||The sections of the internal
flues shall each be in one plate and shall be bent while
cold to circular form and shall be welded longitudinally.
||The maximum permissible variation
in diameter at any cross section shall not exceed the
thickness of the plate.
||The weld shall be placed at
the lower part of the flues, and shall break joint in
successive sections by at least 12 inches.
||Each flange for the circular
seams shall be formed at one heat by suitable machinery.
||The sections shall be allowed
to cool gradually to avoid internal stresses.
||The caulking edges of all flue
flanges shall be machined or machine gas cut.
||The circular seams shall be
arranged so that they do not fall in line with those of
the adjacent flue or with the circumferential seams of
the shell and are at least 6 inches apart.
||When flues are flanged for
attachment to both end plates the total length of each
completed flue shall not exceed the length of the shell
measured from the inner surface of the back end plate
to the inner surface of the front end plate, both adjacent
to the shell.
||Where the flues are flanged
for attachment to the end plates, the end sections shall
be 1/16 inch thicker than the remaining sections, except
in cases where the calculated thickness is over 13/16 inch,
when the end section shall be 7/8 inch in thickness.
||The flanged portion of furnace
rings shall have radius of curvature of not less than
1 inch on water side.
||Sections of corrugated flues
may be fusion butt welded circumferentially and afterwards
stress relieved by heat treatment.
||As an alternative to Adamson
flanges, furnaces which are partly fitted with corrugated
sections shall be strengthened by means of suitable stiffening
rings adequately welded to the furnaces. The moment of
inertia of the stiffener shall be not less than that required
by Regulation 592(b).
In no case shall a flat stiffener be less than 63 mm.
x 13 mm. (2½ x ½).