Repair system for pipes

This standard defines the design, installation, test and inspection criteria for the use of composite repair systems for oil and gas pipelines and pipework carrying petrochemicals. Compliance of the Loctite Composite Pipe Repair System with this standard gives industry a time-served system with the added assurance of certified safety and performance.

One of the first companies to take advantage of this combination in the UK is Bilfinger Industrial Services, a leading supplier to the UK process, petrochemical, oil & gas and power industries. The company prides itself on delivering long term engineering and maintenance solutions for customers and considers the Composite Pipe Repair System a useful addition to its armoury.

As specified in the ISO certification and required by DNV GL, Bilfinger engineers have completed the specially developed, certified training programme for pipe repair at Henkel’s Technical Applications Centre in Hemel Hempstead.  

Repair not replace

Steel pipelines are costly to install and effective maintenance is therefore essential to maximise their service life. The structures are exposed, both internally and externally, to the combined corrosive effect of the climate, mechanical stress and chemical attack. As the renewal of damaged and ageing sections stops production, maintenance and repair organisations are increasingly choosing to repair rather than replace pipework. 

Central to the Loctite Pipe Repair System is a resin-based composite material reinforced with fibres. It is similar to materials developed by Henkel that are used by manufacturers of rotor blades for wind power generation or lightweight components for the automotive industry. When used for steel pipelines, the composite reinforces the damaged pipe sections while also protecting against renewed corrosion.

The Composite Repair System is suitable to repair both Type A (non-through wall) and Type B (through wall) defects, covering all repair classes 1 – 3.  In addition to straight pipes, the system can be used to repair other structures and components such as bends, tees, reducers and flanges.

The process

The first step in the repair procedure is to clean and sandblast the surface of the damaged area. As this treatment makes the substrates susceptible to flash rust, Henkel recommends applying the corrosion inhibitor, Loctite SF 7515, to provide immediate, temporary protection.

For Type A defects, the original outer pipe diameter needs to be restored by filling the cavities with Loctite EA 3478, a ferro-silicone filled epoxy compound that provides excellent compression strength. This product was specifically developed for renewing surfaces subject to compression, thrust, impact and harsh environments.

The pipe is then wrapped with high-strength, glass-carbon fibre tape, Loctite 5085, that has been impregnated with temperature-resistant, two-part epoxy resin Loctite PC 7210; this product is designed for bonding steel substrates and is said to exhibit exceptionally high adhesion.

The repaired section is finally sealed with the sprayable ceramic topcoat, Loctite PC 7255, a two-part epoxy which is WRAS approved. The resultant composite repair effectively reinforces steel pipes for continued duty under high pressure and thermal cycling while increasing their chemical resistance.

Benefits

In addition to certified safety, the Composite Repair System is said to offer substantial cost savings as it eliminates the need to replace pipe components. Corroded pipes can be repaired in situ, without any interruption to operations and even with high internal pressure. Also, Henkel says that the quality achieved by the repair can increase the lifetime of steel pipelines by up to 20 years.  

As part of the package, Henkel is offering to provide calculations of the project-specific repair designs. These differ from project to project depending on the range of parameters such as the forces acting on the pipeline, temperature, pressure and the extent of damage. To maximise the safety and efficiency of this process, Henkel has developed a software tool to determine how the repair should be executed; this is also covered by DNV GL certification.