Volume-II of IV - GAIL

The heat shrink wraparound sleeve shall have the required adhesive properties when
applied on various commercial pipe-coating materials. The pre-heat and application
temperatures required for the application of the shrink sleeve shall not cause loss of
functional properties of the pipe coating.
Heat shrink wraparound field joint coating system manufactured by M/s Tyco Adhesives
– Raychem and M/s Canusa are acceptable for the supply of field joint coating
materials. The Contractor shall propose the specific grade of field joint coating system
meeting the requirements of this specification from these manufacturers. In case the
Contractor proposes to supply heat shrink wraparound sleeve from any other
manufacturer, then the Contractor shall propose only those coating systems that have
been previously used in pipelines of similar size and operating conditions.
3.1.2 Cold Applied Tapes
Cold applied tapes system shall comprise of primer, an inner wrap and an outer
wrap. The inner and outer wraps shall be asymmetric 3-ply tape with co-extruded
polyethylene carrier film and butyl rubber adhesive layers on both sides. The inner
layer of butyl rubber adhesive of inner wrap shall have a thickness of min. 1.0mm.
The inner and outer wraps are to be spirally wrapped with 55% overlap, equivalent
to two layers each providing a total minimum thickness of 3.0 mm on the pipe body
and 2.5mm on the weld.
The Contractor shall propose only those cold applied tape coating systems that have
been previously used in pipelines of similar size and operating conditions.
3.2 Functional Requirements of Field Joint Coating
3.2.1 Properties of the PE backing shall be as follows :
Sl.
No.
Property Unit Requirement Test Method
a) Tensile Strength at @+25°C N/mm 2
≥12 DIN EN 12068
b) Ultimate Elongation @+ 25°C % ≥250 DIN EN 12068
c) Dielectric withstand with 1000
Volts/sec
kv ≥30 ASTM D 149
d) Water absorption
@+ 25°C for 24 hours
% ≤0.05 ASTM D 570
e) Volume Resistivity @+25°C Ohm-cm ≥10 15
ASTM D 257
3.2.2 Functional Properties of Joint Coating System (As applied)
As applied field joint coating system shall comply the requirements of DIN EN 12068.
Table 1 and 2 corresponding to designation DIN EN 12068 – C HT 60 UV, except as
modified below :
a) Cathodic Disbondment Resistance at Tmax i.e. 60°Cshall be 20mm when tested
as per Annexure K of DIN EN 12068. Test shall be carried out at (+) 60°C.
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