Concentric plastic tubes with plastic foam-filled annular space - are held apart by T=section plastic spacers

摘要

The spacer is intended for maintaining distance between an outer tube and a co-axial inner tube, the annular space between them being filled with plastic foam material. It is formed as a plastic, e.g. PVC, T-section of which the end of the vertical portion engages the outer tube whilst the cross-bar directly or indirectly engages the inner tube. The cross-bar may have at least one projection to prevent its displacement. This projection may be formed as a ridge. The cross-bar and projections preferably have a lesser wall thickness than the vertical portion. The inner tube may be in glass fibre-reinforced plastic whilst the outer tube is in poly-alkene material.