Costly failures in propulsion, machinery design, installation and operation How to avoid them?

Transcription

1 MARITIME Costly failures in propulsion, machinery design, installation and operation How to avoid them? Johan J. Iseskär 24 May DNV GL 24 May 2018 SAFER, SMARTER, GREENER

2 Maritime Advisory services in DNV GL ( High value advisory services Safety, Risk and Reliability Lifecycle Management Structures Hydrodynamics Noise & Vibration Mechanical & Systems Shipping and Environment ECO solutions Marine Cybernetics Advisory 2

3 Costly failures in propulsion, machinery design, installation and operation Some examples of failures Stern tube failures OD-shaft failure Water lubricated stern tube failure Root cause investigation principles 5 why s Failure tree DNV GL - Loss / cause Mitigation of risk for failures by preventive qualification Fit for Purpose concept 3

4 Costly failures in propulsion, machinery design, installation and operation OD-shaft fatigue 4

5 Stern tubes Failure modes and recent damage trends 5

6 Aft stern tube bearing failure modes Wiping damage Wiping (overheating) Loss of hydrodynamic oil film Inability to dissipate heat generated by metal to metal contact Melting/smearing of white metal layer Initiated in bearing aft end Detected by abrupt rise in bearing temperature 6

7 Aft stern tube bearing failure modes Fatigue damage Fatigue (cracking/ spalling) Excessive cyclic loading and/or poor bonding Flaking of white metal layer Developing over a period of time Detected through oil sampling Initiated in bearing aft end 7

8 Aft stern tube bearing damage trends Failures on single stern tube bearing installations are most predominant More wiping related damages have been reported than before mostly occurring during hard turning conditions in the upper speed range Increased number of early life failures mooring trials, sea trials or within the first few weeks/months in service The industry is reportedly affected in general However, most damages affecting bulk, tanker and container segments 8

9 Typical damage scenario Extreme turning condition at high ship speed Transient conditions at hard manoeuvring Downwards acting propeller bending moment Edge loading in aft stern tube bearing aft end Mixed/Boundary lubrication conditions 9

10 Summary Several contributing factors Design trend: Increased focus on energy efficiency Larger diameter and heavier propellers Reduced RPM Hull and propeller wake optimization features (asymmetric sterns, sleek aft hull forms etc.) New stern tube configurations Single bearing stern tube designs Pre-fabricated and chock fasted stern tubes Unfavourable operation Partially-submerged propeller combined with high RPM Different types of Lubricants Mineral oils, Environmentally Acceptable Lubricants (EALs) etc. Various viscosities used 10

11 Main aspects of the DNV GL shaft alignment rules 1. Hydrodynamic propeller loads need to be considered Evaluate both static and running conditions 11

12 Main aspects of the DNV GL shaft alignment rules 2. Main focus on aft stern tube bearing (ASB) Shaft vs. bearing contact area is a key parameter Angular misalignment and shaft curvature inside the bearing influence the contact area The way to optimize shaft vs bearing contact area is through bearing sloping 12

13 Main aspects of the DNV GL shaft alignment rules acceptance criteria Aft stern tube bearing -oil film lubrication acceptance criteria The DNV GL oil film lubrication criteria aims to ensure that hydrodynamic lubrication is achieved for all continuous operating conditions by considering Coefficient of friction, µ Boundary lubrication Mixed lubrication Hydrodynamic lubrication -bearing internal load distribution -shaft vs bearing slope -rpm -geometry -oil viscosity Lubrication parameter, ŋ V/P 13

14 The DNV GL approach to mitigate the risks Revising Main Class Rules for shaft alignment Rules for Ships Pt.4 Ch.2 Sec.4 Class notations Shaft Align(1) & Shaft Align(2) State-of-the-art approach for enhanced design margins Initiating JDP on EAL lubrication performance Closing knowledge gaps 14

15 DNV GL Main Class Rules Pt.4 Ch.2 Sec.4 (Jan 2018) Focused attention on single bearing stern tube designs Single slope bearing design 1)Higher shaft vs aft stern tube bearing (ASB) relative slope in turning condition Requirement: Multi-sloped ASB Requirement: Increased downward bending moment to 30% of MCR torque Double slope bearing design 2)Traditional alignment installation and verification methods may not be accurate enough. Requirement: Increased focus on yard installation procedure Note: Red colour is indication of small shaft vs bearing gap. The larger the red area the easier it is to build a satisfactory oil film 15

16 Environmentally acceptable lubricants regulatory background: VGP (2013) Final Vessel General Permit (VGP) 2013: in force since Dec This permit is applicable to discharges incidental to the normal operation in waters of the United States All vessels must use Environmentally acceptable lubricants (EAL) in all oil to sea interfaces, unless technically infeasible EALs are lubricants that have been demonstrated to meet standards for biodegradability, toxicity and bioaccumulation potential that minimize adverse consequences in the aquatic environment. Technically infeasible means: no EAL products are approved for use in a given application no available alternatives manufactured with EALs not available within any port in which the vessel calls, or changeover and use of an EAL must wait until the vessel s next drydocking 16

17 EALs as stern tube lubricants - overview EAL base oils Ester oils Vegetable oils Polyglycols Synthetic hydrocarbons HEES Triglycerides / HETG PAG / HEPG PAO / HEPR Natural esters Synthetic esters Unsaturated Fully saturated 17

18 EALs as stern tube lubricants ongoing JDP Phase 1 19

19 OD Shaft fatigue failure 21

20 VERSION 16 May 2018 Slide 22

21 Version Slide 23

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29 Torque, knm Shaft speed, rpm Time, sec 55

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32 600 Notch Strain Analysis Stress, MPa Strain-Life Curve Total strain Strain amplitude Number of load cycles

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35 Water lubricated stern tube failure Closed loop 37

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42 Sterntube bearing damaged Bearings and shaft journals heavily worn. Marks of heavy corrosion in system. Abrasive wear Adhesive wear Fretting and hammered bearing No signs of fatigue damage on bearings - STOP Bearing corrosion and oxidation wear No signs seen. STOP Particles in lubricant Rough surface Lack of hydrodynamic lubrication Too high temperature Internal Contamination External Contamination Selfcontaminated bearing Corrosion within system Impurities from NB Contaminated coolant Ingress through seal

43 Sterntube bearing damaged Bearings and shaft journals heavily worn. Marks of heavy corrosion in system. Abrasive wear Adhesive wear Fretting and hammered bearing No signs of fatigue damage on bearings - STOP Bearing corrosion and oxidation wear No signs seen. STOP Particles in lubricant Rough surface Lack of hydrodynamic lubrication Too high temperature Internal Contamination External Contamination Selfcontaminated bearing Corrosion within system Impurities from NB Contaminated coolant Ingress through seal

44 Sterntubebearing damaged Bearings and shaft journals heavily worn. Marks of heavy corrosion in system. Abrasive wear Adhesive wear Fretting and hammered bearing Bearing corrosion and oxidation wear No signs of fatigue damage on bearings - STOP No signs seen. STOP Particles in lubricant Rough surface Lack of hydrodynamic lubrication Too high temperature Internal Contamination External Contamination Selfcontaminated bearing Corrosion within system Impurities from NB Contaminated coolant Ingress through seal Galvanic corrosion Under deposit corrosion General Corrosion Bio corrosion Lack of inhibition in system Insufficient flow capacity Insufficient local flow Poor inhibition system Lack of circulation Lack of sacrificial anodes Chemical properties of coolant Cooling system design Lack of biocides Too low ph Accumulation of bio-products Seawater ingress Low ph

45 Sterntube bearing damaged Bearings and shaft journals heavily worn. Marks of heavy corrosion in system. Abrasive wear Adhesive wear Fretting and hammered bearing Bearing corrosion and oxidation wear No signs of fatigue damage on bearings - STOP No signs seen. STOP Particles in lubricant Rough surface Lack of hydrodynamic lubrication Too high temperature Internal Contamination External Contamination Manufacturing of shaft liner Degradation of shaft surface finish in service High bearing pressure Excessive loads Selfcontaminated bearing Corrosion within system Impurities from NB Contaminate d coolant Ingress through seal Grinding process Assembly Process Wear Corrosion/ chemical attack Nominal bearing load Grounding Vibrations Galvanic corrosion Under deposit corrosion General Corrosion Bio corrosion Nominal pressure Local pressure Lack of inhibition in system Insufficient flow capacity Insufficient local flow Poor inhibition system Lack of circulation Geometry Viscocity of lubricant Edge loading Lack of sacrificial anodes Chemical properties of coolant Cooling system design Lack of biocides Too low ph Accumulation of bioproducts Misalignment High hydrodynami c loads Installation Hull deflections Seawater ingress Low ph Incorrect wake estimation Turning condition loads Reversing condition

46 Sterntube bearing damaged Bearings and shaft journals heavily worn. Marks of heavy corrosion in system. Abrasive wear Adhesive wear Fretting and hammered bearing No signs of fatigue damage on bearings - STOP Bearing corrosion and oxidation wear No signs seen. STOP Particles in lubricant Rough surface Lack of hydrodynamic lubrication Too high temperature Internal Contamination External Contamination Manufacturing of shaft liner Degradation of shaft surface finish in service High bearing pressure Excessive loads Incorrect bearing clearance Geometrical deficiencies Reaction point in washway Insufficient flow Insufficient local flow Insufficient heat removal Selfcontaminat ed bearing Corrosion within system Impurities from NB Contaminat ed coolant Ingress through seal Grinding process Assembly Process Wear Corrosion/ chemical attack Nominal bearing load Grounding Vibrations Swelling of bearing Ovality Runout Pump sixe(s) Capacity through filters Capacity through pipes System design Temperatur e balance System setpoint Galvanic corrosion Under deposit corrosion General Corrosion Bio corrosion Nominal pressure Local pressure Compatibilit y Swelling rate vs temperatur e Operational monitoring Operational monitoring? Lack of inhibition in system Insufficient flow capacity Insufficient local flow Poor inhibition system Lack of circulation Geometry Viscocity of lubricant Edge loading Lack of sacrificial anodes Chemical properties of coolant Cooling system design Lack of biocides Too low ph Accumulati on of bioproducts Misalignme nt High hydrodyna mic loads Installation Hull deflections Seawater ingress Low ph Incorrect wake estimation Turning condition loads Reversing condition

47 Sterntube bearing damaged Bearings and shaft journals heavily worn. Marks of heavy corrosion in system. Abrasive wear Adhesive wear Fretting and hammered bearing No signs of fatigue damage on bearings - STOP Bearing corrosion and oxidation wear No signs seen. STOP Particles in lubricant Rough surface Lack of hydrodynamic lubrication Too high temperature Internal Contamination External Contamination Manufacturing of shaft liner Degradation of shaft surface finish in service High bearing pressure Excessive loads Incorrect bearing clearance Geometrical deficiencies Reaction point in washway Insufficient flow Insufficient local flow Insufficient heat removal Selfcontaminat ed bearing Corrosion within system Impurities from NB Contaminat ed coolant Ingress through seal Grinding process Assembly Process Wear Corrosion/ chemical attack Nominal bearing load Grounding Vibrations Swelling of bearing Ovality Runout Pump sixe(s) Capacity through filters Capacity through pipes System design Temperatur e balance System setpoint Galvanic corrosion Under deposit corrosion General Corrosion Bio corrosion Nominal pressure Local pressure Compatibilit y Swelling rate vs temperatur e Operational monitoring Operational monitoring? Lack of inhibition in system Insufficient flow capacity Insufficient local flow Poor inhibition system Lack of circulation Geometry Viscocity of lubricant Edge loading Lack of sacrificial anodes Chemical properties of coolant Cooling system design Lack of biocides Too low ph Accumulati on of bioproducts Misalignme nt High hydrodyna mic loads Installation Hull deflections Seawater ingress Low ph Incorrect wake estimation Turning condition loads Reversing condition

48 Sterntube bearing damaged Bearings and shaft journals heavily worn. Marks of heavy corrosion in system. Abrasive wear Adhesive wear Fretting and hammered bearing No signs of fatigue damage on bearings - STOP Bearing corrosion and oxidation wear No signs seen. STOP Particles in lubricant Rough surface Lack of hydrodynamic lubrication Too high temperature Internal Contamination External Contamination Manufacturing of shaft liner Degradation of shaft surface finish in service High bearing pressure Excessive loads Incorrect bearing clearance Geometrical deficiencies Reaction point in washway Insufficient flow Insufficient local flow Insufficient heat removal Selfcontaminat ed bearing Corrosion within system Impurities from NB Contaminat ed coolant Ingress through seal Grinding process Assembly Process Wear Corrosion/ chemical attack Nominal bearing load Grounding Vibrations Swelling of bearing Ovality Runout Pump sixe(s) Capacity through filters Capacity through pipes System design Temperatur e balance System setpoint Galvanic corrosion Under deposit corrosion General Corrosion Bio corrosion Nominal pressure Local pressure Compatibilit y Swelling rate vs temperatur e Operational monitoring Operational monitoring? Lack of inhibition in system Insufficient flow capacity Insufficient local flow Poor inhibition system Lack of circulation Geometry Viscocity of lubricant Edge loading Lack of sacrificial anodes Chemical properties of coolant Cooling system design Lack of biocides Too low ph Accumulati on of bioproducts Misalignme nt High hydrodyna mic loads Installation Hull deflections Seawater ingress Low ph Incorrect wake estimation Turning condition loads Reversing condition

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51 Sterntube bearing damaged Bearings and shaft journals heavily worn. Marks of heavy corrosion in system. Abrasive wear Adhesive wear Fretting and hammered bearing No signs of fatigue damage on bearings - STOP Bearing corrosion and oxidation wear No signs seen. STOP Particles in lubricant Rough surface Lack of hydrodynamic lubrication Too high temperature Internal Contamination External Contamination Manufacturing of shaft liner Degradation of shaft surface finish in service High bearing pressure Excessive loads Incorrect bearing clearance Geometrical deficiencies Reaction point in washway Insufficient flow Insufficient local flow Insufficient heat removal Selfcontaminat ed bearing Corrosion within system Impurities from NB Contaminat ed coolant Ingress through seal Grinding process Assembly Process Wear Corrosion/ chemical attack Nominal bearing load Grounding Vibrations Swelling of bearing Ovality Runout Pump sixe(s) Capacity through filters Capacity through pipes System design Temperatur e balance System setpoint Galvanic corrosion Under deposit corrosion General Corrosion Bio corrosion Nominal pressure Local pressure Compatibilit y Swelling rate vs temperatur e Operational monitoring Operational monitoring? Lack of inhibition in system Insufficient flow capacity Insufficient local flow Poor inhibition system Lack of circulation Geometry Viscocity of lubricant Edge loading Lack of sacrificial anodes Chemical properties of coolant Cooling system design Lack of biocides Too low ph Accumulati on of bioproducts Misalignme nt High hydrodyna mic loads Installation Hull deflections Seawater ingress Low ph Incorrect wake estimation Turning condition loads Reversing condition

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55 Root cause investigation principles & tools Slide Version May 2018

56 Root cause investigation principles & tools 5 Why s Easy way to present essence Easy presentation of symptoms and cause Not suitable for analyzing complex problems Quick to use Failure tree Method to analyze complex matters For complex issues Good for technical problems Important to work with hypothesis and evidence Never conclude without evidence Loss Cause Immediate and Basic cause Understanding underlying basic cause Barriers against loss control (operational and technical) The mood of problem solving instead of denying 58 Co-operative spirit amongst stakeholders and the blame game

57 Root cause investigation Funnel thinking Hypothesis #2 Hypothesis #1 Hypothesis #5 Hypothesis #4 Hypothesis #3 Hypothesis #6 Issue / symptom Issue / symptom 59

58 Failure tree RCA Initial studies and fact finding Main problem Hypothesis #1 Hypothesis #2 Hypothesis #3 Hypothesis #4 Hypothesis #5 Claim 1.1 Claim 2.1 Claim 3.1 Claim 3.2 Claim 4.1 Claim 4.2 Evidence Condition Evidence Condition Evidence Evidence Evidence Open Open Closed Open Open 60 Plausible

59 Root cause investigation principles & tools Scoping an action plan considering: 5. CONFIRM 1. IDENTIFY 1. Measures to better understand the behaviour (Fact finding, analyses, measurements etc.) 2. Immediate actions (if needed) 3. Finding evidence to confirm or close the different hypotheses 4. Analyse corrective actions 5. Verify effect of actions / changes 4. IMPLEMENT 2. IMMEDIATE 3. GATHER 61

60 Root cause investigation Symptoms and integrated causes Problems often: Involves several contributing factors and causes Symptoms are often misleading Hypothesis #1 Independent domain expert s second opinion is key to be able to decode the root cause from the symptoms Hypothesis #3 Patience with methodology and brainstorming is needed. Hypothesis #2 Hypothesis #4 Never accept random coincidence, such need further investigation Prove and disprove evidence against hypotheses Hypothesis #6 Hypothesis, #8 Iterate the process Hypothesis #5 Hypothesis #7 Hypothesis, #9 62

61 Root cause investigation of technical failures key important details to succeed To gather a team with multidisciplinary competence from both design and operation! To involve 3 rd party independent competence in the investigation! Working for a cooperative spirit instead of blaming is key to success... and the buyer is crucial in establishing good atmosphere amongst the stakeholders Try to have some patience... by fixing the primary root cause will save a lot later Lack of control Basic Cause Immediate Cause Incident Event Loss 63

62 Root cause investigation principles DNV GL Loss -Causation 64

63 How to avoid getting there? Prevention of supplier / yard lack of control, how to do it? Will this increase the cost of the product? Cost of components / systems in relation to Operational Uptime? How much is uptime worth for your operation? How to verify the products are Fit for Purpose 65

64 The Fit for Purpose Concept Requirement Client requirement level in new reality Voluntary class notations Class and statutory requirements How can a supplier prove that the product is developed in alignment with client requirement and is fit for purpose? Scope of technology 66

65 Technology Qualification is the solution to prove fit The process of providing evidence that the technology will function within specified limits with an acceptable level of confidence". What is the purpose of technology qualification? The purpose is to enable industry to cost effectively put technology into safe use. Can you qualify anything? Yes, almost. The methods and tools may be applicable for : large projects (e.g. subsea facilities) specific components limited deviation from an applicable standard general technology of wide application 67

66 Technology Qualification is a transparent process providing confidence that the chosen alternative is fit for purpose Statement of Feasibility 1. Clarify expectations & functional requirements 2. Map the new technology (new/known) 3. Threat analysis (FMECA, HAZOP/HAZID etc.) 5. Execute the plan: testing, documentation, design changes, procedures TECHNICAL REPORT Technology Qualification Plan 4. Prepare the plan for how to mitigate the threats DET NORSKE VERITAS Statement of Fitness for Service 6. Verify that the results are adhering to stakeholders expectations/requirements 68

67 Step 2 - Threat Assessment and Technology Qualification Plan FMECA (Failure Mode, Effect and Criticality Analysis) Provides listing of all failure modes, their consequences (effect), criticality and possible actions for mitigation. The latter is the important part that defines the qualification activities (testing, analyses and others) needed to adequately address the failure modes. Hazard analysis of the technology throughout the life time; design, installation, commissioning, training, logistics support, integration to all other ship systems (control systems, power, etc.) and operation. Based on the findings of the analysis, a Qualification Plan for reducing the risk where this has been found to be above acceptable levels is developed. The Qualification Plan will define the qualification activities (testing, analyses and others) needed to adequately address these failure modes. 69

68 Step 3 Carry out verification plan Carry out verification plan and validate technology Document review Onsite inspections Onsite function tests If successful the verification statement will be issued. 70

69 DNV GL Maritime Technical Advisory approach Compliance Based Document compliance with rules, regulations and industry standards Not only DNVGL Rules and procedures Assessment Verification Advise on solutions Beyond Compliance Conceptual development Performance Saving Fuel Fit for purpose Best Practice State of the art tools and procedures Assess new technologies 71

70 Maritime advisory provides high quality technical support for reduction of risk and optimisation of project deliveries Contract Tech. NB spec. Pre-contract Design Construction Fleet in service Planned analysis according to e.g. contract specification Additional analysis initialized to fill gaps as they occur Complement Client s project team fill roles in the team and coordinate efforts to the areas with highest risk Added value and compliance beyond class scope Client KPIs/ acceptance criteria, functional and performance requirements Tailoring for specific needs for maximum value creation Advisory Risk management workshop Specification assessment Tender process assistance Bid evaluation Yard assessment Technical benchmarking and verification of proposed designs Project- and risk management support role Drawing appraisal beyond class scope Technical assessments and clarification support Engineering optimisation Verification of performance vs. spec. and contract Shaft alignment Contract speed Cavitation etc. Hydrodynamics and energy efficiency Environment and emissions Machinery and systems Noise and vibrations Performance management In-service vessel optimisation Ship data quality assurance Condition based decision support Backed up by knowledge from involvement in previous stages, class vessel information system 72

71 Costly failures in propulsion, machinery design, installation and operation DNV GL Maritime Advisory Machinery & Systems SAFER, SMARTER, GREENER The trademarks DNV GL, the Horizon Graphic and Det Norske Veritas are the properties of companies in the Det Norske Veritas group. All rights reserved 73