Apparatus (1;101) for aligning and supporting a first (2;102) and a second (3;103) length of thermoplastic tubing, preparatory to and during cutting and welding of said lengths of tubing, said apparatus comprising the following components arranged on a base support: a) a first holder (5;105) arranged to accommodate portions of said first and second lengths of tubing in a first (6;106) and a second (7;107) elongated holding space respectively, wherein said holding spaces are essentially parallel to each other and separated from each other by a first distance (8;108); b) a second holder (9;109) arranged to accommodate portions of said first and second lengths of tubing in a third (10;110) and a fourth (11;111) elongated holding space respectively, wherein said holding spaces are essentially parallel to each other and to the holding spaces in the first holder and separated from each other by a second distance (12;112) substantially the same as the first distance (8;108), and wherein said second holder is movable in a direction essentially perpendicular to the holding spaces of the first and second holders from a cutting position where said first holding space (6;106) is aligned with said third holding space (10;110) and said second holding space (7;107) is aligned with said fourth holding space (11;111) to a welding position where said first holding space (6;106) is aligned with said fourth holding space (11;111); c) cutting means (13;113) arranged between said first and second holders for cutting said lengths of tubing when the second holder is in the cutting position; and the apparatus characterized in that it further comprises, arranged on the base support: d) aligning means arranged to abut the outside of a cut length of tubing accommodated in the first holding space (6;106) and the outside of a cut length of tubing accommodated in the fourth holding space (11;111) and to align these lengths of tubing with each other, wherein the aligning means comprises a first (14;114) and a second (15;115) aligning plate, both having substantially the same width, each movable in a direction essentially perpendicular to the holding spaces of the first and second holders, and an abutment plate (16;116) attached to said base support, wherein, when the second holder is in the welding position, said first aligning plate is arranged to abut said abutment plate and the outside of a cut length of tubing accommodated in the first holding space (6;106) and said second aligning plate is arranged to abut said abutment plate and the outside of a cut length of tubing accommodated in the fourth holding space (11;111) such that the cut lengths of tubing in the first and second holding spaces are aligned with each other. a) a first holder (5;105) arranged to accommodate portions of said first and second lengths of tubing in a first (6;106) and a second (7;107) elongated holding space respectively, wherein said holding spaces are essentially parallel to each other and separated from each other by a first distance (8;108); b) a second holder (9;109) arranged to accommodate portions of said first and second lengths of tubing in a third (10;110) and a fourth (11;111) elongated holding space respectively, wherein said holding spaces are essentially parallel to each other and to the holding spaces in the first holder and separated from each other by a second distance (12;112) substantially the same as the first distance (8;108), and wherein said second holder is movable in a direction essentially perpendicular to the holding spaces of the first and second holders from a cutting position where said first holding space (6;106) is aligned with said third holding space (10;110) and said second holding space (7;107) is aligned with said fourth holding space (11;111) to a welding position where said first holding space (6;106) is aligned with said fourth holding space (11;111); c) cutting means (13;113) arranged between said first and second holders for cutting said lengths of tubing when the second holder is in the cutting position;