An Overview of API 570 – Piping Inspection Code: Complete Overview

Introduction and Scope

API 570, published by the American Petroleum Institute (API), is the industry standard for the inspection, repair, alteration, and rerating of in-service piping systems. It specifically addresses metallic and some non-metallic piping systems typically found in petroleum refineries, chemical plants, and other similar facilities. The goal of API 570 is to enhance safety, improve reliability, and ensure regulatory compliance by establishing a structured inspection and maintenance framework.

The standard applies to process piping and associated components such as pipe spools, valves, and fittings. It complements other API codes like API 510 (pressure vessels) and API 653 (storage tanks), together forming the backbone of mechanical integrity programs in the oil, gas, and petrochemical industries.

Key Sections of the API 570 Code

API 570 is organized into several critical sections:

  • Section 1: Scope – Defines the applicability of the code to piping systems and sets general boundaries.
  • Section 3: Definitions – Clarifies important terms like “Inspection Interval,” “Piping System,” “Rerating,” and “Corrosion Rate.”
  • Section 5: Inspection Practices – Details inspection techniques (visual, ultrasonic, radiographic, magnetic particle testing, etc.) and inspection frequencies.
  • Section 6: Repair, Alteration, and Rerating – Provides rules for making repairs, modifications, and re-rating piping systems while ensuring continued integrity.
  • Section 7: Inspection Organization and Qualifications – Lists requirements for Inspectors, Engineers, and Inspection Supervisors, including certifications such as the API 570 Piping Inspector certification.

  • Appendices – Offer supplementary information like sample inspection forms, recommended practices, and sample calculations.

How to Use API 570

Using API 570 effectively involves several steps:

  1. Classify the Piping System:

    • Determine which piping falls under API 570 jurisdiction (e.g., high-pressure, corrosive service). Identify the piping class (Class 1, 2, or 3) based on fluid service and potential consequences of failure.

  2. Establish Inspection Intervals:

    • Determine internal, external, and on-stream inspection intervals using factors like corrosion rates and system criticality. Based on corrosion rates and risk assessments, set inspection frequencies (typically 3-10 years).

  3. Perform Inspections:

    • Conduct visual and non-destructive examinations (NDE) following the specified techniques. e.g., UT, RT, PT, MT.

  4. Evaluate Results:

    • Compare findings against acceptance criteria for wall thickness, corrosion, and other defects.

  5. Plan Repairs or Alterations:

    • When required, design and execute repairs following qualified welding procedures and approval by a competent Engineer or Inspector.

  6. Document Everything:

    • Maintain complete inspection and repair records, including corrosion monitoring data and fitness-for-service assessments.

Key Takeaways from API 570

  • Safety First: Regular inspections significantly reduce the risk of catastrophic failures.

  • Inspection Frequency Matters: Properly scheduled inspections prevent unplanned outages and expensive repairs.

  • Qualified Personnel: Only certified API 570 Inspectors should perform critical inspection evaluations.

  • Repair Standards: All repairs and alterations must comply with established welding and design codes (e.g., ASME B31.3 for Process Piping).

  • Documentation Is Vital: Thorough record-keeping supports better decision-making and regulatory compliance.

Practical Example: Applying API 570 in the Field

Scenario: A refinery identifies a 10-inch process line transporting high-temperature hydrocarbon liquids. A scheduled external inspection reveals localized external corrosion under insulation (CUI).

Application of API 570:

  1. Classification:

    • The line is classified as Class 1 piping due to the hazardous nature of the contents.

  2. Inspection:

    • Thickness measurements using ultrasonic testing (UT) show a reduction of 40% of the original wall thickness in the worst area.

  3. Evaluation:

    • Based on minimum thickness calculations (using formulas provided in the code and ASME B31.3), the line is still above the required minimum thickness but approaching the retirement limit.

  4. Repair Planning:

    • The engineer recommends installing a welded-on patch (repad) and re-insulating the pipe with improved moisture barriers.

  5. Documentation:

    • The repair, inspection findings, and updated corrosion rates are recorded and used to revise the next inspection interval from 5 years to 3 years.

 

Through structured use of API 570, the refinery avoids potential leaks, ensures operational safety, and demonstrates proactive asset management to regulatory authorities.