4 of the end component this in turn leads to very efficient damming of the melt formed at the weld surfaces a further embodiment of an end component for use in the method of the present invention is shown in fig6 and 7 in which a small annular projection 25 is provided on the underside of the range 6 such a projection will engage the end of the tube during welding and will provide effective damming of the melt from the weld when the appropriate axial loading 34 pt 34 is applied the annular projection may be provided as an alternative to chamfering the end of the tube 1 or may be provided in combination therewith in a preferred method the materials selected for the tube and the end component have different characteristics all high density polyethylenes have a similar melting point of about 130 u00b0 c but their latent heat of fusion dhm the amount of heat energy necessary to melt one gram of material at the melting point temperature varies according to their crystalline content in general the more crystalline the polymer the greater the latent heat of fusion dhm by selecting the materials used for making the tube and the end component one or other can be made to melt preferentially at the weld area such a selection of materials is particularly advantageous in respect of the end component shown in fig6 and in an example the end component was made of high density polyethylene having a dhm of 176 j gm whereas the tube was made of a high density polyethylene having a dhm of 148 j gm during spin welding the tube melts more readily than.