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 44 OF 53
MEC/S/05/62/01 REVISION A
12.2.3 A suitable concrete foundation as directed by COMPANY shall be constructed
on which the valve shall be firmly installed, after embedding an insulating sheet
of hard polyethylene with a thickness of atleast 5mm or equivalent. Such
insulating sheet is also to be installed under pipe clamps, etc.
12.2.4 Valves with flow arrows shall be installed according to the normal flow in the
pipeline. During, welding, the valves shall be in fully open position. In addition all
manufacturer's instructions shall be followed.
Care shall be taken to avoid entry of sand particles etc. to valve body, seals etc.
during transportation, storage, assembly and installation.
12.2.5 For valves and piping installed below ground and/or above ground, the anticorrosion
coating/painting shall be as per the requirements of the relevant
specifications issued for the purpose. The anti-corrosion coating below ground
shall extend upto 300mm above grade at the lowest point.
12.2.6 Sectionalizing valves shall be installed on sections of the pipeline in the
horizontal position only or with an inclination not greater than that allowed by the
valve manufacturer. Installation shall be done in such a way that there is no
strain in the welded joint while the pipeline at upstream and downstream sides
are straight.
12.2.7 All valves shall always be handled using equipment and methods to avoid
impact, shaking and other stresses. In particular, the equipment and tools for
lifting and handling shall never be done through handwheel, valve stem, joints
and other parts which may suffer damage.
12.2.8 All sectionalizing valve and any other inline assemblies shall be prefabricated
and tested hydrostatically ex-situ as per applicable specification. All such
assemblies shall be installed at the locations shown in the drawings only after
successful completion of the hydrostatic test and dewatering. Thereafter the
ends of the assembly shall be closed off. CONTRACTOR shall carry out
necessary excavation, cutting, bevelling and welding of the tie-ins required for
the installation of such assembly. The tie-in joints shall be radiographically
examined over 100% length and also 100% ultrasonically examined prior to
backfilling. All works shall be executed in accordance with the relevant
specifications issued for the purpose.