Method for quenching steel pipe, equipment for quenching steel pipe, and method for manufacturing steel pipe

Equipment for quenching a steel pipe,

• the equipment comprising:
• a revolving conveyance apparatus for conveying a steel pipe;
• a rotatable supporting member that supports the steel pipe conveyed by the revolving conveyance apparatus, the rotatable supporting member supporting the steel pipe by rotating the steel pipe about a pipe axis of the steel pipe in a state where movements of the steel pipe in a direction parallel to and in a direction perpendicular to the pipe axis are stopped;
• and
• first spray nozzles that cool the steel pipe from above the steel pipe rotating on the rotatable supporting member,
• the first spray nozzles being disposed along an axial direction of the steel pipe with an angle of 20 to 70° from the uppermost part of the pipe in a circumferential direction,
• the first spray nozzles being disposed except a swept range W of the revolving conveyance apparatus in a longitudinal direction of the steel pipe,
• the first spray nozzles including inclined spray nozzles that are disposed by being tilted toward the swept range W, and flat spray nozzles that are disposed adjacent to the inclined spray nozzles at equal intervals with a predetermined pitch D in the longitudinal direction of the steel pipe,
• the inclined spray nozzles being disposed by being offset by a distance S from the predetermined pitch D, and being tilted with an angle θ of 30° or less, where the angle θ is determined in terms of the relationship θ=arctan(S/H), where S is the distance from the predetermined pitch D of the flat spray nozzles and H is an injection height of the first spray nozzles, and
• the inclined spray nozzles spraying water asymmetrically with respect to a center axis of the inclined spray nozzles to produce a uniform distribution of water flow in the longitudinal direction of the steel pipe.

A method of manufacturing a steel pipe by quenching whereby a steel pipe as raw material is cooled after heating, or a hot-rolled high-temperature steel pipe is directly subjected to cooling,

• the cooling in the quenching comprising the steps of:
• conveying a steel pipe onto a rotatable supporting member using a revolving conveyance apparatus;
• and
• cooling the steel pipe with first spray nozzles disposed above the pipe while the steel pipe is being rotated about a pipe axis of the steel pipe on the rotatable supporting member in a state where movements of the steel pipe in a direction parallel to and in a direction perpendicular to the pipe axis are stopped,
• the first spray nozzles being disposed along an axial direction of the steel pipe with an angle of 20 to 70° from the uppermost part of the pipe in a circumferential direction,
• the first spray nozzles being disposed except a swept range W of the revolving conveyance apparatus in a longitudinal direction of the steel pipe,
• the first spray nozzles including inclined spray nozzles that are disposed by being tilted toward the swept range W, and flat spray nozzles that are disposed adjacent to the inclined spray nozzles at equal intervals with a predetermined pitch D in the longitudinal direction of the steel pipe,
• the inclined spray nozzles being disposed by being offset by a distance S from the predetermined pitch D, and being tilted with an angle θ of 30° or less, where the angle θ is determined in terms of the relationship θ=arctan(S/H), where S is the distance from the predetermined pitch D of the flat spray nozzles and H is an injection height of the first spray nozzles, and
• the inclined spray nozzles spraying water asymmetrically with respect to a center axis of the inclined spray nozzles to produce a uniform distribution of water flow in the longitudinal direction of the steel pipe.