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Reg. 365 F
Shell Joints
| 1) |
Riveted Shells. Preparation of plates, butt
straps, rivet holes and riveting shall comply with the
relevant Regulations of Chapter
III.
Longitudinal joints of riveted shells may be lap jointed
or fitted with double butt straps, but in cases where
the design pressure exceeds 130 lbs/sq. in. or the product
of the design pressure in lbs/sq. in. and maximum internal
diameter in inches exceeds 9,500, the longitudinal joints
shall be butt jointed with double cover strap. The design
of riveted joints shall be in accordance with Regulation
177 to 184.
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| 2) |
Fusion Welded Shells.-
These shall be classified as follows:-
Class I-No limit to scantlings.
Class II- When none of the following limits is exceeded:-
| (i) |
Working pressure –
35 kg/sq. cm. (500 lbs/sq. in.) |
| (ii) |
Product of Working Pressure
and internal diameter-3750 (21,000) |
| (iii) |
Design temperature -
343°C (650°F). |
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Class III-When none of the following limits is exceeded:-
| (i) |
Working Pressure –7.4
kg/sq. cm. (105 p si). |
| (ii) |
Product of Working Pressure
and internal diameter-940 (5250) |
| (iii) |
Design temperature-171°C
(340°F). |
Fusion welds, preparation of seams, the method of formation
of cylindrical shells including heat treatment after bending,
method of making welded seams, types of welded joints, test
plates and circularity of shells shall all conform to the requirements
of Chapter V, except
for the following namely-
Whenever practicable, seams shall be welded from both sides
of the plate. Additional runs of metal shall be deposited at
both surfaces of the welded seams to build up to a thickness
10 per cent greater than thickness of the plate. The surfaces
of welds wherever carried out on both sides shall be ground
smooth and flush with the respective surfaces of the plates.
Where the seam is welded from one side only, these provisions
shall apply to the exposed of the surface weld.
Tests for Class I fusion welded seams shall comply with the
requirements of the relevant Regulations of Chapter
V.
Tests for Class II fusion welded seams shall comply with the
requirements of those of Chapter
XII, except that an additional provision for one micro and
macro examination shall be made.
Tests for Class III fusion welded seams shall comply with the
requirements of those of Chapter
XII.
Class I and Class II shells shall be effectively stress relieved
by heat treatment when the wall thickness exceeds 20mm or the
carbon content exceeds 0.25% or the pipes are made of alloy
steel. |
| (3) |
Seamless Forged Shells.- These shall comply with the
requirements of Regulation
235 to 243. |
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