Volume-II of IV - GAIL

MECON LIMITED
Delhi
PROCESS & PIPING
DESIGN SECTION
TECHNICAL SPECIFICATION
FOR
PIPELINE CROSSINGS USING
HORIZONTAL DIRECTIONAL
DRILLING METHOD
TECHNICAL SPECIFICATION NO. : MEC/S/05/62/75 REV-0 Page 7 of 11
d) Pipeline string preparation details (hauling, stringing, welding etc.)
e) Hydrostatic test procedure (pre and post installation)
f) Disposal methodology of bentonite slurry.
g) Method of installation covering all steps of construction, viz. Rig up,
Pilot hole, Back-Reaming, Pulling Down, Backfilling etc.
h) Calculation for maximum pulling force on the rig and recommended
maximum pulling velocity.
i) Time schedule for construction.
3.1.3 The time schedule shall be in accordance with overall time schedule for the
project.
3.1.4 Approval by Owner of the methods used by Contractor shall in no way relieve
Contractor from the sole responsibility for safe and satisfactory installation,
working and operational use of the pipeline crossing.
3.2 Pipe String Preparation
3.3 Pre-testing
Complete pipe string shall be prepared as a single string for pulling. Welding,
radiographic inspection of joints and joint coating of the string shall be
performed in accordance with the respective applicable specifications included
in the Contract document.
3.3.1 Contractor shall hydrostatically pre-test the complete pipe string of each
crossing before installation as per approved procedure for a minimum period of
24 hours.
3.3.2 After pre-testing, joint coating of the welds shall be done as per specification
for specific field joint coating of pipeline for HDD crossing included in the
contract document
3.3.3 The section of the pipeline corresponding to the crossing shall, before
installation, be subjected to hydrostatic test pressure as stipulated in the
Special Conditions of Contract. During the test, Contractor shall check all welds
for leakage. Failure, if any, during the test shall be rectified by the Contractor.
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