To some, a Process Safety Management (PSM) audit that uncovers no issues is cause for celebration, but should it be? According to ABB Consulting’s Conrad Ellison, it’s likely that there’s still plenty more that could be done to improve your company’s process safety performance.
A Process Safety Management System (PSMS) provides a framework of high level procedures (or risk control systems), in order to maintain protective equipment and operations in a healthy state. It is often expected that a PSM audit showing year-on-year improvement is good news.
However, it can be an indication that performance has reached a plateau, and it is in fact a cause for concern. A serious incident could happen at any time. Operators therefore need to consider ways in which their process safety performance can be made even more thorough and comprehensive.
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To begin with, thought needs to be given as to whether the issues covered by the audit on a yearly basis are even the right ones. If they are not, you won’t see any improvements in the number of process safety incidents (PSIs).
You’re likely to find that leading process safety performance indicators are not consistent with the audit performance, and the lagging indicators show a concerning trend with the number of process safety incidents remaining the same or even increasing.
A notable limitation of PSM audits is that they’re constructed around distinct generic elements, which are audited in turn without consideration for how they interact with each other. At the PSM audit level, this potential interaction between barriers is often not visible. Interactions may be missed in accordance with the ‘Swiss Cheese Model’ of accident causation.
This demonstrates that although many layers or barriers of defence lie between hazards and accidents, there can be flaws in each layer. It’s when these flaws combine that accidents can occur.
The Deep Dive Audit
Taking this into consideration, auditing PSM system elements may not actually identify the potential for a process safety incident. Instead an assessment of specific accident scenarios and the verification of specific barriers is required. A Deep Dive audit is the answer.
This approach can provide assurance that process safety is being managed appropriately. It aims to complement conventional, (but not replace PSM audits); taking them to the next level and identifying issues that wouldn’t normally be picked up on from a regular audit (Figure 1).
This type of audit can be undertaken in approximately three days whereas the PSM audit can take up to three weeks. This makes it a rapid and practical assessment process. Crucially, it identifies if PSM is delivering on site and does so in a collaborative way, which requires minimal preparation from the operators.
| Factor | Regular PSM audit | Deep Dive Audit |
|---|---|---|
| Scope | All PSM system elements | Major accident hazard scenarios |
| Objective | Achieve best practice for individual elements | Ensure specific risk control barriers are working effectively |
| Focus of audit | Suitability of and adherence to written procedures | Weaknesses in plant, process or people aspects of barriers |
| Method | Check completeness of documents and test experience with system owner and users | Verify effectiveness of barriers based on plant records, understanding of staff and field observations |
Figure 1: Outlines the main differences between the two types of safety audit
The main focus of a Deep Dive audit is to analyse major accident scenarios and their associated barriers and to provide rigorous assurance that they are working effectively. This type of audit is designed to:
- Establish all major accident scenarios;
- Confirm the basis of safety (BoS) is robust;
- Check that the design of barriers allows for the required risk reduction and that they are installed correctly;
- Ensure barriers are appropriately maintained and tested; and
- Confirm workforce competency with barrier management.
Collectively the above provides an overview of the process safety ‘vital signs’ and ensures that best practice in management systems is being achieved.
A benefit of the Deep Dive approach is that it’s applicable to Seveso Directive and non-Seveso Directive facilities with process safety issues. It identifies specific actions relating to scenarios as well as generic site-wide issues and the methodology aligns to that employed by regulatory bodies during interventions. It’s an approach which can be used to benchmark across a number of sites.
A typical Deep Dive Audit agenda
DAY 1 – Understanding
How does the site manage its process safety?
A range of hazard analysis reports such as HAZID and HAZOP reports must be reviewed to identify major accidents and the required barriers. Based on these, a list of varying high-risk scenarios for the detailed Deep Dive audit can be established with a view to assessing the different types of prevention, control and mitigation barriers.
DAY 2 – Verification and field visit
What layers of protection are in place for the key scenarios?
Verification is then sought for the effective functioning of each scenario and its associated barriers. There are three foci to this stage: barrier verifications; processes and the people operating them.
Experience has shown that the best results can be obtained by deploying two process safety specialists as assessors; one with a PSMS and operations background and the other with a plant engineering and asset integrity management background.
Onsite process engineers, operating managers and maintenance engineers, also provide a valuable source of knowledge to help with the understanding of major accident scenarios.
Part of this process is conducting a field visit, which focuses on verifying specific barriers. Firstly, the barriers are visually checked to ensure that they are in good condition and have been installed as per design. Photographs of any deficiencies can provide excellent, high-impact evidence to site management.
Following this we hold discussions about the barriers with operators and maintenance technicians. This is to test their understanding of the potential for major accidents on the site and their role in maintaining the barriers. We’ve had several cases where we’ve found operators are unaware of the emergency procedures necessary for preventing the escalation of incidents.
Other issues regularly highlighted at the verification stage have included: inhibited alarms, non-Atex approved equipment in hazardous areas and gaps in earth and lightning protection testing (Figure 2).
DAY 3 – Reporting
Carrying out additional verifications and forming feedback
The audit report provides details of the assessment for each barrier, along with a decision on whether it is working effectively or whether a related weakness needs to be addressed. This could relate to the plant, processes or people involved.
| | Common Findings |
|---|---|
| 1 | Testing / inspection of active fire system found to be excessive in some areas and deficient in others |
| 2 | Non-Atex approved equipment found in hazardous areas |
| 3 | Calibration of test equipment not recorded on proof tests |
| 4 | Inspection of pressure equipment focusses on short-term and long-term asset sustainability |
| 5 | No formal auditing of permit to work system |
| 6 | Alarms found inhibited |
| 7 | No standard set of control of initial mechanical isolation to achieve isolation standards |
| 8 | Lack of identification of safety critical procedures |
| 9 | Gaps in earth and lightning protection testing |
| 10 | Inspection of electrical equipment in Atex areas not to relevant good practice |
Figure 2: The top 10 common findings uncovered by conducting a Deep Dive AuditConclusion
Preventing process incidents from occurring is at the heart of process safety management. Therefore it makes sense to devote some assurance effort directly to the scenarios themselves, focusing on the specific risks and layers of protection.
A Deep Dive audit of key process incident scenarios can be a very direct and cost-effective way to provide this assurance. This approach is fast becoming a necessary accompaniment to the traditional audit, as it takes process safety even further and provides operators with a high degree of confidence that barriers are working as effectively as possibly.
