Erosion Resistance of Tungsten Carbide Braze Cladding Conveyance Piping

Transcription

1 Erosion Resistance of Tungsten Carbide Braze Cladding Conveyance Piping Chad Juliot Conforma Clad Inc. 501 Park East Boulevard New Albany, Indiana Ken Bowles Solvay Advanced Polymers 3702 Clanton Road Augusta, GA 30906

2 Introduction As an alternative to weld overlay wear resistant coatings, brazed tungsten carbide cladding provides increased erosion protection with less added weight When used correctly, these claddings have been shown to be superior in piping, chutes, diverters and conveyance fans and other applications where erosion by solid particles and corrosion are the principal mechanisms of failure Erosion resistance depends not only on the particular material selected but also on the method of application, impact angle, velocity and eroding media

3 Introduction This presentation will discuss several standard materials and test conditions Testing was performed per the ASTM G76, Standard Test Method for Conducting Erosion Tests by Solid Particle Impingement Using Gas Jets Plain carbon steel, tungsten, tungsten carbide composites, tungsten carbide thermal spray and chrome carbide weld overlay were examined for erosion resistance at various angles and particle velocities

4 Introduction The principal conclusions reaffirm three basic concepts: At 90 impact angles there are no outstanding performers As the angle of impact decreases, the commonly employed materials begin to segregate into two groups (positive and negative correlation) based on wear mechanism and performance The rule of mixtures applies to performance in that composite or metal matrix material erosion directly correlates to the proportions of reinforcing particle and matrix material

5 Introduction When evaluating the relative erosion resistance of materials, a number of factors must be considered Temperature Velocity of the impacting particles Particle size and shape Impacting angle These factors can be controlled in standardized testing but combining their range of variability to comprehensively evaluate performance in real applications is limited

6 Introduction Standardized testing procedures, such as ASTM G76, reduce a number of the variables with the intent of providing a common baseline for comparison The issue with such standardized tests is that the differences in erosion rates can be diminished to the point where differentiation is difficult or misleading Short of full scale tests, this leaves variation of the standardized tests as the only means to more accurately mimic actual conditions and rank erosion resistance in a meaningful way

7 Introduction Constitutive models, based on intrinsic properties (1) are used to predict erosion resistance and have been making progress over the last ten years but are still immature Fluid dynamic models used to predict flow patterns of particle laden streams have become quite good and are commonly used for critical applications (2,3) (1) R. Pieters, Surface Nitriding of Ti-6Al-4V Alloy in Nitrogen Atmosphere Using PW and CW Nd:YAG Lasers, Colorado School of Mines,Ph.D. Thesis, Golden CO., (2) Y. D. Jun, W.Tabakoff, Numerical Simulation of a Dilute Particulate Flow (laminar) Over Tube Banks, J. Fluid Eng. (Trans of the ASME), 116: , December (3) Y. Hamabe, K. Toda, M Yamamoto, Numerical Simulation of Sand Erosion Phenomena in Particle Separator, European Congress on Computational Methods in Applied Sciences and Engineering, Barcelona, September 2000.

8 Infiltration Brazed Cladding Infiltration brazing, as defined here, means to fill by capillary action with molten filler metal, a porous coating or structure that has a melting point higher than the filler metal While there are many means for applying the carbide and braze in preparation for infiltration braze coating, the principal method discussed here involves a non-woven preformed cloth

9 Infiltration Brazed Cladding Optical micrograph showing substrate/ cladding interface

10 Results & Discussion Differences in erosion behavior are generally categorized by broad descriptions of the type of wear In general, soft materials (a decidedly relative term) erode by plowing or cutting when impacted at low angles Relatively soft materials can be distinguished from relatively hard materials by the fact that their erosion rate tends to increase at lower angles of impact Increasing erosion rate with decreasing impact angle is often referred to as negative correlation, referring to the slope of the erosion versus impact angle

11 Results & Discussion

12 Results & Discussion Hansen (4) evaluated over 200 materials at 90 impact with alumina, 558 fts -1 (170 ms -1 ), 5g/min Showed that nearly all metals and metallic alloys, except tungsten and molybdenum, had similar erosion resistance at room temperature for 90 impingement Only a 30 percent improvement within the range of materials tested at 90 impingement Conclusion: If a metallic component fails prematurely by erosion, at 90, better performance could not be obtained from the substitution of another metallic alloy regardless of hardness (4) J.S. Hansen, Relative Erosion Resistance of Several Materials, Erosion: Prevention and Useful Applications, ASTM Symposium, Vail CO, pp , Oct

13 Results & Discussion Alternatively, tungsten carbide cermets show improved erosion resistance in a manner related to the binder content Uuemyis and Kleis (5) verified a mechanism which eroded the metallic binder from around carbide grains Maximize the area of carbide presented to the eroding media (minimize binder content) and erosion resistance increases 3x - 4x and as much as 10x - 15x compared to cermets with high binder content (>40 volume percent) or metallic alloys, respectively (5) K. Uuemyis, I. Kleis, V. Tumanov and T. Tiideman, translated from Poroshkovaya Metallurtiya, no. 3, (135) Appeared in Siviet Powder Metallurgy and Metal Ceramics, pp , July 1972.

14 Results & Discussion As a measure of erosion performance related to cladding microstructure, Lindsley and Marder (6) showed the dependence of erosion resistance on a modified Hall-Petch relationship: property = initial property value + k (microstructural parameter) Property of interest in this case is erosion resistance Initial value functionally related to an intrinsic material property Proportionality constant k is related to a microstructural parameter, Microstructural parameter = mean free path length between carbide particles (6) B.A. Lindsley, A.R. Marder, Solid Particle Erosion of an Fe-Fe3C Metal Matrix Composite, Metallurgical and Materials Transactions, v. 29A, pp , March

15 Results & Discussion Erosion rate of infiltration brazed tungsten carbide as a function of mean free path (particle spacing decreases left-to-right). Test conditions: 70 m/s using 50 µm alumina, 2.1 g/min., tube diameter 6.4 mm (0.25 in.).

16 Conclusion Particle erosion of alloys and composite coatings strongly influenced by impingement angle of eroding particles Variable fluid flow, particle loading, temperature and geometry further complicate the direct transfer of standard testing to engineering applications ASTM G76 standard provides reasonable correlation of laboratory data to field performance in that the magnitude of volume loss per unit mass of eroding media delivered permits ranking of relative erosion rates

17 Conclusion Based on ASTM G76 testing and results from field testing, infiltration brazed tungsten carbide claddings eroded at a rate 1/15 th to 1/4 th that of chrome carbide weld overlay in the 30 to 90 range of impingement angles, respectively In general, all the materials tested showed less relative difference in erosion at 90 impingement angle. The erosion rate of infiltration brazed tungsten carbide composites is a function of the carbide spacing (mean free path). This dependence has also been characterized on the basis of matrix material indicating that as matrix fraction increases, erosion resistance decreases.

18 Conforma Clad Solving Dilute Phase Pneumatic Conveying Wear Issues Ken Bowles Solvay Advanced Polymers 3702 Clanton Road Augusta, GA 30906

19 Options to Eliminate Wear- 45% Glass Filled Plastic Pellet Pressure Conveying Service Long Radius Bends Standard 304/316 SS Elbows (Schedule 10/40, Short Radius) Waeschle Gamma Bends / Hammertek Elbows Ceramic Lined Elbows Glass and Glass Lined Elbows Dense Phase Product Pneumatic Conveying Chrome Coating / WC Flame Spray Spiral Conveyors / Vibratory Feeders

20 Long Radius Bends Longer Turn = More Cross Sectional Area For Blow Outs Higher Pellet Degradation More Dust, Fines and Angel Hair Generation

21 Standard 304/316 SS Elbows (Schedule 10/40, Short Radius) Service Life is 7~21 Days in Low Pressure (4 psi) Pressure Conveying Service Blowouts Create: Yield Losses Process Disruptions Safety Issues (High Velocity Pellets) Housekeeping Problems

22 Pocket Back / Deflection Elbows Require Proper Solids to Air Conveying Ratio System Must Be Designed to Handle These Types of Elbows. Retrofit is Difficult. At Optimum Conditions, MTBF is 9~12 Months Must Remove Elbow for Clean Out when Changing Colors or Product Grades

23 Ceramic Lined Elbows Risks the Generation of Individual ~ Ø1mm Ceramic Beads Ceramic Beads Cannot Be Detected with a Metal Detector Potential Ceramic Contamination in E/E Industry Ceramic Beads can Plug Feed Gates in Automated Molding Equipment MTBR is typically 12 ~ 18 Months

24 Glass & Glass Lined Elbows Must Be Torqued Routinely in a Low Torque Bolting Sequence Usually Replaced due to Breakage (Catastrophic Failure vs. Wear Over Time) Glass Cannot Be Detected by Standard Metal Detection Equipment Disruption of Molding Lines Can Be Caused by Broken Glass Mixed with Pellets MTBF is Typically 12 ~ 18 Months

25 Dense Phase Product Pneumatic Conveyance Lower Conveying Velocity vs. Dilute Phase Conveying Initial Investment Cost is Higher Than That of Dilute Phase Conveying Pellet Attrition / Fines Generation is Greatly Reduced System Complexity is Increased Clean Outs for Color or Product Changes are Difficult Due to Pressure Pots and Air Side Tie Ins

26 Chrome Coating (Hard Chrome) / WC Flame Spray Thickness Limitations are Typically ~ Adheres to Base Metal Via Mechanical Bond Prone to Flaking and Contamination of Process Rough Surface Finish Results in High Potential for Product Attrition May be More Cost Effective for Large Pieces

27 Spiral Conveyors / Vibratory Conveyance Cost is 3x of Standard System 20 Height Limit (Over 20 the System Costs Become Much Higher) Moisture Absorption Can Be a Concern.

28 Cost of Wear / Blowouts Safety Lost Yields Product Quality Maintenance Costs

29 Safety Creates Housekeeping Problems Slipping and Falling Hazards High Velocity Pellets Leaking From Line Can Cause Injury to Personnel Wrong Approach to Housekeeping: Focusing on Cleaning vs. Removing Root Cause of Blowout

30 Lost Yields Extended Plant Real Estate Creates Potential Product Losses That Can Go Undetected Cost of One Hour of Undetected Blowout is $4,000/line Lost Yield Impact From Blowouts Approached 0.7% Yield/Yr (Over $200,000 Worth of Un- Useable Product/ Yr

31 Product Quality Quick Fixes Can Introduce the Potential for Product Contamination (Duct Tape, Gloves, Metal Plates, etc..) Weld Repairs of Lines with Patched Weaken the Surrounding Metal and Can Make the Area of Failure Spread

32 Maintenance Costs Cost of Repairs in Piping and Equipment Downstream of Pelletizer Was Nearly Two Operators (128 hrs/month, $70000 Annually Built into Maintenance Budget in Labor Alone) Repair Approach was Reactive, not Proactive Acceptance of Failures Sent the Wrong Message Many Products Advertised as Wear Materials Did Not Meet the Advertised Standards

33 Demonstrated Results with Conforma Clad Product Installations

34 Pressure Conveying Pipe 1995 Short Radius 45 & 90 Elbows on Dilute Phase 4, 6 and 8 Conveying Lines Downstream Pipe Section After Elbow or Turn Added 2003 Additional Field Repair Lengths. Pipe Rotation on Straight Sections, Four Points at Applied to Gravity Side Conveying Systems After Cyclone Rotary Valve (Previous MTBR was 12~ 19 Months)

35 Short Radius 45 & 90 Elbows on the Dilute Phase 4, 6 & 8 Lines (1995)

36 Downstream Straight Sections Field Repair Lengths (1997, 2003)

37 Gravity Side Conveying Systems Worn Pipe Before Conforma Clad (2003)

38 Gravity Side Conveying Systems After Conforma Clad (2003)

39 Additional Pressure Conveying Equipment Cyclones (2002) Diverter Valves (2001) Special Transition Pieces / Eductors (2003) Rotary Valves (2004) Product Sampler Transition (2003)

40 Additional Pressure Conveying Equipment

41 Additional Polymer Extrusion Equipment Applications Pelletizer Strand Guides and Discharge Transition Chute (High Velocity Impact) ( ) Metals Reject Valve Bell Housing (2003)

42 Conclusion The Augusta, GA Facility Has Never Replaced One Line or Component Blowout of a Component that was Clad with Conforma Clad (0.030 Thickness) The Conforma Clad Process has Demonstrated Field Results in Excess of Nine Years at the Augusta, GA Facility.