Pentair Valves & Controls Addresses Limitations

Shawn Statham, Global Product Manager

Figure 1 – Statistical Failure Data
Despite rigorous risk assessments and SIL analyses in accordance with International Electrotechnical Commission (IEC) I61508 and IEC 61511 Safety Instrumented System standards, Emergency Shutdown Valve (ESDV) failures continue to occur and are often attributed to systematic failures.

IEC 61508, Functional Safety of Electrical/Electronic/ Programmable Electronic (E/E/PE) Safety-Related Systems, covers the entire safety life cycle. IEC 61511, ‘Functional Safety - Safety Instrumented Systems for the Process Industry Sector,’ outlines best practices in the engineering of Safety Instrumented Systems, (www.iec.ch). International Standards Association 84.01 (ISA 84.01) gives requirements for the specification, design, installation, operation and maintenance of a safety instrumented system, so that it can be confidently entrusted to place and/ or maintain the process in a safe state. This standard has been developed as a process sector implementation of IEC 61508, (www.isa.org).

“These standards do not take the position of prescribing the type of components, architecture, diagnostic testing, and functionally tests required for an SIS. Instead, it lays out a framework with which each individual user, designer, and owner can determine what is appropriate for their specific application. An SIS prevents or reduces hazardous events by taking the process to a safe state when predetermined conditions are violated. An SIS typically includes the design and implementation of a variety of shutdown and/or blowdown valves,” commented Shawn Statham, Global Product Manager for Actuated Safety Systems with Pentair Valves & Controls. Statham is based in Seattle, Washington.

An SIS includes sensors or initiators that detect process conditions; a logic solver that processes an input from the sensors to an output to the final elements; and, final elements that perform corrective actions by bringing the process to a safe state. An Emergency Shutdown Valve (ESDV) is the SIS Final Element. The Valve/Actuation Package (also known as the SIS final control element) is the weakest link in the Safety Instrumented Function (SIF), contributing greater than 50 percent of total Probability of Failure on Demand (PFD) for an SIF. The reliability, safety , and design of the final element has a significant impact on the overall Risk Reduction Factor (see figure 1).

End users can benefit extensively from implementing a complete, sole source Original Equipment Manufacturer (OEM) solution that harmonizes these standards through control over the engineering, design, and manufacture of the entire Emergency Shutdown Valve package. Pentair Valves & Controls has a proven track record for improving ESDV reliability within refineries, chemical and petrochemical facilities, and power generation plants in virtually every region of the world. Statham can be reached at +001 360 739 1555 or shawn.statham@pentair.com.

Pentair entered into an agreement in August 2016 to sell its Valves & Controls business. To read the official announcement, please visit their website.

Tel: +44(0)1858 467281
Email: salesuk@pentair.com
Web: www.valves.pentair.com/sis

Published in Valve User Magazine Issue 41


Spring 2017 // Issue 40
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