Steel boiler materials

[ejparrott]

I've spent an awful long time looking to find the required or acceptable specs for the steel bits for model boilers. To that end, I thought it would be a good idea to have a thread which listed them.

For my barrel, I asked for seamless hot finished to EN355EN10297/1 and have been offered ASTM A106

For the platework I asked for BS1501:1980161430A/B and was offered BS 1501 161 430A/B. A google search of both will bring up material specs.

Now, what I have yet to find....

What grade of round bar should be used for rod stays, either as plain rod or if screwcut to form a threaded stay?

What grade of round bar should be used for making fitting bosses, either for a bolted flange, parrallel ME thread or tapered BSP/NPT thread? I'm thinking things like the 4-bolt flanges for the water gauges, and the taper threaded fusable plug boss.

Cheers

[elly]

3b is what gns used,make sure you get certs,
For it.

[ejparrott]

3b, really? That does surprise me, I was expecting something tougher than that! 3b's no problem, Macreays will supply it in 3m lengths only, but at least its a material that will get used in a whole multitude of jobs.

Certs very important yes.

[weldsol]

On my Shay boiler for the stays and bushes I used black bar BS EN 10025 S275JR with a 3.1 test certificate

Paul

[ejparrott]

I may be completly wrong, and I'd appreciate someone telling me if I am. It seems En3b is due more credit than I give it...according to The Orange Book (Macreadys) En3b has a tensile strength of 32 ton f/in^2 minimum at a size of 16mm/5/8". A google search found me a calculator which converte that to be 492.8MPa, which is at the bottom end of the range on a table here:

www.metals4u.co.uk/EN3B-Bright-Mild-Steel.asp

That seems to convert then using another google calculator to be 71474.6PSi which is a value that will fit in with the stay bolt equasion here :

www.classicsteamengineering.com/index.php?action=printpage%3btopic=250.0

and allow me to calculate the MWP of a 5/8" stay....yes?

[ejparrott]

Sept 27, 2012 8:25:57 GMT weldsol said:

On my Shay boiler for the stays and bushes I used black bar BS EN 10025 S275JR with a 3.1 test certificate

Paul

We've been using 30mm square S275JR bar for rings at work, rolled and welded. Its apparently a bar form of 43a plate, and it certainly is much more stable than the En3/070M20 bar that we also use, and cheaper! Unfortunatly google has yet to find me a source of round bar, need to contact Macreadys I think.

[weldsol]

I also used ASTM106B for the tube and LT50 BS1501-224-490B for the plate material

Paul

Also I think the EN3B bright bar only comes with a 2.2 test cert

[ejparrott]

Is there are requirement for what certificate is required for the material or not? The materials purchaser at work believes you are correct and EN3B does not come with a 3.1, but if GNS are using it on commercial boilers.....

[mutley]

My steel boiler has EN3b stays and no cert of compliance was include for the reason above. Didnt seem to both LLoyds the notified body who inspected it.

A

[ejparrott]

I've had another person say EN3b too, he also says he doesn't have certs for it, and has never been asked for it.

[elly]

I know that certs were needed for the insurance company, and also the insurance company wanted to have each inner firebox heat treated.

later boilers were laser cut and different material for the stays but these
were for largeish locomotives

[weldsol]

I suppose it depends on how boiler testers interprit the insurers requirements for what cat,your bar/ltr puts your boiler into
On the last two of my boilers I have had to produce certs for all materials and consumables used in the construction, Also I had to stamp the cert number on each visible part i.e. boiler shell, Backhead, side plates and front tube plate.
It is all to do with tracability

Paul

[ejparrott]

I'm going to have a chat with warker midgley at the show, assuming they're there, and see what they have to say. Our club isn't insured with them I don't think at present, but they should still be able to give me the right answers.

If I do use EN3b, I'll get certs for it anyway.

[fostergp6nhp]

Ed, Tony Wood of Walker Midgley is at the show.

[ejparrott]

Excellent, I'll have a word on Saturday. Cheers Phil!

[ejparrott]

I finally (!) got around to speaking to RSA tonight....it is En3b for stays and for bosses, with a C of C required for the file.


I've decided I'm going to have RSA approve the design, it'll cost me about £800 to do, but I think it will be money well spent. Should I ever have to i'll be able to sell the engine for what its worth, having the paperwork for the boiler, I'll be able to market the deisign should I choose to, the engine could potentially be 'employed', which isn't I don't believe covered by exisiting insurance policies. Anyway, whilest they (RSA) might not be keen on it, 3b is tha material to use.

Thought I'd let you know.

[RLWP]

EN3B - that's the EN standard that was made obsolete in the 1970s, isn't it? ;D

Richard

[locoian]

EN 3 is perfectly adequate for stays in most boilers, where ductility is probabally more important than absolute strength, the B suffix denoting bright bar.

You are unlikely to get a 3.1 cert showing mechanical properties with bright bar unless you have a piece tested..

The manufature of bright bar is often undertaken as a cottage industry ( yes I know quite a cottage) and the re rollers and drawers who undertake the process tend not to have the drawn bars tested and just use the chemical analysis of the black bar that they started with.

Why not use EN 3A black, which will be cheaper and most likely will come with a 3.1 cert. Seems a shame to use bright bar in a rusty old boiler.

Ian

[ejparrott]

RSA ask for a C of C, not a 3.1 material cert for the En3. I will use bright bar not black, as it will fit the collet chuck.

Feb 13, 2013 22:07:50 GMT RLWP said:

EN3B - that's the EN standard that was made obsolete in the 1970s, isn't it? ;D

Richard

Yup, and we still use it every day!

[RLWP]

That's the nice thing about standards. There are so many to choose from...

Richard