There is no single document called “ASME Patched Standard.” Instead, the requirements for patching are spread across several key ASME codes, primarily and, historically, API 510 and API 653 (which reference ASME standards). The gold standard for engineered patches today is ASME PCC-2, Article 2.2: “Repair of Equipment by Welding” – specifically the section covering Full-Encirclement Steel Reinforcing Pads and Lap Patches .
The answer often lies in a specific phrase searched by maintenance managers worldwide: .
Here are the of an ASME-compliant patch, based on ASME Section VIII, Division 1 (and relevant rules from Division 2):
Localized cracks in the shell or head that can be removed and replaced. Through-Wall Defects: Pits or holes that have caused leaks. 3. Engineering Requirements for ASME Standard Patches
The design must account for the high eccentricity and bending stresses induced by the thickness offset of the lap joint.
Inspectors must determine the root cause of the defect (e.g., localized corrosion, erosion, or cracking). Non-Destructive Examination (NDE) methods like Ultrasonic Testing (UT) map the exact boundaries of the thinned or damaged zone. Step 2: Design and Calculations
ASME Standard Patched Repairs: A Guide to PCC-2 Flush Patches and Insert Plates
A plate is laid directly over the thinned or corroded area. Welding: Attached around its perimeter using fillet welds .
Generally treated as a temporary repair . Lap patches introduce crevice corrosion risks and eccentric bending stresses. They are meant to bridge safe operation until the next scheduled shutdown.
: Must be a full-penetration butt weld, often requiring double-welding where accessible.