Field Joint Coating (FJC)

Nominal length of one pipeline joint is 12.2m. Field Joint is the end of each pipeline joint where it is left bare without external coating for the purpose to facilitate girth welding to join 2 pipe section together. Field joint needs to be coated to provide protection to pipeline and reduce CP system drainage.

The objective of FJC, Ref. 2:

• Corrosion control
• Mechanical protection
• Thermal insulation
• Smooth transition to a concrete weight coating of linepipe (Infill)

The welded pipe/field joint is cleaned before application of field joint coatings.
Some of the popular field joint coatings include:

• Tape wrap
• Heat Shrink Sleeve
• FBE
• 3 Layer Polyolefin

Tape Wrap
Tape wrap is an adhesive backed heavy-duty plastic tape consists of a spirally wound tape made of PVC, polyolefin or fiberglass, with or without mastic primer is applied to cold or preheated field joints (cold applied). Tape wrap is applied as a double wrap around the pipe joint. The tape shall be sufficient to cover the full joint and overlap the external coating on the pipeline beyond the cutback on both side of the joint. (The length of overlapping needs to refer to codes and standards being used)


Heat Shrink Sleeve, HSS
HSS is formed by preheating and stretching the main coating material which is PP or PE in the circumferential direction. HSS will return to original size on reheating.

Liquid Epoxy is used as a primer to apply on the field joint surface before application of HSS to produce a better corrosion protection.


FBE
FBE FJC application onto the field joint is very similar with the parent coating (FBE external coating) where the field joint is cleaned, heated up, then the epoxy particles/powder are flocked onto the field joint.

Field Joint Infill Material
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References:

1. Palmer, A. C., King R. A. King (2004) Subsea Pipeline Engineering. Tulsa, Oklahoma: PennWell.
2. DNV-RP-F102, Pipeline Field Joint Coating and Field Repair of Linepipe Coating, 2003