3"burrell

hi

my 3" burrell has a steel boiler with expanded steel tubes i keep having problems with tubes going.

have been thinking about using copper tubes anyone have any ideas

cheers

pete

You might have problems with difference of expansion steel vs copper. What problem are you experiencing? Leaking and or corrosion?

Hi Peter I used to make steam generators for an industrial processes for bending wood. They were made by two plates with a pattern of holes with grooves like circlip grooves in the holes. The lengths of copper tube were expanded into the holes with a special tool like an expanding ream but with ball bearings instead of cutting blades. They were pressure tested to 20 bar on assembly with the case and end caps.

David

hi mike

i steam up today and a single tube started leaking when it got above 30 p.s.i

this the second time it has happened in about eight years but it is a total strip down

to remove the tubes as i wouldnt just replace one tube because others could fail

with regard to copper tubes my theory is copper expands at a greater rate than steel

thus helping it to be water tight

regards

pete

Peter,

8 years from a re tube to leaky tube? Or second re-tube in 8 years? Assume the leak is due to perforation of the tube and not from the expanded tube plate joint? If the latter you can have a go at re-rolling, if the former, yup best idea is change all the tubes!

Plenty of reasons why your tubes may be failing which I guess you already know but to summarise, poor quality tubes (plenty about), poor boiler water management (water treatment), perhaps a poor lay up routine between steamings / seasons, etc. Most full size boilers are re-tubed every 10 years, unless the boiler inspector is really impressed with condition.

To answer your direct question plenty of boilers have used copper or even cunifer tubes (less of the latter I feel). Easy to fit, easy to go too mad when rolling them in and make them thin, tend to last well, (I have a 2” TE steel boiler with copper tubes, been in there years with no issues). Not tolerant to low water conditions, not tolerant at the firebox end (yes they do expand more when hot but they deform plastically so however hard you roll them once heated a few times the fit can only be so tight). Copper can be re-rolled a few times, cunifer is prone to cracking if you re-roll. However, if you get an issue they can be right b######s to get out and replace! If you go that route it’s worth getting a tube smaller than the tube plate hole and then have the ends swaged out to suit the tube plates for rolling, then if you are lucky you can cut the ends of the tubes, drive the ends inside the boiler and thread the tube out easily through the plate (descale before you start though). Then retrieve the ends you drove in through the man hole, but I suspect on a 3” you may not have a manhole? In which case you are a bit stuck! This is all because with steel tubes even when rusted they generally still have enough compressive strength to be able to drag them out with a stud or hollow jack and rod. You can’t pull copper tubes in the same way, they just collapse under the tension, get too big for the hole and you have no way of getting them out. That means burning out the smokebox tube plate, making a new tube plate and welding back in before re-tubing in the normal manner, probably the quickest way!

If you are on the second set of tubes that have perforated then maybe you need to have a detailed inspection of the shell as that may also have corroded beyond limits unless they were poor quality material. It’s all steel and it all rusts! Have a careful check of the bottom of the barrel at the front tube plate and the bottom third of the tube plate.

So, by all means you can fit copper tubes, that may be the last set of tubes you fit before the boiler becomes scrap or needs extensive work. Before you do anything I would talk to your boiler inspector and try and work out why you are getting these failures and assess the rest of the boiler and then make an informed decision. Best plan is to get a replacement set of steel tubes with traceability to Germany or UK, don’t touch material from China with a barge pole, likely to have inclusions that will result in lots of pin holes that look like someone has drilled a hole in them! Probably also worth annealing the ends as well before you fit them, although some don’t.

Paul.

hi paul

thanks for your reply

this the second tube failure in 8 years and yes a perforation not a joint failure

with regards to lay up over the winter i,m not sure of the best solution whether to have the boiler

full or empty last winter i had it full .

i,m not sure which way to go with replacement tubes i will decide when when i have the old ones stripped out

its a lot of work which ever way i choose

regards

pete

Peter,

The age old debate, how to lay up a miniature steel boiler! The basic question is as you say, full or empty. If it’s going to be full, then my approach would be on the last steaming before you let the fire go, blow down about half a glass and then as the fire dies down fill it - right up to the top with well treated water, right to the very top! Idea being to get as much water in to dispel as much oxygen as possible and with it still in steam the boiled water should have the minimum free oxygen content. I know a fellow with a 4” Foster that fills to the brim every winter and his boiler is still on the original tubes and is in exceptional condition.

If it’s going to be empty, then it needs to be exactly that, empty and DRY. This on a small boiler is hard to achieve as unless you have a decent manhole and wash out plugs it’s very hard to get the air to circulate within to get it dry. While some hold hands up in horror one way to get it dry is to light a small wood fire (SMALL!) to get a little heat into it to drive off the moisture - if you are careful you are not going to heat it up to the point of damage, you don’t want a steam raising fire, just a small warming fire!

If you are going to use steel tubes, quality is very difficult to maintain but to last you need good known material. There have been innumerable reports of latter day boiler tubes not lasting the distance, a few full size have suffered tube failures in 2 years in extreme cases! There is on the web a very good report dating back to the 80’s if I remember rightly where they conducted a detailed metallurgical examination on a marine boiler smoke tube that suffered localised corrosion and under the microscope they found the material at the pit held an impurity inclusion from the steel production and mill drawing process. I would strongly recommend finding a supplier that sources the material from a reputable mill that is making steel from the ore, not recycled scrap and try to get a certificate that evidences the source, still not guaranteed but probably the best you can do.

The last bit (which is also controversial and subject to many opinions) is water treatment. Some love it, some hate it, personally I am in the in between camp and use it and try and maintain a regular regime and concentration taking the view is it is unlikely to do any harm and if it does some good, it’s definitely not bad!

Lastly if you want to get through to the winter and it’s only one tube, turn up some shallow taper plugs and blank that one off by knocking one in each end or even putting a long stud through them (don’t overtighten though). Worked on full size back in the day to get them to a point where they could plan the job proper ( check your boiler inspectors attitude first though).

Good luck,

Paul

There are lots of steel boilers with copper tubes, even in full size locos. My engine has a 10" dia steel shell and 1" dia copper tubes which have been expanded with a tube roller and I have not had any problem with leaking.

It has been stored, both dry and wet with a fully filled boiler.

even full size locos.