Rationale: Erratum identified during internal audit where corrosion rate units were inconsistent, potentially leading to underestimation of required thickness.
The ASME (American Society of Mechanical Engineers) standard patched refers to a document or code section where updates, corrections, or localized modifications—commonly called "patches"—have been applied to a baseline ASME standard. Such patches can include errata, addenda, interim guidance, or organization-specific amendments intended to address omissions, clarify requirements, or adapt the standard to a particular regulatory or operational context.
The following guide outlines the standard procedures for performing physical repairs under ASME Section VIII (Pressure Vessels) and ASME PCC-2
For more permanent solutions, ASME PCC-2 Article 201 details butt-welded insert plates , which involve replacing the damaged section entirely rather than just covering it. asme standard patched
For a truly permanent repair that completely restores the original equipment design margins, engineers turn to flush patches. This requires cutting out the defective, degraded metal entirely and inserting a matching replacement metal plate. PCC-2 - Repair of Pressure Equipment and Piping - ASME
Lap patches sit over the damaged area instead of replacing it. ASME PCC-2 Article 2.12 outlines the strict criteria for these components.
A chemical plant in Texas discovered a 6-inch diameter region of pitting corrosion in a 10-foot horizontal propane tank. The wall thickness had dropped from 0.50" to 0.18" (required minimum is 0.25"). The following guide outlines the standard procedures for
– The patch must resist internal pressure without bulging. Design often follows the rules for reinforcing pads (ASME BPVC VIII, UG-37 for nozzles, adapted for patches).
Must maintain the original Maximum Allowable Working Pressure (MAWP) of the equipment. Post-Weld Heat Treatment (PWHT):
Post-repair verification is a mandatory phase of any ASME standard patched protocol. Inspection Method Application PCC-2 - Repair of Pressure Equipment and Piping
These are applied over the damaged area and attached with fillet welds. They are generally applied on the pressure side of the sheet and are not exposed to radiant heat. The maximum opening diameter is limited to 8 inches or 16 times the plate thickness, and the minimum lap (overlap) is 1/2 inch.
Once welded, the patch undergoes NDE to confirm joint integrity.
These involve cutting out a damaged area and welding in a replacement piece flush with the original surface. The weld must be a full penetration weld, with accessible surfaces ground flush where required. The patch must be made from material at least equal in quality and thickness to the original, and corners must be rounded to avoid stress points.