Specifically applies to gas-fired general service heaters in refineries and petrochemical plants.

: Invokes concepts of Safety Instrumented Systems (SIS) and provides guidance on identifying hazards and associated shutdown functions .

The most recent version, the , was reaffirmed in 2024 and significantly updated the 1997 original to reflect modern advances in safety automation and process control. Scope and Application of API RP 556

In the meantime, here is a you can adapt for either purpose:

It does not cover oil-fired heaters, utility water tube boilers (covered by NFPA 85), or heat recovery steam generators (HRSG).

(Recommended Practice) provides the industry standard for instrumentation, control, and protective systems for gas-fired heaters used in petroleum refineries and chemical plants . Key Functional Areas

: Sets requirements for primary measuring and actuating instruments (e.g., flow, pressure, and temperature sensors).

The PDF of API RP 556 is well-formatted with selectable text and decent bookmarks for major sections. Figures are legible, but some older flow diagrams appear slightly low-resolution when zoomed. The document is searchable, which helps when looking for keywords like “burner management” or “trip logic.” My only complaint is the lack of clickable cross-references between sections. Overall, a usable digital version for engineers.

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Clear, searchable PDF – good for reference