# US 10,369,655 B2 · Electric resistance welded steel pipe having identifiable seam portion and method for manufacturing the same

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- Number: US 10,369,655 B2
- Document ID: US10369655B2
- Status: Granted
- Kind: B2
- Application number: 15/555,401
- Filed: 2016-03-01
- Published: 2018-02-08
- Granted: 2019-08-06
- Earliest claimed: 2015-03-03
- Assignees: Jfe Steel Corporation
- Applicants: Jfe Steel Corporation
- Inventors: Shinsaku Kokubo; Kenichi Iwazaki; Hiromichi Hori
- Web page: https://patentgrep.com/patent/US10369655B2

## CPC

- B23K 11/36: Auxiliary equipment (B23K11/31 takes precedence)
- B21C 1/24: by means of mandrels
- B21C 37/08: Making tubes with welded or soldered seams {(with helically arranged seams B21C37/122)}
- B21C 37/30: Finishing tubes, e.g. sizing, burnishing
- B23K 11/0873: {of the longitudinal seam of tubes}
- B23K 31/10: relating to cutting or desurfacing
- F16L 9/165: {of metal}
- F16L 9/17: obtained by bending a sheet longitudinally and connecting the edges
- C21D 9/08: for tubular bodies or pipes
- C23C 22/12: containing zinc cations
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B21C: MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
- F16L: PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)

## Abstract

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.

## Claims

### Claim 1

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

### Claim 2 (depends on 1)

The electric resistance welded steel pipe according to claim 1, wherein a thickness of the coating portion is 1 to 30 μm.

### Claim 3 (depends on 1)

The electric resistance welded steel pipe according to claim 1, wherein the color difference portion is whiter than the other parts of the coating portion.