Volume-II of IV - GAIL

MECON LIMITED
REGD. OFF : RANCHI (BIHAR)
Document6
PROCESS & PIPING
DESIGN SECTION
NEW DELHI
TITLE MAINLINE CONSTRUCTION
(ONSHORE)
STANDARD SPECIFICATION
SPECIFICATION NO. PAGE 41 OF 53
MEC/S/05/62/01 REVISION A
Stainless steel lines will be "swaged" using permanent fittings installed with a
hydraulic device.
Cold bending for the fitting of 1/2" and 1/4" pipes is allowed when special
bending tools are used with guides to prevent flattening. The minimum radius
allowed shall not be less than R = 10 D where D is the outside diameter of pipe.
The bending tool shall be subject to COMPANY's approval.
CONTRACTOR shall ensure that the piping assemblies are not in a strain prior
to the final bolting or welding. CONTRACTOR shall also ensure that all
equipment and piping are thoroughly swabbed clean of all dust, refuse, weldingspatter,
scale, or any potentially detachable matter prior to the tie-in or final
bolting.
12.1.2 Dimensional tolerances.
These tolerances apply to in line items and corrections for other lines. These
tolerances can be executed on items such as vents, drains, dummy supports,
field supports, temperature and pressure connections, where the deviation will
not affect another spool.
a) General dimension such as face to face, face or end to end, face or end
to center, and center to center : ± 3 mm.
b) Inclination of flange face from true in any direction: 4 mm per meter.
c) Displacement of branch connection from indicated location: ± 1.6mm.
When multiple branches are involved, the displacement of the branches
shall not exceed 3mm from a common point.
d) Rotation of flange bolt holes shall not exceed 1.6 mm.
12.1.3 Flanged connections.
CONTRACTOR shall ensure that all flange faces are parallel and centered,
according to standard practice, prior to final bolting. CONTRACTOR shall not
use bolting forces as a means for attaining alignment. A gasket of proper size
and quality shall be installed between the flanges at each joint.