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Reg. 267 a, Reg. 267 b, Reg. 267 c, Reg. 267 D

(a) Heat Treatment
After the completion of the welding of the seams and the welding on of the stand pipes and including welding repairs but before the hydraulic test, each drum shall be heat treated for stress relieving; during this heat treatment the official test plates shall be lying inside the drum.

Heat treatment of Alloy Steel plates shall be carried out on the basis of composition of the alloy as shown in the table below:-

                                                                     Table
Type of Steel

Range of Temperature in degree centigrade

Time at temperature per mm of thickness of plate

½Mo

½Cr ½Mo

620-660

2.5 minutes (30 minutes min.)

1Cr ½Mo

1½Cr ½Mo

630-670

2.5 minutes (30 minutes min.

2¼Cr 1Mo

650-750

2.5 minutes (1 hour min.)

                Note.- For pipes of 2¼Cr 1Mo specification upto and including 127 mm outside diameter and upto 13 mm wall thickness, the time may be 30 minutes minimum.

                The heat treatment of steels having Cr Mo V shall be carried out as per the requirements of the code of manufacture of plates, pipes.

aa) The heat treatment referred to in clause (a) shall not be necessary in case of Carbon Steel.

Provided that the thickness of the part/weld/recess does not exceed 20 mm, and the carbon content does not exceed 0.25%.
ab) Where the welded joint connects parts that are of different thickness, the thickness, the thickness to be considered in applying the limiting thickness of 20 mm for carbon steel shall be the following nominal thickness including corrosion allowance:

i) The thinner of two adjacent butt welded component including shell to end connections;
ii) the thickness of the shell in connections to flat ends;
iii) the thickness of the shell or end in nozzle attachment welds;
iv) the thickness of the nozzle at the joint in nozzle to flange connections;
v) the thickness of the pressure parts at the point of attachment where a non-pressure part is welded to a pressure part, in case of butt welds;
v) the thickness of the fillet weld at the point of attachment where a non-pressure part is welded to a pressure part, in case of fillet welds.”



Reg. 267 b

 

Where the shell is subjected to a primary stress relieving treatment identical to the final heat treatment to be given to the drum, the test plates may be placed inside the shell during the primary treatment and thereafter cut up and tested without waiting for the final treatment of the drum.



Reg. 267 c

 

Where the shell is not subjected to primary stress relieving treatment or is subject to a primary stress relieving treatment which is not identical with the final heat treatment, the test plates may be placed inside any other drum of comparable dimensions which is to be heat treated in accordance with this Chapter. The heat treatment is to take place in the furnace in which the drum relating to the test plates will eventually be given its final heat treatment.





Reg. 267 d

 

Temperature charts shall be submitted to indicate that the test plates and the drums they represent have been subjected to identical heating, soaking and cooling treatment.

 
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