3.3 Visual & Destructive Test Specimen Layout

3.3 Visual & Destructive Test Specimen Layout

A completed welder qualification coupon passes through three gates in order: visual examination (6.4), then destructive testing (6.5) or — at the company's option — nondestructive testing (6.6). Failing any gate fails the welder.

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1. Visual Examination (6.4)

Before any specimen is cut, the intact test weld must show:

• No cracks and no inadequate penetration, anywhere around the joint.
• A neat, workmanlike appearance acceptable to the company.
• Burn-through: butt welds allow no BT at all. Branch connections allow no BT longer than 1/4 in. (6 mm), and the sum of maximum dimensions of separate unrepaired BTs may not exceed 1/2 in. (13 mm) in any continuous 12 in. (300 mm) of weld.
• Undercut: external (and internal, when practical) undercut is evaluated to 9.7 / Table 8; exceeding the Table 8 limits disqualifies the welder.
• All dimensional requirements of the WPS must be met. With semiautomatic or mechanized welding, filler wire protruding into the pipe is kept to a minimum; the company sets the acceptance criteria for protruding wires.

Failure at visual eliminates all further testing — no specimens are cut from a visually failed coupon.

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2. Destructive Specimen Counts (Table 7)

*For OD ≤ 1.315 in. (33.4 mm), the company chooses: one full-section tensile specimen, or nick-break + root bend specimens from two welds.

Specimens are cut at the Figure 12 locations (full circumference) or Figure 13 locations (half circumference), or spaced equidistantly; they never include the longitudinal seam weld, and they are air-cooled to ambient temperature before testing.

Specimen Failure and Replacement

• Nick-break: if any specimen exceeds the 5.6.3.3 soundness limits, the welder is disqualified — replacement of a nick-break specimen is not permitted for welder qualification.
• Bend: if a bend specimen fails but the company judges the imperfection unrepresentative of the weld, ONE additional specimen cut adjacent to the failed one may be substituted; if that specimen also fails, the welder is disqualified. Welds are not rejected solely because a specimen fails to bend to the full U-shape — cracked-open specimens whose exposed surfaces meet 5.6.3.3 are acceptable.

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3. Branch and Fillet Weld Testing

The branch connection test weld yields exactly four nick-break specimens from the Figure 10/11 locations around the branch perimeter (top and bottom crotch, both saddles), each about 1 in. (25 mm) wide and notched approximately 1/8 in. (3 mm) deep on each edge at the weld centerline. They are broken in the weld — vise-and-hammer or tension — and the exposed surfaces must meet the 5.8.3 limits: complete penetration and fusion, individual gas pockets ≤ 1/16 in. (1.6 mm), combined gas area ≤ 2%, slag ≤ 1/32 in. (0.8 mm) deep and ≤ 1/8 in. (3 mm) or t/2 long, separated by ≥ 1/2 in. (13 mm).

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4. The NDT Alternative (6.6) and the GMAW-S Rule

If the company requests it, a butt-weld qualification coupon may be examined by radiography (evaluated to Section 9.3) or automated ultrasonic testing (AUT) (to Section 9.6) instead of — or in addition to — destructive testing. Two limits apply:

• NDT may not be used to locate sound or defective areas and then selectively destructively test those areas to qualify or disqualify a welder.
• If the company uses BOTH NDT and destructive testing, failing either acceptance standard fails the test weld (6.7).

GMAW-S. Short-circuiting gas metal arc welding is prone to tight, planar lack-of-sidewall-fusion (cold lap) that radiography can miss. Rather than banning NDT for GMAW-S coupons, the 22nd edition controls the process through the welder essential variables: a welder may use GMAW-S in production only for the same passes welded with GMAW-S during the qualification test (6.2.2).

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5. Nick-Break and Bend Mechanics (5.6.3-5.6.4)

The destructive tests behind the Table 7 counts carry their own specimen geometry and acceptance rules, and exam questions target them directly.

Nick-Break Specimen Geometry and Method (5.6.3)

• Butt-weld nick-break specimens are approximately 9 in. (230 mm) long and 1 in. (25 mm) wide, notched approximately 1/8 in. (3 mm) deep on each side at the weld centerline, with smooth, parallel edges.
• When experience shows a mechanized or semiautomatic weld will fracture through the pipe instead of the weld, the external reinforcement may be notched up to 1/16 in. (1.6 mm) to force the break into the weld.
• The specimen is broken through the weld by any convenient method — pulling, bending, or striking — and the exposed fracture surface must be at least 3/4 in. (19 mm) wide to be evaluated.

The 5.6.3.3 Soundness Limits

Every exposed nick-break (and broken tensile) surface is judged to one soundness rule: complete penetration and fusion; the greatest dimension of any gas pocket may not exceed 1/16 in. (1.6 mm), and the combined gas area may not exceed 2% of the exposed surface; slag inclusions may not be more than 1/32 in. (0.8 mm) deep nor longer than 1/8 in. (3 mm) or one-half the specified wall thickness, whichever is smaller, with at least 1/2 in. (13 mm) of separation between adjacent slag inclusions. Fisheyes are not cause for rejection. Imperfections on the fracture are dimensioned per Figure 6.

Bend Acceptance (5.6.4.3)

After bending in the guided-bend jig, a specimen passes when the convex surface shows no crack or other imperfection exceeding 1/8 in. (3 mm) or one-half the specified wall thickness, whichever is smaller, in any direction, in the weld or between the weld and the fusion zone. Corner cracks shorter than 1/4 in. (6 mm) that originate along the specimen edges during bending are disregarded unless obvious evidence ties them to slag inclusions or other internal defects.

The Welder-Qualification Tensile Shortcut

For welder qualification — unlike procedure qualification — the tensile strength does not need to be calculated, and the tensile test may be omitted; the specimens designated for tensile testing are then simply nick-broken and evaluated to the 5.6.3.3 soundness limits.