| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a steel pipe screw joint excellent in seizure resistance, rust-proofness and air tightness without using compound grease containing heavy metal which may give ill effects to environment or human bodies. <P>SOLUTION: The steel pipe screw joint comprises a pin and a box each provided with a contact surface having a screw portion and a non-screwed metal contact portion. On the contact surface of at least one member of the pin and the box, there are formed a first layer of Hv100-500 consisting of a first metal or alloy, a second layer of Hv10-150 consisting of a second metal or alloy softer than that, and an uppermost solid lubrication overcoat layer (an overcoat layer formed by binding lubricating powder with organic or inorganic binder). <P>COPYRIGHT: (C)2008,JPO&INPIT |
