Under ASME PCC-2 Part 2 (Welded Repairs), patches are classified based on their geometry, attachment mechanism, and intended service duration. Flush Patches (Insert Plates)
: Provides the overarching "Engineering Drawing Practices," ensuring that any updated (patched) drawings maintain consistent formatting. 3. Compliance and Certification
: Often categorized alongside patching, this involves adding external weld metal to repair internal thinning. 2. Difference Between Construction and Post-Construction asme standard patched
While focuses on new construction, it does not provide rules for post-construction repairs. Instead, technical guidance for patching in-service equipment is found in the following standards: 1. ASME PCC-2 (Post-Construction Code) This is the primary technical standard for repair methods.
A patch plate welded over the damaged area with fillet welds. Usually considered a temporary repair unless specifically designed as a permanent one under stringent requirements. Under ASME PCC-2 Part 2 (Welded Repairs), patches
A standard patch repair is usually considered a "Routine Repair" if it meets the criteria in the NBIC, which allows for simplified documentation, though it still requires a "Certificate of Inspection" 2.2.3. Summary of ASME Patching Steps
Log the repair details in the equipment's permanent history file, updating Form R-1 or relevant alteration documents. Post-Weld Heat Treatment (PWHT):
When a pressure-retaining component suffers local damage like thinning, pitting, or corrosion, engineers turn to specific ASME codes to determine if a patch is a safe, compliant solution: Repair or Alteration of Pressure Vessels
The standard classifies patches based on their geometry and attachment methods, most notably and lap patches (overlay patches) . 2. Core Typologies of ASME Patches
Must maintain the original Maximum Allowable Working Pressure (MAWP) of the equipment. Post-Weld Heat Treatment (PWHT):