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(i) Material.- Material, tube grade and chemical composition for
these tubes shall be in accordance with the appropriate clause
of Regulation 58.
(ii)
Manufacture.- Tube
shall be manufactured as prescribed in Regulation 58(b) and
subsequently cold drawn.
(iii) Tolerances.- Tolerance on thickness and outside diameter shall
be as follows :
Thickness - Plus
7.5% minus 7.5%
Outside diameter
Plus 0.5% minus 0.5%
(With a minimum of 0.10 mm over and under).
Tolerance
on length shall be in accordance with Regulation 58(f).
(iv) Heat Treatment.- After final cold finishing the tubes shall be
heat treated as follows :
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Tubes
Grade
|
Heat
treatment
|
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WC
1
|
Normalized*
or sub-critically annealed#
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WC
2, WC 3
|
Normalized*
|
The
ends which are subjected to cold working operation shall be
suitably normalized or sub-critically annealed as above.
*Temperature
range 880 Deg.C to 940 Deg.C.
#
Temperature range 660 Deg.C to 720 Deg.C.
(v) Tests.- (a)Tensile Test. – This test shall be comply with the
provision of Regulation 60.
(b) Flattening test.–
This test shall comply with the provision of Regulation 59(a).
(c) Flaring test.– This
shall comply with the provision of Regulation 59(b).
(vi) Hydraulic test.- This shall comply with the provision of
Regulation 61.
(vii) Test specimens.-These shall comply with the provision of
Regulation 62.
(viii) Number of tests.- These shall comply with the provisions of
Regulation 63
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