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Reg. 545
End Plates, Crown Plates and Tube Plates
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The end plate of welded Lancashire and Cornish boilers
shall be flanged for attachment to shell plates.
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| a) |
The dished end plates
of boilers shall be in one piece made from one rolled
plate. The flat end plates may be made from two pieces
by fusion butt-welding. (See figures XII/1 and
XII/2). In
the latter case, the line of welding shall be parallel
to the horizontal axis of the boiler and shall run through
the centre line of furnace or furnaces of Lancashire and
similar types of boilers. In the case of Marine type boilers,
the weld shall be located preferably between two rows
of bar stays or if there is only one row of bar stays,
between this row and the top row of stay tubes and shall
be subjected to a spot radiographic examination, otherwise
it shall subjected to full radiographic examination.
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| b) |
The segments for
hemispherical shell crown plates shall be pressed in one
heat to correct curvature and shall be butt-welded together
in accordance with Figures XII/3, XII/4, XII/5 or XII/6.
The cylindrical portion of the crown shall be tangential
to the hemispherical portion.
Where hemispherical shell crowns are pressed from one
plate the provisions of Regulation
547(b) shall apply. |
| c) |
Flanging of plates shall be done by machine. Such flanging
shall be done hot, preferably in one operation, but where
this is impracticable, creep machine flanging may be used
provided that the plate is worked at a suitable temperature
and heated for an adequate distance beyond that portion
of the plate under immediate treatment.
After completion of the flanging operation, flanges shall
be of true peripheral contour (either circular of straight
as necessary to ensure accurate alignment with the connecting
parts), and of good surface, free from bulges, grooves
or other local irregularities; flat portions of the plate
shall be free from set or distortion.
In the construction
of unfired boilers when the dished ends do not form a
part of the heating surface, cold spun dished ends conforming
to IS:2825 may be used.
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| cc)
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| d) |
Where flats are
pressed in dished end plates for the attachment of mountings
they shall be formed with an ample radius at the junction
of the flat and curved surfaces, and shall be free from
sharp corners or tool marks; the plate shall not be unduly
thinned. |
| e) |
Plates which are flanged
in accordance with Regulation 545
(c), shall be welded
to the parts to which they are to be connected as follows:
Where dished ends or crowns are used they shall be flanged
for connection to the shell or the cylindrical portion
of the firebox. Flat shell and firebox crown plates of
vertical boilers shall also be flanged for connection
to the cylindrical portions of the shell or firebox.
The opening in the firebox crown plate of a vertical boiler
for the uptake shall be flanged and the connection to
the uptake made by means of a circumferential butt-weld.
( See Figs.
XII /3, XII/4,XII/5, XII/6).
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