Abstract: Provided is a pressure pipe connection structure that reduces man-hours for machining one or more pressure pipes and does not require high machining precision. Multiple arc members form a ring shape that makes a circle by matching the end faces thereof to each other. Non-penetrating holes may be provided on the outer circumference of the arc members. The ring formed by the multiple arc members has an inner diameter that is smaller than the outer diameter and larger than the inner diameter of a pressure pipe. A cylindrical sleeve has an inner cylindrical surface inside which the entire outer circumferences of arc members are fitted into a hollow internal space, into which respective one or more pressure pipes are inserted from one or more opposing entrances; and multiple through holes, which penetrate from the outside and are provided with female thread ridges.

Abstract: A metal member (3) is bonded with an adhesive (6) to have a bond strength higher than the basic material strength of the metal member (3). A metal insertion coupling has a socket portion (4) in which an insertion hole (2a) for inserting the end portion of the metal member (3) is formed. The socket portion (4) has a tapered outer surface extending from the opening end to the back side. The tensile strength of the socket portion (4) at the deepest position along the center line of the insertion hole is equal to or higher than the tensile strength of the metal member (3) in the direction of the center line. The insertion hole (2a) has a width 0.2 mm-0.6 mm larger than that of the end portion of the metal member (3). The end portion of the metal member (3) is pressed into the insertion hole (2a), and an adhesive exists densely between the end portion of the metal member (3) and the surface of the insertion hole (2a), by quenching or cold working the end portion of the metal member (3).

Abstract: A metal member (3) to be bonded is bonded with an adhesive (6) to have a strength higher than the basic material strength of the metal member (3) to be bonded. A metal insertion coupling has a socket portion (4) in which an insertion hole (2a) for inserting the end portion of the metal member (3) is formed. The socket portion (4) has a tapered outer surface extending from the opening end to the back side. The tensile strength of the socket portion (4) at the deepest position of the center line of the insertion hole is equal to or higher than the tensile strength of the metal member (3) in the direction of the center line. In the metal insertion coupling, insertion hole (2a) is formed to have a larger width as compared with the end portion of the metal member (3) in the range of 0.2 mm-0.6 mm.