PUMP CASING WITH PRE-STRESSED LINING

Abstract

A method is described for forming a lining on an inner surface of a pump casing. The lining can protect the pump casing from corrosive and abrasive fluids. The method disclosed improves the durability and reliability of the lining by introducing a compressive pre-stress to the lining when the casing is not loaded such that during normal operation, the lining can be in a stress state near neutral and avoid failures related to excessive tensile strains. The method includes securing at least a portion of the casing in a stationary position and applying an external load to deform the casing. The method further includes depositing the lining onto the inner surface of the casing, curing the lining, and removing the external load to pre-stress the lining.

Description

TECHNICAL FIELD

This disclosure relates to industrial pumps, and in particular, to protective linings for casings of such pumps.

BACKGROUND

Industrial pumps oftentimes include linings on the inner casing surfaces to prevent corrosion and other associated damage caused by the pumped fluid. For example, in a flue-gas desulfurization system, sulfur dioxide is removed from exhaust flue gases of fossil-fuel power plants by pumps removing corrosive fluids, such as acidic limestone, or gypsum slurries. Linings protect the pumps from corrosion during operation and when the corrosive fluids are left inside the pumps. One common type of lining is a ceramic lining that is applied to the interior surface of the pump casing and/or to the surfaces of other components within or associated with the pump casings.

In operation, such linings are subjected to fluctuating high pressures, heat, corrosive fluid flow, or other operation factors, which can cause the lining to fail and otherwise lose its adherence to the inner surface of the casing. This is especially prevalent with ceramic liners, since the performance of such liners is significantly decreased under tensile stresses, which commonly occurs in pumping applications. Left unchecked, linings detach from the casing and cause mechanical damage to other components of the pumps and otherwise cause the unprotected surfaces to corrode. Such failures can lead to significant down-time, require replacement, increase maintenance frequency, and cause other counter-productive consequences.

SUMMARY

According to a first aspect, there is provided a method for forming a lining on an inner surface of a pump casing. The method includes securing at least a portion of the casing in a stationary position and applying an external load to deform the casing. The method further includes depositing the lining onto the inner surface of the casing and curing the lining. The method continues by removing the external load to allow the casing to return to its un-deformed shape in order to pre-stress the lining.

According to certain embodiments, curing the lining includes adhering the lining to the inner surface of the casing and solidifying the lining such that the lining becomes compressed when the external load is released.

In other certain embodiments, the method includes roughening the inner surface and treating the inner surface with a bonding agent to facilitate the lining adhering to the casing.

According to yet another embodiment, curing the lining further includes applying a load to the lining such that the lining is compressed when the lining is cured.

In still yet another embodiment, curing the lining further includes inducing a compressive stress as the lining solidifies.

In still other embodiments, applying the external load is performed prior to curing the lining.

According to other embodiments, curing the lining is performed prior to applying the external load.

In other embodiments, depositing the lining includes depositing a silicon carbide polymer onto the inner surface of the casing.

In yet another embodiment, depositing the lining includes depositing at least one of a rubber, a resin, a polymer, and a ceramic composite onto the inner surface of the casing.

In still other embodiments, the casing encloses an impeller, propeller, or rotor of the pump and is subject to fluctuating fluid pressure having a maximum operation load.

In yet other embodiments, the external load corresponds to the maximum operation load exerted on the casing during operation of the pump.

In certain embodiments, applying the external load comprises bending the casing.

In other certain embodiments, applying the external load includes applying a pressure differential between the inner surface and an outer surface of the casing.

In still other embodiments, applying the external load includes bending the casing and applying a pressure differential between the inner surface and an outer surface of the casing.

According to certain embodiments, depositing the lining further includes providing a mold, positioning the mold to form a gap between the mold and the inner surface of the casing, and filling the gap with the lining at a predetermined pressure that induces a pre-stress in the casing.

In still other certain embodiments, depositing the lining includes forming a layer of material having a thickness between about 4 mm and 50 mm.

According to a second aspect, there is provided a pump casing assembly for enclosing a pumping element. The casing assembly is formed having an inner surface and lining adhered to the inner surface of the casing assembly. The lining is compressively pre-stressed by the casing assembly to withstand cyclic stresses and is formed of an anti-corrosive or anti-abrasive material to reduce corrosion or increase wear resistance.

According to certain embodiments, the casing assembly includes a first casing half and a second casing half. The first casing half includes a first lining adhered to the first casing half and the second casing half includes a second lining adhered to the second casing half, the first and second linings being compressively pre-stressed.

In other embodiments, the pumping element includes an impeller, a propeller, or a rotor.

In still other embodiments, the first and the second lining is formed of a silicon carbide polymer.

In yet another embodiment, the first and second linings include one of a rubber, a resin, a polymer, and a ceramic composite.

According to some embodiments, the first and second linings each include a layer of material having a thickness between about 4 mm and 50 mm.

In still other embodiments, the first casing half and a second casing half further include an intake and an outlet.

According to a third aspect, there is provided a casing enclosing a pumping element for pumping fluids. The casing includes a metal structure having an inner surface facing the pumping element and a lining overlaying the metal structure for protecting the metal structure from corrosion or abrasion. The lining forms a uniform layer compressively pre-stressed when the metal structure is under an unloaded condition.

In certain embodiments, the lining includes a silicon carbide polymer.

In other certain embodiments, the lining includes a layer of material having a thickness between about 4 mm and 50 mm.

Other aspects, features, and advantages will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are part of this disclosure and which illustrate, by way of example, principles of the disclosure.

DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a rotodynamic pump having a lining along the inner surfaces of the pump casing.

FIG. 2 is a partial cross-sectional side view of the pump taken along the line 2-2 of FIG. 1.

FIG. 3 is flow chart illustrating one exemplary method for forming a pre-stressed lining on the inner surfaces of the pump.

FIG. 4A illustrates tensioning of a generic pump casing.

FIG. 4B illustrates the pump casing of FIG. 4A in its relaxed state and pre-stressing the linings.

FIG. 5 is a flow chart illustrating one exemplary method for forming a pre-stressed lining.

FIG. 6A illustrates compressing of a generic pump casing.

FIG. 6B illustrates the pump casing of FIG. 6A in its relaxed state and pre-stressing the linings.

FIG. 7 is an illustration of a portion of the pump casing of FIG. 2 and a system for tensioning the pump casing.

FIG. 8 is an illustration of a portion of the pump casing of FIG. 2 and another system for tensioning the pump casing.

FIG. 9 is an illustration of a portion of the pump casing of FIG. 2 and yet another system for tensioning the pump casing.

FIG. 10 is an illustration of a portion of the pump casing of FIG. 2 and an additional system for tensioning the pump casing.

DETAILED DESCRIPTION

This disclosure describes a pump casing having a pre-stressed lining and a method for improving durability of a pump by applying and pre-stressing the lining. Industrial pumps oftentimes are formed using heavy metal casings for housing pump elements such as an impeller, a propeller, or a rotor. In use, the metal casing is exposed to corrosive fluids such as acidic slurries. A protective lining is oftentimes applied to the metal casing to protect against corrosion and abrasion resistance.

A ceramic lining, such as, for example, a silicon carbide polymer, is one type of lining that can provide such corrosion and abrasion resistance. Ceramic linings are, however, susceptible to failure or disintegration when subjected to certain over-limit tensile strain. For example, when the pump operates at a high pressure condition, the lining may elongate excessively and fail in forms of disintegration, loss of adhesion to the casing, or in other related forms. The disclosed method compressively pre-stresses the ceramic lining, which can sustain a higher level of a compression strain than tensile strain, to achieve a pre-stressed state when the pump casing is not loaded and to achieve a near neutral stress state during operations. This reduces the likelihood of a lining failure and increases the pump casing's tolerance to higher pressure loading.

FIG. 1 is a schematic perspective view of a pump 100 with a representative lining 112. The pump 100 is illustrated as a generic rotodynamic pump; however, the pump 100 may be other types of pumps, machines or components that include linings protecting part or all of the exposed surfaces. In the embodiment illustrated in FIG. 1, the pump 100 includes an inlet 110 for receiving fluids, an impeller 115 for pumping fluids, and an outlet 120 for discharging fluids. A shaft 105 connects the impeller 115 with a power source, such as a motor, an engine, or other rotary power source.

In FIG. 1, the inlet 110 and the outlet 120 are formed with a casing assembly 130 that encloses and supports the impeller 115 and part of shaft 105. Other components not illustrated may be assembled to or part of the casing, such as seals, bearings, lubrication chambers, etc. In some embodiments, the impeller 115 may be a different type of pumping element, such as a propeller, a rotor, or the like. In some embodiments, the casing assembly 130 may be an integrated piece, or an assembly of several components for ease of maintenance, inspection, and repair.

According to one embodiment, the lining 112 is applied to the inner surface of the casing assembly 130 by adhesion during a curing process. The lining 112 protects the casing assembly 130 from corrosion, abrasion, shocks, or other operation induced factors. As described in further detail below, when no loads are acting on the casing assembly 130, the lining 112 is compressively pre-stressed, for example, by the casing assembly 130. The lining 112 in general represents all linings within the casing assembly 130; though in some embodiments, the lining 112 may be subdivided into multiple segments as shown in FIG. 2. The lining 112 is made of an anti-corrosion and anti-abrasion material, such as a silicon carbide polymer or other appropriate materials (such as rubber, resin, polymer, ceramic composites, or metal). In some embodiments, the lining 112 reduces flow resistance, dampens vibration caused by fluid turbulence, or provides other related functions.

FIG. 2 is a partial cross-sectional side view of the pump 100 as illustrated in FIG. 1. Referring to FIG. 2, the casing assembly 130 includes a first casing half 210 and a second casing half 212 forming a pump chamber 218. The first casing half 210 and the second casing half 212 mate at a mid-surface 230 and are fastened together at multiple bolt channels 240. A first lining 220 is applied to the inner surface of the first casing half 210 and a second lining 222 is applied to the inner surface of the second casing half 212. Casing linings 213 and 214 further cover the inner surface of other inner areas of the pump chamber 218 when the casing assembly 130 includes multiple pieces as illustrated.

Though in FIG. 2 the lining 112 is specifically referring to a portion near the inlet 110, the lining 112 may generally represent all (as used in descriptions for FIGS. 3 to 6B) of the first lining 220, the second lining 222, and the casing linings 213 and 214. As discussed in greater detail below, the linings 213, 214, 220, and 222 are compressively pre-stressed when the casing assembly 130 is not loaded. In other examples when casing halves 210 and 212 are made in one piece, the linings 220 and 222 are correspondingly made into one piece. The compressive pre-stress allows the linings 112, 213, 214, 220, and 222 to be subject to less tensile strain under normal operation loading conditions, therefore improving durability, reliability, and longevity of the linings 112, 213, 214, 220, and 222. Methods for forming the lining 112 and others are further described below with respect to FIGS. 3 and 5.

FIG. 3 is flow chart 300 illustrating an exemplary method for forming a pre-stressed lining. The method described in flow chart 300 may be generally applied to forming the lining 112 to the casing assembly 130 of FIGS. 1 and 2. At block 310, at least a portion of the casing assembly 130 is secured in a stationary position. For example, the mid-surface 230 is secured to an external tool (such as a support plate 850 of FIG. 8). In some embodiments, the flange around the inlet 110 may be secured to another tool (such as the loading fixture 726 of FIG. 7). In some embodiments, both the mid-surface 230 and the flange around the inlet 110 may be secured to different tools or a same tool (e.g., fixtures shown in FIGS. 9 and 10).

At block 320, an external load is applied to the inner surface (e.g., inner surfaces 215, 217 of FIG. 2) of the casing assembly 130. For example, a force, a torque, a pressure, or a combination thereof, is applied to the casing for tensioning the surface to which the lining is to be applied. One example is illustrated in the schematic of FIG. 4A, wherein a pair of forces 410a and 410b are applied to two opposite points on a cross section of the casing assembly 130 to elastically deform the casing assembly 130. The elastic deformation tensions the inner surface between the lining 112 and the casing assembly 130.

In some embodiments, the external load applied onto the casing assembly may simulate the loading condition under which the maximum pressure is experienced by the casing assembly 130. For example, during operation, the casing assembly 130 and the lining 112 enclose the impeller 115 (or any similar pumping element, such as a propeller, or a rotor, etc.) and is subjected to a fluctuating fluid pressure having a maximum value. The external load forces 410a and 410b may be applied to cause a similar level of strain or stress in the inner surface of the casing assembly 130 as the strain and stress caused by the maximum value of the fluctuating pressure.

In some embodiments, prior to applying the external load, the inner surface may be roughened by sanding, scratching, or otherwise grooved for increasing the bonding contact surface with the lining 112. A bonding agent may further be used to treat the roughened inner surface. The bonding agent increases adherence between the lining 112 and the inner surface of the casing assembly 130. In other embodiments, surface roughening and the bonding agent treatment may be applied after the external load is applied.

At block 330, the lining 112 is deposited onto the inner surface of the casing assembly 130 and cured. The lining 112 can be a layer of material having a thickness between about 4 mm and 50 mm, though other values of thickness are possible. The lining 112 includes silicon carbide polymer, or similar materials that resist corrosion, abrasion, or wear, such as a rubber, a resin, a polymer, a ceramic, or the like. The lining 112 may be deposited using various techniques. For example, the lining 112 may be made from curable fluids of various viscosities. For low viscosity fluids, spraying, brushing, or both may be used to deposit the lining material. For high viscosity fluids, a mold or a similar tool may be used to form a cavity that defines the thickness of the lining 112 and the lining material may be filled into the cavity using gravity or added pressure.

In some embodiments, multiple techniques may be combined for specific lining materials, for example, the lining 112 may be applied by sputtering, pouring, painting, dipping the casing assembly 130 into the lining material, among others. In some embodiments, the lining 112 may be an uncured material pre-formed for a uniform thickness and mechanically deposited against the inner surface of the casing assembly 130.

In some embodiments, curing of the lining 112 includes adhering the lining 112 to the inner surface of the casing assembly 130. For example, the material of the lining 112 (e.g., silicon carbide polymer, resin, rubber, ceramic composite, or similar ceramic or polymer) may have inherent adhesive properties. During curing, the material for the lining 112 solidifies in a neutral stress state. For example, no significant residual stress is present when the lining 112 is completely cured. In other embodiments, curing the lining 112 further includes applying a load (e.g., a pressure) to the lining 112 such that the lining 112 is compressed when the lining is cured. The load is not removed until the lining 112 is completely cured with a compressive pre-stress. This may be achieved using exemplary techniques illustrated in FIGS. 7-10 and as discussed in greater detail below.

At block 340, the external load is removed and the casing assembly 130 is relaxed. Removing the external load allows the casing assembly 130 to elastically return to its near original shape, as best illustrated in the schematic of FIG. 4B. When in this position, the lining 112 is compressed by the casing assembly 130 on the inner surface when the casing assembly 130 is not loaded (e.g., when the pump is at rest). Thus, when the pump is operating under pressure, the internal pressure tensions the lining 112 and brings the stress state near or closer to neutral, therefore avoiding over-tensioning the lining 112 as would have occurred if the lining 112 was not pre-stressed.

FIG. 5 is a flow chart 500 illustrating another exemplary method for forming a pre-stressed lining 112 on the casing assembly 130 of FIG. 1. One difference between the method illustrated in FIG. 5 with the method illustrated in FIG. 3 is that the external load is applied to the casing assembly after the lining 112 has been cured. For example, the external load plastically compresses the casing assembly 130 into a designed shape. Similar to the method of flow chart 300, at block 510, like at block 310, at least a portion of the casing assembly 130 is secured in a stationary position.

At block 520, the lining 112 is deposited onto the inner surface of the casing assembly 130 and subsequently cured. At block 530, external loads are applied onto the casing assembly 130 to plastically compress the casing assembly 130 for inducing a compressive pre-stress in the lining 112. For example, as is illustrated in the schematic of FIG. 6A, after the lining 112 has cured, a pair of forces 610a and 610b are applied onto the casing assembly 130 to plastically deform the casing assembly 130 into an intended shape, as shown in the schematic of FIG. 6B. The deformation caused by the forces 610a and 610b results in compressive pre-stresses in the cured lining 112. At block 540, the external loads are removed to relax the casing assembly 130, which leaves the lining 112 at a compressive pre-stressed state. This achieves similar results as in step 340 of the flow chart 300.

In some embodiments, in addition to the external loads applied to the casing assembly 130, the lining 112 may induce a compressive pre-stress during curing. For example, the material used as the lining 112 may tend to increase volume as it solidifies, but because the lining 112 is confined inside the casing assembly 130, such tendency is suppressed and a corresponding compressive stress is induced. This induced compressive pre-stress can be of a same level as the pre-stress created using the methods presented in FIGS. 3 and 5.

FIG. 7 is a first exemplary system of tensioning the pump casing 212 of FIG. 2 in accordance with the method illustrated in FIG. 3. The second casing half 212 is secured to a loading fixture 726 by fastening bolts 730 to hold the side surface 728 towards the loading fixture 726. Multiple tie bolts 738 hold the peripheral portion of the casing 212 through the bolt channels 240 to the loading fixture 726. By tightening the tie bolts 738 to shorten the distance between the peripheral portion of the casing 212 and the loading fixture 726, the casing 212 is deflected and the inner surface 740 of the second casing half 212 is tensioned. The lining 222 is then deposited and cured onto the inner surface 740. When the second casing half 212 is released from the loading fixture 726, the lining 222 is compressively pre-stressed by the second casing half 212.

FIG. 8 is a second exemplary system of tensioning the pump casing 212 of FIG. 2. The mid surface 230 of the second casing half 212 is secured to a support plate 850 via bolts 852 through the bolt channels 240. A cover plate 854 is secured to the other side of the casing 212 using cover bolts 856. An aperture 860 in the support plate 850 allows a fluid conduit 862 to commute fluids in or out of the chamber 810 formed by the support plate 850, the casing 212, and the cover plate 854. A gage 864 monitors the pressure in the chamber 810. In FIG. 8, the lining 222 has been deposited onto the inner surface 740 of the casing 212 but has not yet cured. Two different configurations may be used in the setup used in FIG. 8.

In a first configuration, the support plate 850 and the cover plate 854 are secured and not allowed for any movement relative to each other. For example, an additional fixture may be used to hold the support plate 850 and the cover plate 854. A positive pressure is then supplied to the chamber 810 to compress the lining 222. The lining 222 cures under this pressure and becomes compressively pre-stressed when cured and the pressure removed.

In a second configuration, the support plate 850 and the cover plate 854 can move freely relative to each other. A negative pressure is supplied to the chamber 810. For example, outer surface 859 of the casing 212 may be subjected to a pressure higher than the pressure 858 in the chamber 810. The low pressure 858 may be created by removing fluids (e.g., vacuum away gas) via the aperture 860 from the chamber 810. The pressure differential between the inner surface 740 and the outer surface 859 deforms the casing 212 such that the inner surface 740 is in tension. When a desired tension strain is achieved at the inner surface 740, the lining 222 is cured. The pressure differential is then removed for the casing 212 to return to an un-loaded shape. The cured lining 222 is then compressively pre-stressed. In some embodiments, the desired tension strain corresponds to an operating strain level when the casing 212 is under maximum operation pressure.

FIG. 9 is a third exemplary system for tensioning the pump casing 212 of FIG. 2. In FIG. 9, the mid surface 230 of the second casing half 212 is secured to a support plate 950 via bolts 952 through the bolt channels 240. The cover plate 976 is secured relative to the support plate 950 such that no relative movement is permitted. A lining channel 980 through the support plate connects a hose or pipe 982 for filling materials to form the lining 222. A mold 970 is placed onto the support plate 950 and defines a cavity 971 for filling the lining 222 between the mold 970 and the inner surface 740 of the casing 212. The size of the mold 970 defines the thickness 972 of the lining 222. According to some embodiments, the thickness 972 of the lining 22 is sized between about 4 mm to 50 mm depending on the particular application that the casing 12 is being used in connection with. When applying the lining 222, the lining material is fed via the piping 982 and the channel 980 to fill the cavity 971 at a predetermined pressure to deposit onto the inner surface 740 and form the lining 222. The lining material is then cured with a compressive residual stress. The casing 212 is then removed from the support plate 950 and the cover plate 976 and the mold 970 are removed.

FIG. 10 is a fourth exemplary system of tensioning the pump casing 212 of FIG. 2. In the embodiment illustrated in FIG. 10, the cover plate 976 has been modified into a loading fixture 1090 with expanded diameter and thickness for installation with corresponding tensioning bolts 1038 though the bolt channel 240 and the support plate 950. The tensioning bolts 1038 are tightened to shorten the distance between the loading fixture 1090 and the support plate 950, therefore deforming the casing 212 for tensioning the inner surface 740. Similar to the system illustrated in FIG. 9, lining material fed via the piping 982 and the channel 980 to fill the cavity 971 at the predetermined pressure to deposit onto the inner surface 740, which forms the lining 222. The effect of tensioning the inner surface 740 by tightening the tension bolts 1038 and the pressure applied to the lining material synergistically compress the lining 222. When cured, the lining 222 becomes compressively pre-stressed.

According to one or more advantages, there is provided a method that compressively pre-stresses a ceramic lining, which can sustain a higher level of a compression strain than tensile strain, to achieve a pre-stressed state when the pump casing is not loaded and to achieve a near neutral stress state during pumping operations. Accordingly, this reduces the likelihood of a lining failure during operation and increases the pump casing's tolerance to higher pressure loading.

In the foregoing description of certain embodiments, specific terminology has been resorted to for the sake of clarity. However, the disclosure is not intended to be limited to the specific terms so selected, and it is to be understood that each specific term includes other technical equivalents which operate in a similar manner to accomplish a similar technical purpose. For example, the disclosed method may also be used to create linings with tensile pre-stress by applying external loads to compress the casing assembly before the lining material cures. Other variations may also be reasonably derived from the general and specific examples of applying the current method.

In addition, the foregoing describes some embodiments of the disclosure, and alterations, modifications, additions and/or changes can be made thereto without departing from the scope and spirit of the disclosed embodiments, the embodiments being illustrative and not restrictive.

Furthermore, the disclosure is not to be limited to the illustrated implementations, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the disclosure. Also, the various embodiments described above may be implemented in conjunction with other embodiments, e.g., aspects of one embodiment may be combined with aspects of another embodiment to realize yet other embodiments. Further, each independent feature or component of any given assembly may constitute an additional embodiment.

Claims

1. A method for forming a lining on an inner surface of a pump casing, the method comprising: securing at least a portion of the casing in a stationary position;applying an external load to deform the casing;depositing the lining onto the inner surface of the casing;curing the lining; andremoving the external load to pre-stress the lining.

2. The method of claim 1, wherein curing the lining comprises: adhering the lining to the inner surface of the casing; andsolidifying the lining such that the lining becomes compressed when the external load is released.

3. The method of claim 1, further comprising: roughening the inner surface; andtreating the inner surface with a bonding agent to facilitate the lining adhering to the casing.

4. The method of claim 1, wherein curing the lining further comprises applying a load to the lining such that the lining is compressed when the lining is cured.

5. The method of claim 1, wherein curing the lining further comprises inducing a compressive stress as the lining solidifies.

6. The method of claim 1, wherein applying the external load is performed prior to curing the lining.

7. The method of claim 1, wherein curing the lining is performed prior to applying the external load.

8. The method of claim 1, wherein depositing the lining comprises depositing a silicon carbide polymer onto the inner surface of the casing.

9. The method of claim 1, wherein depositing the lining comprises depositing at least one of a rubber, a resin, a polymer, and a ceramic composite onto the inner surface of the casing.

10. The method of claim 1, wherein the casing encloses an impeller, propeller, or rotor of the pump and is subject to fluctuating fluid pressure having a maximum operation load.

11. The method of claim 10, wherein the external load corresponds to the maximum operation load exerted on the casing during operation of the pump.

12. The method of claim 1, wherein applying the external load comprises bending the casing.

13. The method of claim 1, wherein applying the external load comprises applying a pressure differential between the inner surface and an outer surface of the casing.

14. The method of claim 1, wherein applying the external load comprises bending the casing and applying a pressure differential between the inner surface and an outer surface of the casing.

15. The method of claim 1, wherein depositing the lining further comprises: providing a mold;positioning the mold to form a gap between the mold and the inner surface of the casing; andfilling the gap with the lining at a predetermined pressure that induces a pre-stress in the casing.

16. The method of claim 1, wherein depositing the lining comprises forming a layer of material having a thickness between about 4 mm and 50 mm.

17. A pump comprising: a casing assembly for enclosing a pumping element, the casing assembly having an inner surface; anda lining adhered to the inner surface of the casing assembly, the lining compressively pre-stressed by the casing assembly to withstand cyclic stresses and is formed of an anti-corrosive or anti-abrasive material to reduce corrosion or increase wear resistance.

18. The pump of claim 17, wherein the casing assembly comprises a first casing half and a second casing half, wherein the first casing half includes a first lining adhered to the first casing half and the second casing half comprises a second lining adhered to the second casing half, the first and second linings being compressively pre-stressed.

19. The pump of claim 17, wherein the pumping element comprises an impeller, a propeller, or a rotor.

20. The pump of claim 17, wherein the first and the second lining is formed of a silicon carbide polymer.

21. The pump of claim 17, wherein the first and second linings comprise one of a rubber, a resin, a polymer, and a ceramic composite.

22. The pump of claim 17, wherein the first and second linings each comprise a layer of material having a thickness between about 4 mm and 50 mm.

23. The pump of claim 17, wherein the first casing half and a second casing half further comprise an intake and an outlet.

24. A casing enclosing a pumping element for pumping fluids, the casing comprising: a metal structure having an inner surface facing the pumping element; anda lining overlaying the metal structure for protecting the metal structure from corrosion or abrasion, wherein the lining forms a uniform layer compressively pre-stressed when the metal structure is under an unloaded condition.

25. The casing of claim 24, wherein the lining comprises a silicon carbide polymer.

26. The casing of claim 24, wherein the lining comprises a layer of material having a thickness between about 4 mm and 50 mm.