Nace Rp0472 Pdf Jun 2026

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This standard is relevant to:

Hardness surveys must be conducted on the Procedure Qualification Record (PQR).

When welding chemistry or thickness makes it impossible to naturally maintain low hardness levels, Post-Weld Heat Treatment (PWHT) is required. nace rp0472 pdf

NACE RP0472 is the essential standard for preventing in-service environmental cracking of carbon steel weldments in the petroleum refining industry. It provides a proven, consensus-based framework for controlling weld hardness and managing the factors that lead to failures. For any professional responsible for the integrity of refinery assets, possessing an official copy of this standard is not just best practice—it is a necessity.

(store.nace.org): As the publisher, NACE International offers the standard directly. The store address for the standard is: https://store.nace.org/rp0472-methods-and-controls-to-prevent-in-service-environmental-cracking-of-carbon-steel-weldments-in-corrosive-petroleum-refining-environments-hd2000 .

When welding chemistry or cooling rates make it difficult to stay below the 200 HBW limit, Post-Weld Heat Treatment (PWHT) becomes mandatory. Heating the completed weldment to a specified temperature (typically between 595°C to 650°C / 1100°F to 1200°F) accomplishes two critical goals: This public link is valid for 7 days

The most frequently cited aspect of NACE RP0472 is its strict hardness criteria. High hardness correlates directly with increased susceptibility to hydrogen-assisted cracking.

Because NACE standards are subject to periodic review and potential revision, it is critical to use the most current edition. The user is cautioned to always verify that they are working with the latest version of the standard. The development of RP0472 has continued from its original 1972 approval through revisions in 1987, 1995, 2000, and 2005, ultimately being re-designated as SP0472, demonstrating the importance of staying current with industry best practices.

The standard focuses primarily on the and the weld metal itself. When carbon steel is welded, the extreme heat followed by rapid cooling can alter the microstructure of the metal, forming a brittle phase known as martensite. High hardness makes the material exceptionally susceptible to environmental cracking when exposed to corrosive refinery process streams containing hydrogen sulfide ( H2Scap H sub 2 cap S ), alkaline sour waters, or amine systems. Can’t copy the link right now

Prevention of environmental cracking in carbon steel weldments. NACE MR0103 / ISO 17945

Using outdated or bootleg copies of the standard introduces severe liability risks, as tables regarding chemistry limits and testing protocols are periodically updated to reflect modern metallurgy.

This standard focuses on Downstream petroleum refining environments. It specifies material selection requirements for sour refinery environments.

NACE SP0472 is the redesignation of NACE RP0472. The standard was redesignated as NACE SP 04 72 around April 2010. This change reflects the standardization of naming conventions within NACE International.

NACE RP0472 (now maintained as NACE SP0472) is a critical international standard for the oil, gas, and refining industries. It establishes strict guidelines for controlling weld hardness in carbon steel equipment to prevent environmental cracking.