Raised hardface overlay valve seat
AssigneeHenry Vogt Machine Co.
InventorHarry W. Girdley
Life of this patent
Estimating the term…
Abstract
A raised hardface overlay valve seat, fused around the periphery of the port of a valve, having an inverted frustoconical body cavity and an inverted frustoconical plug inserted into said cavity in sealing engagement therewith. A major advantage of the raised hardface overlay seat is that it has a taper conforming to the taper of the plug and as a consequence, reduces the area in contact with the plug and effectively intensifies the sealing stress that can be generated between the plug and the seats by a downward force. The plug may be used with lapping compound to lap the seats, both prior to service and in the field. Sufficient space is allowed in the cavity for a substantial relap life.
Claims20
A valve, comprising:
- A. a metallic body, having
- 1. a body cavity, defining an inerted frustoconical wall;
- 2. a through flow passage;
- and
- 3. a port on each of the opposed sides of the frustoconical wall of said body cavity, said port communicating with said body cavity and through said through flow passage;
- B. a metal plug, havig an inverted frustoconical surface parallel to the frustoconical wall of said body cavity and extending into said body cavity across said through flow passage;
- C. hardface overlay raised seats, fused onto the metallic body surrounding said port on each of the opposed sides of the frustoconical wall of the body cavity and extending beyond the body wall into the body cavity, toward said plug, said valve seats comprising:
- 1. a brazing, hardface alloy powder, having a solidus temperature lower than the metal of said body and which, in the molten state, wers the metal, and
- 2. a powered filler, having a solidus temperature higher than the metal of the metallic body or of the hardface alloy which is wetted by the molten hardface alloy;
- D. said raised hardface overlay seats having been machined and lapped with said metal plug inside said body cavity, into perfect mating engagement with said plug;
- E. operating means for moving the plug in the body cavity out of engagement with the hardface overlay seats surrounding the ports of the through flow passage, to establish flow through the body.
For use with a valve body, having a metallic body, including a cavity defined by an inverted frustoconical wall, a through-flow passage and ports emptying into said cavity, with raised, hardface overlay seats surrounding said ports and a frustoconical plug extending into said cavity and contacting said raised seats,
- A. a seat-lapping tool, for the field lapping of said valve seats with said plug, comprising:
- 1. attachment means for attachment of said tool to said plug;
- 2. an elongated shaft;
- 3. means for rotating said tool and said plug at low speed against the hardface overlay seats surrounding said ports;
- and
- 4. a shaft alignment guide.
A process for field lapping of raised, hardface overlay valve seats on an inverted frustoconical wall of a valve body cavity, which comprises the steps of;
- A. placing the valve out of service;
- B. disassembling the valve;
- C. removing the valve plug and stem;
- D. applying lapping compound to the plug;
- E. inserting the valve plug into the body cavity of the valve;
- F. rotating the valve plug at low speeds with the lapping compound in contact with the surface of said raised valve seats;
- G. removing the plug and cleaning the lapping compound from said surfaces;
- H. reassembling the valve;
- I. placing the valve back in service.
A process for fusing a raised, hardface overlay valve seat onto the surface surrounding the port of a metallic valve body, which comprises the steps of;
- A. treating the surface surrounding the port by pickling or grit blasting;
- B. cutting a cloth-like, flexible, nonwoven preform to conform precisely with the area of the prepared surface surrounding the port;
- C. said preform comprising;
- 1. a brazing, hardface alloy powder, having a solidus temperature lower than the metal of said body and which, in the molten state, wets the metal;
- 2. a powdered filler, having a solidus temperature higher than the metal of the metallic body or of the hardface alloy and which is wetted by the hardface molten alloy;
- and
- 3. a fibrillated organic binder for the brazing powder and for the filler;
- D. adhesively securing said preform in position on said treated surface;
- E. heating the area to a temperature sufficient to decompose and remove the organic binder, melt the brazing alloy, fuse the particulate material and bond it to the pretreated surface;
- F. cooling the product to obtain a valve with fused, hardface raised seats;
- G. machining or grinding the seats;
- H. inserting a plug into contact with said fused hardface raised seats;
- I. rotating the valve plug at low speeds with lapping compound, in contact with the surface of said raised valve seat;
- J. removing the plug and cleaning the lapping compound from said surface;
- and
- K. assembling the valve.
Dependencies are inferred from the claim text.