Monolithic Joints for Electrically Isolating Pipelines

October 25th, 2017 by Amanda Schumann

Monolithic insulated Joints are available in sizes ranging from 50 NB to 200 NB (2” thru 48”) and pressure ranging from ANSI 150 to ANSI 900.

Monolithic Insulated Joints electrically isolate sections of gas, oil and water pipelines to prevent corrosion caused by stray electrical currents or interference from other pipelines and power transmission cables. Electrical isolation is assured by three features: 1) insulated gasketing that prevents metal-to-metal contact across the joint, 2) internal cavities filled with a special dielectric compound, and 3) internal and external surfaces coated with two (2) coats of non-conductive epoxy paint, or coating per the customer’s specification. Insulating joint hubs are provided in compliance with the customer’s piping specification, and optional extra-length pipe pups can be included in the completed joint.

Global Supply Line (GSL) supplies monolithic joints that feature a pre-fabricated, non-separable, and bolt-less design to satisfy customers that require a single-piece construction for simplicity of installation, elimination of maintenance, and ease of final wrapping and coating after installation in the pipeline. Pressure fatigue, torsion and bending-proof testing of the design was carried out to provide a design that is physically stronger than the pipe to which it is attached.

Each joint supplied by GSL is completely factory assembled and hydro-statically tested to 1.5 times the working pressure before shipment. In addition, each joint is electrically tested to verify it’s insulating capability. No maintenance or parts replacement is required for the entire service life of the insulating joint.

Our strength is we can supply quality USA & European made monolithic insulation joints ex stock or in very short delivery for special configurations in ANSI (ASME) 150, 300, 600, 900, 1500, 2500, in schedule: – standard weight XS, 40, 80, 160 & XXS.

Insulated Joints

Triple Protection

  1. Insulated gaskets prevent metal-to-metal contact across the insulated joint.
  2. All internal cavities of the insulated joints are filled with a special dielectric compound to provide an additional electrical barrier.
  3. Each metal component is individually coated with two coats of epoxy paint.

Standard Material

ASTM A694/ASME SA105 or SA 106 Gr.C (Minimum Yield 52,000 psi) High Yield X52, X60, X65, ASTM 707, etc. on request.

Elastomer O-rings

Viton O-rings are standard in each insulated joint. Other O-ring compounds are available upon request.

Insulated Gasket Material

Epoxy base/glass fiber reinforced high strength laminate.


Epoxy base paint. Coal tar epoxy available upon request.

Welded Insulated Joint Dimensions

When ordering, please specify bore required. Insulated joints are normally thru bored to the same ID as the matching pipe. One or both ends can be taper bored at customer request. Joints also available in sizes not listed and for higher pressure ratings.

For more information click here for the Monolithic Overview at our website.