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Each bar stay or firebox stay shall be made from a
solid rolled bar without weld in its length, except
where it is attached to the plate it supports.
Bar stays which have been worked in the fire shall be
subsequently annealed.
It is preferred that when the stay is in position in
the boiler, its axis shall be normal to the plate it
supports, but where this cannot be so arranged, then,
if the stay is fitted with nuts, beveled washers shall
be provided between the nuts and the plate.
Stays shall be secured to the plates they support by
one of the following methods:-
| a) |
Bar Stays
| i) |
Plain bars, passing
through clearing holes in the plates and welded
thereto (see Figure
XII/42). |
| ii) |
Plain bars passing through clearing holes
in the plates and fitted with washers on
the outside, the stay and washers being
welded to the plates in accordance with
any one of the methods shown in Figures XII/43(a),
XII/43(b),
XII/44(a),
XII/44(b),
XII/45(a),
XII/45(b).
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Note:- Cleaning hole for the purpose of this regulation
means a machined cylindrical hole having a diameter
not exceeding that of bar stay by more than 2%.
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| b) |
Firebox Stays
| i) |
Screwed stays, screwed
through the plates and riveted over at each
end to form substantial heads, or fitted with
nuts, or the projecting ends fillet-welded
as indicated in Figures XII/39 and
XII/40.
It is recommended that where the stays are
screwed, this shall be with a fine thread
and the stays and holes shall be screwed with
a continuous thread.
The stays shall be screwed with fine threads
of not less than 11 threads per inch.
The screw threads on the stays shall be clean,
free from checks or imperfections, of full
depth, of a correct standard form and a good
fit in the holes.
The middle portion shall preferably be turned
down to the bottom of the thread.
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| ii) |
Plain stays shall be strength welded to
the plates (See Figures XII/41
and Fig XII/41A).
NOTE:This form of attachment is also
suitable for plain bar stays all dimensions
are in mm attacment of firebox abd reversal
chamber stays.
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All screwed stays less than 14 inches long should
preferably be drilled with a tell-tale hole 3/16
inch diameter to a depth of ½ inch beyond
the inner face of the plate. Stays which are obscure
on one side should preferably be made from hollow
staybar. |
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