NOVELTY - The method involves positioning ends (2a, 3a) of seals (2, 3) on a sealing surface so as to connect the ends, and conveying and assembling a portable injection molding machine (1) on a site. The molding machine is positioned on the surface in vertical alignment with the ends. Previously heated thermoplastic polyurethane is injected between the ends at hot condition by the molding machine. The thermoplastic polyurethane injected between the ends is cooled. Pressure of the injected thermoplastic polyurethane is maintained during the cooling step, and the machine is disassembled.    USE - Method for connecting ends of single open seal or of seals, that are used for assuring static and dynamic sealing of hydraulic cylinders, cylinders of extruder or sealing of hydroelectric turbine or wind turbine blades, on a site by a portable injection molding machine (claimed) i.e. direct injection molding machine, used in fields of hydroelectricity, power hydraulics, machine tools, offshore platforms, drilling, wind and naval or civil engineering.    ADVANTAGE - The method enables utilizing the thermoplastic polyurethane for connecting the ends of the seals with high quality. The thermoplastic polyurethane provides better abrasive resistant properties. The method enables connecting the ends of the single open seal or of the seals on the site to avoid disassembling of mechanical installations to carry out the maintenance operations, and allows the maintenance operations to be performed in short period of time to limit operating losses.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a portable injection molding machine for implementing a method for connecting ends of open seal or of seals on a site.    DESCRIPTION OF DRAWING(S) - The drawing shows an exploded perspective view illustrating a method for connecting ends of seals from left to right.    Direct injection molding machine (1)    Seals (2, 3)    Ends of seals (2a, 3a)    Mold (5)    Injection head (6)