(i) All pipes
of grades in table-1 except P91 and X20CrMoV121 shall be
reheated and furnished in full annealed, isothermal annealed
or normalised and tempered condition.
If furnished in the normalised and tempered condition,
the minimum tempering temperature for grade P1, P2, P11 and
P12 shall be 650 degree C and the minimum tempering
temperature for grades P5, P9 and P22 shall be 675 degree C.
(ii) Pipes of grades P1, P2 and P12 either hot finished or cold
drawn may be given a final heat treatment at 650 degree C to
705 degree C, instead of heat treatment specified in
sub-clause (i) above at the option of the manufacturer.
(iii) Grades P91 shall be normalised at 1040 degree C minimum and
tempered at 730 degree minimum as a final heat treatment.
(iv) Grades X20CrMoV121 shall be normalised at 1020 - 1070 degree
C and tempered at 730-780 degree C for a period of one hour