Weld Inspection Methods: Visual, Guided-Bend, and Weld Symbols Introduction

Why Weld Inspection Matters

A weld that looks finished is not necessarily a weld that is safe. Structural welds in buildings, bridges, and pressure-containing systems carry loads that can injure or kill if a joint fails. Weld inspection is the process of comparing the actual weld against an accepted standard — in structural steel work, that standard is AWS D1.1 Structural Welding Code — Steel. Learning to inspect your own work and your partner's work before the part leaves your hands is a core professional skill and a direct preparation for the AWS D1.1 Certified Welder performance test.

Safety Before You Start

Inspection takes place near hot metal and grinding operations. Wear your full PPE even when you are not welding:

• Safety glasses or a face shield whenever you handle freshly welded coupons or watch grinding.
• Heat-resistant gloves when handling specimens that may still be warm.
• Steel-toed boots — coupons and the bend jig are heavy.
• Keep the guided-bend jig area clear of bystanders; the hydraulic or mechanical ram applies significant force and can eject fragments if a specimen breaks unexpectedly.
• When cleaning a coupon with a wire brush or grinder before inspection, use hearing protection and guard the grinder properly.

Always follow your shop's lockout/tagout (LOTO) procedure before adjusting or repositioning the guided-bend jig.

Visual Inspection: The First and Most Important Test

AWS D1.1 requires visual inspection (VT) on every completed weld before any other test is performed. Visual inspection is fast, requires no special equipment beyond a weld gauge and good lighting, and catches the most common discontinuities.

Inspection sequence under AWS D1.1:

1. Clean the weld. Remove slag, spatter, and scale. A wire brush is usually sufficient; a grinder may be used if its marks will not mask a crack.

2. Check for cracks. Examine the weld face, toes, and heat-affected zone (HAZ) under good light. Use a magnifying glass when in doubt. Any crack is a reject — no dimensional exception exists.

3. Measure undercut. Undercut is a groove melted into the base metal along the weld toe. Use a weld gauge (also called a fillet gauge or V-WAC gauge) to measure depth. AWS D1.1 limits undercut depth for statically loaded structures; consult the current edition's applicable table for the exact limit, which depends on weld orientation and loading condition.

4. Measure weld reinforcement. On a groove weld, reinforcement is the weld metal above the base metal surface. Excessive reinforcement creates a stress riser. AWS D1.1 sets a maximum height; measure with the weld gauge across the crown.

5. Check fusion and overlap. Incomplete fusion appears as a seam at the weld toe where the weld metal did not bond to the base metal. Overlap (rollover) is weld metal that flows over the base metal surface without fusing — both are rejects.

6. Verify crater fill. The crater at the end of a weld bead must be filled to avoid crater cracks. A crater that is cracked or grossly unfilled is a reject.

Record every measurement and judgment on the standardized inspection report form. Cite the specific AWS D1.1 table or paragraph that defines the acceptance criterion you applied — this habit is required for the credential exam.

Guided-Bend Test: Mechanical Verification

The guided-bend test is a destructive mechanical test that reveals subsurface discontinuities — incomplete fusion, porosity clusters, or slag inclusions — that visual inspection cannot detect. It is required for welder qualification under both AWS D1.1 and ASME Section IX.

How it works: A specimen cut from the groove weld coupon is placed in a guided-bend jig (also called a wraparound or plunger-type jig). The jig bends the specimen around a die of a specified radius until the specimen forms a U-shape (180° bend). Two specimen orientations are tested:

• Face-bend — weld face placed in tension (on the outside of the bend)
• Root-bend — weld root placed in tension

Acceptance criterion: After bending, examine the convex (tensile) surface. The weld and HAZ must not show any open discontinuity exceeding the dimension specified in AWS D1.1 for the applicable test. Corner cracks that originate at the edge of the specimen rather than in the weld itself are typically not cause for rejection — check the current edition for the specific rule. Any crack or open discontinuity greater than the allowed size on the convex surface is a reject.

The jig dimensions — die radius, shoulder width — are determined by base metal thickness and type. Always verify the jig is set up for your specimen before bending.

Weld Symbols: Reading the Blueprint

Before you can inspect a weld correctly, you must know what the designer intended. Weld symbols on engineering drawings follow the AWS A2.4 standard and communicate:

• Weld type (groove, fillet, plug, etc.) — shown by the symbol on the reference line
• Weld size — number to the left of the symbol
• Length and pitch — numbers to the right
• Which side of the joint — arrow side (below the line) or other side (above the line)
• All-around weld — circle at the flag junction
• Field weld — filled flag at the junction

Connecting symbol literacy to inspection: if the symbol calls for a 5/16 in. fillet weld, your gauge measurement confirming actual throat or leg size must match. A weld that is undersized fails inspection regardless of appearance.

Connecting to Your Credentials

The visual inspection sequence and the guided-bend test procedure appear directly in the AWS D1.1 Certified Welder performance test. NCCER Welding Levels 2 and 3 assess blueprint reading including weld symbols. ASME Section IX pipe qualification also uses guided-bend specimens as the primary mechanical acceptance test. Mastering these three skills now prepares you for every credential exam in this program.