2.3 Mechanical Testing Requirements and Specimen Preparation

2.3 Mechanical Testing Requirements and Specimen Preparation

Once a procedure qualification test joint has been welded, it is cut into destructive-test specimens per Section 5.6 and Table 3 of API 1104:2021. Destructive testing verifies tensile strength, internal soundness, and ductility of the joint before the WPS may be used in production.

Specimen Counts — Table 3 (22nd Edition)

Counts depend on pipe outside diameter AND on whether wall thickness exceeds 0.500 in. (12.7 mm):

Three Table 3 footnotes are exam favorites:

• (a) For materials with nominal SMYS greater than Grade X42, a minimum of one tensile test is required.
• (b) Nick-break tests are not required when the procedure weld is examined by radiography or ultrasonic testing and found acceptable per Section 9 — but if the RT/UT result is unacceptable, the procedure is rejected.
• (c) Below 2.375 in. OD, two test joints are made to obtain the required specimens; at or below 1.315 in. (33.4 mm) OD, one full-section tensile specimen may be tested instead.

Specimens are removed at equally spaced locations around the circumference (Figure 3), may be rotated at the company's option provided equal spacing, and never include the pipe's longitudinal seam weld. All specimens are air-cooled to ambient temperature before testing.

Specimen Geometry and Preparation

• Tensile (5.6.2): full-thickness strap, full-section or reduced-section per Figure 4; weld reinforcement may be removed. Tensile strength = maximum load ÷ smallest cross-sectional area measured before loading.
• Nick-break (5.6.3): approximately 9 in. (230 mm) long × 1 in. (25 mm) wide, notched on each side at the weld centerline approximately 1/8 in. (3 mm) deep, edges smooth and parallel. Broken by pulling, bending, or striking; the exposed fracture must be at least 3/4 in. (19 mm) wide. For mechanized/semiautomatic welds prone to breaking through the pipe instead of the weld, the external reinforcement may be notched up to 1/16 in. (1.6 mm) from the original weld surface.
• Root/face bend (5.6.4): approximately 9 in. × 1 in.; long edges rounded; cover and root reinforcement removed flush; surfaces smooth with any scratches light and transverse to the weld; never flattened before testing.
• Side bend (5.6.5): approximately 9 in. long × 1/2 in. (13 mm) wide (cut oversize then machined to width); reinforcement removed flush.

Guided-Bend Jig (Figure 8)

Bend specimens are forced into a U-shape in a guided-bend jig whose radii are fixed by the standard: plunger radius 1-3/4 in. (45 mm), die radius 2-5/16 in. (60 mm), die width 2 in. (50 mm). The company specifies the fixture and bend radii, which may not exceed the Figure 8 radii.

Additional Rules Candidates Miss

• Small pipe needs two joints. For pipe under 2.375 in. (60.3 mm) OD, two test joints are welded to obtain the required specimens — one nick-break and one root bend from each. At or below 1.315 in. (33.4 mm) OD, a single full-section tensile specimen may replace them.
• Location discipline. Specimens come from the Figure 3 locations; the company may rotate the locations provided they remain equally spaced around the circumference, and specimens never include the pipe's longitudinal seam weld.
• Cooling before testing. All specimens are air-cooled to ambient temperature before testing — no quenching to speed the lab schedule.
• Macroetch option. At the company's option, nick-break specimens for semiautomatic or mechanized procedure qualifications may be macroetched before being nicked (5.6.3.1 Note 2), exposing the weld profile before fracture.
• Hardness/toughness additions. When the company specifies hardness or toughness requirements (Category II), it also specifies the specimen preparation, testing, and acceptance criteria for those measurements.