Threaded connection for pipe or tube and method of producing the threaded connection for pipe or tube
View Patent ↗An objective of the present invention is to provide a threaded connection for pipe or tube having an excellent anti-misalignment property and an appropriate shouldering torque, and further having excellent corrosion resistance and an excellent adhesiveness of a solid lubricant coating, and to provide a method of producing the threaded connection for pipe or tube. The threaded connection for pipe or tube according to the present embodiment includes a pin and a box. The pin and the box have contact surfaces including thread portions and unthreaded metal contact portions. The threaded connection for pipe or tube comprises an alloy plating layer consisting of a Zn—Ni alloy on the contact surface of at least one of the pin and the box, a phosphating layer, and a solid lubricant coating. These are stacked in an order of the alloy plating layer, phosphating layer, and the solid lubricant coating, from a contact surface side.
1. A threaded connection for pipe or tube comprising a pin and a box, the pin and the box each including a contact surface that includes a thread portion and an unthreaded metal contact portion, the threaded connection for pipe or tube comprising:
on the contact surface of at least one of the pin and the box,
an alloy plating layer consisting of a Zn—Ni alloy;
a phosphating layer on the alloy plating layer; and
a solid lubricant coating on the phosphating layer.
2. The threaded connection for pipe or tube according to claim 1 , wherein the alloy plating layer has a thickness of 1 to 20 μm, the phosphating layer has a thickness of 5 to 20 μm, and the solid lubricant coating has a thickness of 5 to 50 μm.
3. The threaded connection for pipe or tube according to claim 1 , wherein the phosphating layer is a manganese phosphating layer.
4. The threaded connection for pipe or tube according to claim 3 , wherein the alloy plating layer has a thickness of 1 to 20 μm, the phosphating layer has a thickness of 5 to 20 μm, and the solid lubricant coating has a thickness of 5 to 50 μm.
5. A method of producing a threaded connection for pipe or tube that includes a pin and a box, the pin and the box each including a contact surface that includes a thread portion and an unthreaded metal contact portion, the method comprising the steps of:
on the contact surface of at least one of the pin and the box,
forming an alloy plating layer consisting of a Zn—Ni alloy;
forming a phosphating layer by performing chemical treatment after forming the alloy plating layer; and
forming a solid lubricant coating after forming the phosphating layer.