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CABLES
A
wide range of cable types is available for use in cathodic protection
applications. ETC-CPS can advise on suitability of cable for a
particular application and can supply from either stocks or specialist
stockists certain preferred sizes and sheathing types. Cathodic
protection cables are generally single core with stranded copper
conductor. As a guide, the following sheathings are commonly
encountered.
PVC
(Polyvinyl chloride)
Thermoplastics are suitable for underground applications particularly in
dry areas. For Above ground use they are usually pigmented with carbon
black. Embrittles by some oils and at temperatures below 0° C.
Maximum service temperature 90° C.
PE
(Polyethylene)
Thermoplastic suitable for underground use, or above ground with added
ultraviolet stabilisers. Superior water and chemical resistance to PVC
but lower maximum operating temperature (70° C). Available in a
range of densities and molecular weights.
HMWPE (High
molecular weight polyethylene)
Cathodic protection cable has an extra thick single insulation which
gives improved resistance to water and chemicals and prevents blistering
and 'wicking' between insulation and sheathing of
conventional constructed cables used for cathodic protection.
Connected as standard on several types of anodes.
XLPE (Cross
Linked Polyethylene)
Polyethylene
can be cross-linked either chemically or by radiation to improve its
maximum operating temperature range to 85° C. Chemical properties
are not significantly affected by cross-linking, although abrasion
resistance is slightly improved.
EPR
(Ethylene Propylene Rubber)
Generally
used as an insulant. Resistant to heat and chemicals, but flammable and
has poor resistance to aromatic solvents and oils. Flexible and
maintains flexibility to -55° C.
CSP (Chlorosulphonated
Polyethylene)
Generally
used to over sheath EPR. Resistant to heat. Maximum
operating temperature 85° C but can be designed for higher temperature
service. Self extinguishing, flexible material whose properties
become less attractive below -10° C. Affected by aromatic
solvents, petrol and mineral oils.
KYNAR/HMWPE
CABLE
Single core,
stranded tinned copper conductor with radiation cross linked primary
insulation of modified Kynar/vinylidene fluoride and an outer jacket of
modified polyolefin. The outstanding dielectric strength and water
resistance of the HMWPE, coupled with its high resistance to corrosive
chemicals, makes this construction a preferred cathodic protection
cable. Kynar is recommended for cable insulation in seawater and
deep well installations where the evolution of chlorine gas is expected.
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