API 521
3 in-depth engineering guides on API 521 — specification, selection, testing and procurement.
Everything on API 521
Vajra's engineering team has published 3 technical guides covering API 521 for industrial valve selection, specification, testing and procurement. Browse the full set below.
Rupture Disc vs Pressure Relief Valve: Overpressure Protection Guide
Rupture discs and pressure relief valves both protect equipment from overpressure, but they work in fundamentally different ways. This guide compares the two devices, explains combination installations, and gives selection rules based on API 520 and API 521.
Thermal Relief Valves: Protecting Blocked-In Liquid Lines from Expansion
A liquid trapped between two closed valves and then heated has nowhere to go. Because liquids are nearly incompressible, even a small temperature rise builds enormous pressure that can rupture pipe, flanges, or exchanger tubes. Thermal relief valves protect blocked-in liquid lines. This guide explains the hazard, sizing, and specification.
Pressure Relief Valve Sizing and Selection: API 520 & API 521 Guide
Pressure relief valves (PRVs) are the last line of defence against vessel overpressure. Correct sizing per API 520 Part I and API 521 is critical for plant safety, regulatory compliance, and avoiding costly undersizing or oversizing errors.
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