with the distal end 24 of the tube 14 abutted against a shoulder 26 connecting portion 18 the tube 14 has an internal surface 28 which forms an air tight seal between the tubular portion 20 of fitting 12 and the tube end 16 the tube 14 has an unstretched internal diameter d 1 and an external surface 30 having an external diameter when it is unstretched of d 2 and when it is stretched over the tube portion 20 a larger diameter of d 3 surrounding the tube end 16 and particularly the portion of the tube that is covering tube portion 20 is a coil spring 32 the coil spring 32 has a tightly coiled forward portion 34 and a more loosely coiled rear portion 36 it likewise has an internal surface 38 which in an unstretched state has a diameter approximately equal to the external diameter d 2 of the tube when in an unstretched position as shown in fig2 the portion of the coil spring 32 surrounding the tube end 16 which covers tubular portion 20 is in a stretched condition and has a diameter less than the diameter of the external surface of the tube d 3 and is embedded into the external surface 30 of the tube end 16 the coiled spring is in a stretched tensional state around tube end 16 applying radial pressure against surface 30 maintaining an air tight seal as shown in fig5 the fitting 12 of the present invention is assembled in a single step the spring 32 is simply slipped over the tubing 14 so that the end 40 of spring 32 is immediately adjacent the end of tube end 24 the spring.