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Fusible Plug

Fusible Plug

Fusible Plug

Dear all,

May I know:

1) For internally-fired fire tube boilers such as the Scotch Marine or package type, where is the location of the fusible plug?

2) For water tube boilers, where is the location of the fusible plug?

Thanks for your help.


RE: Fusible Plug

Locomotive-type firetube boilers, in the crown sheet [roof of the fire box].
Scotch Marine firetube boilers, crown of the combustion chamber[s].
Water tube boilers with fusible plugs not so common, I believe...


"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

RE: Fusible Plug

More on this as per vintage books:

Old legislation, possibly obsolete by now, actually prohibited use of fusible plugs for boilers operating at a pressure greater than 250 psig; perhaps with use of different alloys this has changed...anyone?

Locomotive and Scotch marine boiler fusible plugs were almost universally accessible from the fire side.

Vertical fire tube boilers could, but did not always, have a fusible plug installed partway down a larger, heavier gauge fire tube fitted especially for that purpose; in such cases a water-side access hand-hole was provided in the boiler shell to facilitate fusible plug replacement.

For package boilers, it would depend upon the design, for example whether the boiler is of wet or dry back, the internal dimensions of the furnace and combustion chamber, etc., as to whether water- or fire-side access would apply.

The foregoing would dictate which type of fusible plug, whether for fire- or water-side installation, would be specified at time of design or for replacement.

[Edit/addition: link to one relevant vintage book https://archive.org/stream/audelsengineersm06grahr... - see pages 2720 > 2722 inclusive.]


"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

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