Asme Standard Patched -

┌──────────────────────────────────────┐ │ ASME Patched Repairs │ └──────────────────┬───────────────────┘ │ ┌─────────────────────────┴─────────────────────────┐ ▼ ▼ ┌─────────────────────────────────┐ ┌─────────────────────────────────┐ │ Flush Patches │ │ Fillet Welded Patches │ │ (Insert Plate Repairs) │ │ (Lap/Scab Plates) │ ├─────────────────────────────────┤ ├─────────────────────────────────┤ │ • Full-penetration groove weld │ │ • Fillet-welded over defect │ │ • Restores original geometry │ │ • Creates eccentric loading │ │ • Classified as PERMANENT │ │ • Classified as TEMPORARY │ └─────────────────────────────────┘ └─────────────────────────────────┘ 1. Flush Patches (Insert Plates) — Permanent Repair

: Used specifically for nuclear power plant components. It has its own stringent rules for "repair/replacement" activities but may use PCC-2 methods as a technical roadmap for non-safety-related items.

– Mismatch between patch and parent material can cause high stresses.

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Lap patches are placed over the damaged area without removing the base metal, attached via fillet welds. asme standard patched

: Regulates the engineering application of advanced high-strength composite wraps and wet-layup fiber-reinforced polymers. Core Patched Repair Methodologies

Checks for surface profile imperfections, undercut, and proper weld reinforcement dimensions. All patches

All joints must be executed by qualified welders using procedures (WPS) compliant with ASME Section IX

Source: Kim, J., Lee, S., & Kim, M. (2020). Finite Element Analysis of Patched Tubing under High-Temperature and High-Pressure Conditions. Journal of Pressure Vessel Technology, 142(2), 021201. – Mismatch between patch and parent material can

: Governs split-sleeve repair clamps, non-welded metallic leak boxes, and mechanical hardware bolting.

Approval: Engineering Standards Committee; approved April 7, 2026.

Implementing an repair allows asset owners to safely extend the lifespans of critical pressure equipment. By strictly adhering to ASME PCC-2 design criteria, executing precise full-penetration welds, and validating the repair through rigorous NDE, industries can mitigate localized degradation without compromising safety or structural integrity.

A key design aspect is the bending stress introduced at the edge of the patch due to eccentricity (the thickness offset between the patch and parent plate). The code's guidance can result in a required patch thickness significantly higher than the vessel's original shell, especially when the required shell thickness is close to its nominal value. Some have criticized PCC-2's approach as overly conservative, with research exploring less restrictive alternatives. Core Patched Repair Methodologies Checks for surface profile

When executing an ASME-compliant patch, engineers utilize the rigorous mechanical design criteria of to satisfy the legal safety mandates of the NBIC or API 510/570 . Primary Types of ASME Patched Repairs

Note: NBIC Part 3 explicitly prohibits fillet-welded scab plates for certain pressure-retaining repairs without strict jurisdictional variances, making flush patches the mandatory path for full structural restoration. Core Engineering Requirements for ASME Flush Patches

A major feature of the ASME PCC-2 guidance is the calculation of required thickness , which must account for bending stresses caused by the eccentricity (the offset between the patch and the original shell). Standard Procedures & Specifications

Log the repair details in the equipment's permanent history file, updating Form R-1 or relevant alteration documents.

: The ASME standard patched framework is not static. Researchers are actively studying the stress distribution in fillet welded patches and proposing design improvements to reduce conservative assumptions.

C --> E[**Flush Patch Repair**<br>(Butt-Welded Insert)]; C --> F[**Fillet Welded Lap Patch**<br>(PCC-2 Art. 212)]; C --> G[**Reinforced Patch with<br>Plug Welds** (PCC-2 Art. 207)]; C --> H[Other Methods<br>(Sleeves, Composite Wrap)];