Pipework Integrity. Deterioration Management. Neil Henry Senior Consultant ABB Engineering Services. OPERA Meeting. March. 2006

Transcription

1 Pipework Integrity Deterioration Management Neil Henry Senior Consultant ABB Engineering Services OPERA Meeting ABB Engineering Services - 1 Pipework Integrity. March. 2006

2 ABB Engineering Services ABB Engineering Services - 2! Eutech Engineering Solutions Ltd. established in 1993 as a subsidiary of ICI. Domain knowledge from:! Chemicals! Oil and Gas! Speciality and Fine Chemicals! Pharmaceuticals! Power and Utility! Sustained growth and development! 300 plus customers world-wide! Over 750 staff in Europe, America and Asia! Over 50 million turnover! Accredited by Investors in People, Lloyds and UKAS (ISO 9001)! Feb 2001, ABB buys Eutech

3 ABB Engineering Services offering! Expert and consultancy & technical services! Project management & design service! Integrated solutions! Unique breadth & depth of services! Innovative approach! Rapid & effective response! Local and global delivery! One-stop shop Manufacturing Improvement Capital Investment Licence to Operate Asset Management ABB Engineering Services - 3 Throughout the asset lifecycle

4 ABB Engineering Services customers Paints ABB Engineering Services - 4

5 Materials Engineering Why is it important? Ageing process plant Life prediction Reliability Repair methods / costs Corrosion ABB Engineering Services - 5

6 Materials Engineering What does a materials engineer do? Specify materials of construction Evaluate performance in service Investigate failures ABB Engineering Services - 6 What are the benefits? Optimised materials of construction (cost, life cycle, maintenance & inspection repairs) Integrity management for process plant

7 Materials Engineering Regulatory requirements PSSR COMAH IPPC Competitive business pressure ABB Engineering Services - 7 Assets working harder (for longer) Confidence in condition / availability Optimising materials for environment

8 Materials Engineering Why do materials deteriorate? Exposure to excessive severe conditions e.g. Temperature Load / Pressure Process operations Flow rates ABB Engineering Services - 8

9 Failure Statistics Failure Mechanism: Frequency rate UK.N.W Number of failures ABB Engineering Services - 9 Types of failure

10 Failure Statistics Cause of failure: Frequency rate UK. N.W Number of occurances ABB Engineering Services Operation Design Maintenance Fabrication Repair Ageing Reason for failures

11 Pipework degradation In order to control degradation processes it is necessary to understand them! What are the mechanisms?! Where do they arise? ABB Engineering Services - 11! What factors influence rate?

12 Pipework degradation! How can they be detected! How it can be managed! Holistic approach to address root causes ABB Engineering Services - 12! Examples from our archives

13 Mechanisms ABB Engineering Services - 13 Deterioration mechanisms! Corrosion! Internal! External! Dissolving metal - reducing thickness! Internal corrosion is related to operating regime! Specification is usually good! Deterioration may occur from weakness in design! Fabrication & Commissioning! Operation changes

14 Mechanisms Deterioration mechanisms! External corrosion is from moisture (or external leak)! Water is electrolyte for corrosion process! Material dependant (c steel, austenitic & duplex ss) ABB Engineering Services - 14 Other common mechanisms:! Environmental cracking, Fatigue, Erosion, Mechanical overload, Metallurgical changes

15 Mechanisms Most common problems! Corrosion under insulation (carbon steel)! Stress corrosion cracking (stainless steel) under insulation! Corrosion at supports! General corrosion! Local environments ABB Engineering Services - 15

16 Corrosion damage! Corrosion at support ABB Engineering Services - 16

17 External Pitting & SCC in Stainless Steel Spool 1, Area 2 3 Pipe ABB Engineering Services - 17 Figure 5: Defect indications previously located using ECT and revealed by LPFD. ECT measured the depth at 1mm.

18 Internal corrosion 96% Sulphuric Acid 316 Stainless Steel ABB Engineering Services - 18 Failed after < 6 month operation Pitting through wall

19 Mechanisms Failure of small bore branches! External corrosion (small size, thinner wall)! Unusual internal corrosion process (stagnant condition)! Cyclic loading leading to fatigue ABB Engineering Services - 19 High vulnerability:! Thermal or mechanical fatigue or process changes in local environment

20 Managing the Problem Criticality Reviews} } Used to set priorities RBI Evaluations } BUT NEED TO HAVE KNOWLEDGE OF: ABB Engineering Services - 20 potential for deterioration highest vulnerability environment and operating regime to optimise the task

21 The Deterioration Rview (examples) Item / Line Process stream composition + contaminants Temp C/ Press psi Materia ls Deterioration Process Current condition monitoring Future cond. Monitoring Future effect on material 3001 Mainly Platfinder prod +reformate from 8000 unit, N2 blanketed. S free. Amb C steel General PVI PVI None anticipated HHS Pipework to vessel Sulphuric Acid 98% / FV psi SS316 L Issues about nozzles! As per H 2 SO 4 pipework pulses (pulsation damper) and moves at high level (investigate why) dye pen welds on bands to look for fatigue PM 12 month Clean off deposits and inspect branches. Internal inspection through m/way Acid concentration changes. Vibration on vessel & pipe supports ABB Engineering Services - 21 HHS Heat exchanger Plate cooling Acetonised Solution 10 psi 100 / -30 SS316 L Small potential for det. Pitting leakage would be CTW into process. No evidence of corrosion in filters before heat exchanger Examine during routine maintenance No other inspection

22 Rates of attack Accelerating factors! Nominal corrosion rate, c steel in atmosphere, 0.1 to 0.2mm/yr. external corrosion! Limited risk of pitting in S Steel! Examples of direct influences! Temperature of surface; 10 C rise, 2 x rate! Design features; crevices, supports! Graph & table, on next slide ABB Engineering Services - 22

23 Rates of attack insulated insulated & steam carbon stl/ traced temperature bare ferritic / ferritic carbon/ferritic deg C alloys/steel alloys alloys corrosion under insulation rates ABB Engineering Services - 23 corrosion rate mm/annum bare ferritic steels/alloys insulated and steam traced temperature deg C insulated carbon/ferritic alloy steels

24 Factors Influencing Corrosion Rates ABB Engineering Services - 24 For example! Time in contact with surface - drying out! Deposition of solids! Contaminants in the water ; acidity / alkalinity! Concentration mechanisms (for s steel)! Cooling tower drift! Steam traps! Leaks

25 Detection methods Prioritisation of Activities confidence in condition! Standards of fabrication! Evaluation of operating conditions & materials! History! Sampling examination & thickness testing! Establish basis of examination process ABB Engineering Services - 25

26 Detection methods External Corrosion! Thorough visual examination first! Screening techniques! Moisture detection! Long range U/S! Profile radiography! Eddy current testing ABB Engineering Services - 26! Selective thickness testing / Dye penetrant

27 Control of deterioration ABB Engineering Services - 27 Managing integrity! The extent of pipework systems is very large & difficult to manage! Prioritisation based on! Fluid hazard! Potential for deterioration! Hazard related to fluid escape! Potential for deterioration is a function of! Pipe Material, conditions & temperature

28 Evaluation of outfall line! 10 years old! Limited history! Not inspectable: part buried, part submerged! Review of design, coatings and protection! Evaluation of environment internally and externally ABB Engineering Services - 28! Conclusion of low risk of failure in 10 years and improvements to extend life

29 Heat transfer fluid line! Operating temp 410 C! Carbon steel, insulated! 10 years service! No nominal risk of corrosion ABB Engineering Services - 29 When inspected:! Metal loss of half wall thickness found! Line was a by pass - only used at start up! Actual operating temp at mid point 80 C! Pipe was a convenient access point for maintenance

30 High temperature hot water! System 20 years old! Lagged carbon steel and (some) stainless steel! Operating temperature circa 110 C! Numerous leaks over several years! Intent to replace at 550K minimum capital ABB Engineering Services - 30! Review identified CUI at poor lagging and cyclic duty items! System was zoned into categories of risk! Sampling NDT by Neutron back scatter & eddy current techniques + sample removal! Resultant replacement was <10% of system, managed in shutdowns

31 Actions to Manage Corrosion Know what is important Understand the relationship to the problem Focus on expenditure for optimum results ABB Engineering Services - 31 Tackle the true root causes

32 EXTRACT FROM REPORT of 12 PAGES Conclusions ABB Engineering Services - 32 Pipe failed due to chloride-induced stress corrosion cracking (SCC) Cracking originated on the outer surface of the pipe Lagging had clearly been wetted producing an acid chloride solution Pipe material Type 302 or 304 not the specified Type 316 alloy

33 EXTRACT FROM REPORT of 12 PAGES Recommendations ABB Engineering Services - 33 Recommendations were made after failed pipe in Same advice applies Hot lagged pipes must have a protection system The NACE 1 document, RPO Epoxy/phenolic or high temperature amine-cured coal tar epoxy Notwithstanding the fact that Type 316 stainless steel would probably have failed in the same manner

34 ABB Recommendations ABB Engineering Services - 34 (Mechanism was agreed as correct) Maintenance standards " Correct gaskets " Missing bolts " Refit supports " Repair external leaks " Renew lagging and aluminium foil

35 ABB Recommendations Operating Review " Identify leaks on process rounds " Change flow controls and temperatures " Identify redundant equipment / systems " Operating controls for valves ABB Engineering Services - 35 (Repair and maintenance training required)

36 Pipework integrity - conclusions ABB Engineering Services - 36 Confidence in pipework condition by:! Review to identify vulnerable areas! Selective replacement only on problem areas! Elimination of root causes eg! Operation and maintenance issues! Design faults! Inadequate lagging! MANAGEMENT OF DETERIORATION STRATEGY USING KNOWLEDGE TO SAVE MONEY

37