Milner Hunslet vs Australian Code

[chrisb]

Does anyone have details of the copper boiler for the Milner 7 1/4" Quarry Hunslet? I am particularly interested with the firebox and crown staying regarding if the design meets the Australian boiler code as drawn or if there are modifications required to make it compliant with the code?
Thanks
Chris

[jma1009]

Hi Chris,

I cant help on the boiler as the example I had experience of had a steel boiler. However if you PM me I can tell you a bit about the valve gear, valves, and that awful circular steam chest.

Cheers,
Julian

[runner42]

Hi Chris,

don't know anything about the boiler specifically but the Australian code is prescriptive in stay diameter and spacing and that girder stays are to be avoided. In the code there is a number of formulae for determining stay diameter and spacing. The one that maybe of interest to you is D = square root of ( 4C² X P/72000) where D = outside diameter of solid stays or root diameter of threaded stays, C = square pitch of stays in mm, P = maximum working pressure in kPa. It's likely that stay diameter and spacing of the boiler does comply with the code, but there is other criteria that would make it deviate. The most expedient way is to obtain a copy of the code and do the evaluation yourself.

Brian 

[steam4ian]

Chris.

To add to what Brian advises there are tables and diagrams in the Australian Code which set out stay spacing. Table 3.4.1A is the most helpful. If you pm me you with your email address I can send you a copy of that page.

On thing that must be remembered is that plate thickness, stay diameter, stay spacing and pressure are all related. (self evident from the formula Brian quoted) The stay/plate interface is the most stressed point as the joint is under shear but this can be overlooked on first consideration.

Shawki on these pages is a "retired" boiler inspector who has built many more boilers than most, I am sure he would be pleased to advise

Ian

[marshall5]

Hi Chris,
I've got the drawings to which you refer - what do you want to know?
Cheers,
Ray.
p.s. Unlike the steel boiler which has girder stays the copper one is direct stayed.

[Shawki Shlemon]

Ian , Unfortunately I am still the club boiler Inspector . Chris , our code remove the need to do any complicated calculations in stress and strain , All is done and tables / pictures and graphs provide all one needs to build a safe boiler in any design with a safety factor of 6 . All requirement are minimum , one can do better if so desire . If the design in question does not meet the code , changes can be made ( consult your boiler Inspector before cutting metal ) .

[chrisb]

Thanks to all of you for your input.
I have a copy of the Aus Code for copper boilers, but was looking at buying a used loco, I am planning on moving to NZ, hence the question. I suppose I need to have a look at the copper boiler drawing and cross check stay diameter and spacing with the code to see if it complies.

[steamcoal]

Chris.

Where are you headed in NZ?

We are a model engineer friendly lot.