Ageing Assets - A Risk Engineer s View

Transcription

1 Ageing Assets - A Risk Engineer s View Andy Goddard Risk Engineer Talbot Underwriting Limited OPERA Seminar Swiss Re Building, London, UK 30 th October 2012

2 Introduction The management of equipment begins with an awareness that ageing is not about how old the equipment is, but is about what is known about its condition and the factors that influence the onset, evolution and mitigation of its degradation Source: Plant Ageing HSE RR Management of ageing assets is largely down to implementation of a comprehensive Asset Integrity programme 60% of major hazard loss of containment incidents are related to technical integrity and, of those, 50% have ageing as a contributory factor Source: Plant Ageing Study HSE RR Loss history suggests comprehensive Asset Integrity programmes are not always in place and that time dependent factors are a major contributor

3 Liberty International Underwriters (LIU) loss data Source: LIU OGPC Loss Database (data to 2010)

4 Scope of this presentation Onshore Oil, Gas & Petrochemical Based upon global experience Asset Integrity rather than Age focussed Focus on Oil Refining Loss data indicates that the Oil Refining sector has the largest number of age related losses Focus on piping systems Loss data indicates that piping systems are the most likely source of a major loss of containment

5 Insurers assessment of age Asset age not normally directly considered as a risk quality factor but rather indirectly considered through the assessment of the Asset Integrity programme Considerable weight normally applied to the effectiveness of the Asset Integrity programme with some Insurers considering this a killer variable Original design features are a function of age and are normally considered as individual risk quality factors Layout & spacing Basic Process Control System & ESD capability (obsolescence issues) Protective systems (ROEIVs, BMS, pump seals, fixed condition monitoring systems etc.) Electrical infrastructure Passive fire protection of structural supports Etc. Retrospective risk based application of current design standards is a common area of debate

6 Case Study #1: Tesoro Refinery - Anacortes WA USA - 02Apr10 Incident occurred on the Naphtha Hydrotreater (NHT) unit involving the feed/effluent heat exchangers (E-6600s) The E-6600s were installed in 1971 (39yrs) as part of the original construction of the NHT Source:

7 Case Study #1: Tesoro Refinery - Anacortes WA USA - 02Apr10 E-6600A/B/C bank were in the process of being brought back online after cleaning E-6600E ruptured resulting in a major release, explosion/fire and 7 fatalities Source:

8 Case Study #1: Tesoro Refinery - Anacortes WA USA - 02Apr10 Failure mechanism: High Temperature Hydrogen Attack (HTHA) to the weld HAZs in E-6600E (same conditions observed in E-6600B) Key Causal Factor Sufficient hydrogen partial pressure and temperature existed for HTHA Key Contributory Elements Lack of instrumentation to monitor HTHA regime Integrity Operating Windows (IOWs) not established IOW monitoring/alert system not established Shell fabricated from carbon steel and not PWHT HTHA not detected prior to failure Stress existed in E-6600E Original design standards did not require PWHT Risk assessment processes need to consider material spec breaks HTHA considered during previous corrosion studies but E-6600E not considered at risk and hence not inspected for HTHA Thermal stress due to temperature cycles

9 Corrosion Control Document (CCD) Systematic development of a CCD should be the fundamental basis for an Asset Integrity programme Process description including shutdown/startup effects Rationale for materials of construction Identification of damage mechanisms Definition of corrosion loops Requires accurate and up to date documentation Process description / H&MB P&IDs / PFDs PHAs / MoCs Mechanical design / Piping specifications Multi-discipline team and project approach required to establish (and periodically review?) CCD a prerequisite for RBI but often absent for regulatory and/or time based defined programmes

10 Integrity Operating Windows (IOWs) IOWs should be an output from the CCD work Clear link with other process safety management systems: PHA, MoC, SOPs, Operator training Modern process monitoring systems can be used to report on IOW performance/excursions Principles of IOWs established several years ago but not commonly adopted by Owners Operating Window Source: API RP 584 Integrity Operating Windows (draft)

11 Case Study #2: Chevron Refinery - Richmond CA USA - 06Aug12 CDU originally dates from 1976 although age of failed pipe not known (36yrs?) Catastrophic failure of 8 carbon steel gasoil line in the CDU Release of high temperature process fluid resulted in large flammable vapour cloud Fortunately ignition resulted in a flash fire rather than VCE with extensive fire damage to the CDU Source:

12 Case Study #2: Chevron Refinery - Richmond CA USA - 06Aug12 Gasoil piping circuit subject to inspection during the Nov11 TAR with thinning detected and some sections replaced Number of TMLs increased due to thinning but TMLs did not cover the 5ft section of pipe which failed If failure due to general thinning then most likely damage mechanism would be sulfidation corrosion Low silicon content (<0.1wt% Si) carbon steel susceptible to accelerated sulfidation corrosion (API RP 939C) Pipe specification ASTM A53 considered high risk in this service (Chevron industry alert) Source:

13 Case Study #2: Chevron Refinery - Richmond CA USA - 06Aug12 What does the CCD say about the gasoil process loop? Was the low Si material specification known to and assessed by the CCD? Was there a retrospective PMI procedure in place? How were TMLs selected? What are the piping replacement criteria? Speculation at this point but CSB investigating

14 Effectiveness of an Asset Integrity programme TMLs only effective for detection of general and not localised corrosion Inspectors should be given the latitude to go beyond predefined TMLs and take additional measurements Asset Integrity programmes should become more extensive with age but improvements often only triggered by loss events Is the Asset Integrity programme subject to external technical audit? Expect the unexpected!

15 Case Study #3: Refinery - Japan Refinery originally dates from 1973 although Residue HDS unit added in 1994 (8yrs) Loss of containment occurred from a 10 carbon steel bypass line Hydrogen release resulted in an explosion and jet fire Total loss of adjacent fin-fan cooler structure

16 Case Study #3: Refinery - Japan B Bypass Line V7 Fractured Spot 12B V6 10B Welding Line 740mm 380mm 80mm 12B

17 Case Study #3: Refinery - Japan Temperature in line had fallen below water dew point allowing formation of ammonium bisulphide (IOW?) Upward swirling flow of process gas resulted in extreme localised corrosion Combination of corrosive ammonium bisulphide and unusual flow characteristics resulted in failure of a circular section of the line Unit had been subject to routine thickness gauging with no notable corrosion identified

18 Case Study #3: Refinery - Japan

19 Case Study #3: Refinery - Japan

20 Case Study #4: Refinery - TX USA Incident occurred on the Saturated Gas Plant which had been installed in 1979 (29yrs) Piping system in the Deisobutaniser bottoms section thinned to the point of failure resulting in an explosion and ensuing fire Causal factors: Incorrect metallurgy Localised corrosion not detected by TMLs Communication failure between Owner and Inspection Contractor Retrospective PMI after the event identified some carbon steel piping in the CDU which should have been 9% Cr low alloy steel

21 Material verification Modern EPC Contractor projects normally have an adequate material verification programme in place including Positive Material Identification (PMI) However for older assets, PMI unlikely to have been utilised in the original project material verification programme Greatest number of material non-conformances found with carbon steel substitution in low alloy steel piping systems (such as Cr-Mo alloys frequently installed in Refining units) For smaller operational changes and maintenance replacement work, often reliance upon mill certificates, heat stamps and supplier qualification with no formal PMI procedure Risk based retrospective PMI rarely adopted by Owners Alloy analyzers relatively low cost and simple to use API RP nd Edition 2010 Material Verification Program for New and Existing Alloy Piping Systems

22 Case Study #5: Refinery - UK Incident occurred on the Dehexaniser Unit which had been installed in 1993 (15yrs) Major loss of containment from the 8 carbon steel feed line to the Dehexaniser column 95degC / 6.5barg / Straight Run Naphtha Release resulted in a significant pool fire from grade up the side of the column

23 Case Study #5: Refinery - UK Insulation breached by field modification during original construction to accommodate installation of diagonal brace for overhead personnel platform Breach allowed ingress of rainwater which collected at the 6 o clock position CUI resulted in pipe wall thinning from 8mm down to 1mm (approx. 0.5mm/yr) Causal factors: Detailed engineering Contractor supervision CUI training/awareness Construction MoC Handover/PSSR CUI inspection programme

24 Corrosion Under Insulation (CUI) Do not always find a fully comprehensive CUI programme Gaps and challenges often include: No systematic identification of CUI areas No CUI training/awareness programme Over reliance upon visual inspection and reluctance to fully strip insulation Access for inspection always a problem Failure to address preventive measures; painting specifications (limited use of Al thermal spray), insulation standards, removal of non-essential insulation UK HSE identify assets >10yrs to be at an increased risk of CUI Piping systems in older assets may never have been painted Owners should have a document in place to describe how CUI is managed API RP 583 Corrosion Under Insulation - currently under development

25 Corrosion Under Insulation (CUI) Holes cut into insulation to facilitate thickness gauging Often poorly engineered and left uncovered allowing water ingress CUI loss coming to a claims department near you soon

26 How should the Inspection department fit within an organisation? Adequate in-house staffing levels with appropriate experience and qualifications Empowered to enforce decisions High profile at management team level Systems designed to aid Inspection activity Inspection priority work orders Dedicated budget formal deferment procedures management reports / KPIs Involved in day-to-day operations and aware of operational status Integral part of key risk management processes; MoC, PHA

27 Limitations of insurance engineering surveys Limited time on site; typically 2-3 days Even more limited time with Inspection; typically 2hrs Surveys look to sample only and are not an in depth audit Do not always get access to Inspection records For a mature survey programme, potential improvements? Lessons learned presentations delivered to the site by attending survey team members If interim update surveys are to be carried out, incorporate a focussed session on Inspection

28 Common Inspection related survey recommendations Inspection reporting line within the organisation Inspection department manning, experience and qualifications Scope of Inspection programme / limited to regulatory requirements New facility baseline Inspection and programme development Corrosion Under Insulation (CUI) Positive Material Identification (PMI) Pressure Relief Valve (PRV) pre-pop testing Management of temporary repairs Inspection deferment Inspection data management systems

29 Concluding remarks Need to understand fundamentals and properly define an Asset Integrity programme Delivery requires senior management sponsorship and organisational wide commitment Ageing facility + Deficient Asset Integrity programme = Warning Sign for Insurers

30 Any further questions?