ASTM A1016 Standard

What is ASTM A1016?

ASTM A1016 is the general requirements specification that provides the common technical framework for all ferritic alloy, austenitic alloy, and stainless steel tube specifications. It consolidates requirements that would otherwise be repeated in every individual product specification, such as dimensional tolerances, test methods, NDE procedures, marking rules, and certification requirements.

In the case of conflict between A1016 and a product specification, the product specification takes precedence. In the case of conflict between either of those and the purchase order, the purchase order takes precedence. This three-tier hierarchy — purchase order > product specification > A1016 — gives buyers control over the final requirements.

Mechanical Tests Defined in ASTM A1016

A1016 defines the standard procedures for seven mechanical tests. Individual product specifications reference these procedures and specify which tests apply, how many samples per lot, and acceptance criteria.

Flattening Test (Section 18)

A tube section (2-1/2 in. / 60 mm min for seamless; 4 in. / 100 mm min for welded) is flattened between parallel plates in two steps. Step 1 tests ductility; no cracks until the plate gap reaches the calculated H-value. Step 2 tests soundness; flattening continues until the specimen breaks or walls meet. For welded tubes, the weld is positioned at 90° to the force.

Reverse Flattening Test (Section 19)

A 4 in. (100 mm) section of welded tube is split 90° from each side of the weld, opened flat, and the weld is placed at the point of maximum bend. No cracks, lack of penetration, or flash-removal overlaps are permitted in the weld. This test applies to welded tubes down to 1/2 in. (12.7 mm) OD.

Reverse Bend Test (Section 20)

A 4 in. (100 mm) section is split 90° from each side of the weld, opened, and bent around a mandrel with a maximum thickness of 4× wall thickness. The weld faces the mandrel at the point of maximum bend. No cracking or weld-thinning overlaps are permitted. This test does not apply when the wall is ≥10% of OD, or the wall ≥0.134 in. (3.4 mm), or the OD <0.375 in. (9.5 mm).

Flaring Test (Section 21)

A 4 in. (100 mm) tube section is expanded with a 60°-included-angle tool until the ID increase reaches the percentages in Table 4. Minimum expansion ranges from 21% (ID/OD ratio 0.9) to 68% (ID/OD ratio 0.3) for carbon-molybdenum and austenitic steels. No cracking or unacceptable imperfections are permitted.

Flange Test (Section 22)

A tube section must form a flange at a right angle to the tube body without cracking. Flange width for austenitic grades is not less than 15% of the specified OD for all sizes. Carbon and alloy steels have graduated requirements: 15% up to 2-1/2 in. OD, 12.5% for 2-1/2 to 3-3/4 in. OD, and 10% for 3-3/4 to 8 in. OD.

Hardness Test (Section 23)

Hardness testing method depends on wall thickness: Brinell, Rockwell, or Vickers for walls ≥0.200 in. (5.1 mm); Rockwell or Vickers for walls 0.065–0.200 in. (1.65–5.1 mm); Vickers only for walls <0.065 in. (1.65 mm) when the product specification permits it. For welded or brazed tubes, hardness is measured away from the joints.

Non-Destructive Examination (NDE)

A1016 Section 24 defines four NDE methods for tube examination: ultrasonic (E213), eddy current for ferromagnetic materials (E309), eddy current for non-magnetic materials (E426), and flux leakage (E570). NDE is performed after all deformation, heat treatment, welding, and straightening operations.

Reference standards are made from the same grade, size, finish, and heat-treatment condition as the production tubing. For eddy current, the standard contains a 0.031 in. (0.8 mm) drilled hole or a notch 12.5% of wall / 0.004 in. (0.1 mm) deep (whichever is greater). Signal-to-noise ratio must be 2.5:1 or greater.

Tubes producing signals equal to or greater than the reference standard are designated “suspect” and separated. They are either rejected, accepted by visual evaluation (for surface imperfections like scratches, dings, straightener marks), or rejected if caused by cracks or unidentifiable imperfections. Imperfections exceeding 0.004 in. (0.1 mm) or 12.5% of the minimum wall (whichever is greater) in depth cause rejection.

Hydrostatic Test (Section 25)

When specified by the purchaser (instead of NDE), each tube is hydrostatically tested to a minimum pressure calculated by:

P = 32,000 × t / D (inch-pound)  or  P = 220.6 × t / D (SI)

Where P = test pressure (psi or MPa), t = specified wall thickness (in. or mm), and D = specified OD (in. or mm). The calculated pressure is rounded to the nearest 50 psi (0.5 MPa) for pressures below 1000 psi (7 MPa), and to the nearest 100 psi (1 MPa) for pressures 1000 psi and above. The minimum required test pressure need not exceed 1000 psi (7 MPa) regardless of the calculation result. Test pressure is held for a minimum of 5 seconds.

Repair Welding (Section 13)

Repair welding of base metal defects is permitted only with the purchaser’s approval. Repaired tubes are marked “WR,” the filler metal composition must be suitable for the base metal, defects are ground out before welding, and each repaired length is reheat-treated and re-examined by NDE. Welding procedures and welders/operators must be qualified per ASME Section IX.

Certification, Marking, and Inspection

A1016 requires the producer to furnish a certificate of compliance stating that the material was manufactured, tested, and inspected per the specification. A signature is not required, but the document must be dated and clearly identify the certifying organisation.

The test report includes: heat number, heat analysis, product analysis (when specified), tensile properties, flattening/flaring/flange test results, hardness values, hydrostatic test pressure or NDE method, and impact test results (when applicable).

Each tube length is stencilled with the manufacturer’s name or brand, specification number, and grade. For tubes less than 1-1/4 in. (31.8 mm) diameter or under 3 ft (1 m) length, marking may be placed on a tag attached to the bundle or box. For austenitic steel tubes, marking paint or ink shall not contain zinc, lead, or copper salts. These metals cause corrosive attack when the tube is heated.

Physical Properties of Common Tube Grades

While A1016 does not specify physical properties (these are grade-specific), the following values apply to the austenitic 304 stainless steel tube and 316 stainless steel tube grades most commonly ordered under A1016 specifications.