Electric resistance welded steel pipe securing the high strength and high toughness demanded from oil well pipe in recent years. The metal structure in a region having a width of 0.5 mm in both the thickness directions from a reference point, when using a point defined as a point of the thickness in the thickness direction from the surface in the base material part of the steel pipe as the reference point, consists of polygonal ferrite: 10 area % or less and a balance: bainitic ferrite. The thickness is 15 mm or more.

The seamless pipe in which a thin-walled portion in a pipe circumferential direction is formed in a pipe axial direction, in which a line segment formed by connecting one end and the other end of the thin-walled portion along a pipe surface with a shortest distance in a formation direction of the thin-walled portion is inclined at an angle of 5.0 or more with respect to the pipe axial direction. It is preferable that one end and the other end of the thin-walled portion are set from a region in a pipe selected with a shorter length between a length of 1.0 m in the pipe axial direction and 90% of a length in the pipe axial direction where the thin-walled portion turns once in the pipe circumferential direction.

A method for producing a tubular underwater pipe including: assembling a structure of peripheral metal elements (3A, 3B, 3C) wound in an S-Z configuration about a central flexible core (1) as the core is driven in movement along its longitudinal axis; providing an inductive sensor (12) arranged for rotation about the central flexible core (1) in a manner synchronized with the longitudinal movement of the core so that the sensor scans the periphery of the structure opposite and in the immediate proximity of peripheral elements wound about the core and during the assembly step; using the sensor (12) to acquire measurement signals (S) of which the amplitude varies according to whether or not the sensor (12) is located opposite a peripheral element during the rotation of the sensor (12); and using the measurement signals to control the positioning of the assembled peripheral elements.

A corrugated metal vent pipe includes a helically corrugated pipe structure formed by helical winding of a corrugated metal strip, wherein the helically corrugated pipe structure has a diameter of between 15 inches and 36 inches and a plurality of vent openings distributed thereon. A first pipe end treatment is located on a first end of the helically corrugated pipe structure, and a second pipe end treatment is located on a second end of the helically corrugated pipe structure.

An electric resistance welded steel pipe having an identifiable seam portion and a method for manufacturing the same. The electric resistance welded steel pipe includes a steel pipe portion with a seam portion, which is formed by electric resistance welding, and a coating portion of zinc phosphate. The coating portion covers at least an outer surface side of the steel pipe portion. A part of the coating portion that is immediately above the seam portion forms a color difference portion that has a width W along a pipe circumferential direction of greater than or equal to 0.1 times a wall thickness of the pipe and less than or equal to the wall thickness of the pipe. The color difference portion has a visually identifiable color difference from the other parts of the coating portion.

A multilayer structure for transporting or storing gas or for exploiting oil or gas deposits under the sea, including, from the inside to the outside, at least one sealing layer and at least one composite reinforcing layer, the innermost composite reinforcing layer being welded to the outermost adjacent sealing layer, the sealing layers of a composition including at least one semi-crystalline thermoplastic polymer, the Tm of which is less than 280 C., wherein at least one of the composite reinforcing layers of a fibrous material in the form of continuous fibers impregnated with a composition including at least one thermoplastic polymer, the thermoplastic polymer having a Tg greater than the maximum temperature of use of the structure (Tu), with TgTu+20 C., Tu being greater than 50 C., and a multilayer structure selected from a reservoir, a pipe or a tube for transporting or storing hydrogen being excluded.

A tubular structure is disclosed. The tubular structure has a first sheet metal having a machine direction. The first sheet metal is convolutely wound about a longitudinal axis and has a tail portion. The tail portion of the first sheet metal is disposed upon and bonded to an immediately subjacent convolution of the first sheet metal.

A pipe gap assembly including an insert sleeve and an adjustment sleeve. The insert sleeve includes a first side large diameter section, a small diameter section and a second side large diameter section, with the insert sleeve having an insert sleeve enlarged lip at the second side thereof. The adjustment sleeve has a first side, a second side and a cylinder having an outer surface, with the outer surface of cylinder of the adjustment sleeve being smaller than an inner surface of the insert sleeve to allow the first end of the adjustment sleeve to be able to be slid within the insert sleeve. The adjustment sleeve further includes a ring seal surrounding the outer surface thereof. The ring seal is not fixed in position on the outer surface of the adjustment sleeve such that the ring seal is able to roll on the outer surface of the adjustment sleeve.

Provided are a welded titanium tube capable of improving heat-transfer performance and detecting surface defects and a manufacturing method therefor. The welded titanium tube is formed of a tubular-shaped titanium plate, whose edges are butt-welded. The welded titanium tube includes an outer peripheral surface and an inner peripheral surface, at least one of which is provided with a concavo-convex pattern including a base surface and a plurality of protrusions. A mean maximum height of the protrusions is in the range of 12 to 45 m. A ratio of a maximum value to a mean pitch of the protrusions is less than 2. A ratio of a mean maximum dimension of the protrusions to the mean pitch is 0.90 or less, and a ratio of the mean maximum height to a wall thickness is 0.11 or less.

A multilayer structure for transporting or storing gas including, from the inside to the outside, at least one sealing layer and at least one composite reinforcing layer, the innermost composite reinforcing layer being welded to the outermost adjacent sealing layer, the sealing layers being a composition predominantly including at least one semi-crystalline thermoplastic polymer P1i (i=1 to n, n being the number of sealing layers), the Tm of which is less than 280 C., and at least one of said composite reinforcing layers being a fibrous material in the form of continuous fibers impregnated with a composition predominantly including at least one thermoplastic polymer P2j, (j=1 to m, m being the number of reinforcing layers), the thermoplastic polymer P2j having a Tg greater than the maximum temperature of use of the structure (Tu), with TgTu +20 C., Tu being greater than 50 C.