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8.3 Temporary and Permanent Repair Methods (ASME PCC-2 & API 570)

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API 570 Piping Inspector Exam

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1 Chapter 1: Piping Inspection Planning & Circuits

1.1 Inspection Planning, History, and Safety 1.2 Piping Circuitization and Circuit Design 1.3 Condition Monitoring Locations (CMLs) & Coverage

2 Chapter 2: Inspection Intervals & Extent of Inspection

2.1 Piping Classifications (Classes 1, 2, 3, and 4) 2.2 Thickness Inspection Intervals (Half-Life & Visual Rules) 2.3 Owner-User QA and Roles (Inspector, Engineer, Examiner)

3 Chapter 3: Calculations & Remaining Life

3.1 Corrosion Rates (Short-Term, Long-Term, and Initial Estimates) 3.2 Remaining Life and Retirement Thickness Calculations 3.3 MAWP Calculations for In-Service Piping

4 Chapter 4: ASME Codes for Piping Design

4.1 Wall Thickness Calculations for Pipe under Pressure (ASME B31.3) 4.2 Flange Ratings & P-T Limits (ASME B16.5) 4.3 Pressure & Leak Testing Rules (Hydrostatic vs. Pneumatic) 4.4 Weld Joint Quality Factors (Ej) and Casting Quality Factors (Ec) 4.5 Impact Testing, MDMT Exemption, and Charpy Requirements 4.6 Thermal Expansion Calculations (ASME B31.3 Appendix C) 4.7 Minimum Required Thickness of Permanent Blanks

5 Chapter 5: Nondestructive Examination (NDE)

5.1 Visual, Penetrant, and Magnetic Testing (VT, PT, MT) per ASME Sec V 5.2 Radiographic and Ultrasonic Testing (RT, UT) per ASME Sec V 5.3 Examiner Selection, Calibrations, and Acceptance Standards 5.4 Leak Testing per ASME Section V Article 10

6 Chapter 6: Welding Procedures & Qualifications

6.1 Reviewing WPS and PQR per ASME Section IX 6.2 Welder Performance Qualification (WPQ) and Limits 6.3 Preheating & PWHT Rules and Controls 6.4 Welding Processes, Inspection, and Metallurgy (API RP 577)

7 Chapter 7: Valves, Components, Materials & PRDs

7.1 Piping Components and Valves (API RP 574) 7.2 Positive Material Identification (PMI) (API RP 578) 7.3 Pressure Relieving Devices (PRDs) (API RP 576)

8 Chapter 8: Damage Mechanisms & Repairs

8.1 Corrosion Under Insulation (CUI) and Ambient Mechanisms 8.2 Process-Driven Damage Mechanisms (API RP 571) 8.3 Temporary and Permanent Repair Methods (ASME PCC-2 & API 570) 8.4 Soil Corrosion, Galvanic Corrosion, and Boiler Water Condensate Corrosion 8.5 Piping Rerating and Alterations (API 570) 8.6 Inspection Records, Reports, and Documentation 8.7 Amine/Caustic SCC, HCl, Sour Water, and MIC (API RP 571)

8.3 Temporary and Permanent Repair Methods (ASME PCC-2 & API 570)

Key Takeaways Explain This Topic AI

Welded split sleeves are used for repairs; Type B sleeves (ends welded) can contain pressure and serve as permanent repairs, while Type A sleeves (ends not welded) only reinforce structurally.

Fillet-welded patches (lap patches) are generally restricted to temporary repairs on low-pressure/non-hazardous systems and must be removed at the next turnaround.

Insert plates (flush patches) with full-penetration butt welds are permanent repairs and must meet construction code NDE requirements (RT or UT).

Piping engineers must approve all repair designs, calculations, and materials, while API 570 inspectors must authorize the repair method before any work begins.

Mechanical clamps (ASME PCC-2 Article 306) are typically temporary bolted enclosures that require design rating checks, leak verification, and tracked removal or permanent replacement.

Last updated: July 2026

8.3 Temporary and Permanent Repair Methods (ASME PCC-2 & API 570)

Repairs, alterations, and rerating of in-service piping systems must comply with the requirements of API 570, Section 8, and the piping design code (such as ASME B31.3). For detailed repair procedures and calculations, API 570 refers to ASME PCC-2, 'Repair of Pressure Equipment and Piping.'

Welded Split-Sleeves (Full-Encirclement Sleeves)

Welded split-sleeves consist of two halves of a pipe or curved plate placed around a damaged piping section and welded together along their longitudinal seams. They are used to repair localized thinning, cracks, or leaks.

Type A Split Sleeves (Non-Pressure Containing)

Type A split-sleeves are welded along their longitudinal seams, but their ends are NOT welded to the pipe wall.

Function : They provide structural reinforcement but cannot contain process pressure.

Limitations : Type A sleeves are not permitted for repairing leaking piping or cracking. They are only suitable for reinforcing areas of localized thinning or external damage. They are considered temporary or permanent depending on the engineering assessment and corrosion allowance.

Type B Split Sleeves (Pressure-Containing)

Type B split-sleeves are welded along their longitudinal seams, and their circumferential ends are welded to the pipe wall.

Function : They are designed to contain full system pressure and load.

Application : They can be used to repair leaking areas, localized thinning, and cracking.

API 570 Rules : A Type B sleeve is considered a permanent repair under API 570 if it is designed by a piping engineer, fabricated from matching or compatible materials, and fully inspected.

In-Service Welding Caution : Welding a Type B sleeve onto an active, pressurized pipeline poses a risk of burn-through if the pipe wall is too thin. The inspector must verify the remaining wall thickness of the pipe under the weld area and calculate the minimum safe wall thickness for in-service welding.

Fillet-Welded Patches (Lap Patches)

Fillet-welded patches (lap patches) are plates that are bent to conform to the pipe radius and fillet-welded over the degraded piping surface.

API 570 Rules for Lap Patches

Temporary Repairs Only : Under API 570, fillet-welded patches are generally restricted to temporary repairs on low-pressure or non-hazardous systems.

Engineering Design : The patch must be designed by a piping engineer to withstand full system pressure. It must have rounded corners (minimum 1-inch radius) and must cover the entire degraded zone plus a margin.

Inspector Approval : The inspector must authorize the installation.

Removal Requirement : Temporary fillet-welded patches must be removed and replaced with a permanent repair (such as an insert plate or spool piece) at the next available turnaround.

Permanent Patch Exception : In rare circumstances, a fillet-welded patch can be approved as a permanent repair if evaluated and approved by both the piping engineer and the inspector, taking into account the fatigue life and service environment.

Engineered Box Enclosures

Engineered box enclosures (leak clamps or enclosures) are custom-designed metal boxes that are bolted or welded around a leak or localized thin spot. The box is then filled with a high-temperature sealant.

Design Requirements : Every box enclosure must be designed by a piping engineer. The design must account for the system pressure, temperature, piping loads, and the potential for the leak to spread within the enclosure.

Authorization : The installation must be authorized by the inspector.

Service Life : Enclosures can remain in service as permanent repairs if designed for the life of the plant, but they must be logged and periodically monitored for leaks or degradation.

Insert Plates (Flush Patches)

Insert plates involve cutting out the degraded section of the pipe wall and welding a new plate flush with the existing pipe.

Welding Requirements : The insert plate must be welded using full-penetration butt welds. Fillet welds are not permitted.

Material & Thickness : The insert plate material, thickness, and welding electrodes must match the original piping specification.

API 570 Status : Insert plates are considered permanent repairs.

NDE & Inspection : The welds must meet the requirements of the construction code (such as ASME B31.3). Radiographic testing (RT) or ultrasonic testing (UT) must be performed on the butt welds.

Composite / Non-Welded Repairs

Composite repairs involve wrapping the pipe with high-strength glass or carbon fibers impregnated with a polymer resin (polyurethane or epoxy).

ASME PCC-2 Standard : Composite repairs must be designed in accordance with ASME PCC-2 Article 4.1 (for non-metallic wraps).

Application : They are highly effective for repairing external corrosion, local thin spots, and minor leaks.

Class Restrictions : Under API 570, composite wraps are typically restricted to temporary repairs in hazardous hydrocarbon services. They can be considered permanent for non-hazardous utility services (such as cooling water, air, or steam condensate) under specific engineering approval.

Design Lifetime : The wrap must be designed for a specific lifetime, which is documented and monitored.

Mechanical Clamp Repairs (ASME PCC-2 Article 306)

Mechanical clamps (also called leak clamps or bolted clamps) are non-welded pressure-retaining enclosures bolted around a leaking or thinned pipe section. ASME PCC-2 Article 306 covers design, materials, installation, and inspection of these clamps. On the February 2026 API 570 BOK, Article 306 is explicitly testable.

  • When Clamps Are Used
  • Temporary leak containment until a permanent welded repair or replacement can be scheduled
  • Locations where hot work is prohibited (hydrocarbon atmosphere, live units)
  • Emergency response when a pinhole or packing leak must be stopped without depressuring the entire unit
  • Inspector Checks for Clamp Repairs

Design package – clamp rated for design pressure/temperature of the circuit; gasket/seal compatible with process fluid

Pipe condition under the clamp – remaining wall must support clamp bearing loads; severe local thinning may require engineered load paths

Bolt torque and follow-up – uneven torque can unload seals; re-check after thermal cycles

Temporary status – API 570 expects temporary repairs to be tracked and removed or made permanent at the next opportunity; leaving a clamp for years without engineering revalidation is an audit finding

NDE after installation – leak check (often bubble test per Section V Article 10 Appendix I) at operating or reduced pressure per the repair plan

Clamp vs Fillet Patch vs Type B Sleeve

  • Method PCC-2 / API 570 role Hot work? Typical status
  • Mechanical clamp (Art. 306) Bolted enclosure No Usually temporary
  • Fillet-welded patch (Art. 212 concepts) Lap plate fillet-welded to pipe Yes Often temporary on process piping

Full-encirclement Type B sleeve (Art. 206 concepts) Ends welded; pressure-containing Yes Can be permanent if designed as such

  • Butt-welded insert plate (Art. 201) Flush replacement of damaged wall Yes Permanent when properly designed
  • ASME PCC-2 Articles on the February 2026 BOK

The API 570 Body of Knowledge lists these PCC-2 articles (and appendices) as testable. Use this map when a question names an article number:

  • Article Subject Inspector takeaway
  • 101 Introduction Scope, definitions, how PCC-2 relates to owner standards
  • 201 Butt-welded insert plates Flush permanent wall replacement
  • 206 Full encirclement steel reinforcing sleeves Type A vs pressure-containing sleeves
  • 209 Alternatives to PWHT Controlled deposition / preheat alternatives when Code PWHT is impractical
  • 210 In-service welding onto carbon steel Hot-tap / live welding controls and thickness limits
  • 211 Weld buildup, overlay, clad restoration Restoring thickness or corrosion-resistant layers
  • 212 Fillet-welded patches Lap patches — usually temporary on process piping
  • 304 Flaw excavation and weld repair Dig out crack/defect and reweld with NDE
  • 305 Flange repair and conversion Machining, weld repair, or conversion of flange faces
  • 306 Mechanical clamp repair Bolted temporary enclosures (see above)
  • 501 Pressure and tightness testing Post-repair pressure/leak testing expectations

502 NDE in lieu of pressure testing When NDE may substitute for hydro/pneumatic tests after repairs/alterations

Authorizations and Approvals

A critical focus area of the API 570 exam is the division of responsibilities between the Piping Engineer and the Piping Inspector.

Piping Engineer Responsibilities

The piping engineer must approve all repair designs. This includes:

Design calculations for split-sleeves, box enclosures, and patches.

Material selection and compatibility checks.

Review of fitness-for-service evaluations.

Approval of permanent fillet-welded patches or composite wraps.

Piping Inspector Responsibilities

The piping inspector is responsible for the authorization and quality control of the repair work. This includes:

Pre-Authorization : The inspector must authorize the repair method prior to the start of any work.

Welder Verification : Ensuring the welders are qualified in accordance with ASME Section IX.

WPS Verification : Verifying the Welding Procedure Specification (WPS) is appropriate for the material and service.

Visual & NDE Checks : Performing visual inspections and verifying that all required NDE (such as RT, UT, PT, or MT) is executed and meets acceptance standards.

Repair Selection Matrix

Repair Method Permitted Status (API 570) Primary Code Reference Weld Type NDE Requirement

Type A Sleeve Temporary or Permanent (subject to engineering) ASME PCC-2 Art. 2.1 Longitudinal fillet weld Visual, MT/PT on welds

Type B Sleeve Permanent ASME PCC-2 Art. 2.1 Longitudinal butt, circumferential fillet Visual, MT/PT on fillet welds, UT/RT

Fillet-Welded Patch Temporary (typically) ASME PCC-2 Art. 2.12 Fillet weld around perimeter Visual, MT/PT on fillet weld

Insert Plate Permanent ASME PCC-2 Art. 2.2 Full-penetration butt weld Visual, UT or RT (volumetric)

Composite Wrap Temporary (utility exception) ASME PCC-2 Art. 4.1 Non-welded wrap Visual monitoring, wrap profile check

  • Exam Tips & Scenarios
  • Worked Scenario: Fillet-Welded Patch Sizing Check

An engineer is designing a temporary fillet-welded patch (lap patch) to repair a localized thin area on a 10-inch nominal (NPS 10) carbon steel piping system (Class 2 service). The host pipe outer diameter ( D o D_o D o ​ ) is 10.75 inches, giving an outer radius ( R R R ) of 5.375 inches. The host pipe nominal wall thickness ( t h o s t t_{host} t h os t ​ ) is 0.365 inches. Inspection data shows a localized circular thinning defect with a diameter of d d e f e c t = 2.5 d_{defect} = 2.5 d d e f ec t ​ = 2.5 inches.

To satisfy ASME PCC-2 Article 2.12, the patch must extend beyond the boundary of the degraded area into sound metal by a minimum distance of R ⋅ t h o s t \sqrt{R \cdot t_{host}} R ⋅ t h os t ​ ​ .

Calculate the Minimum Extension ( W m i n W_{min} W min ​ ) : W m i n = R ⋅ t h o s t W_{min} = \sqrt{R \cdot t_{host}} W min ​ = R ⋅ t h os t ​ ​ W m i n = 5.375 inches × 0.365 inches = 1.9619 ≈ 1.40 inches W_{min} = \sqrt{5.375\text{ inches} \times 0.365\text{ inches}} = \sqrt{1.9619} \approx 1.40\text{ inches} W min ​ = 5.375 inches × 0.365 inches ​ = 1.9619 ​ ≈ 1.40 inches

Calculate the Minimum Patch Diameter ( D p a t c h D_{patch} D p a t c h ​ ) :

The patch must cover the defect diameter plus the minimum extension on all sides: D p a t c h = d d e f e c t + 2 ⋅ W m i n D_{patch} = d_{defect} + 2 \cdot W_{min} D p a t c h ​ = d d e f ec t ​ + 2 ⋅ W min ​ D p a t c h = 2.5 inches + 2 × 1.40 inches = 5.30 inches D_{patch} = 2.5\text{ inches} + 2 \times 1.40\text{ inches} = 5.30\text{ inches} D p a t c h ​ = 2.5 inches + 2 × 1.40 inches = 5.30 inches

Final Patch Sizing :

The engineer rounds the design up to a standard circular patch diameter of 5.5 inches (or a 5.5-inch square patch with 1.0-inch radius rounded corners). The size of the fillet weld leg must be specified by the engineer (typically matching the patch plate thickness, which must be at least equal to t h o s t = 0.365 t_{host} = 0.365 t h os t ​ = 0.365 inches). The inspector verifies these dimensions before authorizing the repair.