Couplings for multilayer pipelines, welding devices, joining methods and resulting assemblies thereof

Abstract

A coupling piece (1) for the outer end of a multilayer pipe (28), comprising a coupling pipe (2) provided on the outer side with a radially upstanding wall (4), wherein the wall is axially positioned at widened at a radial distance from the outer side of the main body, wherein the outer side of the coupling pipe, the upstanding wall and the widening surround an annular insertion space (22) into which the outer end of the pipe can be inserted directly (22), wherein the inner wall of the connecting pipe is reinforced with an adjacent reinforcing layer (50) having a strength greater than that of the material of the connecting pipe, and this layer is provided with an axial engagement element (52), while the inner wall is provided with a corresponding Axial connecting element (26) at and connected to the engagement element.

Description

technical field [0001] The present invention relates to coupling pieces for multilayer pipelines, in particular to coupling pieces for multilayer pipelines suitable for socket welding (international term: polyfusion welding). Background technique [0002] Multilayer piping for plastic piping systems (PCS) is considered an alternative to steel and copper for many applications, such as water drainage and water, gas and chemical supply. Multilayer pipes may comprise different types of plastic, with a base such as aluminum embedded in the plastic for the purpose of improving pressure resistance. Mainly thermoplastics are used, such as polypropylene (PP), polyethylene (PE), polybutylene (PB) and sometimes PVC. Installation of the system includes forming a combination of pipes and connections, couplings and / or fittings. The type of accessory also determines the nature of the tool that must be used. Multilayer pipes constructed from PE pipes with an aluminum base layer are used ...

AI Technical Summary

Problems solved by technology

[0013] In the coupling of such multilayer pipes with couplings as according to JP'374, it has been found that the integrity of the outer layer is lost: it is not technically possible to remove a part of the outer layer while still having enough outer layer to cover the metal layer easily achievable

There is thus an increased risk that part of the metal layer of the pipe becomes exposed, whereby undesired corrosion of the metal layer may occur

[0014] The second problem occurs at the outlet of the coupling pipe during multiple fusion welding to the pipe end

[0016] A third problem is that the coupling obtained between the coupling and the two pipe outer ends is mechanically vulnerable at the location of the coupling with respect to various tensile or axial and torsional forces

When high torsional forces are applied to the outer end of the pipe connected to the coupling, the coupling may crack and break, e.g. at the location of the widening

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