Making Changes to Boiler Plant

Transcription

1 RCR Energy New Zealand Making Changes to Boiler Plant September 2016

2 20MW Gas-Fired Boiler 2

3 Making Changes to Boiler Plant - What You Need To Know The Code of Practice for Boilers ( COPB ) places responsibilities on the Owner when it comes to alterations and additions to boiler plant The Code of Practice is generally well-followed for new plant, but the detail in the Code often gets forgotten through the fullness of time, especially when it comes to changes to the plant The following presentation aims to highlight the obligations imposed by the Code of Practice, and hence the PECPR regulations and the HSE Act. 3

4 COPB Alterations and Additions All changes to the boiler structure, the boiler control system and associated equipment shall be fully documented with drawings and all relevant data. No changes shall be made to the boiler or the boiler control system without the consent and backing of the boiler manufacturer and the equipment inspector. 4

5 What s The Problem? Within the industry it is very common to find alterations and additions made without full documentation and consultation This leads to: Incorrect wiring schematics held by both the OEM and the owner. This makes trouble-shooting difficult, and future changes become more difficult due to lack of accurate documentation Incorrect copies of automation code held by the OEM. Backup recovery is not possible Design verification for Pressure Equipment and Pressure Piping changes not completed Design verification for the Boiler Control System documentation changes not completed Control Narratives supplied with the O&M manuals not being current and don t reflect the current operation of the boiler Unexpected consequences of PLC code changes! 5

6 Managing the Risk There are 4 main areas of risk: Changes to the Boiler Control System (BCS) Changes to the Pressure Equipment, leading to- Additional seismic requirements Maintaining the accuracy of documentation 6

7 Boiler Control System (BCS) Documentation The BCS documentation contains details of the equipment and instruments that have been fitted to the boiler as specified by the COPB, and how they operate. This documentation is then design verified to confirm compliance with the COPB. Additionally the inspector verifies on site that all the relevant equipment is fitted and that that equipment operates in accordance with the design verified documentation. A Producer Statement is generated by the manufacturer. The Producer Statement is only valid for the equipment listed and operating as detailed in the BCS 7

8 Included in this BCS documentation is information on: Level gauges Safety valves Pressure gauges Blowdown valve Level switches Level and pressure transmitters Continuous blowdown equipment Condensate monitoring Power failure safeguards 8

9 Supporting this documentation are electrical schematics, P&ID s and a control narrative of how each safety device and circuit works If any of the above change, then a revision to the BCS is required eg a change to the brand of level gauge requires a BCS update A change to the type or model or control of the steam shut in valve requires an update 9

10 Changes to Pressure Equipment Implications of changes to pressure equipment needs to be considered, such as: Changes to piping routes or the equipment fitted to piping eg addition of a second block valve for double block and bleed isolation Changes to structural supports will the structure still carry the pre-determined loads? Like-for-Like replacements in most instances will still require a new DV due to the lack of availability of materials that match the original design code 10

11 Seismic Assessments of New Equipment As an outcome of the Canterbury earthquakes of 2010/2011, IPENZ lead an industry-represented committee to address seismic design of pressure equipment This resulted in a Practice Note (known as PN19) being release. It is known as Seismic Design of Pressure Equipment 11

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13 All new boilers supplied into NZ need to be designed in accordance with this Practice Note 13

14 Design Office Classification of Seismic Risk of Existing Pressure Equipment Yes AS 4343 Hazard Level C, D or E? No AS 4343 Hazard Level A? Yes No Would loss of containment have a significant effect? (Note i) Yes No Is the equipment operating outside its design parameters? (Note ii) Yes Weight > 1 tonne or CoG > 1m above lowest part? Yes No No Is the equipment operating outside its design parameters? (Note ii) Yes No Low Risk Meduim Risk High Risk Figure D1: Decision Tree for Initial Risk Classification 14

15 Fitness for service or remaining life assessment Proposed modification Proposed repair Assessment to recognised code, e.g. API 579, AS 3788 Design to recognised code e.g. ASME PCC-2 NO Repair is like for like? Repair required? YES Is alteration above the trigger points specified in 5? YES YES NO NO Re-rating required? YES Design of new parts only Design of new parts and assessment of seismic loading NO AS 4343 Hazard level A to D? NO YES Design Verification Fabrication AS 4343 Hazard Level A to C? NO YES Fabrication inspecton AS 4343 Hazard level A to D? NO YES Certificate of Inspection Return to service Figure D2. Procedure for Pressure Equipment Repairs and Alterations 15

16 Case Study Superheater vs Deaerator Replacement Using PN19 Appendix D, different outcomes will be reached Superheater: Trigger For Seismic Assessment of Vessel? (eg added weight): No Loss of Containment?: No. ie Medium risk Assessment of Structure and Foundation Reqd? (Vessel >20% of total weight): No No seismic assessments required Deaerator: Trigger For Seismic Assessment of Vessel: No Loss of Containment: Yes. High risk Assessment of Structure and Foundation Reqd? (Vessel >20% of total weight): Yes % of Current Seismic Design Load to Use for High Risk: 50% 16

17 Conclusion To meet our obligations under the HSE Act, changes associated with: The Boiler Control System The Pressure equipment Modifications requiring a seismic evaluation Changed operating procedures must be assessed, documented and controlled. This risk is best managed by having an agreement with the OEM around change control and what the expectations are between both parties. That way we can hopefully avoid incidents such as 17

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