Evaluate system architecture with Fault Trees (Reliability/Safety analysis): GRIF Tree - Fault Tree Analysis Software

• With the intuitive graphical interface of GRIF Tree module - Fault Tree Analysis software, it’s easy to create fault trees and enter gates (AND, OR, K/N, NOT, XOR, NAND, NOR, IF, THEN, ELSE) according to the logic of the system being studied, as well as more than 20 probability distributions: Exponential, Weibull, Gamma Lambda Mu, Exponential Periodically Tested, Weibull Periodically Tested, and so on.
• If a probability distribution is unavailable, you can provide your own probability distribution using either a value table or a Markov graph. Once the tree has been created, Common Cause Failures can easily be identified using different CCF models (Beta Factor, MGL, Shock models).
• With the “Attribute” feature (system with custom properties), you can add any information you wish to each object of the document, either to provide a more precise description or for traceability purposes.

The ALBIZIA engine, developed by TotalEnergies, produces a wide range of results for analytical calculations:

• Unavailability: Q(t), U(t) or PFD(t), Availability: A(t), Reliability: R(t), Unreliability: F(t);
• Frequency: W(t), UFI(t) or PFH(t); and Failure rate: λeq(t), λv(t) or CFI(t);
• Usual mean values: MTTF, MTBF, MUT, MDT, number of failures;
• Minimal cut sets (probability and frequency of cut sets);
• Reliability allocation;
• Many importance factors (Birnbaum MIF, Critical CIF, Vesely, DIF, etc.) that help users identify and correct system weaknesses.

Calculating the time spent in the SIL zones: in addition to the calculations defined above, ALBIZIA is the only engine that can calculate how long the PFD(t), PFH(t) or EqLambda(t) of a system spends in the various intervals during its operational life.

The figure below shows a mean availability of 8.44E-3, which corresponds to SIL2. However, it also indicates the percentage of time the system spent in each SIL over its 30 years’ operation. In this case, it spent 39.77% of the time in SIL1.

User-friendly design:

• Groups/sub-trees are easy to create and with the automatic layout feature, users can effortlessly organize their tree simply by pressing the F7 key.
• With the sub-tree templates, it’s easy to build trees for systems that use known equipment.
• In addition to the editing window for each object, GRIF produces data tables that make it easier to control the quality of input data and modify information (find/replace, suffixes, prefixes).
• • GRIF features plug-ins for entering input data, either based on internal feedback from the field, standards or commercial sources. Having accurate input data saves time for users.

Propagation of uncertainty: To simulate real-life conditions as closely as possible, parameter-related uncertainties can be factored in. For example, you can specify whether a failure rate follows a Uniform, Normal or Log-Normal distribution. A Monte-Carlo simulation is performed in addition to the BDD calculation to obtain mean values. Finally, a quantile calculation is performed to provide a confidence interval for each result. It can be an interval of 60, 70, 80, 85, 90, 95 or 99% (centered or not).

N.B. it is a requirement with the IEC standard 61511. 

• Option to automate calculations (batch runs) and draw variations for sensitivity analysis.
• Results are stored in the document and can be exported in a variety of formats (csv, XML, Excel, etc.).
• Results can be viewed as line graphs, pie charts or histograms.
• Printing in PDF vector format produces high-quality images and the files are small enough to be sent by email, even if the document contains hundreds of pages.
• External files (PDF certificates, system images, etc.) can be added to the document and incorporated into the full report.
• Interaction with the operating system: option to copy/paste either to or from word processing software, spreadsheets, or presentation tools.