Joint mechanism and connection method for steel pipe

Abstract

Contemplated are simplification and cost reduction in arrangement of connecting a pair of steel pipes to each other. A joint mechanism for a pair of steel pipe piles 1 A, 1 B includes an inner joint 10 A provided in the steel pipe pile 1 A, an inner joint 10 B, an outer joint 20 disposed circumferentially between and across the inner joint 10 A of the steel pipe pile 1 A and the inner joint 10 B of the steel pipe pile 1 B, and a key member 30 configured to prevent relative movement between the pair of steel pipe piles 1 A, 1 B in a longitudinal direction of these steel pipes 1 . The outer joint 20 includes an opening portion 22 ( 22 A, 22 B) for inserting, from its outer circumferential face, split key members 31 constituting the key member 30 into a key groove constituted of an outward circumferential groove 13 ( 13 A, 13 B) provided in the outer circumference of the inner joint 10 A and the inner joint 10 B respectively and an inward circumferential groove 23 ( 23 A, 23 B) provided in the inner circumference of the outer joint 20 in opposition to the outward circumferential groove 13 ( 13 A, 13 B).

1 . A joint mechanism for a steel pipe comprising:
 a first inner joint provided at one end of one steel pipe;   a second inner joint provided at the other end of the other steel pipe;   an outer joint disposed circumferentially between and across the first inner joint and the second inner joint for connecting a pair of the steel pipes to each other when the first inner joint of one steel pipe is placed adjacent the second inner joint of the other steel pipe;   a key member for engaging the first inner joint with the outer joint and also engaging the second inner joint with the outer joint, thereby to prevent relative movement between the pair of steel pipes in a longitudinal direction of these steel pipes;   an outward circumferential groove provided respectively in an outer circumference of the first inner joint and an outer circumference of the second inner joint;   an inward circumferential groove provided in an inner circumference of the outer joint in opposition to the outward circumferential grooves provided in the outer circumferences of the first inner joint and the second inner joint respectively; and   the outer joint includes an opening portion for inserting the key member from an outer circumference of the outer joint into a key groove constituted of the outward circumferential groove and the inward circumferential groove.   
     
     
         2 . The joint mechanism according to  claim 1 , wherein the key member comprises a plurality of split key members each constituting a portion of a circle, and a closing member having a function of the split key member and a function of closing the opening portion. 
     
     
         3 . The joint mechanism according to  claim 2 , wherein the outer joint comprises a plurality of unit members disposed side by side around the first inner joint and the second inner joint. 
     
     
         4 . The joint mechanism according to  claim 3 , wherein the plurality of unit members include an opening unit member having the opening portion and a standard unit member not having the opening portion. 
     
     
         5 . The joint mechanism according to  claim 3  or  11 , wherein:
 the plurality of unit members include: 
 a reference unit member to be disposed circumferentially across and between the first inner joint and the second inner joint when the first inner joint and the second inner joint are placed in contact with each other; and 
 an extended unit member to be disposed circumferentially across and between the first inner joint and the second inner joint when the first inner joint and the second inner joint are placed apart from each other. 
 
     
     
         6 . The joint mechanism according to  claim 5 , wherein:
 each of the first inner joint and the second inner joint includes a base portion and an inner fitting portion extending continuously from the base portion;   an annular engaging sunk portion is provided annularly in an end face of the base portion facing the inner fitting portion;   the outward circumferential groove is provided annularly in an outer circumference of the inner fitting portion;   at upper and lower end portions of the reference unit member and the extended unit member respectively, there are provided a pair of engaging projecting portions engageable with the engaging portion when the reference unit member and the extended unit member are disposed circumferentially across and around the first inner joint and the second inner joint;   in an inner circumference of the reference unit member and the extended unit member respectively, a pair of the inward circumferential grooves are provided in opposition to a pair of the outward circumferential grooves;   a distance between the pair of inward circumferential grooves of the reference unit member is set equal to a distance between the pair of outward circumferential grooves when the first inner joint and the second inner joint are placed in contact with each other; and   a distance between the pair of inward circumferential grooves of the extended unit member is set equal to a distance between the pair of outward circumferential grooves when the first inner joint and the second inner joint are placed apart from each other.   
     
     
         7 . The joint mechanism according to  claim 1 , wherein:
 at least the outer joint comprises a straight seam steel pipe; and   the bonding portion is disposed at a position not overlapped with the opening portion in the outer joint.   
     
     
         8 . The joint mechanism according to  claim 1 , wherein:
 at least the outer joint comprises a straight seam steel pipe; and   a bonding portion included in the straight seam steel pipe is disposed at a position not overlapped with a position of fixing the closing member in the inner joint.   
     
     
         9 . The joint mechanism according to  claim 1 , wherein:
 at least the outer joint comprises a straight seam steel pipe; and   a bonding portion included in the straight seam steel pipe is disposed at a position not overlapped with a counter bore portion formed in the inner joint or with a counter bore portion formed in the outer joint constituting a rotation preventing key groove.   
     
     
         10 . A connection method connecting a pair of steel pipes to each other with using the joint mechanism according to  claim 1 , the method comprising the steps of:
 disposing an outer joint circumferentially of a first inner joint provided at one one end of one steel pipe;   disposing the first inner joint and a second inner joint provided at the other end of the other steel pipe adjacent each other to insert the second inner joint to an inner face of the outer joint, thereby to dispose the outer joint across and between the first inner joint and the second inner joint;   inserting a key member for engaging the first inner joint with the outer joint and engaging the second inner joint with the outer joint to prevent relative movement between the pair of steel pipes in the longitudinal direction of these steel pipes through an opening portion provided in the outer joint from an outer circumferential face of the outer joint into a key groove including an outward circumferential groove provided in an outer circumference of the first inner joint and the second inner joint respectively and an inward circumferential groove provided in an inner circumference of the outer joint in opposition to the outward circumferential groove and then sliding the key member inserted into the key groove along a circumferential direction within the key groove, so that the key member is disposed at a predetermined position within the key groove, except for a portion of the key groove corresponding to the opening portion; and   closing the opening portion with using a closing member having a function of the key member and having also a function of closing the opening portion.   
     
     
         11 . A connection method connecting a pair of steel pipes to each other with using the joint mechanism according to  claim 1 , the method comprising the steps of:
 disposing an outer joint circumferentially of a first inner joint provided at one one end of one steel pipe;   disposing the first inner joint and a second inner joint provided at the other end of the other steel pipe adjacent each other to insert the second inner joint to an inner face of the outer joint, thereby to dispose the outer joint across and between the first inner joint and the second inner joint;   inserting a key member for engaging the first inner joint with the outer joint and engaging the second inner joint with the outer joint to prevent relative movement between the pair of steel pipes in the longitudinal direction of these steel pipes through an opening portion provided in the outer joint from an outer circumferential face of the outer joint into a key groove including an outward circumferential groove provided in an outer circumference of the first inner joint and the second inner joint respectively and an inward circumferential groove provided in an inner circumference of the outer joint in opposition to the outward circumferential groove and then sliding the key member inserted into the key groove along a circumferential direction within the key groove, so that the key member is disposed at a predetermined position within the key groove, except for a portion of the key groove corresponding to the opening portion; and   closing the opening portion with using a closing member having a function of the key member and having also a function of closing the opening portion;   wherein the step of disposing the outer joint circumferentially includes a step of tilting an axis of the one steel pipe and an axis of the other steel pipe by constituting the outer joint disposed across and between the first inner joint and the second inner joint of a plurality of unit members one or some of which constitute the reference unit members and the other of which constitute the extended unit members.