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Method and apparatus for refurbishing valves

Imported: 23 Feb '17 | Published: 22 Oct '02

Lennard J. McGoey

USPTO - Utility Patents

Abstract

A method and apparatus for in situ refurbishment of valve seats are disclosed in which a worn valve seat is initially ground to a flat surface, a buildup of weld metal is deposited on the flat surface, and the weld buildup is machined to the final dimensions of the valve seat. The apparatus comprises a machining apparatus for machining and machining of the valve seat, a gas metal arc welding apparatus for deposition of weld metal, and support structures to support the weld buildup as it is being formed. Preferably, the support structures are in the form of metal chill blocks which act both to support the buildup of weld metal and to act as heat sinks and remove excess heat from the buildup, resulting in a higher quality buildup of metal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of the valve body of a conventional high temperature, high pressure safety valve;

FIG. 2 is a perspective view of the valve body of FIG. 1 illustrating the mounting of a mounting plate of the preferred apparatus to a flat upper surface thereof;

FIG. 3 is a perspective view of a valve machining apparatus for use in the preferred method and apparatus of the present invention;

FIG. 4 is a preferred gas metal arc welding apparatus for use in the preferred method and apparatus of the present invention;

FIG. 5 is a cross-sectional side elevational view of the valve body of FIG. 1 with the mounting plate attached thereto, and with the welding head of the welding apparatus depositing a buildup of weld metal on the valve seat;

FIGS. 6 and 7 illustrate machining heads for machining the buildup of weld metal to the final dimensions of the valve seat;

FIG. 8 is a cross-sectional side view of a valve seat prior to refurbishing;

FIG. 9 illustrates a valve seat after the initial machining operation, with the desired profile of the valve seat being shown in dashed lines;

FIG. 10 illustrates the buildup of weld metal between the chill blocks, with the final profile of the valve seat being indicated by dashed lines;

FIG. 11 is a cross-sectional side view of the valve seat after the final machining operation; and

FIG. 12 is a perspective view of the chill blocks of FIGS. 5 and 10 shown in isolation.

Claims

1. An apparatus for refurbishing a worn valve seat of a high temperature, high pressure safety valve in situ, said valve seat being generally circular and being provided at one end of a hollow, cylindrical valve nozzle which is attached to a valve body of said valve, said valve seat being accessible through an access opening in said valve body located above said valve seat, said apparatus comprising:

2. The apparatus of claim 1, wherein said inner support structure comprises a cylindrical metal sleeve, a cylindrical outer surface of which corresponds to the substantially vertical cylindrical surface of the inner support structure.

3. The apparatus of claim 1, wherein said height sufficient to support the weld metal buildup is about the same as a final height of the weld metal buildup.

4. The apparatus of claim 3, wherein the inner support structure is received inside the end of the valve nozzle in which the valve seat is provided.

5. The apparatus of claim 1, wherein the outer support structure comprises an annular block of metal, a cylindrical inner surface of which corresponds to the inner, substantially vertical cylindrical surface of the outer support structure.

6. The apparatus of claim 5, wherein the annular block of metal comprising the outer support structure is made up of two C-shaped segments which are releasably connectable to one another.

7. The apparatus of claim 6, wherein the end of the valve nozzle on which the valve seat is provided protrudes above a surface of the valve body immediately adjacent to said valve seat, and wherein the two C-shaped segments of the outer support structure clamp an outer cylindrical surface of the end of the valve nozzle.

8. The apparatus of claim 1, wherein said valve machining means includes a central alignment shaft having a distal end provided with outwardly expanding clamping means which secure the distal end of the alignment shaft inside the valve nozzle with the alignment shaft protruding substantially vertically therefrom, said first cutter means being rotatable about said shaft and being movable axially along said shaft.

9. The apparatus of claim 1, wherein said access opening of said valve body has a flat outer surface situated above and substantially parallel to the flat surface of the valve seat, said apparatus further comprising a mounting plate to which a base of the gas metal arc welding apparatus is secured, said mounting plate being attachable to the flat outer surface of the access opening and having a side extending horizontally outwardly from said access opening, the outwardly extending side of the mounting plate having mounting means for attachment to the base of the gas metal arc welding apparatus.

10. The apparatus of claim 9, wherein the base of the gas metal arc welding apparatus is provided with mounting apertures which receive a plurality of studs extending upwardly from the outwardly extending side of the mounting plate.

11. The apparatus of claim 10, wherein the mounting apertures in the base of the gas metal arc welding apparatus are in the form of parallel slots which permit adjustment of the base of the gas metal arc welding apparatus relative to the access opening.

12. A method for refurbishing a worn valve seat of a high temperature, high pressure safety valve in situ, said valve seat being generally circular and being provided at one end of hollow, cylindrical valve nozzle which is attached to a valve body of said valve, said valve seat being accessible through an access opening in said valve body located above said valve seat, the method comprising: