Riser tensioner

Abstract

A riser tensioner that tensions a riser extending to the seabed from a drilling ship which drills for submarine resources such as oil. The riser tensioner is disposed under a drilling ship to tension a riser used for drilling operation of submarine resources and includes a plurality of cylinders. The riser tensioner further includes: an injection nozzle for injecting water to a surface of a piston rod exposed from each of the cylinders; and a scraper unit which removes salt or seawater from the surface of the piston rod by scrapping the surface of the piston rod to prevent salt from accumulating on the surface of the piston rod.

1 . A riser tensioner disposed under a drilling ship to tension a riser used for drilling operation of submarine resources and including a plurality of cylinders, the riser tensioner further comprising:
 an injection nozzle for injecting water to a surface of a piston rod to prevent salt from being accumulated on the surface of the piston rod exposed from each of the cylinders; and   a scraper unit which removes salt or seawater from the surface of the piston rod by scrapping the surface of the piston rod to prevent salt from being accumulated on the surface of the piston rod.   
     
     
         2 . The riser tensioner of  claim 1 , wherein the scraper unit is operated immediately after the injection nozzle injects water. 
     
     
         3 . The riser tensioner of  claim 1 , wherein the scraper unit is provided to one end of the cylinder. 
     
     
         4 . The riser tensioner of  claim 1 , wherein the scraper unit comprises a scraper which is brought into close contact with the surface of the piston rod in operation and is separated from the surface of the piston rod during non-operation of the scraper unit.