NEMO Hybrid System - A Novel Field Joint Solution
Authors: Cunha Normando 
Published: October 2017

Field joint coatings are key to the integrity of pipeline. A functional field joint must be compatible with the thermal insulation system from factory coating, can be applied within a suitable cycle time of the process and can withstand static and dynamic mechanical strengths during its fabrication, handling and pipeline installation.

Past projects have presented technical challenges concerning the compatibility of the field joint coating solution with the materials in the parent coating, the integrity of the linepipe coating and field joint coating interface and the imposed mechanical strengths observed during the installation of fabricated stalks through the reeling operation. Appearance of cracks at field joint body and/or interface with parent insulation system were evidenced and in some cases attributed to the high insulation thickness of system, low installation temperatures and stringent radius. But limited study was done in the industry to prove this is the case.

These issues can lead to significant delays during the onshore and offshore operations, resulting in investigation costs and halt of personnel, equipment and installation vessel while expensive repairs are executed.

The objective of this work is to present a field joint system which features good insulation properties, full compatibility with the insulation parent coating and the ability to withstand the mechanical strengths imposed on the field joint during installation and in-service conditions.

Shawcor has committed to resolve such challenges and has therefore developed a novel Field Joint Coating solution (NEMO Hybrid Field Joint Coating) that will reduce the risks of failures, providing the industry with additional options when engineering coating systems.

The method consists of an hourglass type injection-molded polypropylene (IMPP). Its main purpose is to act as a heat barrier to the infill material and bond to the parent coating. The next steps involve plural components epoxyurethane applied in low-pressure casting to complete the body of field joint.

The NEMO Hybrid system was assessed for its insulation and mechanical performances, encompassing installation and in-service requirements as well as temperature/pressure simulated service tests.

Key product properties such as density, thermal conductivity, hardness, long term tri-axial creep, water absorption rate, tensile and uniaxial stress compression were evaluated, taking into consideration the main standards and specifications known in the coating industry. Furthermore, full scale tests related to simulated reeling, fatigue, shear strength, model tensioner and simulated service tests were also performed to assess the hybrid field joint system.

The NEMO Hybrid FJC solution was successfully tested on a real project in the GoM with more opportunities to come. It presented excellent compatibility with polypropylene-based parent coatings, demonstrating suitable insulation capacity and helping the parent coating to keep heat loss lower than the typical requested U-values by the industry.

No cracking was observed through the field joint system and the sliced sections showed no evidence of foaming, disbondment or other signs of damages after simulated reeling test and simulated service test.

The field joint system demonstrated proper field performances on mechanical testing, reduced creep at high temperatures and elevated pressures and improved hydrolysis resistance in the subsea environment.

NEMO Hybrid is a novel insulation field joint system duly tested and now available for the industry as a solution for minimizing risks during pipeline installation phases. This system will offer a new blend of materials technology to the oil and gas industry, providing excellent long-term insulation properties and proven mechanical resistance mainly during reel lay operations.