Fusible plug in a 5″ gauge copper boiler?

[BazParticipant @baz89810]

I believe all the Polly range of locos have fusible plugs fitted and have done right from when the pollys were made by JGS Clarke.

Edited By Baz on 30/06/2021 16:42:27

[John Billard 1Participant @johnbillard1]

Thank you for all your comments and advice!

It seems pretty clear to me that there is little advantage in fitting a fusible plug into a 5" gauge copper boiler. It was a good discussion.

Kind regards

John B

[duncan webster 1Participant @duncanwebster1]

Just to be pedantic (who me) a mix of lead and tin will always melt below 328 and can be as low as 183 (eutectic)

[Dave Smith 14Participant @davesmith14]

Posted by Paul Lousick on 30/06/2021 14:46:22:

Hi Dave, Your extract from the model code is not exactly correct.

I checked with my copy of the AMBSC code for copper boilers, Issue 8-2012 which I believe is the latest edition and it states in para 5.7.1 that: "If used, fusible plugs shall be fitted in the highest point of the inner firebox crown that is readilly accessible for plug replacement" and not shall be fitted. So it is optional.

5.7.2 The clear area thru any fusible plug shall be equal to 20% of the area thru the safety valves, with a maximum bore of 4mm diameter. (The pressure valve orifice diameter is taken a Nomogram diagram)

Paul

Paul I am very confused extract from my copy of issue 8 – 2012? This copy came from a fellow club member so I am not sure where he got it from.

[Paul LousickParticipant @paullousick59116]

Hi Dave,

I am equally confused. This a copy of my code. Also Issue 8 – 2012 for copper boilers and paragraph 5.7.1 is different ??????

I will contact my boiler inspector to see if I can clarify the matter.

Paul

[Dave HalfordParticipant @davehalford22513]

This may be a case of issue8A and issue8B. there should be a list of changes somewhere.

[Paul LousickParticipant @paullousick59116]

Hi Dave H.

There are no changes listed. The revisions are controlled by the "Issue" number and I have checked with my boiler inspector who confirms that Issue 8-2012 is the latest copy.

Dave S.

My boiler inspector told me that fusible plugs are optional on copper boilers with a barrel OD of 50 – 203mm. Steel boilers require at least one fusible plug.

He is at a loss as to why your copy is different but queried the page that you posted and asked if the Issue 8-2012 that is shown on page 37 is also at the bottom of page 38.

Paul

[Dave Smith 14Participant @davesmith14]

Paul

Copy of the whole page. We will go with your version as it makes more sense at our scale. Also It does not matter to me as I only use it as a guide, although a very good one.

[Paul LousickParticipant @paullousick59116]

I'm stil at a loss as to why there are differences and will search further for a reason. As you say, our code is only a guide and as long as your boiler complies with your own code, everything will be OK.

Good luck with your build and have fun.

Paul

[Paul LousickParticipant @paullousick59116]

Hi Dave,

I have stirred up a bit of a hornets nest here after I brought the matter to the attention of the boiler inspectors at our club who passed the question to the committee members responsible for the code.

They cannot explain exactly why there are 2 different copies of the code for fusible plugs in copper boilers but suspect that a preliminary copy "escaped" while preparing the final document for publishing.

They have confirmed that the use of fusible plugs in a copper boiler is optional and either way will comply with the Australian code. (It would have been a different matter if the other way around)

Paul

[Dave Smith 14Participant @davesmith14]

Paul..

Always happy to oblige with hornets nests. Thanks for the update.

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