Chapter 8: Welding Inspection & Visual Acceptance Criteria

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📘 8.1 Importance of Welding Inspection in QA/QC

Welding inspection ensures that welds meet:

Code requirements (ASME, AWS, ISO)

Client specifications
Safety standards

🛠️ Inspection helps avoid structural failure, leaks, explosions, and rework.

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🔍 8.2 Types of Welding Inspection

Stage	Type	Purpose
Before Welding	Fit-up, alignment, material check	Ensure preparation is correct
During Welding	Arc control, interpass cleaning, parameter verification	Prevent defects from forming
After Welding	Visual, NDT (UT, RT, MPI, DPI)	Confirm weld integrity

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👁️ 8.3 Visual Inspection (VT) – First Line of QA

Conducted before any NDT

Checks include:

• Cracks, undercut, porosity

• Weld size and shape

• Slag inclusion or spatter

• Root pass visibility

Tools Used:

• Weld gauges

• Flashlight

• Mirror

• Magnifier

📌 Standards: AWS D1.1, ASME Section V, ISO 5817

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📐 8.4 Visual Acceptance Criteria (Common)

Defect	Maximum Allowance (Typical)
Undercut	≤ 1/32 inch (0.8 mm)
Porosity	Limited by size and number
Incomplete fusion	Not allowed
Excess weld reinforcement	≤ 3 mm
Slag inclusion	Not allowed
Cracks	Not allowed under any code

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📦 8.5 Weld Defects – Classification

Type	Examples
Surface Defects	Cracks, spatter, undercut
Internal Defects	Lack of fusion, porosity, slag
Dimensional Defects	Misalignment, excessive root gap

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🛠️ 8.6 Industrial Practice – Visual Weld Log

Example: Boiler Fabrication Shop

• Each weld joint logged with:

Welder ID

WPS No.
Date/time
Fit-up & root pass photo
Visual check remarks
Inspector signature

📁 This log is submitted in the final QA dossier for client/TPI.

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🧪 8.7 What if Welds Fail Visual Inspection?

Minor Defect → Repaired as per weld repair procedure
Major Defect → Joint cut out and rewelded with documentation

📌 All repairs must be tracked in a Weld Repair Log.

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🏭 8.8 Field Example: Storage Tank Welding

Scenario: Storage tank bottom weld showed porosity during VT.

Weld rejected
Joint marked, cut, and rewelded
Inspector logged defect and repair
Re-inspected before continuing work

👉 Saved from future leak risk and inspection hold from client.

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📜 8.9 Documentation Checklist for Welding Inspection

Visual Inspection Reports (VT)
Weld Maps
Repair Logs
Welder IDs and WPQ certificates
WPS & PQR copies
Calibration logs of measuring tools

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🔄 8.10 Integration with NDT

Visual inspection is always:

First step before RT, UT, DPI
Required even if NDT passes
Used to detect surface issues that RT/UT may miss

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🔑 8.11 Summary

Visual inspection is a non-negotiable part of QA/QC

Follows code-based acceptance criteria
Saves cost and rework by detecting early issues
Requires trained personnel and documented process

Quiz: Welding Inspection & Visual Standards

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Q1. Which of the following is the first step in the welding inspection process?
A) Radiographic Testing
B) Ultrasonic Testing
C) Visual Inspection
D) Heat Treatment
🟩 Correct Answer: C

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Q2. Which weld defect is generally not allowed under any welding code?
A) Spatter
B) Undercut
C) Porosity
D) Crack
🟩 Correct Answer: D

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Q3. Visual inspection should be done:
A) Only after welding is completed
B) Before, during, and after welding
C) Only during welding
D) Only when instructed by the client
🟩 Correct Answer: B

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Q4. Which tool is not commonly used in visual inspection of welds?
A) Weld gauge
B) Magnifier
C) Flashlight
D) Voltmeter
🟩 Correct Answer: D

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Q5. Which standard is commonly used for visual inspection in structural welding?
A) ASME Section II
B) AWS D1.1
C) API 650
D) ISO 31000
🟩 Correct Answer: B

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Q6. What is the typical maximum allowable undercut in a weld?
A) 5 mm
B) 0.5 mm
C) 1/32 inch (≈0.8 mm)
D) 3 mm
🟩 Correct Answer: C

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Q7. Which of the following is considered a dimensional defect in welding?
A) Crack
B) Slag inclusion
C) Misalignment
D) Porosity
🟩 Correct Answer: C

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Q8. If a weld fails visual inspection due to porosity, what is the typical next step?
A) Accept as it is
B) Ignore the defect
C) Repair the weld as per procedure
D) Start the entire project again
🟩 Correct Answer: C

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Q9. A Weld Visual Log typically includes:
A) Project budget
B) Painting specification
C) Welder ID, joint info, inspection result
D) Only welder's salary
🟩 Correct Answer: C

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Q10. Visual inspection is required even if:
A) NDT reports are already accepted
B) The client agrees to skip it
C) The welder is certified
D) Welds look okay from a distance
🟩 Correct Answer: A