Many companies subscribe to the thought process that simply completing compliance documentation identified by IEC 61511 is the end goal. Anything more than that is deemed too tedious and represents a substantial cost center. Unfortunately, documentation is just one aspect of the lifecycle, and one that isn’t substantially making your assets safer from one day to the next. We believe the essence of the standard is to not only generate documentation, but to monitor the performance of protections layers vs. assumptions made in the front of the lifecycle. As poor assumptions are identified, companies can sustain their business by eliminating the root cause, therefore removing the previously invisible risk.
Recently, aeSolutions briefed ARC Advisory Group on its safety lifecycle solution. The company was established over fifteen years ago as an auto- mation engineering and systems integration company focused on continuously improving the process safety performance of process indus- tries. About three years ago, the company productized its expertise in managing the safety system lifecycle in its aeShield product and maintains a dedicated staff of over 20 employees for its development. The company points to aeShield’s real-time ability to make an enterprise’s safety perfor- mance clearly visible to operations and management personnel as a key differentiator in the market.
A systematic database approach can be used to design, develop and test a Safety Instrumented System (SIS) using methodologies that are in compliance with the safety lifecycle management requirements specified in ANSI/ISA S84.01. This paper will demonstrate that through a database approach, the design deliverables and system configuration quality are improved and the implementation effort is reduced.
As facilities are assessing risk, making recommendations for gap closure, and designing safety instrumented functions (SIFs), assumptions are made to facilitate calculations in the design phase of protection layers used to reduce the likelihood of hazards occurring. Each of these assumptions are made based on design standards, process safety experience, and data supplied by the manufacturers concerning operability and reliability. The purpose of this white paper is to identify key assumptions and replace the assumptions with real-world operations data to prove that the risk may be greater than perceptions based on design. This case study will focus on looking at real functional test intervals verses those applied in the safety integrity level (SIL) calculations. It will also compare unsafe bypasses verses probability of failure on demand (PFD) and the count of initiating causes compared to the frequencies documented in the layer of protection analysis (LOPA).
IEC61511: Functional Safety – Safety Instrumented Systems for the Process Industry Sector mandates end users comply with a performance based approach to managing risks to personnel and / or the environment through adoption of the safety lifecycle. Simplistically, the safety lifecycle embodies a three-step methodology to overall risk management, which can be summarized as follows:
- Execute safety lifecycle documentation
- Monitor leading/lagging process safety indicators
- Sustain safe unit operations through corrective actions