Covalence^®

Properties

• Backing material made of infusible, heat shrinkable bonded polyolefin
• Coating with hot-melt adhesive, high adhesion, moisture-proof, impact- and abrasion-resistant material, remains flexible and free of cracks even under continuous stress
• Quick and easy installation by shrinking on with gentle propane gas flame without additional adhesive or primer
• Provides protection against creepage, rotting and UV resistant
• Compatible with all common pipeline coatings
• Low preheat requirements, self-healing effect due to viscoelastic sealant
• Dimpled structure in the backing material as an installation aid

Fields of application

Subsequent coating of:

• Welded seams
• Connecting sockets (type Tyton, Fuchs etc.)
• Couplings, bolt connections and pipe bends
• Flanges
• Damaged factory coatings
• Welding electrodes
• Weld seams with higher mechanical load

Sealing of:

• Casing pipes
• Vitrified clay pipes
• Packed and bolt gland sockets

Description

Application: Under normal conditions, no primer is required for heat shrink products. As with all corrosion protection systems, the surface to be coated or subsequently insulated must be clean, free of grease, and dry. With heat-shrinkable corrosion protection systems, it is particularly important to pay attention to compliance with the specified pre-heating temperatures. The more precisely the pre-heating temperatures are kept to, the better and longer lasting the peel and shear resistances of the hotmelt adhesives will be.

The hot melt adhesive liquifies during the shrink process onto the pipe (using a propane gas flame).

The liquefied hot melt adhesive then completely moistens the surface to be coated or subsequently insulated, sticking in any unevenness and fills any small cavities (e.g. transition from steel to factory coating or edges of welded seam). This process is supported by the shrink tension in the retainer material which occurs during processing.

The shrinkage stress of the backing which is in the retainer material is permanently present, and the adhesion of the hot-melt adhesive fix the shrinking tube or the shrink sleeve in place, even if the pipe moves and if there are active shearing forces at the given point.

The backing material, which solidifies after cooling, offers the relatively soft hot-melt adhesive optimal mechanical protection.

DIRAX System

The DIRAX system is a wrap-around heat-shrinkable sleeve reinforced with fiberglass. DIRAX is designed to protect girth welds against corrosion and is the optimum joint protection for PE and FBE coated pipes used in Horizontal Directional Drilling (HDD-Pull Through) applications. The reinforcement gives the backing greater wear resistance.

Construction: Three-layer system

• First layer: Liquid epoxy, solvent-free two-component.
• Second layer: High shear strength copolymer adhesive.
• Third layer: Thick, fiberglass reinforced, radiation cross-linked polyethylene.
• Additional component: Wear Cone as extra protection against pull-through forces, of the same construction as the main sleeve.

Notes

During installation, the epoxy resin is applied to the prepared pipe surface and the heat-shrinkable sleeve is immediately wrapped around the joint on the wet epoxy resin.

The sleeve is then heated and shrunk so that it tightly encloses the joint. During the curing process, the epoxy resin forms strong mechanical and chemical bonds with the pipe surface and the copolymer adhesive layer.

The radiation-cured outer layer forms a robust barrier against mechanical damage and moisture transfer.

• The heat shrink product must be completely smooth and bubble-free
• The hot-melt adhesive must have been pressed out at the edges all around the circumference of the pipe

• The required overlap to the factory coating must be at least 50 mm on both sides
• The factory-applied dimpled structure in the backing material (PCI) is no longer visible