Steel boiler welding

[bhk]

Jul 19, 2014 19:18:21 GMT fang said:

This post seems to have a slight similarity to my post about material thickness and accepted joining methods for boilers. As i have stated before the calculated thickness for a steel boiler is far to thin to be a sensible thickness to construct a boiler from, but as stated here the green book offers no guidance as to accepted joining methods or minimum material thicknesses/calculations.

I am interested in becoming coded for boilers but as stated here the green book gives no information as to what coding is required and what the accepted weld process is.

It was stated that MIG welding is not allowed, but I know of people who have had boilers built by coded welders and these have been MIG welded

Hi Fang,

Without knowing exactly what code is required in the uk I can't help out, me answer to Ed above is my best understanding if why certain weld types may not be allowed.

It may well be that the boilers you have seen constructed with MIG are to ASME IX. It can be done and the code allows it as far as I'm aware. Just a case of going through the certification procedure, which is a complex process.

www.weldingengineer.com/Section%20IX%20of%20asme_bpvc.htm

This link should give you a bit of a idea.

Cheers
Sean

[klendo]

Regarding the rules in the UK.. Have these changed in recent years? last boiler I made and im not coded. was for a 4" traction engine. Yes all the plate work was stamped and such like and was all tig rooted and stick filled. It was only during the testing method that the rules were different to that of a boiler which was coded welded. The initial hydraulic was 2.5 x the working pressure and then on the subsequent was 2 x, opposed to 2x on the initial and 1.5 x there after. As my father and I had a full sized traction engine at the time we used a full sized boiler inspector and all was fine.

[ejparrott]

Yes and no. There's no 2.5xWP test, but there is a clause in there that says weld samples MUST be presented for inspection before commencing construction. That has been in the code in its previous blue and red formats though I think. Off the top of my head, I don't think its specifies what sort of inspection they must be subject too.....

[bhk]

Aug 7, 2014 17:12:27 GMT ejparrott said:

Yes and no. There's no 2.5xWP test, but there is a clause in there that says weld samples MUST be presented for inspection before commencing construction. That has been in the code in its previous blue and red formats though I think. Off the top of my head, I don't think its specifies what sort of inspection they must be subject too.....

I would hope it is tested to the same standard as the code required by the book. But do remember that these boiler rules do only apply to boilers that wish to come under it and benefit from the southern federations insurance etc etc

It is of course possible to build a boiler to which ever code you like, but you will then have to insure it on your own.

It scares me what klendo is saying if no weld samples were tested. I have seen (and I'm not saying it's the case here) some welding done by people who think they can weld that is no where near the required standard.

And I think anyone who had worked in the welding training world will tell you the same. The last weld test I took, I was made to take a qualifying test before he would even humour me for the code test.

[klendo]

Why does that scare you if no weld samples were sent? In my particular case mine wasn't insured through the southern fed but through private insurance as per the full size. What would the southern fed think if I constructed a boiler as per full size practice? Horn plates as an integral part of the boiler and flanged and riveted with a full complement of stays, expanded tubes and not welded ones.

[ejparrott]

Proven design is the key to it. If you showed me a historic design for such a boiler it would be accepted. If you showed me design calculations that proved the design was ok, it would be accepted - subject to hydraulic test of course. That shows up our code to be very lax, in my opinion.

[ettingtonliam]

Aug 7, 2014 12:13:16 GMT klendo said:

Regarding the rules in the UK.. Have these changed in recent years? last boiler I made and im not coded. was for a 4" traction engine. Yes all the plate work was stamped and such like and was all tig rooted and stick filled. It was only during the testing method that the rules were different to that of a boiler which was coded welded. The initial hydraulic was 2.5 x the working pressure and then on the subsequent was 2 x, opposed to 2x on the initial and 1.5 x there after. As my father and I had a full sized traction engine at the time we used a full sized boiler inspector and all was fine.

I think it depends what you mean by 'recently'. By coincidence, I turned up a copy of 'Minimum Requirements for the\Examination and Testing of Miniature Steam Boilers' issued by the Southern Federation in 1991.

Sample statements in the section for steel boilers are 'The welding should preferably have been accepted by a reputable insurance company. The welding should be carried out by a suitably qualified welder' (Note the use of 'should' rather than 'must')

3.4.2 The test pressure to be applied shall be two and one half times the working pressure unless the conditions in the following paragraph are met in full

3.4.3 When the Boiler has been constructed to a design which has been accepted by a reputable Insurance Company, and the boiler as been constructed using-
a) Correctly certified material with relevant material certificates beingavailable.
b) Welded by a certificated coded welder.
c) Inspected at various stages of construction

then the test shall be One and One Half times working pressure.

It sounds as if back then you could turn up with a steel boiler not of an accepted design, no material certs, not welded by a coded welder, and provided it withstood hydraulic to 2 1/2 time WP, you'd be fine. Not any longer I'm afraid.

When it all changed I can't tell you.

Richard

[klendo]

Thank you richard