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FLANGE INSULATION
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Type D: PSI Gask O Seal |
Type F: Raised Face |
Flange insulation is
used to electrically isolate sections of pipelines from each other or
from tanks and other plant. This prevents leakage of cathodic
protection currents from the protected pipeline(s) to other structure
thus allowing economic application and closer control of the cathodic
protection system. Insulation can take the form of factory
assembled Monobloc Insulating Joints or site installed insulating flange
kits.
Insulating Kits:
ETC's insulating flange kits consist of following items:
1. Gasket
2. Insulating sleeves
3. Insulating washers
4. Bright steel washers
Monoblock joints
Exploded view of typical monoblock joint
Monoblock joints are
factory manufactured and assembled and cannot be dismantled on site.
Joints are available in sizes ranging from ¾" to 70", operating
pressures up to ANSI 2500 and temperatures from -50° C to 280° C. Monobloc joints are made to a higher specification than assembled kits
and are more reliable but considerably more expensive.
Isolating Spools
ETC recommends to fit
insulating spools pieces where high conductivity fluids are being
carried to increase the electrical resistance through the electrolyte.
ETC engineers are available anytime to advise where spool pieces are
required.
Flange Protection:
ETC-CPS recommends
that once insulating flange kits are installed, they should be protected
against lightning and fault currents. Where the possibility of
lightning strikes and fault currents being conducted down pipeline
exists, it is necessary to bridge over the isolating coupling to prevent
damage to the flange insulation and damage from explosion where
flammable products are being carried. Suitable recommended
equipment to be considered are:
Surge
Arrestors
and spark gaps are available for direct
connection insulating joints. Specific requirements can be met if
design fault current/duration and type of fault are
specified. Surge arrestors are available for hazardous or
non-hazardous areas
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