A method of fabricating a conduit comprises steps of attaching a first tubular-outboard-ply end of a tubular outboard ply to a first inner collar portion of a first collar with a third weld and attaching a second tubular-outboard-ply end to a second inner collar portion of a second collar with a fifth weld. The method additionally comprises steps of interconnecting the first inner collar portion and a first outer collar portion of the first collar with a first weld and interconnecting the second inner collar portion and a second outer collar portion of the second collar with a sixth weld. The method also comprises attaching a trimmed first corrugated-inboard-ply end to the first outer collar portion with a second weld, attaching a trimmed second corrugated-inboard-ply end to the second outer collar portion with a fourth weld, and communicatively coupling a first sensor with an interstitial space.

A method of fabricating a conduit comprises steps of attaching a first tubular-outboard-ply end of a tubular outboard ply to a first inner collar portion of a first collar with a third weld and attaching a second tubular-outboard-ply end to a second inner collar portion of a second collar with a fifth weld. The method additionally comprises steps of interconnecting the first inner collar portion and a first outer collar portion of the first collar with a first weld and interconnecting the second inner collar portion and a second outer collar portion of the second collar with a sixth weld. The method also comprises attaching a trimmed first corrugated-inboard-ply end to the first outer collar portion with a second weld, attaching a trimmed second corrugated-inboard-ply end to the second outer collar portion with a fourth weld, and communicatively coupling a first sensor with an interstitial space.

There is provided a method of manufacturing a variable wall thickness steel pipe with a hollow tubular raw pipe. The method of manufacturing a variable wall thickness steel pipe includes locking the raw pipe in a die by thrusting a plug into the raw pipe from an one end side, so as to expand an outer shape on the one end side in a state, where the raw pipe is disposed inside the die and movement of the raw pipe in a longitudinal direction is restricted; and performing ironing in which an inner shape of the raw pipe is expanded while the outer shape is maintained so that a thin portion is formed by further thrusting the plug toward the other end side of the raw pipe while the locked state of the raw pipe is maintained, whereas the restriction on the raw pipe is relaxed.

To provide methods, apparatuses and drawing mandrels in which the shaping process can be monitored as closely as possible, a drawing machine and a drawing method manufactures or processes tubes, which extend in the direction of longitudinal extent, from a semi-manufactured product, wherein the drawing machine includes a drawing device for drawing a hollow workpiece formed by the tube and the semi-manufactured product in the direction of longitudinal extent, a drawing ring and a drawing mandrel and acts on the workpiece in a shaping manner via the drawing mandrel and the drawing ring while the workpiece is drawn by the drawing device around the drawing mandrel and through the drawing ring. A sensor is located on the drawing mandrel, or physical properties are measured in the interior of the workpiece and/or on the drawing mandrel using a sensor on the drawing mandrel.

To provide methods, apparatuses and drawing mandrels in which the shaping process can be monitored as closely as possible, a drawing machine and a drawing method manufactures or processes tubes, which extend in the direction of longitudinal extent, from a semi-manufactured product, wherein the drawing machine includes a drawing device for drawing a hollow workpiece formed by the tube and the semi-manufactured product in the direction of longitudinal extent, a drawing ring and a drawing mandrel and acts on the workpiece in a shaping manner via the drawing mandrel and the drawing ring while the workpiece is drawn by the drawing device around the drawing mandrel and through the drawing ring. A sensor is located on the drawing mandrel, or physical properties are measured in the interior of the workpiece and/or on the drawing mandrel using a sensor on the drawing mandrel.

The production method for producing a rifled tube, which includes a plurality of first helical ribs on its inner surface, includes: a steps of: preparing a steel tube; and producing a rifled tube by performing cold drawing on a steel tube by using a plug which includes a plurality of second helical ribs, the plug satisfying Formulae and:

0.08 <W×(A−B)×N/(2π×A)<0.26  (1)

0.83<S×(A−B)×N/(2×M)<2.0  (2) where, W is a width of a groove bottom surface of the helical groove; A is a maximum diameter of the plug; B is a minimum diameter of the plug; N is a number of the second helical ribs; S is the width of the groove bottom surface; and M is a pitch of adjacent second helical ribs.

The production method for producing a rifled tube, which includes a plurality of first helical ribs on its inner surface, includes: a steps of: preparing a steel tube; and producing a rifled tube by performing cold drawing on a steel tube by using a plug which includes a plurality of second helical ribs, the plug satisfying Formulae and:

0.08 <W×(A−B)×N/(2π×A)<0.26  (1)

0.83<S×(A−B)×N/(2×M)<2.0  (2) where, W is a width of a groove bottom surface of the helical groove; A is a maximum diameter of the plug; B is a minimum diameter of the plug; N is a number of the second helical ribs; S is the width of the groove bottom surface; and M is a pitch of adjacent second helical ribs.

A method of fabricating a conduit comprises steps of attaching a first tubular-outboard-ply end of a tubular outboard ply to a first inner collar portion of a first collar with a third weld and attaching a second tubular-outboard-ply end to a second inner collar portion of a second collar with a fifth weld. The method additionally comprises steps of interconnecting the first inner collar portion and a first outer collar portion of the first collar with a first weld and interconnecting the second inner collar portion and a second outer collar portion of the second collar with a sixth weld. The method also comprises attaching a trimmed first corrugated-inboard-ply end to the first outer collar portion with a second weld, attaching a trimmed second corrugated-inboard-ply end to the second outer collar portion with a fourth weld, and communicatively coupling a first sensor with an interstitial space.

A method of fabricating a conduit comprises steps of attaching a first tubular-outboard-ply end of a tubular outboard ply to a first inner collar portion of a first collar with a third weld and attaching a second tubular-outboard-ply end to a second inner collar portion of a second collar with a fifth weld. The method additionally comprises steps of interconnecting the first inner collar portion and a first outer collar portion of the first collar with a first weld and interconnecting the second inner collar portion and a second outer collar portion of the second collar with a sixth weld. The method also comprises attaching a trimmed first corrugated-inboard-ply end to the first outer collar portion with a second weld, attaching a trimmed second corrugated-inboard-ply end to the second outer collar portion with a fourth weld, and communicatively coupling a first sensor with an interstitial space.

A conduit for transporting a fluid comprises a first collar, a second collar, and a bellows. The bellows comprises a corrugated inboard ply, a corrugated outboard ply, and an interstitial space, interposed between the corrugated inboard ply and the corrugated outboard ply. The conduit additionally comprises a second weld, hermetically coupling the corrugated inboard ply and a first outer collar portion, a third weld, hermetically coupling the corrugated outboard ply and a first inner collar portion, a fourth weld, hermetically coupling the corrugated inboard ply and a second outer collar portion, a fifth weld, hermetically coupling the corrugated outboard ply and a second inner collar portion, and a first sensor, communicatively coupled with the interstitial space.