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Tests for mechanical and technological properties of tubes
Published:2013-07-07 14:38:07    Text Size:【BIG】【MEDIUM】【SMALL

Tests for mechanical and technological properties of tubes

Selection of tests shall be governed by relevant standards that apply to individual products. These values apply for dimensions and material condition specified in the standards. Unless otherwise specified, tests relate to samples taken longitudinally.

Tests for mechanical properties of tubes

Tensile test at ambient temperature
Determined values:
The upper yield point ReH, or 0.2% of the agreed limit Rp0, 2 (MPa)
Tensile strength Rm (MPa)
Elongation at break Amin. (%)
EN 10002-1 is replaced by EN ISO 6892-1, DIN 50145, ISO / STN 42 0310, ASTM A370 standards and TDP standard

Tensile test at elevated temperature (optional)
Determined values:
Agreed yield strength Rp0, 2 at a given temperature (MPa)
EN 10002-5, DIN 50145, ISO / STN 42 0312

Hardness test (optional, as required by the agreement and options)
Determined values:
The hardness values according to the individually used (possible) methods. The possibility to set an approximate value of the tensile test by conversion from hardness value.
Brinell: EN 10003, EN ISO 6506, DIN 50 351, CSN 42 0371, ASTM E 10
Rockwell: EN 10004, EN ISO 6508, DIN 50103, ASTM E 18
Vickers: EN ISO 6507, DIN 50133, ASTM E 92, ASTM E 384
DIN 50 150 contains a table of informative calculation of "hardness - tensile strength Rm."

Bending impact test at 20 ° C
Bending impact test at low temperatures
The possibility of making the examination depends on the dimension of tubes.
Determined values:
The minimum average impact energy KV (J).
EN 10045-1, DIN 50115, ISO / STN 42 0381, ASTM A370 (ASME SA 370)

Creep tests (creep) - are not subject of tube acceptance, steel is long-term tested during the verification of the production technology.
Determined values: 
Yield creep RT (t / A / T) is the strain that during the time t at temperature T causes A (%) mean of permanent elongation measured length of the trial bar. e.g. A = 1% for 10 000 hours at 500 ° C - RT 10 000/1/500 = 70 MPa.

Stress-rupture RMT (t / T) is the strain at which permanent operation at temperature T is the mean time to fracture t. e.g. stress of 100 MPa causes at the temperature of 600 ° C for 10 000 hours fracture of part - RMT 10 000/600 = 100 MPa. Data are presented in the Annexes of standards and may be used for calculations. At present, in practice, the second value is used and for strength calculations it is compared with the below creep area of the yield stress at higher temperatures. The lower value is always used.

EN 10 291 + bbl 1, CSN / STN 42 0351 (42 0302), ASTM E139

Tests of metal fatigue - are not included in the TDP for the tubes delivery.

Tests of the technological properties of tubes

Bending test
The test examines the ability of plastic deformation in metallic tubes of circular cross section. The tube bends around the pulleys with the specified radius, up to a prescribed angle. While this is being done, visible cracks are not allowed to form. Tubes tested are with a diameter of 65 mm. EN 10232 is replaced by EN ISO 8491, ISO 42 0415.3, ASTM A370 (A 2, A 2.5)

Test by flattening 
The sample is flattened between the plates until the distance between them reaches a value H prescribed by standard. This depends on the steel, forming constant C and the tube dimensions.
After the test, the samples must not have visible cracks and fissures.
EN 10233 is replaced by EN ISO 8492, DIN 50136, DIN 42 0415.4, ASTM A370
(ASME SA 370) and TDP standard
The test is performed to a diameter of 600 mm and a wall thickness of less than 15% of D.

Flaring test 
The sample is expanded by a 60 ° tapered mandrel until the percentage of flaring of the outside diameter obtains values stated in standard. After the test, the samples must not have visible cracks and fissures.
EN 10234 is replaced by EN ISO 8493, DIN 50135, ISO / STN 42 0415.5, ASTM A370 (ASME SA 370) and TDP standards.
The test is performed to a diameter of 150 mm and wall thickness 10 mm.

Flanging test 
The samples end is formed into a flange, which lies in a plane perpendicular to the axis of the tube until value reaches the value of the outside diameter of flange, which is determined in the standard of the product.
EN 10235 is replaced by EN ISO 8494, DIN 50139, ISO / STN 42 0415.6, ASTM A370 (ASME SA 370) and TDP standards.
Tube dimensions: D up to 150 mm, T up to 10 mm.

Ring expanding test (ring test)
The test ring is expanded by a mandrel until it fractures. On the surface, in addition to the fracture may not be visible cracks and fissures.
EN 10236 is replaced by EN ISO 8495, DIN 50137, ISO / STN 42 0415.7
Tube dimensions: D = 18 to 150 mm, T = 2 to 16 mm.

Tensile test of a ring
The test ring is suspended on two circular cylinders (pins). Axes of pins are parallel and the pins to each other and are moving. Pins are moving away from each other, thereby loading the ring in the transverse direction of its axis, until breakage occurs. Outside of the breakage area no cracks should be developing.
The test is performed on tubes with an outside diameter above 150 mm, with inside diameter above 100 mm and wall thickness up to 40 mm.
EN 10237 is replaced by EN ISO 8496, DIN 50 138.

Other supplemental technological tests

Crush test / Upsetting test 
The tested ring is placed perpendicular to the surface and is crushed to the value prescribed by the standard of the product. 

Reverse flattening test 
It is used in electrically welded tubes. The sample is semi-circular (180 °) and the weld is placed on the top semicircle. The sample is flattened into a plane.

Bend test of welds 
It is used to determine the plasticity of fusion welds. 

ISO 377
Steel and steel products - Location of sampling and preparation of samples and test pieces for mechanical tests.
The definition of the status and nomenclature of heat treatment of steel tubes .
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