Patent ID: 12234922

These drawings and any description herein represent examples that may disclose or explain the invention. The examples include the best mode and enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The drawings are not to scale unless the discussion indicates otherwise. Elements in the examples may appear in one or more of the several views or in combinations of the several views. The drawings may use like reference characters to designate identical or corresponding elements. Methods are exemplary only and may be modified by, for example, reordering, adding, removing, and/or altering individual steps or stages. The specification may identify such stages, as well as any parts, components, elements, or functions, in the singular with the word “a” or “an;” however, this should not exclude plural of any such designation, unless the specification explicitly recites or explains such exclusion. Likewise, any references to “one embodiment” or “one implementation” does not exclude the existence of additional embodiments or implementations that also incorporate the recited features.

DESCRIPTION

The discussion now turns to describe features of the examples shown in the drawings noted above. These features prevent thermal stress cracking of conformal coatings that cover plugs or like closure members found on valves. Other embodiments are within the scope of this disclosure.

FIG.1depicts an example of a closure member100. This example is found in a distribution network102, typically designed to carry material104through a network of conduit106. The network102may include a flow control108that has a valve body110to connect in-line with the conduit106. A valve stem112may couple the closure member100with an actuator114. This arrangement can manage the position of the closure member100relative to a seat116. In one implementation, the closure member100may form a plug118with a coating120.

Broadly, the closure member100may be configured to better survive harsh working fluids or like operating conditions. These configurations may embody parts that use different materials in different (and often strategic) locations, particularly locations that reside in flow of the working fluid. The parts may help regulate flow through a valve; although the concepts here may apply to other functions within these types of devices.

The distribution system102may be configured to deliver or move resources. These configurations may embody vast infrastructure. Material104may comprise gases, liquids, solids, or mixes, as well. The conduit106may include pipes or pipelines, often that connect to pumps, compressors, vessels, boilers, and the like. The pipes may also connect to tanks or reservoirs. In many facilities, this equipment forms complex networks.

The flow control108may be configured to regulate flow of material104through the conduit106in these complex networks. These configurations may include control valves and like devices. The valve body110is often made of cast or machined metals. This structure may form a flange at openings I, O. Adjacent pipes106may connect to these flanges. The valve stem112may form an elongate cylinder or rod that directs a load from the actuator114to the closure member100. The load may result from compressed air along with a piston, spring (or springs), or a flexible diaphragm. This feature helps locate the closure member100in a desired position relative to the seat116. This desired position or “set point” may correspond with flow parameters for the material104to meet process requirements or parameters. The plug118may move relative to the seat116to meet or achieve the set point. Movement is generally along an axis of the seat116, or “up” or “down” for those valves that orient vertically on the process line. As noted, the position of the plug118may correspond directly with the flow rate of natural gas (or other resource) that flows through the seat116(or from its upstream side to its downstream side).

The coating120may be configured to protect the plug118. These configurations may include layers that are less likely to breakdown or erode over time in service. The layers may include structure to regulate or self-regulate crack propagation, for example, stress reliefs that direct cracks to form in certain areas or under certain conditions. The reliefs may react to thermal variations or cycling that the part may encounter in service. Additive manufacturing techniques may deposit the layers to ensure strong bonds with underlying material of the plug118. These techniques may also help to integrate any stress reliefs or other cracking profile (or geometry) as part of the deposited layer. For example, the layer may thin at or along the stress reliefs. The part may undergo pre-emptive thermal cycling to cause or “force” cracks to form along these thinned sections prior to use in the field. This pre-cracking strategy can elongate life of the protective layer (and, in turn, the underlying plug118) because the cracks can accommodate additional thermal expansion of the part that occurs in the field to prevent additional crack formation and eventual flaking of the protective layer.

FIG.2depicts a plan view for an example of the coating120. This example forms a thin layer122(or multiple “layers122”) that covers all or most of the underlying plug118. The thin layer122may comprise materials that are harder than the plug118. This property is important to protect the plug118from damage that can occur in service. Crack “lines”124may populate at least part of the thin layer122. The lines124may, by design, cause the thin layer122to fail before other parts of the thin layer122. For example, the lines124may correspond with sections or areas of the thin layer122that are thinner than adjacent sections. These thinner parts may succumb to thermal cycling easier or faster than the thicker parts. Other features or anomalies may also help to facilitate crack propagation as well, for example, the lines124may comprise materials that are different that the rest of the thin layer122or the lines124may have dimensions or a cross-section that is prone to crack under thermal cycling or other stress.

FIG.3depicts an elevation view of the cross-section of the coating120ofFIG.2. Configurations of the lines124may arrest crack formation to a maximum depth D. This configuration may stop the crack before it penetrates through the thickness T of the layer122. This feature can improve protection because it prevents cracking of the entire protective layer. The remaining thickness (T−D) may preserve the conformal coating of the layer124over the underlying plug118. This remaining, conformal layer is less susceptible to cracking because the existing cracks that develop at the lines124prior to service operate as stress reliefs that can accommodate for any additional thermal deviations that the part sees in the field. In one implementation, the layer122may include a material (identified generally as L1) that helps to arrest crack development because it simply does not allow the cracks to propagate any further toward the plug118. The material L1may foreclose the need to precisely engineer the lines124to consistently obtain the proper depth D and, thus, not expose any surface of the plug118to highly-erosive working fluid.

FIGS.4and5depict plan views of examples of the coating120. The lines124may form a crack profile126that defines a pattern128. Examples of the pattern may form a grid, for example, in which lines124intersect with one another to form squares or rectangles. This disclosure contemplates that the design can form other shapes (e.g., triangles, diamonds, etc.), as well as combinations thereof. As best shown inFIG.5, the grid may form hexagonal shapes. Post-thermal cycling, this design can cause pre-cracking that take on a visual appearance of “crocodile skin.” This appearance is useful because it can alert manufacturers or operators that the part is ready for use in the field.

The pattern128may comprise a collection of individual tiles130. Space or gap132may separate adjacent tiles130from one another. In one implementations, dimensions for the gap132may allow for contact between the printed tiles130, for example, at the time of manufacture. This arrangement may keep working fluid away from the underlying plug118because the working fluid can't percolate or penetrate the “net zero” space between adjacent tiles130, much like a uniform, conformal coating with the pre-defined cracking structure contemplated herein. Separation between the tiles130though may provide expansion relief because adjacent tiles130may move relative to one another to account for thermal expansion between the parts118,120.

FIG.6depicts an elevation view of the cross-section of structure for the flow control108. The valve body110may comprise an upper member134that secures with a lower member or “flange”136. Fasteners F, like nuts and bolts, may work for this purpose. The seat116may comprise a seat ring138. A venturi housing140may reside below the seat ring138in the flange136. In one implementation, the valve stem112may extend through packing142in the member134to locate the plug118in proximity to a seat ring138. The packing142is useful to allow movement of the valve stem112, but prevent the flow control108from emitting fugitive emissions.

In view of the foregoing, the improvements herein offer a new approach to construct valve parts, like plugs or closure members, that reside in the flow of highly-erosive working fluids. This approach addresses operator concerns about life expectancy of certain parts on their process lines. These concerns frustrate use of certain materials because their inherent properties are not conducive with the working fluids. For example, hardened martensitic stainless steel lacks corrosion resistance to survive harsh or corrosive working fluids. Base-level austenitic stainless steels have the necessary corrosion resistance; but these materials are inherently too soft for mechanical loading seen in flow controls found in many process lines. On the other hand, high-performance alloys or ceramics, like Inconel or solid tungsten carbide, appear to meet requirements for corrosion, hardness, or strength. But many types of these materials are too brittle or, like other steels, become too brittle as hardness increases to survive under duress of harsh or corrosive working fluids. This weakness can lead to fracture under non-symmetrical mechanical loading, which may occur when particles or debris entrained in working fluid becomes caught between moving parts. Further, brittle materials often fail in response to vibration. These conditions may arise in high-pressure systems from a combination of pressure drops along the system and changes in direction of the high-velocity flow of working fluid.

The examples below include certain elements or clauses to describe embodiments contemplated within the scope of this specification. These elements may be combined with other elements and clauses to also describe embodiments. This specification may include and contemplate other examples that occur to those skilled in the art. These other examples fall within the scope of the claims, for example, if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.