Fusion coated ball valve trim

Abstract

Provided are a ball for a ball valve, which is provided with a metal substrate having a surface-modified portion that acts as the valve seat surface of the valve seat of the ball valve, and a valve seat ring for a ball valve, which is provided with a metal substrate having a surface-modified portion that acts as the valve seat surface of the ball of the ball valve.

Description

[Technical field]

[0001] The present invention relates to fusion coated trim components of ball valves, such as balls and valve seats. [Background technology]

[0002]

[0002] Ball valves used in heavy duty applications such as pressure acid leaching of ores are exposed to high temperatures, high pressures, abrasive solids, and acid corrosion. Trim components of ball valves, such as balls and valve seats, are often thermally spray coated to improve reliability and resistance to deterioration or wear, such as abrasion, erosion, and corrosion. For example, balls and valve seats made of titanium are thermally spray coated with coatings such as chromium carbide.

[0003]

[0003] Conventional thermal spray coated balls and valve seats suffer from several drawbacks. In use, the thermal spray coating can unintentionally spall or spall from the trim components, reducing the sealing efficiency of the ball valve. This spalling and spalling can provide increased access for abrasive solids and corrosive acids to the underlying metal substrate, causing an intensified cycle of deterioration, wear, and corrosion. The spalled or spalled coating also creates a risk of contamination and damage to plant and process equipment downstream of the ball valve.

[0004]

[0004] In light of this background, there is a need for improved coated balls and valve seats for heavy-duty ball valves that have increased resistance to wear and corrosion but reduced spalling and spalling (or increased adhesion strength). Summary of the Invention

[0005]

[0005] In accordance with the present invention, a ball for a ball valve is provided, the ball comprising a metal substrate having a surface modified portion that acts as a seat surface of a valve seat of the ball valve.

[0006]

[0006] The substrate and the surface modified portion may each comprise titanium or a titanium alloy.

[0007] The surface modified portion may be formed by nitriding.

[0008]

[0008] The surface modified portion can be formed by nitriding a surface portion of the substrate to form a hard titanium nitride phase, and alloying the nitrided surface portion with a beta stabilizer to form a tough beta titanium phase surrounding the hard titanium phase.

[0009]

[0009] The surface modified portion may be densified to fill cracks or voids.

[0010]

[0010] The surface modification portion may include a raised annular band.

[0011]

[0011] The raised annular band may be metallurgically fused to the substrate by fusion welding.

[0012]

[0012] The present invention also provides a seat ring for a ball valve, the seat ring comprising a metal substrate having a surface-modified portion that acts as a seat surface for a ball of the ball valve.

[0013]

[0013] The substrate and the surface modified portion may each comprise titanium or a titanium alloy.

[0014] The surface modified portion may be formed by nitriding.

[0015]

[0015] The surface modified portion can be formed by nitriding a surface portion of the substrate to form a hard titanium nitride phase, and alloying the nitrided surface portion with a beta stabilizer to form a tough beta titanium phase surrounding the hard titanium phase.

[0016]

[0016] The surface modified portion may be densified to fill cracks or voids.

[0017]

[0017] The surface modified portion may include a raised annular band.

[0018]

[0018] The raised annular band may be metallurgically fused to the substrate by fusion welding.

[0019] The surface modification may include two axially spaced apart raised annular bands.

[0020]

[0020] The seat ring may further comprise a band of low friction material between two axially spaced apart raised annular bands.

[0021]

[0021] The present invention further provides a complete set of ball valve components comprising the ball and two seat rings described above. [Brief description of the drawings]

[0022]

[0022] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0023] [Figure 1] FIG. 1 is an exploded perspective view of a ball valve showing a fusion coated ball and two fusion coated seat rings according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of the fusion coated ball of FIG. [Diagram 3] FIG. 2 is a perspective view of the fusion coated seat ring of FIG. [Figure 4] 1 is a photograph of a raised annular band of surface modified titanium or titanium alloy created with a weld bead on a ball. [Diagram 5] 1 is a photograph of the raised annular band of the ball after machining. [Figure 6] 1 is an optical micrograph showing metallurgical fusion between the raised annular band and the substrate. [Figure 7] 1 is a graph of the hardness profile of the surface of a raised annular band. [Figure 9] 1 is a photograph of a conventional thermal spray coated ball after heavy use. [Figure 10] 1 is a photograph of a fusion coated ball according to one embodiment of the present invention after heavy use. [Figure 11] 1 is a photograph of a fusion coated ball according to one embodiment of the present invention after heavy use. [Figure 12] 1 is a photograph of a fusion coated ball according to one embodiment of the present invention after heavy use. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] 1-3, a fused coated trim component of a ball valve 10 according to one embodiment of the present invention may generally include a ball 12 between two seat rings 14. Prior to assembly of the ball valve 10, a new or repairable ball 12 and seat ring 14 may be provided and coated in the following manner.

[0025]

[0024] The ball 12 may comprise a metallic substrate having a surface modification 16 that serves as a seating surface for the seat ring 14 of the ball valve 10. The substrate and surface modification may each comprise titanium or a titanium alloy, such as titanium grade 12.

[0026]

[0025] The surface modified portion 16 may be formed by nitriding. Nitridation may be performed alone or in combination with additional surface modification techniques, such as those described in WO 2020 / 212883 by Callidus Welding Solutions Pty Ltd, which is incorporated herein by reference in its entirety. WO 2020 / 212883 describes, among other things, forming a surface modified portion by nitriding a surface portion of a substrate to form a hard titanium nitride phase, and alloying the nitrided surface portion of the substrate with a beta stabilizer to form a tough beta titanium phase surrounding the hard titanium phase.

[0027]

[0026] The surface modified portion 16 may be densified to fill cracks or voids, for example, with a thermal spray coating of one or more metal oxides or one or more metal carbides. Additionally or alternatively, the surface modified portion 16 may be densified with a suitable sealant or filler, such as "XP61" ceramic coating manufactured by Fireside Coatings. The densified surface modified portion may then be machined to remove excess densified material from the valve seat surface.

[0028]

[0027] With reference to Figures 4 and 5, the surface modified portion 16 of ball 12 may comprise a raised annular band. The raised annular band 16 may be metallurgically fused to the substrate, for example, by fusion welding, such as gas tungsten arc welding (GTAW). As shown in Figure 4, the raised annular band 16 may be initially formed on ball 12 as an annular adjacent weld bead, and later machined to the required dimensions and surface finish, for example, by grinding, computer numerical control (CNC) machining, lapping, match lapping, etc., as shown in Figure 5.

[0029] 3, the seat ring 14 may comprise a metallic substrate having a surface modified portion 16 that serves as a seating surface for the ball 12 of the ball valve 10. Each of the two seat rings 14 may be formed, machined, and densified using the same or similar materials and techniques as described above for the raised annular band 16 of the fusion coated ball 12.

[0030] In some embodiments, each seat ring 14 may include two or more axially spaced apart raised annular bands 16 which act as two or more spaced apart seating surfaces for the ball 12. Each seat ring 14 may further include bands 18 of low friction material, such as polytetrafluoroethylene (PTFE) or polyetheretherketone (PEEK), between each pair of adjacent axially spaced apart raised annular bands 16.

[0031]

[0030] The ball 12 may be match-lapped to two seat rings 14 and the completed fusion coated trim component may be supplied to an end user as a complete ball valve assembly.

[0032]

[0031] The following examples are intended to illustrate the present invention, but are not intended to limit the scope of the invention.

[0033] Working Example

[0032] An example titanium alloy fusion coated ball and two seat rings of a 10 inch class 600 ball valve were prepared and coated in the manner described above. The surface modified raised annular bands on the ball and seat ring were densified with a thermal spray coating of TiOxCrOx to leave a metallurgically fused coating with a finish thickness of approximately 1.5 mm. In comparison, the conventional thermal spray coated ball has a coating thickness of approximately 0.5 mm.

[0034]

[0033] Figure 6 is an optical micrograph showing the metallurgical fusion between the surface-modified raised annular band and the substrate of the fusion-coated ball of this example. Figure 7 shows that the surface-modified raised annular band of the ball of this example had an increased hardness of up to approximately 1100 HV. In contrast, the conventional thermal spray-coated ball has a lower hardness of up to 900 HV.

[0035] The fusion coated balls of this example were installed in-line in a high pressure acid leach (HPAL) nickel plant as isolation trim in an autoclave train alongside conventional thermal spray coated titanium balls. Each ball was then exposed to similar conditions of temperature, pressure, and acidic slurry.

[0036]

[0035] The fusion coated ball of this example was checked at 12 months and immediately returned to service due to very good condition of the trim. At 29 months it was removed for research and development purposes and was determined to be in satisfactory condition for repair and reuse. Figure 8 shows the fusion coated ball of this example after 29 months of in-line use. In comparison, the service life of thermal spray coated balls in similar locations ranged from 7 months to 24 months before unexpected spalling resulted in loss of sealing efficiency. Figure 9 shows an example of a conventional thermal spray coated ball where the thermal spray had spalled off after 7 months of in-line use.

[0037]

[0036] In addition to the in-line testing described above, the fusion coated trim of this example was subjected to accelerated in-house testing. Prior to the accelerated testing, the fusion coated trim was tested against API 6D, a standardized pipeline valve specification. The leak rate was 0 ml / min, compared to an acceptable factory acceptance test of 1.5 ml / min. The fusion coated trim of this example was then accelerated tested with a client-supplied acidic slurry under simulated HPAL conditions of 255°C and 4,500 kPa, where the valve was subjected to over 200 pressure strokes and over 20 full differential pressure strokes, simulating 4 years of heavy use. The valve operated within acceptable torque demands and isolation performance throughout the entire test. No seizure occurred throughout the duration of the test. As shown in Figures 10 to 12, after this accelerated testing, the fusion coated ball of this example showed minimal galling and could be returned to service without repair.

[0038]

[0037] In view of the above, it is believed that the fused coated trim of this embodiment may significantly extend trim life, particularly under severe conditions such as flashing during the opening and closing phases.

[0039]

[0038] Embodiments of the present invention provide fused coated trim components of ball valves, such as balls and valve seats, both of which are particularly and generally useful in heavy duty ball valves such as those used in pressure leaching applications.

[0040]

[0039] Although embodiments of the present invention have been described above merely by way of example in the context of trim components of heavy duty metal seat ball valves, it will be understood that these embodiments may alternatively be implemented to metallurgically fusion coat any and all metal components used in any and all industrial processes requiring increased resistance to wear and corrosion but reduced spalling and spalling (or increased adhesion strength) as compared to conventional thermal spray coatings.

[0041]

[0040] As used in this specification, the word "comprising" means "including but not limited to" and the word "comprises" has a corresponding meaning.

[0042]

[0041] The above embodiments have been described by way of example only and can be modified within the scope of the following claims.

Claims

1. A ball for a metal ball valve, comprising: first and second concentric bands metallurgically fused to first and second opposing sides of the ball; third and fourth concentric bands metallurgically fused to third and fourth opposing sides of the ball perpendicular to the first and second opposing sides; The first, second, third and fourth concentric bands are surface hardened and serve as four seating surfaces of a pair of seat rings of the metal ball valve in a closed position and an open position.

2. A valve seat ring for a metal ball valve, comprising: a first and second concentric bands metallurgically fused to the seat ring; The first and second concentric bands are surface hardened and serve as two seating surfaces for a ball of the metal ball valve.

3. A set of parts for a metal ball valve comprising a ball and a pair of valve seat rings, the ball has first and second concentric bands metallurgically fused to first and second opposing sides of the ball, and third and fourth concentric bands metallurgically fused to third and fourth opposing sides of the ball perpendicular to the first and second opposing sides, the first, second, third and fourth concentric bands being case hardened and functioning as four seating surfaces of the pair of seat rings of the metallic ball valve in a closed position and an open position; a pair of seat rings, each having first and second concentric bands metallurgically fused thereto, the first and second concentric bands being case hardened and serving as two seating surfaces for the ball of the metal ball valve;

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