API RP 583

Description

This recommended practice covers the design, maintenance, inspection, and mitigation practices to address
external corrosion under insulation (CUI) and corrosion under fireproofing (CUF). The document discusses the
external corrosion of carbon and low alloy steels under insulation and fireproofing and the external chloride
stress corrosion cracking (ECSCC) of austenitic and duplex stainless steels under insulation. The document
does not cover atmospheric corrosion or corrosion at uninsulated pipe supports but does discuss corrosion at
insulated pipe supports.

The purpose of this recommended practice is to:
— help owner-operators understand the complexity of the many CUI/CUF issues;
— provide owner-operators with an understanding on the capabilities and limitations of the various nondestructive
examination methods used to identify CUI and CUF damage;
— provide owner-operators with an approach to likelihood assessment for CUI and CUF damage; and
— provide owner-operators guidance on how to design, install, and maintain insulation systems to avoid CUI
and CUF damage.

The practices described in this document apply to pressure vessels, piping, and storage tanks and spheres. The
document discusses the factors impacting damage mechanisms, the guidelines to prevent external corrosion/
cracking under insulation, the maintenance practices to avoid damage, the inspection practices to detect/assess
damage, and the guidelines for likelihood assessments of equipment or structural steel subject to CUI and CUF
damage.

** This version of the Standard is not current. Please check for Errata and Addendums **