, back about 1900 over 50K/yr people were being killed by boiler explosions....No joke, that many.That was the age of the great steam revolution and ANYONE could build a boiler and they did...So they did and of course they exploded like popcorn all over the country.FINALLY, a very smart engineer studied the problem and learned that most failures were related to poor design, material quality controls, and improper operation and maintance.....As a result of his efforts he designed boilers and complete boiler plants, but could not sell his designs unless he offered insurance to back up his claims.So, to sell his designs he had to first become an insurance man. That was the birth of Hartford Steam Boiler Inspection and Insurance Co.....They are still in the business, we they gave birth to our present day ASME and NBIC codes that are now adopted by every state and many parts of the world.I received my commission thru Hartford over 20 years ago
Reply:Sounds like a pretty cool project. With your skill and experience in your shop and a the customer being a engineer, it sounds like a fun thing to do. You should make a thread and post pics along the way if you do decide to go this route.
Reply:My old shop teacher back in highschool was on a navy ship, he told me that steam leaks in those vessels were loud as all hell, and to find them they would wave a broom stick in front of them, and if they were close to the leak it would cut the broomstick in half!!Steam has always had my interest because of how powerful and useful it could be, I understand everyones concern with the subject, but I am confident enough in my abilities, and those along with me for this project that everything will be fine.and to @SR20steve, I will start a thread when we start building it and post pictures, it will be a pretty fun undertaking.@wornoutoldwelder Thank you for the vote of confidence, Ill see if I cant tag you in the post when im done with it, and all of the pictures with the build!Miller Spoolmate 200 w/t S-52 WirefeederMM 211'09 Miller Trailblazer 302Fascinating thread!! Best regards, Bob
Reply:Ian,I highly recommend you get a subscription to "Live Steam" magazine.  http://www.livesteam.net/It's geared specifically to what you're talking about doing.