What Are The Uses And Benefits Of Composite Wrap For Pipeline Defects

Composite repair systems using composite wrap remain a constant repair option for industries requiring the repair and rehabilitation of piping systems. Various techniques and testing methods, which have the ability to handle different critical conditions onsite, are being developed in order to meet the demands of the industry. Composite wrap materials are recognized as a reliable and effective means of repairing corrosion damage, mitigating corrosion concerns and keeping critical piping systems in production.

When left unmonitored, excessive external corrosion, internal corrosion, erosion, abrasion, dents and cracks can all potentially lead to disaster. These pipeline defects if not repaired, can cause expensive and potentially deadly consequences to asset owners and equipment operators. Therefore, these pipeline defects require suitable repairs or replacements, depending on the severity of the defects.

Safer Solution to Repair of Pipeline Defects

Composite wraps have been used as transmission pipeline repair methods for more 20 years. Within that time frame, specific composite repair systems have proven to be a permanent repair of potentially catastrophic pipeline defects. Along with the guidelines issued for non-metallic repairs to pipelines in ASME PCC-2 Article 4.1, composite repair manufacturers design composite repairs solutions for specific field applications.

Fundamentals of composite repair systems

While operating pressure is not always high, the chemicals and the elevated temperatures of some piping processes accelerate internal and external corrosion. In most cases, wall loss is severe and in many cases, it has become a safety hazard or is leaking. Through wall defects or complete wall loss and pinhole leaking is a regular occurrence within many facilities. In order to repair these types of defects, a composite system must meet the minimum requirements and perform at the expected level under extreme conditions. Whilst numerous composite wrap materials are available on the market, there are few that have the testing and capability to perform at the elevated temperatures that may be experienced.

Types of composite repair systems

Layered systems and wet lay-up systems are general types of repair systems used for composite repair. The wet lay-up system involves pre-impregnated fibreglass cloth that is activated in the flied by water. An advantage of this system is that the cure state tends to be monolithic and can be used to cover a range of geometries, including tees, elbows, bends and even valves. When designing a repair system using composite wrap materials, engineers must consider both strength and stiffness. From a composite standpoint, strength relates to the tensile strength of a particular system, while stiffness relates to elastic modulus. For most conventional repair systems, there is a direct correlation.

Composite Repair System Uses and Benefits

Composite repair systems are suitable for use on pipeline defects including wall loss of up to 80 percent (e.g. external or internal pipe corrosion, erosion etc.), dents and gouges in pipes and pipe fittings. The composite repair solution is considered a replacement option to the crop-and-replace method of replacing a new pipe section.

There are many advantages of composite repair including:

(1) Able to installed while the pipeline is operation
(2) Operating pressure may not need to be reduced during repair works
(3) No hot works required to install the composite repair systems
(4) Remediate, repair and reinforce the pipe defects by increasing wall thickness
(5) Reduce unnecessary heat infected zone weld induced stresses induced from welding
(6) Versatile for application on complex pipe geometries (e.g. elbows, tees, nozzles and bends)
(6) Faster project implementation duration
(7) Economical repair solution