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 34 OF 53
MEC/S/05/62/01 REVISION A
At every seven meters along the trench sand/earth filled bags shall be placed
between the parallel pipelines so as to ensure maintenance of the minimum
stipulated distance between the parallel lines.
9.2 Overhead Sections and Sections in Tunnel
9.2.1 The following works shall be completed before proceeding with the assembly
and laying of overhead pipelines :
- Construction of the pipe support structures or of mounts on supports.
- Paints and/or coating of the pipework, as indicated in the engineering
specification.
9.2.2 The erection of the supports shall be carried out taking care that the elevation
and alignment is in accordance with the drawings.
In the case of metal work supports, prefabrication and/or assembly shall take
into account the maximum allowed free span and the supports shall not interfere
with the pipeline welds.
9.2.3 In case roller supports are used, the roller shall be lubricated, then checked for
smooth rotation and, in case of seizure, the defect shall be repaired or roller
shall be replaced. In the case of overhead section where the pipeline is slanting,
the alignment of the end supports shall be made after placing the pipeline in
position. Before installation of the pipe section, all the rollers shall be perfectly
centered acting on the seat of the support plates.
The above alignment operations shall be carried out before connecting the
overhead section with the ends of the buried section.
9.2.4 Lifting, moving and laying of the pipeline shall be carried out in accordance with
the provisions of clause 9.1.5.
An insulation sheet shall be installed to isolate the pipe from the support or
support from the earth.
The sheet shall be hard polyethylene at least 5mm thick.
It shall extend at least to 1cm outside the saddles or clamps.