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 25 OF 53
MEC/S/05/62/01 REVISION A
Acceptable padding shall be placed under the pipeline before its installation, and
around after installation to establish at both sides and on top of the pipe a
permanent layer of padding. The thickness of compacted padding on top of pipe
corrosion coating shall be at least 150mm. Padding materials that are approved
by COMPANY shall be graded soil/ sand and/ or other materials containing no
gravel, rock, or lumps of hard soil. Sand used for padding shall pass through
sieve size ASTM-10 or ISO-2.00.
When specified in the CONTRACT, rock shield may be used in place of or in
addition to sand padding as indicated above. Such rock shield shall be in
accordance with the specification issued for the purpose and shall be subject to
COMPANY approval.
6.9 Protection of Trench
CONTRACTOR shall keep the trench in good condition until the pipe is laid, and
no claim is to be made to the COMPANY by reason of its caving either before or
after pipe is laid.
All lumber, sheet-piling jacks or other materials, that may be necessary to shore
the trench, in order to prevent caving are to be furnished and removed by
CONTRACTOR.
CONTRACTOR shall dewater if necessary, using well point system or other
suitable systems, shore, or do what else might be required to excavate the
trench, install the pipe in it and backfill the trench in accordance with these
specifications at no extra cost to COMPANY.
6.10 Protection of Underground Utilities and Special Methods
Details of some underground utilities, as far as acquired by COMPANY, shall be
indicated in the Drawings. However, CONTRACTOR shall obtain plans and full
details of all existing and planned underground services from the relevant Local
Authorities and shall follow these plans closely at all times during the
performance of work. CONTRACTOR shall be responsible for location and
protection of all underground lines and structures. In special locations the use of
trenching machine, backhoe may result in damage to property and subsurface
structures likely to be encountered during excavation. At such places,
CONTRACTOR shall excavate the trench manually to same specification at no
extra cost.