Structure feactures:

  1. Bow-springs and finlike whirl steels fitting the requirements are adopted.
  2. Finlike whirl steels are fixed on bows of bow-springs in the manner of right-hand rotation or left-hand rotation.
  3. The centralizer fit the most casings and wellbores specified in the standard API 10D.
  4. Whirl steels are heat treated spring steels.
  5. Generally it is installed under the stop collar.