Saudi Wells Technology Factory Company (SWTF) offers Partial Stroke Panels that are designed and tailored to suit the individual project specifications or client developed standardized design philosophies, always incorporating safety, environmental and statutory requirements by regulatory bodies such as the International Electro Technical Commission (IEC) and the Instrument Society of Automation (ISA). The following are the standards appropriate to these bodies.
IEC61508 – Functional safety of electrical/electronic/programmable electronic safety-related systems
IEC61511 – Functional safety – Safety instrumented systems for the process industry sector
ANSI/ISA-84.00.01 – Functional safety: Safety instrumented systems for the process industry sector
Partial stroke testing (or PST) is a technique used in a control system to allow the user to test a percentage of the possible failure modes of a shutdown valve without the need to physically close the valve.
PST is used to assist in determining that the safety function will operate on demand. PST is most often used on high integrity emergency shutdown valves (ESDVs), SSV in applications where closing the valve will have a high cost burden yet proving the integrity of the valve is essential to maintaining a safe facility.
In addition to ESDVs PST is also used on high integrity pressure protection systems or HIPPS. Partial stroke testing is not a replacement for the need to fully stroke valves as proof testing is still a mandatory requirement.