Volume-II of IV - GAIL

MECON LIMITED
Delhi
PROCESS & PIPING
DESIGN SECTION
TECHNICAL SPECIFICATION FOR
TEMPORARY CATHODIC
PROTECTION SYSTEM
TECHNICAL SPECIFICATION NO. : MEC/TS/05/62/016A REV-1 Page 9 of 19
6.3 Test Stations
Recommended dimensional tolerance shall be as follows:
Length ± 2.5%
Width/thickness ± 5%
6.3.1 Test stations shall be provided along the pipeline ROW for monitoring the performance
of the Cathodic Protection system at intervals not exceeding 1000 meters in
uncongested & 250 meters in congested area unless otherwise specified. In addition
to above, test stations shall also be provided at the following locations:
a. At both sides of major road crossings
b. At all insulating joints
c. At vulnerable locations with drastic changes in soil resistivity
d. At connections of surge diverters, grounding cells and polarisation cells
e. At HT AC/DC overhead line crossings and selected locations where HT
overhead line is in the vicinity of the pipeline.
f. At railway line crossings and running parallel to the pipeline.
g. At both sides of major river crossings.
h. At high voltage cable crossings or along routes where HV cables are running in
parallel.
i. In the vicinity of DC net works or grounding system where interference
problems are suspected.
j. At crossings/parallel running of other pipeline structures
k. At both sides of cased crossings
l. At any other locations considered vulnerable locations where interference is
expected
m. At any other locations considered necessary by owner/owner’s representative
6.3.2 Test stations for bonding shall be provided with shunt and resistor as a means to
monitor and control current.
6.3.3 Test stations used for sacrificial anodes shall have shunt for measurement of anode
current, and provision for resistance insertion to limit the anode current output.
6.3.4 Test station with current measuring facility shall be provided at each intermediate CP
station drainage point (to measure pipeline from drainage point), at interference prone
areas, on both sides of major river crossings and at least at two additional locations
along the pipeline ROW between two CP stations.
6.3.5 All test stations shall have weather proof enclosure, having degree of protection IP 55
with hinged lockable shutter. Enclosure shall be made of sheet steel of at least 3 mm
thickness and shall be suitable for M.S. post mounting. The test stations shall be
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