How to Write NDT Procedures: ASME Section V Compliant Guide for Level III Professionals [2026]

Why NDT Procedure Quality Matters

NDT procedures are the foundation of every inspection program. A well-written procedure ensures consistent, repeatable, and code-compliant inspections. A poorly written one leads to rejected reports, audit findings, and—in worst cases—missed defects that compromise safety.

This guide provides a practical framework for writing NDT procedures that satisfy ASME Section V, API standards, and client specifications.

Who Is Responsible for NDT Procedures?

Under most qualification schemes (SNT-TC-1A, CP-189, ISO 9712), the Level III is responsible for:

• Developing and approving NDT procedures
• Ensuring procedures comply with applicable codes and standards
• Reviewing and revising procedures when codes change
• Validating that procedures are technically adequate for their intended application

Even if Level II technicians draft procedures, Level III review and approval is required for code compliance.

Understanding ASME Section V Requirements

ASME Section V is the primary NDT code for pressure equipment. It establishes two types of documents:

Written Procedure

A detailed document specifying all parameters and steps for performing a specific NDT examination. Must address all "essential variables" and "nonessential variables" defined in the applicable article.

Technique Sheet

A supplementary document that captures job-specific parameters within the framework of an approved procedure. Technique sheets allow one procedure to cover multiple applications.

Essential Elements of an NDT Procedure

1. Scope and Purpose

Clearly define what the procedure covers: the NDT method, material types, product forms, thickness ranges, and applicable code editions. Be specific—vague scope statements are a common audit finding.

2. References and Applicable Codes

List all referenced codes, standards, and specifications with edition dates. Common references include:

• ASME Section V (specify article and edition)
• ASME Section VIII Div. 1 or 2 (acceptance criteria)
• API 510, 570, or 653 (for in-service inspection)
• Client specifications and supplementary requirements
• Equipment manufacturer requirements

3. Personnel Qualifications

Specify minimum certification levels required to perform and evaluate examinations. Reference the qualification standard (SNT-TC-1A, CP-189, or ISO 9712) and any additional client or regulatory requirements.

4. Equipment and Materials

Document all equipment required with sufficient detail for verification:

• Instrument make, model, and specifications
• Transducers/probes (type, frequency, size, angle)
• Calibration blocks and reference standards
• Couplant, penetrant materials, magnetic particles
• Auxiliary equipment (demagnetization, UV lights, etc.)

5. Surface Preparation

Define required surface condition, cleaning methods, and temperature requirements. Specify acceptance criteria for surface preparation and any limitations on surface condition.

6. Calibration Requirements

Detail the complete calibration procedure including:

• Calibration blocks to be used (IIW, DSC, actual component mockups)
• Calibration sequence and acceptance criteria
• Calibration check intervals during examination
• Actions required when calibration checks fail

7. Examination Technique

This is the core of the procedure. Describe the examination methodology in sufficient detail that a qualified technician can perform the examination consistently. Include:

• Scanning technique and pattern
• Coverage requirements and scanning speed
• Instrument settings and sensitivity levels
• Detection and evaluation criteria
• Transfer correction methods

8. Acceptance Criteria

Reference the specific acceptance criteria from the construction or inspection code. Do not paraphrase acceptance criteria—reference the code section directly or reproduce it exactly. Incorrect or ambiguous acceptance criteria are a leading cause of report rejections.

9. Documentation and Reporting

Specify report format, required information, record retention requirements, and data recording methods. Reference any standard report forms to be used.

10. Essential and Nonessential Variables

List all essential variables as defined by the applicable ASME Section V article. Essential variable changes require procedure re-qualification; nonessential variable changes require only procedure revision.

Procedure Qualification (Demonstration)

ASME Section V requires that NDT procedures be demonstrated (qualified) before use. Demonstration requirements include:

• Performing the examination on a representative sample or calibration standard
• Verifying that all essential variables produce acceptable results
• Documenting the demonstration with records of results
• Re-demonstrating when essential variables change

Some client specifications require blind demonstration using samples with known defects.

Common Procedure Rejection Causes

Based on Level III consulting experience, the most frequent procedure deficiencies include:

• Missing essential variables: Not addressing all variables required by the ASME article
• Incorrect code references: Using outdated editions or wrong articles
• Vague technique descriptions: Insufficient detail for consistent application
• Paraphrased acceptance criteria: Summarizing instead of directly referencing the code
• Missing calibration details: Incomplete calibration sequences or missing check intervals
• No demonstration records: Procedure not demonstrated per ASME requirements
• Scope limitations not defined: Not specifying material, thickness, or geometry limitations
• No revision control: Missing revision history, dates, and approval signatures

Best Practices From Level III Consultants

• Use a checklist: Create a compliance checklist for each ASME article to verify all requirements are addressed
• Write for the technician: Procedures should be clear enough for a qualified Level II to follow without interpretation
• Keep it modular: Use a master procedure with technique sheets for different applications
• Version control: Implement formal revision control with change history
• Peer review: Have another Level III review procedures before approval
• Regular updates: Review procedures when codes are updated (typically every 2-3 years)
• Client-specific addenda: Use supplementary sheets for client requirements rather than creating entirely new procedures

Method-Specific Considerations

Ultrasonic Testing Procedures

UT procedures require particular attention to search unit selection, scanning sensitivity, distance-amplitude correction, transfer correction, and coverage documentation. ASME V Articles 4 and 5 have different requirements for welds vs. materials.

Radiographic Testing Procedures

RT procedures must address source selection, geometric unsharpness calculations, exposure techniques, IQI selection and placement, and radiographic density requirements. Safety and regulatory compliance sections are essential.

Magnetic Particle and Liquid Penetrant Procedures

Surface methods require careful attention to surface preparation, temperature limitations, dwell times, lighting requirements, and post-examination cleaning. Process control verification steps are critical.

How Atlantis NDT Can Help

Atlantis NDT provides comprehensive procedure development and review services:

• New procedure development for any NDT method per ASME Section V
• Existing procedure review and gap analysis
• Procedure updates for new code editions
• Client specification compliance review
• Procedure demonstration support

Contact us for expert Level III procedure development and review services.