Getting more for your assets....
TWI Bulletin, September - October 2009
an approach to assured availability
Chris Ablitt is the manager of the Asset Integrity section at TWI and is responsible for management of ageing asset activities within TWI. He plays a leading role in promoting and developing AIM services throughout the UK and international offices. Chris is responsible for both Fitness for Service (FFS) and Risk Based Inspection (RBI) assessment projects for pressure systems in the process industries and energy sector. He also takes a leading role in the planning, execution and optimisation of inspection, assessment, monitoring and repair strategies for ageing and new plant.
TWI's Asset Integrity Management group offers a unique service to new asset ventures. The service aims to ensure that new asset ventures deliver target productivity by ensuring fabrication is satisfactory and that in-service plant integrity management is appropriate and optimised. As Chris Ablitt writes the service centres around providing an independent, third party review of both the fabrication plans of the Engineering, Procurement and Construction (EPC) contracts, and also a risk-based review of the potential availability limiting damage mechanisms, with a view to optimising in-service inspection, maintenance and operation plans for the built assets.
TWI's service aims specifically to cover from the conceptual pre-construction phase of new build plant, up to the end of the first 12 months operation, with options and plans to extend and manage some of the services after this period. However, the service can be modified and applied at any stage during a plant's life cycle, particularly when new owners are taking on older assets or when expansion, refurbishment and rehabilitation are required.
Objectives
- Provide a high level screening overview that the venture concept can meet its target availability, before progressing further to a more detailed availability assurance project.
- Provide evidence that the plant was built to prevailing standards, thus reducing the risk associated with unplanned outages caused by component failure due to potential quality issues during fabrication.
- Produce a tailored risk-based integrity management software system.
- Implement and maintain a risk-based integrity management system in order to produce optimised written schemes of examination for all pressure components for the first 12 months' operation.
- Provide evidence that the systems and processes in place for operating and maintaining the plant will be appropriate and will be executed by competent persons, thereby reducing the risk of unplanned outages due to human error.
Benefits
The service aims to provide confidence to venture consortium investors and all interested parties, by increasing plant availability by reducing the risk of unplanned outages due to integrity issues associated with:
- Venture consortium
- Technology selected
- Design errors and oversights
- Fabrication defects
- Inadequate and non-optimised in-service inspection
- Non-best practice plant maintenance and operation
Approach
The availability assurance process covers four main areas:
- Venture concept review
- Fabrication audits
- Risk-based management
- Operation and maintenance audits
Figure 1 illustrates the proposed project approach.
Fig.1. Global project flow
Venture concept review
A high level review is conducted at the start of the process. The aim of the review is to highlight any deficiencies in the general project concept, before further expense is incurred in proving its availability. This review is done by way of questionnaire and addresses the following areas:
- Project consortium
- Project management
- Technology selection
- Design
- Technology
- Quality control
- Plant inputs
- Manufacture
- Operation
- Emissions and solid residue
- Target outputs
The outcome of the review is a spider chart highlighting deficiencies and an overall project risk banding in terms of expected percentage availability and associated recommendations.
Fabrication audits
The fabrication audits are split into two main phases:
- Pre-build phase audits.
- Build phase audits.
A master document (project compliance guideline) is produced first against which all audits are conducted. Throughout the pre-build and the build phases of the project, reviews of the EPC contractor and their subcontractors' (fabricators) technical plans, specifications and quality systems are conducted along with on-site targeted audits of the EPC and selected fabricators.
The aim of the audits is to minimise the risk associated with premature failures or low reliability caused by poor quality during fabrication.
Risk-based management
Risk-based inspection (RBI) is used to develop optimised integrity management plans and written schemes of examination for each piece of pressure equipment. The approach is split in to three phases:
- RBI software customisation
- Pre-commissioning RBI study
- In-service RBI reporting and updating
Prior to the plant going into service it is mandatory that written schemes of examination are in place for all pressure equipment under PSSR (Pressure Systems Safety Regulations). In addition to pressure equipment, coverage of these optimised written schemes is extended to cover all equipment that will have an impact on availability.
RBI is a continuous process and must be based on the status quo. Assessments require updating as conditions change. The pre-commissioning RBI study will aim to highlight key performance indicators (KPI) that will need to be monitored in order to trigger possible requirements to update the RBI assessments once the plant is up and running, therefore offering a continuous improvement programme throughout the life of the venture, see Fig.2.
Fig.2. The risk matrix - likelihood plotted against consequence
Operation and maintenance audits
Conventional utility plant performance is typically influenced by the quality and effectiveness of the technical management processes. Implementation of technical management procedures is dependent on local (site) management. Establishing the availability and reliability risk typically requires evaluation against best practice by consideration of the historical O&M performance of the plant, the technical management programmes, and how well these programmes are implemented.
Industry best practices used in existing utility plants may not be directly relevant to operating and maintaining the ventures in question. TWI will produce a customised O&M audit guideline, tailoring existing best practices to present guidance on what processes and/or systems should be in place to minimise the risk of downtime as a result of deficiencies in operation and maintenance.
The O&M audit guideline includes systems, processes, management and personnel competence. This forms the basis against which the operator will be audited by TWI and their O&M systems will have a benchmark upon which they can continually aim to improve.
For further information, please contact aim@twi.co.uk
