The present invention relates to a piping system including a semiconductor manufacturing apparatus or liquid crystal devices, chemicals-producing device, the tube device and a tube device which is used for food production line, the tube device is provided with a casing and a union nut, the casing It is made of a synthetic resin tube, and with at least one sealing surface (42) a first synthetic resin cover member 5 of the pair respectively provided with the mouth portion (8) receiving the end of the tube provided in the spout portion one end and the other end respectively on the outside at the same time is fitted, a union nut of a pair of synthetic resin in which are respectively screwed into the end having the mouth portion of the lid member in the enlarged section 43, the diameter of the tube formed ( provided, said cover member 5 is a tube connecting portion (B) is introduced, disclose a tube connecting portion (a) constituting the casing, the fluid in the casing, the Devices 6) Includes a tube connecting portion (C) is introduced, disclose a fluid's, the union nut is, by one end by the fastening due to screw advancement of the portion press to push the tube from the outside, the slide pressing action of the lid member is characterized in that the sealing portion 44 in at least one place is formed by the sealing face 42 of the lid member and the enlarged diameter portion 43 of the tube is in close contact with each other.