Connecting mechanism for thin stainless steel pipe and joint

This kind of related art includes a structure disclosed in Japanese Utility Model Publication No. 2-37015 (patent document 1) which has been proposed by the applicant of the present application in advance. When describing based on FIG. 10showing a connecting structure for a thin stainless steel pipe and a joint which is obtained by further adding an improvement to this related art, this related art is constructed by a thin stainless steel pipe 1 in which a chevron type projection portion5 having two inclined surfaces 5a and 5b is formed in an outer periphery of an end portion, a joint 2 in which a male thread portion 7 is formed in an outer peripheral surface of an end portion as well as having an inner diameter to which the thinstainless steel pipe 1 is inserted, a nut 4 which has a female thread portion 8 engaging with the male thread portion 7 of the joint 2 as well as having a fitting portion 11 outwardly fitted to the thin stainless steel pipe 1 so as to oppose to the joint2 on the boundary of the chevron type projection portion 5, and a packing 3 which is provided between the joint 2 and the thin stainless steel pipe 1.


In the joint 2, there is formed a packing fitting portion 6 for fitting the packing 3 closely attached to one inclined surface 5b close to the end portion of the chevron type projection portion 5 to an inner periphery close to an open end portion2a thereof. Further, a pipe insertion hole 2d expanded at a thickness of the thin stainless steel pipe 1 for inserting an end portion of the thin stainless steel pipe 1 is formed in both ends of an inner hole 2c in a center portion.


In the nut 4, there is formed an inclined notch portion 10 closely attached to the other inclined surface 5a of the chevron type projection portion 5 in an inner end portion of the fitting portion 11 outwardly fitted to the thin stainless steelpipe 1, and there is formed a joint contact surface 9 with which the opening end portion 2a of the joint 2 is brought into contact at a time of screwing and firmly attaching the female thread portion 8 of the nut 4 and the male thread portion 7 of thejoint 2. The joint contact surface 9 is formed based on an inner diameter difference between the fitting portion 11 and the female thread portion 8.


In accordance with the related art mentioned above, since it is hard to discriminate from an outer side even in a case where the female thread 8 of the nut 4 is not sufficiently fastened to the male thread 7 of the joint 2 such as a temporalfastening by a manual fastening having a weak fastening force at a time of a piping execution, this matter is often passed over at a time of inspecting a construction finish. Further, a water leak is checked by tentatively circulating a pressure waterafter the end of the piping construction, however, since the packing 3 is closely attached to the joint 2 and the inclined surface 5b of the thin stainless steel pipe 2 even in the manual fastening stage, the water is not so leaked, so that this matteris often passed over. Due to the reason mentioned above, if the nut 4 is started to use in a state where the nut 4 is not sufficiently fastened to the joint 2, which causes a problem that the connection between the nut 4 and the joint 2 is detached, andthe water leak of the fluid such as the water flowing within the thin stainless steel pipe 1 or the like simultaneously arises, whereby a portion within a building is soiled.


This invention is made for solving the problem mentioned above, and an object of this invention is to provide a connecting mechanism for a thin stainless steel pipe and a joint which can check out a fastening failure and an insufficient fasteningat a time of a piping execution for screwing and firmly attaching a male thread portion of a joint to a female thread portion of a nut fitted to a thin stainless steel pipe, based on a leakage of a pressure water.


In accordance with the connecting mechanism for the thin stainless steel and the joint based on the first aspect of the present invention, the water intruding into a space generated between the packing pressing surface of the packing fittingportion and the packing passes through the release groove formed in the packing outer peripheral contact surface via the gap between the joint and the thin stainless steel pipe at a position at which the fastening of the nut is insufficient, even in astate in which the outer peripheral surface of the packing is brought into contact with the packing outer peripheral contact surface of the packing fitting portion, thereby leaking out to the external portion from the screwed portion between the nut andthe joint or the joint portion between the nut and the thin stainless steel pipe. On the other hand, at a position at which the nut is sufficiently fastened, since the packing pressing surface of the packing fitting portion of the joint presses thepacking against the joint contact surface of the nut and the inclined surface of the thin stainless steel pipe so as to stop water, the water in the thin stainless steel pipe does not leak out to the external portion. Further, even if a small space isgenerated between the packing pressing surface of the packing fitting portion and the packing and the water intrudes thereinto, the packing compressed by fastening the nut evaginates from the packing fitting portion and the release groove is filled up. Accordingly, no water leaks out to the external portion through the release groove. As mentioned above, it is possible to securely find out the position at which the fastening of the nut is insufficient, by circulating the pressure water to the thinstainless steel pipe so as to specify the position at which the water leak is generated. Further, it is preferable to fasten the nut at which the water leaks out.


In the connection between the thin stainless steel pipe 1 and the joint 2, first of all, the packing 3 is pressed into the packing fitting portion 6 of the joint 2, and the end portion of the thin stainless steel pipe 1 is thereafter inserted tothe inner portion of the pipe insertion hole 2d of the joint 2. Further, it may screw the male thread 7 formed in the outer periphery of the end portion of the joint 2 and the female thread portion 8 of the nut 4 which is outwardly fitted to the thinstainless steel pipe 1 in advance until the joint contact surface 9 of the nut 4 is brought into contact with the end portion of the joint 2. Accordingly, the chevron type projection portion 5 of the thin stainless steel pipe 1 is pinched by the cornerportion 2b of the joint 2, the inclined notch portion 10 of the nut 4 and the packing 3 so as to be fixed, and the packing 3 is closely attached to the other inclined surface 5b of the chevron type projection portion 5, the packing fitting portion 6b andthe joint contact surface 9, thereby preventing the leakage of the fluid flowing within the thin stainless steel pipe 1. Since the case where the fastening is insufficient is the same as the first embodiment, a description thereof will be omitted.