13.3 SNT-TC-1A vs CP-189 Comparison

ASNT NDT Level III Basic Examination Exam

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1 Introduction & Exam Overview

1.1 Current Exam Facts 1.2 Level III Role and Certification Path 1.3 Eligibility, Fees, Scheduling, and Retakes 1.4 Study Strategy and Exam-Day Approach

2 Chapter 2: Materials Fundamentals for NDT

2.1 Ferrous Metals and Iron-Carbon Phases 2.2 Non-Ferrous Metals and Alloys 2.3 Mechanical Properties and Crystal Structure

3 Chapter 3: Manufacturing Processes

3.1 Casting Processes and Cast Discontinuities 3.2 Forging, Rolling, and Forming 3.3 Extrusion, Drawing, and Machining 3.4 Heat Treatment Effects

4 Chapter 4: Welding and Joining Processes

4.1 Fusion Welding Processes 4.2 Weld Metal and HAZ Discontinuities 4.3 Brazing, Soldering, and Mechanical Joining

5 Chapter 5: Discontinuity Classification

5.1 Inherent Discontinuities 5.2 Processing Discontinuities 5.3 Service Discontinuities

6 Chapter 6: Specific Discontinuity Types

6.1 Cracks and Fracture Modes 6.2 Porosity, Inclusions, and Lack of Fusion 6.3 Laminations, Seams, Laps, and Undercut 6.4 Relevant vs Non-Relevant Indications

7 Chapter 7: NDT Method Selection and Inspection Planning

7.1 Method Selection Principles 7.2 Surface vs Volumetric Methods 7.3 Inspection Planning and Flaw Expectations

8 Chapter 8: Ultrasonic and Radiographic Testing

8.1 Ultrasonic Testing Principles and Applications 8.2 UT Limitations, Calibration, and Evaluation 8.3 Radiographic Testing Principles and Applications 8.4 RT Limitations, Image Quality, and Safety Basics

9 Chapter 9: Magnetic Particle, Liquid Penetrant, and Visual Testing

9.1 Magnetic Particle Testing 9.2 Liquid Penetrant Testing 9.3 Visual Testing

10 Chapter 10: Electromagnetic, Leak, Acoustic Emission, and Infrared Testing

10.1 Electromagnetic / Eddy Current Testing 10.2 Leak Testing 10.3 Acoustic Emission Testing 10.4 Thermal / Infrared Testing

11 Chapter 11: Specialty Methods and Method Comparison

11.1 Neutron Radiography 11.2 Magnetic Flux Leakage 11.3 Method Comparison and Supplemental Examinations

12 Chapter 12: SNT-TC-1A Recommended Practice

12.1 SNT-TC-1A Overview and Written Practice 12.2 SNT-TC-1A Training and Experience 12.3 SNT-TC-1A Examinations and Recertification

13 Chapter 13: CP-189 Standard Practice

13.1 CP-189 Overview and Scope 13.2 CP-189 Mandatory Requirements 13.3 SNT-TC-1A vs CP-189 Comparison

14 Chapter 14: CP-105 and NDT Training Programs

14.1 CP-105 Purpose and Topical Outlines 14.2 Developing and Approving NDT Training 14.3 OJT, Mentoring, and Instructor Oversight

15 Chapter 15: Building and Managing Certification Programs

15.1 Building Qualification and Certification Programs 15.2 Administering Examinations and Evaluating Competency 15.3 Program Audits and Managing Certifications

16 Chapter 16: Codes, Standards, Procedures, and Quality

16.1 Interpreting Codes, Standards, and Specifications 16.2 Developing and Approving NDT Procedures 16.3 Acceptance Criteria and Quality Control 16.4 External Audits and Inspection Documentation

13.3 SNT-TC-1A vs CP-189 Comparison

Key Takeaways Explain This Topic AI

SNT-TC-1A is a recommended practice with guideline language; CP-189 is an ANSI standard with mandatory shall language once invoked.

Both still require an employer written program and keep the employer as certifying authority—CP-189 does not abolish the Written Practice or hand certifying power to ASNT by default.

SNT-TC-1A presents recommended training/experience minimums with more room for Written Practice tailoring; CP-189 sets mandatory minimums that shall not be reduced.

CP-189 is characteristically stricter on examination control (Level III administer/approve with records) and recertification (re-examination; max interval), which Basic loves to test.

Choose SNT-TC-1A when contracts accept recommended-practice flexibility; choose or accept CP-189 when customers, codes, or risk posture demand a non-reducible standard baseline.

Last updated: July 2026

13.3 SNT-TC-1A vs CP-189 Comparison

Quick Answer: SNT-TC-1A = recommended practice (guidelines, should/may character, Written Practice tailoring). CP-189 = ANSI standard ( shall language, mandatory minimums once invoked). Both keep the employer as certifying authority and both require a written program . CP-189 is not “SNT for nuclear only,” does not eliminate the Written Practice, and does not automatically equal ASNT Central Certification. For Basic after 1 January 2026 , both references are the 2024 editions. When in doubt on a standards item, ask: Is this soft guidance or a non-reducible shall?

This section is the highest-yield standards comparison on the Basic exam. If you can deploy the table below under time pressure and then solve short scenarios, you will convert many Domain 1 points that method-physics specialists still miss.

Master Comparison Table

• Theme SNT-TC-1A CP-189
• Document nature ASNT recommended practice ANSI/ASNT consensus standard
• Language character Should / may / recommended guidance Shall requirements when invoked

How it binds Adopted/tailored through employer Written Practice; contracts may still invoke “in accordance with” language Invoked by contract, code, specification, or written program → mandatory compliance with minimums

Employer written document Written Practice required to implement the program Written practice / certification procedure still required

Certifying authority Employer Still employer

Training & experience Recommended minimums; Written Practice may discuss tailoring concepts within the recommended-practice model Mandatory minimums that shall not be reduced by employer preference

Examinations General / specific / practical framework; Level III technical control emphasized Same multi-part idea with stricter mandatory control : exams administered or approved by Level III with documented records

Vision Program element defined in Written Practice (near vision; color as method needs) Program element under standard requirements (same practical themes; mandatory program inclusion)

Recertification Recommended maximum interval on the order of five years; continuing satisfactory performance and/or re-exam as Written Practice allows Maximum interval not more than five years ; re-examination required —experience alone not sufficient

Lapse Controlled by Written Practice re-qualification logic Reinstatement through qualification process appropriate to the lapse (not auto-reissue)

Outside agency Level III Commonly allowed when documented in Written Practice Allowed when person is qualified and arrangement/responsibilities are documented

Flexibility Higher—guideline philosophy Lower—standard floor

Typical why chosen Broad industrial use when customers accept recommended-practice programs Customers/codes want enforceable, non-reducible personnel minimums

Not the same as ASNT Central Certification ASNT Central Certification

Memorize the table’s spine in one line: recommended practice vs standard; should vs shall; tailor vs do-not-reduce; experience-possible recert stories vs re-examination required; employer still certifies under both.

Nature: Recommended Practice vs Standard

SNT-TC-1A was built so employers could build a sensible local program using ASNT’s guidelines. That flexibility is a feature, not a bug—but it means two “SNT-compliant” shops can look different at the edges.

CP-189 was built so a purchaser can write a specification that locks a floor . When CP-189 is on the contract, an auditor is not merely asking “did you think about the guidelines?” They are asking “can you show you met the standard’s requirements ?”

Exam wording cues:

• “guidelines,” “recommended,” “should,” “Written Practice may specify” → SNT-TC-1A flavor
• “shall,” “requirements,” “shall not be reduced,” “mandatory when invoked” → CP-189 flavor
• Written Practice vs Certification Procedure (Same Job, Different Force)

Do not invent a false dichotomy that only one document name is legal. Employers may title the controlling document a Written Practice , certification procedure , or similar. The exam cares that:

• A controlling employer document exists
• It implements the chosen reference (SNT and/or CP-189 as invoked)
• Under CP-189, that document cannot undercut the standard’s mandatory minimums

If a question says “CP-189 eliminates the need for a written practice,” mark it wrong .

Flexibility and Tailoring

Situation Under SNT-TC-1A thinking Under CP-189 thinking

Employer wants slightly different training path Discuss within recommended-practice / Written Practice logic Cannot go below CP-189 minimums

Customer imposes stricter rules than the ASNT document Written Practice can be stricter Written practice can be stricter; still cannot undercut CP-189 floor

Production pressure to cut exam rigor Level III must still protect recommended exam structure Level III shall protect mandatory exam administration/approval and records

Desire to recertify by signature + time-in-grade only May appear in flexible performance-evidence discussions (Written Practice dependent) Fails CP-189 re-examination character

Examination Requirements Character

Both systems expect meaningful general, specific, and practical evaluation for Level I/II paths. The Basic differentiator is force and control :

SNT-TC-1A: Level III develops, administers, or approves exams and protects integrity; recommended grading schemes (e.g., each exam at least about 70% with composite about 80%) appear as recommendations to confirm in the current edition and Written Practice.

CP-189: Examinations shall be administered or approved by a Level III with documented records —a cleaner “mandatory control” hook for multiple-choice stems.

Scenario practice: a Level II scores the practical for a peer and files no Level III approval trail. That is a program failure under either serious employer system—and an almost automatic CP-189 fail on exam items that mention mandatory Level III administration/approval.

Level III and Outside Agency Use

Both frameworks recognize that not every employer keeps a full-time Level III on payroll for every method.

Shared truth:

• Outside Level III support is a documented relationship , not an informal favor
• The employer remains the certifying authority
• Responsibilities (who writes procedures, who builds exams, who signs certifications) must be clear

CP-189 exam stems often add the explicit pair: qualified person + documented written-practice arrangement .

When Employers Choose Which

Use this decision framing on scenario items:

Lean SNT-TC-1A when:

• Contracts accept recommended-practice language
• The industry sector historically runs employer programs to SNT
• The shop wants guideline flexibility while still running a credible Written Practice
• No customer/code has imposed CP-189

Lean CP-189 when:

• Purchase orders, nuclear or other high-spec work, or client quality manuals invoke CP-189
• Stakeholders want enforceable minimums that local managers cannot bargain away
• Auditors expect shall-based evidence of training floors, Level III exam control, and recertification by exam
• The organization wants a single “standard compliance” claim rather than “we tailored a recommended practice”

Hybrid reality (common in industry, useful on exams):

An employer Written Practice may state it meets SNT-TC-1A and also meets CP-189 for work requiring the standard

Personnel performing CP-189-invoked work must meet the stricter applicable requirements

Holding ASNT Central Certification may be recognized inside either program, but it does not automatically replace employer certification unless the written program says how recognition works

Scenario Drill (Level III Thinking)

Work these mentally before exam day:

Contract says “qualify personnel to ANSI/ASNT CP-189.” Manager wants to keep last year’s looser SNT hours that undercut CP-189 minimums.

→ Not acceptable for that work. Meet CP-189 floors; update written practice and records.

Shop claims CP-189 compliance but has no written practice.

→ Fundamental failure. Standard still requires a local controlling document.

Recertification packet has only attendance sheets and a supervisor “still good” email—no re-exam under a CP-189 program.

→ Fails CP-189 recertification character. Experience alone is not enough.

Outside Level III grades exams; contract is silent; written practice never names the outside agency.

→ Documentation failure under CP-189 (and poor practice under SNT).

Candidate confuses “I passed ASNT NDT Level III Basic and UT method” with “I am certified under the employer’s CP-189 UT Level II.”

→ Different authority models. Central credential ≠ automatic employer certification.

Question stem: “Which differs most clearly?”

→ Answer family: mandatory requirements vs recommendations / shall not reduce minimums .

Stem claims CP-189 is only nuclear.

→ Reject. Nuclear often uses it; the document is not limited to that sector by Basic-level characterization.

• High-Yield Traps for the Comparison Block
• Swapping labels: calling SNT a standard or CP-189 a recommended practice
• Believing CP-189 makes ASNT the everyday shop certifier
• Believing either document is a method acceptance code
• Forgetting both need a written employer program
• Treating 2020 as current Basic default after the 2024 switch date
• Using CP-105 as a synonym for CP-189 (CP-105 = training topical outlines)

Assuming “stricter customer requirements” somehow allow cutting below CP-189 when CP-189 is invoked (stricter is allowed; looser is not)

Closing the CP-189 Arc

Across Chapter 13 you should now defend:

What CP-189 is — ANSI/ASNT standard with mandatory requirements for employer-based NDT personnel qualification/certification when invoked

• What controls the local program — the employer’s written practice/procedure implementing those requirements
• What cannot be reduced — mandatory training/experience/exam/vision/recertification floors

Who owns exams — Level III administers or approves with records; outside Level III only when qualified and documented

• How it differs from SNT-TC-1A — recommended practice vs standard; should vs shall; flexible vs non-reducible
• Edition for Basic after 1 Jan 2026 — 2024

Chapter 14 moves to CP-105 , the training topical-outline companion that feeds the training content side of both SNT-TC-1A and CP-189 programs. Keep the standards hierarchy clean: SNT = guidelines, CP-189 = mandatory standard when invoked, CP-105 = what to teach.