ASME Standard Patched Repairs: A Guide to PCC-2 Flush Patches and Insert Plates
Governed technically by , a flush patch involves cutting out the damaged or corroded section of the pressure boundary entirely and inserting a replacement plate. The new plate sits perfectly flush with the existing shell and is joined using a full-penetration butt weld . PCC-2 - Repair of Pressure Equipment and Piping - ASME
ASME PCC-2 is a post-construction code specifically designed for equipment that has already been placed in service. It categorizes repairs into three main types, two of which commonly involve "patches": asme standard patched
ASME PCC-2 has strict rules regarding the maximum size and thickness of fillet-welded patches. C. Welded Leak Boxes
, a "patched" feature typically refers to the permanent or temporary repair of a pressure-retaining component. ASME Standard Patched Repairs: A Guide to PCC-2
An Authorized Inspector (AI) measures the remaining thickness. If the wall loss exceeds the corrosion allowance, a patch is considered.
Repairs generally fall into two categories based on the application method and the intended lifespan of the fix. 1. Flush Patches (Permanent Repairs) It categorizes repairs into three main types, two
Addresses repairs using patches with reinforcing plug welds.
: These are legally binding codes mandated by jurisdictional authorities. They dictate the overall administrative rules, inspector authorization, and documentation needed to maintain a vessel’s official stamp.
A hydrostatic or pneumatic leak test is usually required after a repair to ensure tightness at maximum operating pressures. 5. Best Practices and Considerations
The patch material must possess nominal tensile strength, yield strength, and chemical composition equivalent to or compatible with the base metal. If the original material is an ASME SA-516 Grade 70 carbon steel plate, the patch must generally use the same specification to avoid differential thermal expansion and galvanic corrosion. Thickness and Stress Calculation The thickness of the patch (