Volume-II of IV - GAIL

MECON LIMITED
Delhi
PROCESS & PIPING
DESIGN SECTION
TECHNICAL SPECIFICATION
FOR
FLANGES AND WELDED FITTINGS
(SIZE 450mm (18”) NB AND ABOVE)
TECHNICAL SPECIFICATION NO. : MEC/TS/05/62/026 REV-0 PAGE 4 OF 9
4.2 Each heat of steel used for the manufacture of fittings and flanges shall
have carbon equivalent (CE) not greater than 0.45 calculated from check
analysis in accordance with the following formula:
Mn Cr + Mo + V Ni + Cu
CE = C + --------- + ------------------- + ------------
6 5 15
4.3 Carbon contents on check analysis shall not exceed 0.22%.
4.4 Unless specified otherwise, Charpy V-notch test shall be conducted at 0°C
temperature for each heat of steel, in accordance with the impact test
provisions of ASTM A370 for flanges and MSS-SP-75 for all fittings.
The average absorbed impact energy values of three full-sized specimens
shall be 27 joules. The minimum impact energy value of any one
specimen of the three specimens analysed as above, shall not be less than
80% of the above mentioned average value. In addition, the average
shear area shall comply the requirements of MSS-SP-75.
4.5 Hardness test shall be carried out as per ASTM A370 for each heat of steel
used. A full thickness cross-section shall be taken for this purpose and
the maximum hardness of base metal, weld metal and heat affected zone
shall not exceed 248 HV10.
4.6 One transverse guided weld bend test shall be performed for each lot of
welded fittings produced from the same heat in accordance with
provisions of MSS-SP-75. The dimension “A” in guided bend test shall not
exceed 4.0 times the nominal wall thickness and dimension “B” shall be
equal to A+2t+3.2mm, where “t” is nominal wall thickness.
4.7 One transverse weld tensile test shall be conducted on each heat/ lot of
welded fittings in accordance with the requirements of MSS-SP-75.
\\Akjha\work contrac\standard TS for Pipe Line WC (Vol-II) MASTER FOLDER\26 flange & welded fittings 18 inch & above\Specification for Flanges & Welded Fittings 26.doc