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Fusible plug in a Steel Boiler

Viceroy

Joined: 14-10-14

Topics: 13

Replies: 18

Posted: Wed 9th Aug 2017, 2:24pm
Fusible plug in a Steel Boiler

Gent’s I have a Steel Boiler for my 7 ¼ G Hunslet with a threaded hole for a fusible plug in the top of the fire box, I have brought a new fusible plug but its much longer than seems correct, threads correct but the plug is long, my question is this, can I cut it down ? must it fit flush in the fire box roof from inside the fire box, and how much should protrude above the fire box roof, into the water.
Any help would be much appreciated.
 

Replies To This Post

Martyhuck

Joined: 9-10-17

Topics: 1

Replies: 6

Posted: Tue 10th Oct 2017, 1:16pm

I would suggest you have 1/2" above the fire box roof, to give you a margin of safety.
 

Mick

Joined: 1-01-89

Topics: 7

Replies: 114

Posted: Tue 10th Oct 2017, 2:20pm

The fusible plug is screwed securely into a bush silver soldered or welded into the firebox crown. In the case of most miniature boilers it will protrude in accordance with its length after being fully screwed home, i.e. how it was manufactured. As far as I am aware nothing is specified in the pressure regulations ('Green Book') we operate under, however in the Australian boiler codes (AMBSC) the protrusion is given as 10mm minimum. Plugs should be removed and checked every 12 months, although it's not a bad idea to check them at more frequent intervals than that in case they might have worked loose. I would caution others to make sure the plug's thread is the same as the firebox crown's - you have done that already. If you shorten the plug this may reduce the amount of low melting point metal slug in the plug and could weaken it.
 

Viceroy

Joined: 14-10-14

Topics: 13

Replies: 18

Posted: Wed 11th Oct 2017, 7:14pm

Martyhuck, Mick thanks for your reply's much appreciated i now undeertand what is needed.

Viceroy
 
 
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