Volume-II of IV - GAIL

MECON LIMITED
REGD. OFF : RANCHI (BIHAR)
PROCESS & PIPING
DESIGN SECTION
NEW DELHI
\\Akjha\work contrac\standard TS for Pipe Line WC (Vol-II) MASTER FOLDER\04A major water crossing\Major Water Crossing -Final 04.doc
STANDARD SPECIFICATION
TITLE MAJOR WATER CROSSINGS SPECIFICATION NO. PAGE 10 OF 14
MEC/S/05/62/04 REVISION 0
6.6 The maximum allowed horizontal deviation from the required center line shall be
limited to the following :-
For pipeline dia. upto and including 24" - 300 mm
For pipeline dia greater than 24" - 500 mm
6.7 Prior to backfill the pipeline shall, when laid in the trench, conform to the bottom
contour of the trench grade, so that it will be firmly, uniformly and continuously
supported. COMPANY may employ a diver or use other suitable methods to
inspect the bottom of the trench and/ or after the pipe is installed prior to
backfilling of the trench. CONTRACTOR shall facilitate the work of the diver and
shall furnish the necessary equipment and helpers (other than actual diving
equipment) necessary for the diver/ inspector to perform his work.
6.8 If the pipe does not properly fit the trench or does not rest at sufficient depth to
satisfy the minimum requirements of cover as specified in approved drawings,
the CONTRACTOR shall make necessary corrections to either trench or the
pipe alignment or to both so that the pipe, when finally in position in the trench,
shall fully meet the specifications, failing which CONTRACTOR may be asked to
remove the pipeline. This shall be done at no extra to the COMPANY.
6.9 Installation of Parallel Pipelines
When parallel pipelines are required to be installed for a major water crossing.
CONTRACTOR shall further comply with the following requirements.
6.9.1 Depending on the diameters of the parallel pipelines, the characteristics of the
crossing and the limitations of CONTRACTOR's equipment, CONTRACTOR
may propose installation of the parallel pipelines either together in a combined
operation or separately in a common trench.
6.9.2 If the pipelines are installed together, the minimum clear distance between the
parallel pipelines (measured from the outside diameters of the concrete coated
pipes) shall be 300mm. CONTRACTOR shall provide spacers at sufficient
intervals along the length of the pipe section(s), securely fixed to the pipes, or
shall propose other suitable alternative methods, so as to ensure that the
stipulated minimum clear distance is maintained. The spacers may be removed
before the trench is backfilled.