Isolation Joints

The IMAC Barlow TMK Surge Arrestor has non-linear voltage current characteristics and limits potentially destructive voltage levels without interfering with cathodic protection. Nominal values are 50 ohms at 250 volts - 30,000 ohms at 3 volts.  It is self-healing and able to survive multiple strikes with your choice of wire size connections.  Designed for above or below ground installation with fiber-glass housings available for above ground installation.

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The Barlow Flange Isolation Joint is welded into place for a permanent solution and designed to the highest possible standards using precision machined heavy duty components.


•  Thicker dielectric sleeves (1/8") machined to precise, close tolerance dimensions, both length and diameter

•  Flange bolt holes line reamed to provide perfect alignment and close tolerance fit to the dielectric sleeves

•  Flange studs machined from Alloy Steel and heat treated to ASTM Designation A-193-52T Grade B-7 resulting in superior strength and greater resistance to stress-induced elongation

•  Coupling nuts machined from Alloy Steel and heat treated to ASTM Designation A-194 Class 2-H

•  Precision machined steel washers, flat, parallel and counterbored allowing for square alignment and clearance for the dielectric sleeves

•  Flange gasket precision cut for ideal fit with small projection into the stream to prevent bridging of the joint inside the pipe

•  Precise assembly with accurate torquing carried out in sequential pattern followed by retorquing after 24 hours

•  Flange gap sealed with epoxy resin to prevent contamination and electrical shorting

•  Dielectric strength test (minimum) 5 kV at 50 hz for 1 minute (dry air)


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For long-term dependability, experts choose the ALFA Monolithic Isolation Joint which is welded into place for a permanent solution.

•  Industry proven double O-ring seals standard (available with triple O-ring seals based on application)

• Standard O-ring material 'NBR' (other materials optional based on application)

•  O-ring design in accordance with ASTM D2240, ASTM D412, ASTM D395, ASTM D1329, ASTM D1817 and ASME VIII Div.1 appendix II.

•  Isolating elements:  NEMA G10/G11 - ASTM D709 Class H

•  Back seal: silicone neutral low module/filler isolator: epoxy resin cold cured 

•  Internal and external coating of amine cure epoxy resin

•  Pipe pups API 5L X52 or API 5L Grade B (other materials available as per customer requirements)

•  Welding in accordance with ASME IX

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IMAC Vent Guards are specially designed to prevent the obstruction of vent openings by protecting outlets from debris, insects and other foreign contaminants.  Manufactured using high strength aluminum or stainless steel (no plastics).  Prevent negative effects from the environment including corrosion, dry rot or UV degradation.


Threaded Angle Vent (90 degree) available in 1/8", 1/4", 3/8", 1/2" and 3/4" NPT

Straight Vent (Button Vent) available in 1/4" NPT

Tube Cap with Set Screw (90 degree) available to fit 1/4" SST tubing, 3/8" SST tubing, 1/4" copper tubing or 5/8" stainless tubing

Female Threaded Vent Cap available in 1/2", 3/4" or 1" NPT

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