Oil & Gas : Introduction to Overpressure Protection & PSV

Identify sources of overpressure and learn how a spring-loaded PSV protects a gas stream from blocked outlet scenarios, with locked-open valves, dehydration, and flare relief.

Learn how a stuck open check valve can cause reverse flow, upstream overpressure, and PSV relief to the flare system, highlighting the value of dissimilar valves.

Explore how a power outage can trigger system overpressure in oil and gas facilities, including refinery shutdowns, with focus on local, partial, and total power failures and PSV protection.

Explore how power outages arise from weather, equipment aging, and voltage spikes, and how loss of cooling water and pumps can drive distillation column overpressure and PSV relief.

Explore instrument air distribution and loss of instrument air, cover air compressors, dryers, receivers, and safety actions to prevent overpressure and support emergency shutdown.

The lecture reviews how a heat exchanger tube rupture can cause shell side overpressure, the role of PSV relief, and the risk of exothermic reactions from fluid mixing.

External fire induces overpressure in gas and liquid-filled equipment via gas expansion and vaporization, risking vessel rupture despite PSV; design temperature around 80 C from solar radiation, with refinery mitigation measures.

Explore how vacuum risks threaten equipment in oil and gas systems, the role of breathing valves and vacuum relief capacity, and how to prevent ignition by venting and nitrogen.

Analyze a control valve failure scenario and how a PSV protects against overpressure by setting relief at equipment design pressure, with placement guidance and a 3% inlet pressure drop limit.

Identify the governing case for PSV sizing by evaluating credible scenarios, with control valve failure identified as the governing case, and apply a checklist to select the worst-case relief load.

Collect and verify drawings such as p&ids, process and utility flow diagrams, and isometrics, plus operating and design data to calculate PSV orifice size and ensure current revisions.

Present an example of PSV orifice size calculation for gas service under critical flow, using discharge area and coefficients to select a pea-sized valve and emphasize safety standards.

Review the PSV nameplate data and multilingual labeling to identify serial and tag numbers, flange sizes and ratings, set pressure, back pressure, and cert marks.

Review the applicable standards, including AP 521 for sizing and installation of pressure relieving devices, API 520 for relief systems, and API 2000 for venting tanks and piping.