API 5ST pdf download Specification for Coiled Tubing U.S. Customary and SI Units
Surface macrohardness shall also be measured on the surfaces of skelp-end and tube-to-tube welds. The hardness values shall comply with the requirements given in Table A.2.
By agreement, and when specified on the purchase agreement, additional macro- or microhardness tests shall be taken at specified locations.
6.2.3 Grain Size For all grades, the grain size shall be ASTM grain size 8 or finer.
6.2.4 Flattening Test All coiled tubing products that are produced to this specification shall comply with the flattening requirements shown in Table A.4. The acceptance criteria for flattening tests are as follows. No cracks or breaks exceeding 0.125 in. (3.2 mm) in any direction in the weld or the parent metal shall occur on the outside surface until the distance between the plates is less than the value calculated by the equations given in Table 4. Cracks that originate at the edge of the specimen and are less than 0.25 in. (6.4 mm) long shall not be cause for rejection. The minimum test frequency for milled lengths of coiled tubing shall be at least one flattening test from each end of each continuously milled length. 6.2.5 Flaring Test All grades of coiled tubing shall be subjected to a flaring test as specified in 8.3.3.
The acceptable criterion is no cracking in the weld seam region or base metal up to a minimum ID expansion of ID f (defined in 8.3.3).
6.2.6 Fracture Toughness Test Fracture toughness testing for Charpy V-Notch energy is required where requested on the purchase order, considering the limitations imposed by diameter and thickness of the tubing ordered. Full size transverse (to the tube direction) specimens should be used when possible based upon pipe geometry per ASTM A370. When full size transverse specimens are not possible, the largest sub size specimens shall be used ( 3 / 4 , 1 / 2 ). When transverse specimens are not possible, 1 / 2 size longitudinal specimens shall be used. The test specimens shall be oriented circumferentially from a location 90° from the weld with the axis of the notch oriented through the pipe wall.
All tests shall be conducted at 32 °F (0 °C). The minimum absorbed energy requirements for full size specimens shall be 20 ft-lb (27 J) average, 15 ft-lb (20 J) minimum individual for full size transverse specimens, 30 ft-lb (41 J) average, 20 ft-lb (27 J) minimum individual for full size longitudinal specimens. The minimum absorbed energy reduction factors for sub-size specimens are: 0.8 for 3 / 4 size, and 0.55 for 1 / 2 size. By agreement between the purchaser and manufacturer, alternate tests may be used if the above requirements can not be met due to pipe geometry.
6.2.7 Metallographic Examination A metallographic examination of a weld cross section shall be performed on both ends of each milled length. The specimen shall be ground, polished, and etched in such a way that the microstructure of the base metal and weld zone can be investigated. In the case of “flash-in” tubing, the profile of the weld root shall show that it is continuous, with smooth curves blending into the inside diameter of the tubing.
7 Dimensions, Masses per Unit Length, Lengths, Defects, and End Finishes
7.1 General Coiled tubing shall be furnished in the sizes, wall thicknesses, and masses shown in Table A.5 as specified on the purchase agreement. (See Table A.6 for the SI unit equivalents of the U.S. customary values given in Table A.5).
7.2 Length of Strings and Sections of Strings
The minimum and maximum length of the tubing shall be specified on the purchase agreement.
The accuracy of length measuring devices shall be equal to or less than 1 %.
7.2.2 Coiled Tubing String Length Profile
The preliminary length profile of a tapered coiled tubing string shall be specified by the purchaser following established criteria for the proposed service, and attached to the purchase agreement form. The final coiled tubing string length profile shall be by agreement between the purchaser and the manufacturer.