# US 10,370,770 B2 · Plating solution for threaded connection for pipe or tube and producing method of threaded connection for pipe or tube

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- Number: US 10,370,770 B2
- Document ID: US10370770B2
- Status: Granted
- Kind: B2
- Application number: 15/308,104
- Filed: 2015-05-15
- Published: 2017-02-23
- Granted: 2019-08-06
- Earliest claimed: 2014-05-15
- Assignees: Nippon Steel Corporation; Vallourec Oil and Gas France
- Applicants: Nippon Steel Corporation; Vallourec Oil and Gas France
- Inventors: Masanari Kimoto; Kazuya Ishii; Kunio Goto; Tatsuya Yamamoto; Masahiro Oshima; Seiichiro Nakao; Daisuke Yamaguchi
- Web page: https://patentgrep.com/patent/US10370770B2

## CPC

- C25D 3/58: containing more than 50% by weight of copper
- C25D 3/56: of alloys
- C25D 7/003: {Threaded pieces, e.g. bolts or nuts}
- C25D 7/04: Tubes; Rings; Hollow bodies
- F16L 15/04: with additional sealings
- C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- F16L: PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL

## Abstract

Provided is a plating solution for a threaded connection used for forming a plating film excellent in galling resistance, crevice corrosion resistance, and exposure corrosion resistance. The plating solution contains no cyanide, but contains copper pyrophosphate, tin pyrophosphate, zinc pyrophosphate, pyrophosphate as a metal complexing agent, and a sulfur-containing compound of 40 g/L or less (excluding 0). The sulfur-containing compound includes: a mercapto compound and a sulfide compound defined by Chemical Formula (1); a dimer formed through a disulfide bond of the mercapto compounds; and one or more types of salts thereof: RS—(CHX1)m—(CHX2)n—CHX3X4 (1), where each of m and n is an integer of 1 or 0; each of X1, X2, X3 and X4 is any one of hydrogen, OH, NH2, SO3H, and CO2H, but excluding that X1, X2, X3, and X4 are all hydrogen; and R is any one of hydrogen, a methyl group, and an ethyl group.

## Claims

### Claim 1

A plating solution for a threaded connection for pipe or tube, the plating solution containing no cyanide,
the plating solution further containing:
copper pyrophosphate;
tin pyrophosphate;
zinc pyrophosphate;
pyrophosphate as a metal complexing agent; and
one or more sulfur-containing compounds of 0.01 to 40 g/L selected from the group consisting of a mercapto compound defined by Chemical Formula (1), a sulfide compound defined by the Chemical Formula (1), and a salt thereof:
wherein the Chemical Formula (1) is defined by RS—(CHX1)m—(CHX2)n—CHX3X4,
where each of m and n is an integer of 1 or 0; each of X1, X2, X3 and X4 is any one of hydrogen, OH, and NH2, but excluding that X1, X2, X3, and X4 are all hydrogen; and R is any one of hydrogen, a methyl group, and an ethyl group.

### Claim 2 (depends on 1)

A producing method of a threaded connection for pipe or tube comprising:
a step of preparing the plating solution according to claim 1; and
a step of subjecting a pin or a box of the threaded connection to electroplating using the plating solution so as to form a Cu—Sn—Zn alloy plating film on the pin or the box.