Volume-II of IV - GAIL

5.2.3 All the coated joints shall be subjected to Holiday Detection test.
5.2.4 An installed sleeve with more than two holiday shall be stripped and a new
one be installed.
6.0 TESTING
a) OWNER reserves the right to test one out of every 30 joint coating
subject to a minimum of 2 joints. CONTRACTOR shall provide all
assistance in removing and testing of field joint coatings. From
each test sleeve, one or more strips of size 25 mm x 200 mm shall
be cut one perpendicular to the pipe axis and slowly peeled off.
This test shall be conducted between either sleeve and metal or
sleeve and mill coating as per direction of Owner/ Engineer-incharge.
b) The required peel strength shall be 60 N/cm (min.) at 23°C. The
system shall fail only in the adhesive layer. No failure either in
adhesion to steel or adhesion to backing shall be permitted. The
adhesive layer that remains on the pipe surface shall be free of
voids resulting from air or gas inclusion.
c) If the sleeve taken away for test does not meet the requirement of
clause 6.0 (b), the adjacent two sleeves do not meet the
requirements of clause 6.0 (b) the field joint coating shall be
stopped until OWNER is satisfied with application methods.
d) For the test tensile strength, two parallel incisions spaced 1 CM.
Apart are made right down to the surface of the steel. A further
incision shall then be at right angles to the first angles to the first
two incisions. With the aid of a 1 cm. Wide knife the coating is lifted
over a length of about 2 cm. And clamped into the tensile tester,
where upon a uniform pull is exerted at an angle of 90 degree. The
tensile strength shall be more than a 2500psi.
e) Coating thickness shall be checked by non destructive method for
each field joint.
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