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API 526

3 in-depth engineering guides on API 526 — specification, selection, testing and procurement.

Everything on API 526

Vajra's engineering team has published 3 technical guides covering API 526 for industrial valve selection, specification, testing and procurement. Browse the full set below.

API 526 Safety Relief Valve Sizing Guide - Orifice Letters, Set Pressures & Back Pressure

API 526 establishes the purchasing standard for flanged spring-loaded safety relief valves used in refinery and chemical plant service - defining orifice letter designations, face-to-face dimensions, flange ratings, and inspection requirements. This guide explains the full API 526 framework alongside API 520 sizing principles for engineers specifying pressure relief devices.

2026-05-2010

Safety Valve vs Pressure Relief Valve: Differences, Standards & Selection

Safety valves and pressure relief valves are often used interchangeably, but they have distinct operating principles, certifications, and applications. This guide clarifies the differences, covers API 526 orifice sizing from D through T, compares ASME Section I boiler requirements versus Section VIII vessel requirements, and provides a systematic selection framework.

2026-05-178

Safety Relief Valve Sizing - API 526 Orifice Areas, Back Pressure, and Set Pressure

A safety relief valve (SRV / PSV) is the last line of defence in a pressure system - it must open at the correct pressure and pass sufficient flow to prevent vessel rupture. API 520 (sizing) and API 526 (dimensional standards) define the engineering framework. This guide explains how to select the orifice size, set pressure, back pressure correction, and trim material for your service.

2026-05-0410

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Reviewed by Engineering Editorial Team, Vajra Industrial SolutionsDiscipline: Industrial Valve Engineering ContentLast reviewed: 20 June 2026

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