Tensioning apparatus and method

• US 6,840,726 B2
• Filed: 12/16/2002
• Issued: 01/11/2005
• Est. Priority Date: 12/16/2002
• Status: Active Grant

• Current Assignee: Siemens Energy Incorporated (Siemens AG)
• Original Assignee: Siemens Westinghouse Power Corporation
• Inventors: Gosling, Martin Charles
• Primary Examiner(s): Saether, Flemming
• Application Number:
  US10/320,775
• Publication Number:
  US 20040115023A1
• Time in Patent Office: 757 Days
• Field of Search: 411/14.5, 411/916, 411/917, 411/339, 411/511, 411/512, 403/5, 403/31, 785/97, 785/106
• US Class Current: 411/14.5
• CPC Class Codes: B23P 11/022 by using pressure fluids
• CPC Class Codes: B25B 29/02 Bolt tensioners
• CPC Class Codes: F16B 31/043 Prestressed connections tensioned by means of liquid, grease, rubber, explosive charge, or the like hydraulic bolt tensioners B25B29/02
• CPC Class Codes: Y10T 403/22 with fluid pressure responsive component

Abstract

A tensioning apparatus (40) for applying a closing force across a flange assembly (42). The tensioning apparatus includes a shank member (44) and an annular member (48) connected to the shank member by an interference fit. The interference fit may be selectively relaxed by applying a fluid pressure (P₁) to a groove (54) between the annular member and the shank member. A tensioner (58) is used to pre-load the shank member by pulling on the shank member while pushing on the annular member while the interference fit is sufficiently relaxed to allow relative movement between the annular member and the shank member. Once the pre-load is established, the interference fit is reestablished by releasing pressure P₁ to lock the annular member in position for maintaining the closure force across the flange assembly after the tensioner is removed. A lock nut (34) may be tightened against the annular member to provide additional protection against the release of the pre-load. Seals (146) may be used to minimize leakage of the fluid used for applying the fluid pressure between the annular member and the shank member.

Claims

1. A tensioning apparatus comprising:

a shank member comprising a means for transferring force against a first side of a flange assembly;

an annular member defining an opening for receiving the shank member, the opening sized to provide an interference fit between the annular member and the shank member;

a supply of pressurized fluid conveying a fluid pressure into the opening to selectively expand the annular member to relax the interference fit; and

a tensioner tool for imparting a tensile load into the shank member by pulling on the shank member to impart force against the first side of the flange assembly while pushing against a second opposed side of the flange assembly through the annular member.

2. The tensioning apparatus of claim 1, further comprising a fluid passageway formed through the annular member from an outside surface of the annular member to the opening for conveying the fluid pressure from the supply of pressurized fluid to the opening.

3. The tensioning apparatus of claim 1, further comprising a fluid passageway formed through a portion of the shank member for conveying the fluid pressure from the supply of pressurized fluid to the opening.

4. The tensioning apparatus of claim 1, wherein the tensioner tool comprises a hydraulic tensioner.

5. The tensioning apparatus of claim 1, further comprising a seal disposed between the shank member and the annular member.

6. A tensioning apparatus comprising:

a stud extending through an aperture in a first side of an assembly;

an annular member attached to the stud by an interference fit for resisting relative motion there between under the influence of a tensioning force transferred against the first side of the assembly;

a means for applying a fluid pressure between parallel opposed axial surfaces of the annular member and the stud to generate a raidial force with no axial force component to selectively expand the annular member to relax the interference fit suffiently to allow relative motion between the annular member and the stud under the influence of the tensioning function force; and

7. The tensioning apparatus of claim 6, wherein the means for applying a fluid pressure comprises a fluid passageway formed in the annular member.

8. The tensioning apparatus of claim 6, wherein the means for applying a fluid pressure comprises a fluid passageway formed in the stud.

9. The tensioning apparatus of claim 6, wherein the means for applying a fluid pressure comprises a groove formed around an inside surface of the annular member.

10. The tensioning apparatus of claim 6, wherein the means for applying a fluid pressure comprises a groove formed around an outside surface of the stud.

11. The tensioning apparatus of claim 6, wherein the means for applying a fluid pressure comprises:

a first groove formed around an inside surface of the annular member along an annular centerline of the annular member; and

a second groove formed around an inside surface of the annular member parallel to the first groove and disposed closer to an annular end of the annular member than to the first groove.

12. The tensioning apparatus of claim 6, wherein the means for applying a fluid pressure comprises a seal.

13. A tensioning apparatus comprising:

a shank member comprising a longitudinal axis having a length extending through an aperture in an assembly to be tensioned with a tensioning force and having an outside surface having a critical dimension portion parallel to the longitudinal axis;

an annular member comprising an inside surface parallel to the longitudinal axis and defining an opening for receiving the shank member with an interference fit between the inside surface and the critical dimension portion of the outside surface; and

a fluid passageway for conveying a fluid pressure between the outside surface and the inside surface for relaxing the interference fit;

wherein the annular member may be moved to any location along the critical dimension portion when the fluid pressure is applied, and wherein the annular member may be affixed to the shank member by the interference fit at any desired location along the critical dimension portion by relieving the fluid pressure with the annular member at the desired location for resisting relative motion between the shank member and the annular member under the influence of a tensioning force exerted by the assembly;

further comprising a means for pulling on the shank member while pushing against the annular member to generate the tensioning force.