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API 526 / 527 / 520 / ISO 4126 Relief valve dimensions, seat tightness, sizing

CurrentLatest edition found. Still confirm amendments with the publisher.
Edition
API 526 8th ed., 2023; API 527 5th ed., 2020 (R2025); API 520 Part I 10th ed., 2020 (Errata 1, 2023); API 520 Part II 7th ed., 2020; ISO 4126-1:2013 + Amd 1:2016; ISO 4126-2:2018
Publisher
API
Part family
Valves
Reviewed
23 October 2026 · source checked

Is API 526 / 527 / 520 / ISO 4126 still current?

Yes. API 526 8th ed., 2023; API 527 5th ed., 2020 (R2025); API 520 Part I 10th ed., 2020 (Errata 1, 2023); API 520 Part II 7th ed., 2020; ISO 4126-1:2013 + Amd 1:2016; ISO 4126-2:2018 is the latest edition MechAtlas found (MechAtlas review: 23 October 2026). Check the publisher for amendments before you specify it.

What it covers

Relief valve dimensions, seat tightness, sizing

Equivalent and related standards

StandardRelationshipNote
SIMRelated reference

“Similar” never means interchangeable without an engineering check.

Official source

MechAtlas does not reproduce standards. Check the official edition at the publisher's page for API 526 / 527 / 520 / ISO 4126 or the API store.

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