Shrink sleeve - a hollow cylinder 500-700 mm long, made of polyethylene by special processing. It is used to protect the joints of pipes insulated by PPU (polyurethane foam film). The heat-shrinkable end sleeve provides reliable waterproofing, protecting against corrosion and leakage, and improves the tightness of the structure.

Heat Shrink End Coupling

Shrink sleeves are hollow polyethylene cylinders used for waterproofing

The use of heat-shrinkable sleeves for pipes PPU

Steel pipes require additional protection to increase their useful life. It's related:

  • with the instability of the metal in relation to the effects of corrosion and substances with properties of chemical activity;
  • with the advent of stray currents and their destructive effect;
  • the presence of welds that quickly fail, especially in conditions of being in the ground.

By isolating the segments of the pipeline, an increase in their level of protection against damaging effects is achieved:

  • precipitation;
  • stray currents;
  • exposure to various substances.

Note! The material for isolation from such effects must be hydrostatic and dielectric. In view of the greatest efficiency, preference is given to polyurethane foam in combination with an additional coating of polyethylene.

Polyurethane foam insulation provides protection for the body of products, which is conventionally called PPU pipes, but it is not applied to technological indents. Open non-insulated sections at the edges are left for further installation of pipelines, for welded joints and coupling placement. A heat-shrinkable sleeve is used just for the isolation of technological indentation during welding. For its manufacture, materials similar to those used for insulation for pipes are used.

Heat Shrink End Coupling

By means of couplings isolate welded joints in pipelines

Heat-shrinkable end couplings, the manufacture of which went to radiation polyethylene, insulation of joints is carried out.

Benefits of using a heat shrink sleeve

Heat-shrinkable end couplings have excellent performance properties and a number of other advantages that are revealed during their installation and use. The thermoshrinkable coupling for PPU pipes is characterized as having:

  • special mechanical strength;
  • resistance to ultraviolet radiation and stray currents;
  • inertness in relation to chemically active substances;
  • thermoelasticity, maintaining a viscous rubbery consistency when heated. Deformation occurs only if the melting point is reached;
  • full tightness and moisture resistance interfering with corrosion processes;
  • multidimensionality, which not only greatly simplifies installation, but also significantly reduces logistics and financial costs;
  • universality. The use of heat-shrinkable couplings is allowed when joining pipes on a heating main or steam pipe, in a cryogenic system, in a pipe with a working pressure of up to 1.6 MPa.The diameter of the heat-shrinkable sleeve (from 110 to 1200 mm) allows for use on industrial pipelines, but does not exclude the possibility of use in domestic;
  • high operational reliability with significant long-term use;
  • quick and easy installation. The installation of the coupling does not require the involvement of highly qualified specialists and sophisticated equipment, a gas burner is enough. After a short heat shrink, she is ready to work. The presence in the kit of auxiliary insulating materials in the form of two liquid components, which fill the space between the joined surfaces, improves the reliability of the connection;
  • environmental safety both during installation work and in relation to the subsequent impact on the environment;
  • preservation of working properties even with long periods of storage;
  • small size, simplifying storage, transportation and installation;
  • practicality and economy of use.
Heat Shrink End Coupling

The installation process of the coupling is not difficult and does not require the involvement of equipment

Such significant advantages explain the preferences of consumers choosing such products.

Mounting technology

The coupling is mounted in parallel with the welding work, in a certain sequence:

  1. The product is removed from the packaging immediately before installation, the inner surface is freed from contamination.
  2. The thermocuff is put on in the middle of the joint, its edges are marked on the pipes with a marker.
  3. Prior to welding, a sleeve is put on one of the pipes and offset about half a meter from the edge.
  4. Pipes are installed in one plane, there is a gap for the weld.
  5. Welding can be carried out using a torch, electric or manual gas, or automatic welding complex.
  6. After welding, the joint takes time to cool. The leak test is carried out depending on the welding technology used.
  7. After verifying the tightness of the seam, the heat-shrink sleeve is displaced, completely covering the non-insulated portion of the pipe.

Important! Heating starts from the bottom of the pipe so that heat is distributed from the middle of the cuff over its entire surface. Exceeding temperatures above 90-110º C is unacceptable, because it will destroy the coupling. Evidence of overheating is a bluish shine that has appeared on the surface.

Heat Shrink End Coupling

So that the coupling tightly "sits" on the pipe, it is heated in the direction from the bottom up

When the pipe insulation is squeezed, the void is filled with polyurethane foam from the kit through the hole provided in the coupling. Air is removed through another hole. After half an hour, the holes are sealed with conical plugs, which should not protrude above the coupling.

With proper work, a visual inspection will confirm:

  • the appearance of the adhesive layer around the circumference of the product;
  • lack of clearance between the coupling and pipe insulation.

Features of storage, transportation and use

The service life of any product will not be reduced if it is properly stored, transported and used. With regard to shrink sleeves, the following rules are mandatory:

  • avoid overheating above 30 degrees, therefore, organize storage and transportation accordingly;
  • storage should be single-tier or using inter-level gaskets;
  • for storage and transportation, a vertical arrangement is provided to prevent ovalization;
  • it is permissible to use the principle of nesting dolls by inserting products of a smaller diameter into larger ones;
  • it is only allowed to remove the protective packaging immediately before installation;
  • installation success is possible only when it is carried out at a temperature above -15º C;
  • more than five degrees of misalignment when docking is not permissible;
  • installation must not be carried out if moisture gets on the surface of the pipes. At least temporary shelter should protect against penetration of precipitation, and the surfaces to be joined should be kept dry. Getting under the cuff of moisture is strictly unacceptable.

Shrink sleeves are used when laying trunk lines, where they exhibit excellent performance properties. regardless of the climatic conditions. Cost-effective and easy-to-install products perfectly protect the welded joints of PPU pipes, eliminating the need to additionally carry out hydro and thermal insulation work.