1 Introduction

Erosion as a problem was identified during the World War II, when damage to the industrial equipments was observed in Australia [1] and Germany [2]. Professor Finnie from USA, earliest one to provoked the interest into erosion research, noticed the degradation of materials in industrial applications like sand blast, abrasive deburring, and drilling processes. Introduction of catalytic cracking process by 1942 further stepped up the erosion of oil industry components [3]. Contemporarily, Professor Philip Bowden, Consultant for Shell Oil Company, UK, noticed the damage on the munitions industry components of Australia by erosion. He pointed that the reasons for the components damage as friction [5], damage due to liquid impact at high speeds [6], and the particles inclusion effect on the damage was also of his keen interest [7].

Industrial components were falling well short before their expected life and research is carried to identify reasons for the early failure [1]. Similar consequences were also observed in industries such as steam turbines, rocket nozzles, and aerospace industries [8, 9]. Early research was pertaining with the erosion of components, and reports about erosion as a problem were described, but the basic understanding received meager attention [10]. Earlier researchers were unable to believe that the damage of components was due to particle inclusions, that too in reducing their life severely [11]. Researchers from versatile backgrounds engaged themselves to study the erosion by building the test set-up and evaluation of the materials, suitable for their applications, either by identifying the use of certain materials with better properties or by modifying the material with suitable techniques [12,13,14,15], but the erosion was there to occur on those materials as well. Finnie estimated the loss for the oil industry in the USA was about $5000 per annum during 1957 by erosion [4]. About 300,000 British pounds incurred only for replacement of offshore oil industry valves, and the damage in these industries is dominated by erosion [16]. Huge financial loss incurred due to erosion across fluids handling and processing industries all across the globe and went unnoticed before the significant emphasis on erosion [17,18,19].

Materials to be used as industrial components were evaluated for its erosion resistance, for which, variety of erosion test set-ups were used [20,21,22,23]. The researchers devised the erosion test set-ups for the operational requirements. Two types of erosion measuring approaches have been employed, first, the pipe wear testing (real conditions, as in industries) and second, laboratory tests (scaled down). Former method is most preferred, as it is more economical both in time and capital cost [24]. Three types of laboratory erosion test set-ups were commonly used to evaluate the materials erosion. They are slinger type, rotating type and the jet erosion test set-ups. In slinger type, multiple specimens were located on the surface of the chamber filled with slurry, rotating drum will carry the slurry to impact on the specimens [25]. In rotating type test set-ups, specimens were mounted on the arm of a shaft, rotates in the vertical plane. Slurry filled in the container impinges on the specimens fixed on the arm [26]. In above two cases, slurry rather than impacting on material was glazing/sliding along their surface, through which the impact characteristics of the erosive particles were found to be unknown. The jet erosion test set-ups permit variation of number of test parameters viz impingement angle, velocity, nozzle diameter, and concentration and significantly provides to evaluate the test materials under pure impact conditions. This system uses pressurized gas/water jet with erosive particles [27, 28].

Many slurry jet erosion test set-ups were developed and used to evaluate the materials erosion resistance/behavior under various slurry erosive conditions. Figure 1 is the geographical indicator shows the countries involved in building slurry jet test set-ups for erosion research. Chronological order 1 indicates first test set-up developed, and 11 indicates last test set-up contributor found from literature. The number of test set-ups developed in the representative nation is shown besides.

Fig. 1
figure 1

Geographical indicator of slurry jet erosion test set-ups built across the globe

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In this article, slurry jet erosion test set-ups built, rebuilt, and used by researchers to evaluate the erosion characteristics of the materials are reviewed. Of the slurry jet test set-ups found, based on the erosive particles induction method, categorized into premixing and postmixing of erosive particles and recirculation (RC) and non-recirculation (NRC) of slurry type. All the test set-ups are derived under four common test methods, namely, Levy, Turenne, Hutchings, and Thapa test methods. Test parameters like velocity, nozzle diameter, particle kinetic energy, concentration, and erosive particles type and size are compared individually for each test methods and at later stage, all the test methods are put together and compared for high and low velocity and high and low concentration test set-up.

2 Classification of Test Set-Ups

2.1 Test Set-Up Type

Slurry jet erosion test set-up is widely used, as it provides flexibility in operating parameters. For better understanding, the test set-ups are divided into two broad categories, namely,

  1. (1)

    re-circulation (RC) and nonrecirculation (NRC) of slurry.

  2. (2)

    premix and postmixing of slurry (pressurizing the fluid with or without erosive particles).

Erosive particles if reused are categorized as recirculation type, as erosive particles are recirculated throughout the testing cycle. In this category, the erosive particles will damage the pump components. While in non-recirculation type, erosive particles are used only once.

2.2 Test Methods

From the literature, numerous slurry jet test set-ups are found, but it was very cumbersome to advance for the review of test set-ups before simplifying the approach. Therefore, the authors narrowed down and classified the test set-ups based on the erosive particle induction method into the driving fluid. Four common test methods are drawn out, their schematic are shown in Fig. 2a–d. The literature shows that the latter researchers have modified/altered the test set-ups keeping the basic concept intact.

Fig. 2
figure 2

Slurry jet erosion test methods

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Figure 2a shows the first conceptual approach called as Levy test method. Water and kerosene were used as the fluids. Known quantity of erosive particles such as coal, aluminum oxide (Al2O3), and silicon carbide (SiC) is added to the container meanwhile stirred by the stirrer. Slurry in the container is pressurized by gas or air, carried through the nozzle to impinge on the material [28]. Figure 2b shows the Turenne test method. Turenne test set-up is incorporated with air-powered slurry pump to pump the premixed quantity of erosive particles added to the fluid forming the slurry mixture [29]. Figure 2c represents the Hutchings test method. Test set-up was provided with a multistage pump to drive the fluid, water. An ejector assembly is positioned along the main flow line to entrain the slurry mixture stored in a tank. A low pressure region is created due to differential cross section at the driving and driven nozzle in the ejector. This low pressure helps to suck the slurry in to the main flow line [30]. Last test method is the Thapa test method shown in Fig. 2d. Thapa test set-up was provided with a centrifugal pump to drive the water. A hopper located along the main flow line is loaded with erosive particles. Erosive particles entry is regulated by varying the orifice opening by the valve. Flow of water causes disturbance to the erosive particles in the hopper and falls into the main flow line due to gravity [31].

Based on the classification of test method, a pie chart is drawn as shown in Fig. 3 to show adoptability of test methods by the researchers. It can be observed that Turenne test method is the most popular test method while Levy test method is less popular.

Fig. 3
figure 3

Test method adopted by researchers

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2.3 Test Parameters

Erosion evaluation depends on material, erosive particles, fluid medium, and flow parameters, and it increases further by the synergetic effects. Properties of materials such as composition, hardness, fatigue, and tensile strength etc., the use of surface modified and coated materials add to the complexity. Properties of erosive particles are its type, density, hardness, shape, size, etc. Fluid properties are fluid viscosity, density, corrosivity, etc. Test parameters are flow type, angle of impingement, velocity, kinetic energy, and concentration. With all these associated factors, the erosion evaluation has been a tedious task. Then coming researchers were under dilemma to adopt the previous test methods, as many of the earlier reports doesn’t provided the necessary data to reproduce, and further loud the trouble as the rebuilt test set-up didn’t yield the prior results [11].

3 Description of Test Methods

Test set-ups developed under each method are tabulated sequentially based on first research article by researchers along with their geographical details, number of research articles published, and the test conditions employed for erosion evaluation and are described in this section.

3.1 Levy Test Method

Levy et al. from the USA in 1980 built the slurry jet erosion test set-up to evaluate the materials’ erosion for coal liquefaction industries [28]. This test method is categorized as premixing type and is NRC type. In this test set-up, variation in velocity is achieved by varying the gas regulator pressure. Literature reveals that Levy test method is used only by the original researchers and has not shown its footprint anywhere else in the future research but in University Berkeley Laboratory, USA. The author draws down the following reasons for the same:

  • non-availability of the test set-up,

  • unable to develop the similar set-up,

  • complexity in developing the similar set-up,

  • may be it has not created any interest.

Test conditions employed by Levy et al. are illustrated in Table 1.

Table 1 Test conditions under Levy test method
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3.2 Turenne Test Method

Turenne et al. from Canada in 1989 have developed a laboratory slurry jet erosion test set-up [29]. Turenne test method falls under the category of RC and premixing type. Basic principle adopted under this method is to pump the water and erosive particles mixture through the pump to cause erosion on the materials. Commonly used pumps are slurry pump and centrifugal pump. Erosive particles are the agents which induce erosion, through the energy carried by the particles in the fluid. In order to achieve increase in concentration, some researchers have used a stirrer in their test set-up [34, 81, 98]. Santa et al. modified centrifugal pump exit such that to locate the material at the exit to provide grazing incidence [79]. Grewal et al. have used two pumps,main pump to drive water and other to pump the slurry [87]. Nguyen et al. have used peristaltic pump to pump the slurry [99]. Water is used as driving fluid in all test set-ups developed by the researchers but Santa et al. only one to use distilled water as driving fluid. Yoganandh et al. have used the test set-up developed by Ducom Instruments. Table 2 illustrates the research articles published and the test conditions with which the researchers evaluated the materials’ erosion under Turenne test method. In the Turenne test method, it can be noticed that, for pumping the premixed slurry into the test chamber, the components of the pump used are susceptible to erosion in turn reducing their performance efficiency.

Table 2 Test conditions under Turenne test method
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Kinetic energy plays an important role in the erosion of materials, because erosion relies on the kinetic energy that the erosive particles possess. It is directly proportional to the square of the velocity indicates that increase in kinetic energy results in increase in erosion and vice versa. Amount of erosion caused depends on the materials hardness. Under Turenne test method, Wood et al. have evaluated the materials at kinetic ranges from 0.017 to 8 µJ. Higher the kinetic energy of the particles, higher is the erosion [63]. Similar approach was adopted by Sugiyama et al., in which erosion evaluation was conducted on SS material. It is observed that, at lesser kinetic energies (< 1 µJ), there was no erosion occurred, as the kinetic energy increased from > 1 µJ, the erosion was occurred and as the energy increases (upto 15 µJ), the erosion of the SS material got increased [70]. The kinetic energy values achieved by Wood and Sugiyama et al. are mentioned in Table 2. No kinetic energy values are found from other researchers under Turenne test method.

3.3 Hutchings Test Method

Hutchings et al. from United Kingdom in 1990 have developed a laboratory slurry jet erosion test set-up [30]. This test method is an interdependent type test method, and velocity and concentration depend on diameter ratio of driver (d) to driven nozzle (D) of ejector. In this test set-up, velocity increases with increase in d/D ratio while concentration decreases with increase in d/D ratio. Slurry after impacting the material will fall back to the slurry tank, and then recirculated through ejector. In this test set-up, driving fluid alone is driven by the pump, while the erosive particles are drawn into the main flow line only through the ejector. Unlike in Turenne test method, rather than pumping the slurry into the test chamber this test method utilizes ejector, which overcomes the erosion of pump components. Test set-up built by Hutchings has been modified by keeping ejector principle intact to evaluate erosion and erosion corrosion by using certain add-ons like electrochemical cell, electrodes [105,106,107,108]. This test method is categorized as postmixing and of recirculating type (RC). To homogenize the erosive particles and water, stirrer was used in the Zhang test set-up. Driving fluid used is water for slurry erosion test. For synergy of erosion corrosion water, sometimes distilled water with suitable chemicals/solutions was used to induce corrosion environment [109]. Table 2 illustrates the test conditions adopted by researchers in their research article under Hutchings test method.

Kinetic energy values under Hutchings test method is mentioned only by Wood et al., which varies from 0.016 to 0.41 µJ. Wood et al. have evaluated the materials’ erosion under both Turenne and Hutchings test method. It can be noticed that kinetic energy values under Turenne test method was ranging from 0.017 to 8 µJ, but while Hutchings test method is used, its value ranges from 0.016 to 0.41 µJ. The velocity under Turenne test method was varied from 4.7 to 28 m/s while in Hutchings test method, it varied from 3.1 to 6.7 m/s, which indicates that higher the velocity, higher the kinetic energy. No kinetic energy values are found from other researchers under Hutchings test method (Table 3).

Table 3 Test conditions under Hutchings test method
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3.4 Thapa Test Method

Bhola Thapa et al. from Nepal in 1999 have developed a laboratory test set-up [31]. Thapa test method falls under the category of postmixing and nonrecirculation type (NRC). Significant importance of this test method is the erosive particles induction into high-pressure fluid flow zone. Under this method, John Sandstorm et al. have used particle injection pump to induct erosive particles, in which the particles are pumped through hydraulic cylinders [131]. Two researchers have not provided details about the principle they adopted for erosive particle induction. Table 4 illustrates the test conditions adopted by the researchers under Thapa test method.

Table 4 Test conditions under Thapa test method
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Thapa et al. have built two test set-ups, named as Thapa 1 and Thapa 2. Working principle involved in the first test set-up is described earlier in Sect. 2.2, while in the second test set-up, they have used 2 hoppers placed one below the other. The lower hopper filled with water, while in the upper hopper, the particles are stored, regulated by valve, and will fall to the lower hopper filled with water and are then carried by the driving fluid to the test chamber [Thapa 2] [31]. Lin et al. and Santa et al. have not mentioned the principle they employed for the erosive particles induction. But they have presented the schematic which represents that they attempted the particles induction into the high velocity stream [80, 132].

4 Comparison of the Test Parameters for the Classified Test Methods

Based on the earlier classification at the Sect. 2.2, velocity adopted by researchers across all the classified test methods is shown in Fig. 4. It is clear from the velocity plot that Hutchings test method is the low velocity test method, while Thapa test method is the high velocity test method. It is also observed from the figure that most of the researchers from all the test methods have evaluated the materials well within 20 m/s velocity except Thapa test method. From literature, materials’ erosion with velocity > 6 m/s is termed as high velocity erosion, lesser are low velocity erosion [140, 141]. Hydraulic turbines are operated with velocity of > 100 m/s [136], majority of the test set-ups developed with Thapa method have evaluated for hydraulic applications, hence to achieve the higher velocity was the researchers’ motive [137].

Fig. 4
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Velocity comparison plot

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Figure 5 shows the comparison plot of nozzle diameters in the test set-ups. Decrease in nozzle diameter results in increase in velocity and vice versa. With the use of lower diameter nozzle, velocity achieved is high, which necessitates the use of large capacity pumps [87]. Velocity achieved by researchers depends majorly on the type of pump used and on nozzle employed. Variation in velocity with the test set-up is achieved through the use of suitable nozzles. Kinetic energy is also depends velocity, higher the velocity, higher the kinetic energy leads to higher energy of the particles results in increase in materials erosion. Velocity in Thapa test method is higher, but the concentration of erosive particles is less,however, the erosion caused on the materials is high, since energy of the particles is high.

Fig. 5
figure 5

Nozzle diameter comparison plot

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Figure 6 shows the concentration comparative plot. It is observed that Stack et al. under Hutchings test method have reached higher concentration compared with all other test methods, while Thapa test method is low concentration test set-up. Stack et al. under Hutchings test method is classified as high concentration test set-up. From Figs. 4 and 6, it is observed that velocity and concentration are interdependent. As Thapa test method is with high velocity, but with very less concentration compared with other test methods, whereas Hutchings method is classified as low velocity test method and is producing higher concentration.

Fig. 6
figure 6

Concentration comparison plot

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Concentration attained in the Levy and Turenne test method is high, as the majority of researchers could able to achieve high concentration compared to all other test methods, as they have premixed the particles with the fluid and pumped through pump, but for postmixing type test set-ups, viz Hutchings and Thapa test methods, In Hutchings test method, the concentration attained depends on the ejector’s driving and driven nozzle diameter ratio. Due to the differential cross section of the ejector, negative pressure is created, through which the slurry is sucked. While in Thapa test method, the particles are made to fall due to gravity into the main flow line, and the method involves various conditions to be met up, as the driving fluid passing in the flow line will enter the particles entry passage which obstructs the flow of particles.

It is observed that concentration of particles in the fluid depends on the type of industries. Concentration in the fluid reaches about 1–2 wt%, and the hydraulic turbines will shut down [142],for offshore applications, the high concentration observed is about 0.01 wt% [65]. Likewise to deal with the erosion in various industries, researchers built the test set-ups to suite for their particular application.

Under Turenne test method, majority of the research carried is concerned with hydraulic industries, as five test set-ups were developed to evaluate material for its applications [68, 76, 79, 85, 87]. Next major research is on material used for offshore gate valve applications, two test set-ups were developed [61, 73], later, each test set-ups were developed to investigate the material for sewage, sludge pump [60], and for nuclear industries application [101],, respectively. Jet test set-ups built under Hutchings test method, mostly finds its usage for slurry transportation industries [30], marine industries [121], aircraft fields [112] while major research in this was carried to evaluate the material for synergy of erosion corrosion [112, 114, 118, 126, 130]. Under Thapa test method, test set-ups are built to evaluate the materials for hydraulic industries [31, 136, 138], while Levy test method is used for coal liquefaction industries [32]. It is observed from the literature that few researchers [29, 72, 81, 84, 98, 104] have not mentioned neither their objective of research either to develop a test set-up to test the material used for a particular application, nor to test the material for its resistance to erosion. This makes difficult for the authors to have these test set-ups under any application. These test set-ups can only be discussed with the parameters used for the test set-ups. It is very obvious that the test parameters diverge considerably for the specific application.

Materials’ erosion also depends on the type and size of erosive particles. Figure 7 shows the type of erosive particles comparison plot from all the classified test methods. It is observed from the literature that larger the size of particles, greater is the erosion damage on the materials and vice versa. Erosion also depends on its shape, i.e., angular and rounded particles. Angular particles produced more erosion since it possessed sharp edges than the rounded particles. Larger the size of the particles, larger is the kinetic energy it possesses and greater is the erosion caused on the materials to evaluate the materials at severe conditions (Fig. 8).

Fig. 7
figure 7

Erosive particles comparison plot

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Fig. 8
figure 8

Impingement angle comparison plot

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Benefit of the slurry jet type set-ups is its ability to evaluate the test materials at various impingement angles ranging from 0° to 90°. Erosion mechanism of materials depends on the type of materials evaluated and on the angle of impingement. If the material is ductile, the mechanism will be in the micro ploughing (chip formation) or micro plastic deformation for lower angles, while micro cutting at higher angles. However, for brittle materials, it is micro fracture [3].

Based on the observations from Figs. 4, 6, and 7, the classified test methods based on velocity and concentration are further classified as low and high test method and are illustrated in Table 5. Table 5 also provides the details of RC and NRC type, premixed and postmixed methods, and the particle size employed in each classified test method.

Table 5 Classification of test methods based on test parameters
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5 Conclusions

Based on the research articles from the researchers on slurry jet erosion test set-up, the following conclusions can be made.

  • Based on the approach of the researchers for building the jet erosion test set-up, it is classified as Levy, Turenne, Hutchings, and Thapa test method, named after the original inventors.

  • Based on the particle induction, test set-ups are classified as premixed and postmixed category and circulating (RC) and nonrecirculating (NRC) type.

  • Levy and Turenne test method falls under premixing type, Hutching, and Thapa test method falls under postmixing category.

  • Turenne test method is found to be the most popular test method; while Levy test method is less popular, based on the number of researchers adopted the test method.

  • Erosion of the materials in the test set-up depends on velocity, concentration, and particles’ size, shape, and kinetic energy

  • Thapa test method is with highest of the velocity (117.3 m/s) but with lower concentration (0.0015 wt%) compared to all other test methods, while Hutchings test method is with highest concentration (40 wt%).

  • Impingement angle in jet erosion test set-up is varied between 0° and 90°. Brittle materials showed higher erosion at 90° (brittle erosion), while ductile materials at 30° (ductile erosion).