SIL Verification of 300+ SIFs in Hydrodesulphurisation Units

risknowlogy 2011-01-18

Buenos Aires, Argentina – January 2011 – Risknowlogy®, a leading provider of risk, reliability, safety services, engineering, consulting, training and certification announced today that it has completed the SIL Verification study of 300+ SIFs in several Hydrodesulphurisation Units belonging to one of the largest refineries in Colombia.

The Client requested Risknowlogy carry out SIL verification including the calculation of the probability of failure on demand, for all safety instrumented functions protecting the process units, and to determine whether the design of the safety instrumented functions are capable of reaching the applicable safety integrity level allocated to them during the hazard and risk analysis.

The verification carried out by Risknowlogy included “… not only the verification of the probability of failure on demand” stated Ricardo Vittoni, Managing Partner of Risknowlogy Argentina, “but also addressed other functional safety requirements of the safety instrumented function in order to comply to a target SIL, including systematic capability of each device, architectural hardware constraints of each subsystem and applicable software safety integrity for the application software and the used logic solvers.”

Risknowlogy engineers used Markov to verify the probability calculations. It’s Markov tool, developed by Risknowlogy, who used to sell, was used to model and calculate the PFD for 600+ subsystems comprised in the project. Different reliability models, already developed by Risknowlogy, where used (i.e. those corresponding to 1oo1, 1oo2, 1oo3, 2oo2 and 2oo3 voting architectures), and other more complex architectures were modeled in and calculated with the tool.

About Client

The Client belongs to the group of the 39 largest oil companies in the world and is one of the five major companies in Latin America.

About Markov

Markov is a probabilistic calculations tool developed by Risknowlogy to model and calculate with state-transition models. For more information on Markov visit:

About Risknowlogy

Risknowlogy is a leading provider of technical risk, reliability, and safety services, engineering, consulting, training and certification solutions. Risknowlogy is located in Switzerland, Argentina, Germany and The Netherlands. For more information visit