Reliability Block Diagram Software

Design for Reliability and Availability

RBD (Reliability Block Diagram) is a standard method for assessing the reliability and availability of complex systems.

BQR’s CARE RBD software module is the ultimate tool for reliability allocation (top-down) and calculation (bottom-up), serving Reliability and System Engineers throughout product design cycle.



  • Improve system reliability and availability from early design phase
  • Accurate and fast calculations
  • Define subcontractor reliability requirements

Special Offer

BQR’s RBD Basic software is now available for only 99$ (annual subscription).


  • Distributions: Exponential, Weibull, Normal, Log-Normal and more
  • Reliability Curve
  • Unlimited hierarchies and project size
  • Configurable Diagrams

Compliance to Standards

Reliability Block Diagram Software by BQR complies with the following standards:

  • IEC 61078
  • IEC 61508
  • IEC 61165
RAM analysis - Reliability Block Diagram Software
RAM analysis - Reliability Block Diagram Software

How It Works

Steps for conducting a RBD analysis


  • Import the block tree and components from BQR’s FMECA or fiXtress using BQR’s Core Database

User Input

  • Define Mission Time
  • Add composite blocks of various types: Serial, Parallel, K out of N, Standby, and assign repair policy to each block
  • Assign failure distributions and MTTR to leaves (blocks in the block tree that have no children)
  • Add network diagrams and Markov chain models if necessary
Reliability Block Diagram Software - screenshot
Block Types


  • The software validates the user data. If data is missing, user is notified
  • The software analyzes the RBD and calculates Reliability, Availability, MTBCF, MTTCF, and MTTR for all blocks on all levels
  • RBD Network analysis
  • Embedded Markov chain models
  • Monte Carlo simulations
Reliability Block Diagram Software - Monte Carlo simulation
Monte Carlo simulation results for two pumps operating in standby model


  • Tree report with all input and calculated data
  • All reports can be saved as Excel, HTML or Word files

Advanced Modules

Reliability Block Diagram Software - Markov Models
Markov model
Reliability Block Diagram Software - RBD Networks
Network model of redundant gas line with intermediate valves


  • Reliability allocation (top-down) and calculation (bottom-up)
  • Import block tree and failure rates from BQR MTBF, FMECA software or Excel
  • RBD Network and embedded Markov chain models
  • Analytic calculation of Mean Time Between Failures (MTBF), Mean Time To Repair / Replace (MTTR), Mean Time To first Failure (MTTF), Reliability, Availability, and Failure Rate
  • Monte Carlo Simulation