text: An adhesive is then applied to the sheet and various manufacturers use proprietary techniques depending on the type, viscosity and melting temperature of the adhesive.  The adhesive is the key to ultimate performance of the installed system, which is why different adhesive types will be specified depending on the pipeline operating conditions.
  The adhesive has many functions; it adheres the installed sleeve to the steel at the coating cutback and mainline coating, it resists shear forces imparted by soil pressure after the pipeline is buried and provides long term corrosion protection to the steel. The choice of which adhesive to use is based on the pipeline design and operating conditions.  As an example, for small diameter flow lines operating at ambient temperatures, a soft mastic-based adhesive may be chosen, while on large diameter pipelines operating at higher temperatures, a hard, semi-crystalline hot-melt adhesive is used.  The adhesive needs to be chosen based on its corrosion protection properties, adhesion strength, and resistance to shear forces imparted by pipe movement and the effects of soil pressures.
  The coated sheet is then cut into individual sleeves suitable for application on a pipeline.  As mentioned before, the sheet is stretched and wants to recover when heated, so a sealing strip or "closure" is applied during sleeve installation so that the sleeve will stay in place during and after recovery.