The so-called verification of SIL (Safety Integrity Level - SIL verification) is one of the main activities of safety engineering, in the risk management of industrial plants, systems and complex machinery.
The SIL verification activities have the aim to verify by calculation that the industrial plants, the systems or the designed machines are compliant to the specified safety integrity requirements; for example, for the sector of the industry and the related standard IEC 61511, the aim is to prove that the safety instrumented functions (SIF - Safety Instrumented Function) reach the required SIL, or, for the machinery and the relative standard CEI EN 62016, the aim is to verify that the SIL achieved by each control safety function (SRCF) is compliant to what is required by the safety standards.
HINTSW - T & T Systems has the ability to perform all the calculations necessary for the SIL verification with respect to the main industrial sectors: process industries (oil & gas and chemical) - IEC 61511; rail - CEI EN 50129; machinery - CEI EN 620 161; etc.
Calculations are performed using standard modeling methods such as simplified equations, fault tree analysis, Markov modeling, reliability block diagram, or, in special cases, using less conventional methods such as Monte Carlo method.
The SIL verification activity, according to the area of application, may present specific features and differences, since the technical standards based on the general standard IEC 61508 (ie ANSI / ISA S84, IEC 61511, IEC 50128, IEC 50129, IEC 62016), according to the application environment, often have special features with respect to the general reference standard. HINTSW - T & T Systems has a good knowledge of many industrial sectors and is able to adapt this activity to the framework of the various standards including modeling factors such as:
- Field device configuration.
- Susceptibility to common cause failures.
- Component failure rate including: probability of failure on demand (PFD); probability of failure per hour (PFH); probability of dangerous failure per hour (PFHD).
- Tolerable hazard rate (THR).
- Safe failure fraction (SFF).
- Level of redundancy and voting.
- Proof tests and intervals.
- Diagnostics, comprising the reliability, the intervals and the coverage of the tests
- Repair times.
- Susceptibility to external influences.
The calculations of SIL verification, according to the degree of complexity, can be performed using tools developed in-house by the "hi-tech" team of HINTSW - T & T Systems, or by using specialized software, available on the market.