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API SC6 Winter Meeting New Business: API Spec 6A Tensile Test Specimen Requirements

API SC6 Winter Meeting New Business: API Spec 6A Tensile Test Specimen Requirements. Tim Haeberle 8 February 2011. Contents. 1. Correction Of Metric Equivalent For Tensile Test Specimens - ISO Version 2. Clarification Of Spec Reference For Tensile Test Specimens

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API SC6 Winter Meeting New Business: API Spec 6A Tensile Test Specimen Requirements

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  1. API SC6 Winter MeetingNew Business:API Spec 6A Tensile Test Specimen Requirements Tim Haeberle 8 February 2011

  2. Contents 1. Correction Of Metric Equivalent For Tensile Test Specimens - ISO Version 2. Clarification Of Spec Reference For Tensile Test Specimens 3. Clarification Of Tensile Test Acceptance Criteria For Mandrel Tubing Hangers And Casing Hangers

  3. Metric Equivalent For Tensile Test Specimens

  4. The Problem CURENT WORDING – ISO Version: • 5.6.4.1 (for TC’s for PSL 1) “Standard-sized, 12,7 mm (0,500 in) diameter tensile specimens shall be used to qualify carbon, low-alloy and stainless steels, unless the physical configuration of the TC prevents their use. In this case, the standard sub-size specimens referenced in ASTM A370 may be used. Either standard 12,7 mm (0,500 in) or standard sub-size specimens (see ASTM A370) may be used to qualify CRA materials.” • 5.7.4.1 (for QTC’s for PSL 2-4) “Standard-sized, 12,7 mm (0,500 in) diameter tensile specimens shall be used, unless the physical configuration of the QTC prevents their use. In this case, the standard sub-size specimens referenced in ASTM A370 may be used.” PROBLEM: • ASTM A370 specifies the metric equivalent for the 0,500 in specimen as 12,5mm, not 12,7 mm.

  5. ASTM A370 Figure 4

  6. The Solution PROPOSED EDITORIAL CORRECTIONS – ISO Version: • 5.6.4.1 “Standard-sized, 12,5 mm (0,500 in) diameter tensile specimens shall be used to qualify carbon, low-alloy and stainless steels, unless the physical configuration of the TC prevents their use. In this case, the standard sub-size specimens referenced in ASTM A370 may be used. Either standard 12,5 mm (0,500 in) or standard sub-size specimens (see ASTM A370) may be used to qualify CRA materials.” • 5.7.4.1 “Standard-sized, 12,5 mm (0,500 in) diameter tensile specimens shall be used, unless the physical configuration of the QTC prevents their use. In this case, the standard sub-size specimens referenced in ASTM A370 may be used.” JUSTIFICATION: • The metric equivalent dimension needs to be corrected to match what is specified in ASTM A370, the referenced standard. • The API Version has been corrected in Annex O.

  7. Spec Reference For Tensile Test Specimens

  8. The Problem CURRENT WORDING • 5.3.5.2 PSL 2 to 4 tensile testing (for mandrel tubing hangers and casing hangers) “b) test method: Perform tensile tests at room temperature in accordance with the procedures specified in ISO 6892-1or ASTM A370. Perform a minimum of one tensile test. The results of the tensile test(s) shall satisfy the manufacturer’s specified requirements.” • 5.4.2.3 PSL 2 to 4 tensile testing (for bodies, bonnets, and end and outlet connections) “b) test method: Perform tensile tests at room temperature in accordance with the procedures specified in ISO 6892-1or ASTM A370. Perform a minimum of one tensile test. The results of the tensile test(s) shall satisfy the applicable requirements of Table 6.”

  9. The Problem CURRENT WORDING • Section 5.6.4.1 (for TC’s for PSL 1) Paragraph 5 - “Standard-sized, 12,7 mm (0,500 in) diameter tensile specimens shall be used to qualify carbon, low-alloy and stainless steels, unless the physical configuration of the TC prevents their use. In this case, the standard sub-size specimens referenced in ASTM A370 may be used. Either standard 12,7 mm (0,500 in) or standard sub-size specimens (see ASTM A370) may be used to qualify CRA materials.” • Section 5.7.4.1 (for QTC’s for PSL 2-4) Paragraph 6 - “Standard-sized, 12,7 mm (0,500 in) diameter tensile specimens shall be used, unless the physical configuration of the QTC prevents their use. In this case, the standard sub-size specimens referenced in ASTM A370 may be used.” PROBLEM: • These paragraphs do not state that the “standard” specimens are ASTM standard-sized specimens, although they do state that when sub-size specimens are used, they shall be the ASTM A370 standard sub-size specimens. This leaves open the use of ISO 6892-1 standard specimens.

  10. The Solution PROPOSED REVISIONS: • Section 5.6.4.1 Paragraph 5 - “ASTM A370standard-sized, 12,5 mm (0,500 in) diameter tensile specimens shall be used to qualify carbon, low-alloy and stainless steels, unless the physical configuration of the TC prevents their use. In this case, the standard sub-size specimens referenced in ASTM A370 may be used. Either standard 12,5 mm (0,500 in) or standard sub-size specimens (see ASTM A370) may be used to qualify CRA materials.” • Section 5.7.4.1 Paragraph 6 - “ASTM A370standard-sized, 12,5 mm (0,500 in) diameter tensile specimens shall be used, unless the physical configuration of the QTC prevents their use. In this case, the standard sub-size specimens referenced in ASTM A370 may be used.”

  11. The Solution JUSTIFICATION: • “ASTM A370” needs to be added to clarify that the only specimen sizes currently permitted are the ASTM A370 specimen sizes. • ISO 6892-1 includes different size specimens that have a higher gage length to diameter ratio. • The longer relative gage length in the ISO 6892-1 specimens can result in failure to meet the API 6A specified elongation acceptance criteria. • The use of ASTM A370 specimen sizes meets ISO 6892-1, since ISO 6892-1, section 6.1.1, paragraphs 7 and 8 state: “The dimensional tolerances of the test pieces shall be in accordance with the Annexes B to E (see 6.2).” Other test pieces such as those specified in relevant product standards or national standards may be used by agreement with the customer, e.g. ISO 3183 [1] (API 5L), ISO 11960 [2] (API 5CT), ASTM A370[6], ASTM E8M [7], DIN 50125 [10], IACS W2 [13], and JIS Z2201 [14]”. • ASTM A370 specimen sizes are routinely used in the US and Europe.

  12. ISO 6892-1 Circular Test Specimens

  13. Tensile Test Acceptance Criteria For Mandrel Tubing Hangers And Casing Hangers

  14. The Problem CURRENT WORDING • 5.3.5.2 PSL 2 to 4 tensile testing (for mandrel tubing hangers and casing hangers) “b) test method: Perform tensile tests at room temperature in accordance with the procedures specified in ISO 6892-1 or ASTM A370. Perform a minimum of one tensile test. The results of the tensile test(s) shall satisfy the manufacturer’s specified requirements.” • 5.4.2.3 PSL 2 to 4 tensile testing (for bodies, bonnets, and end and outlet connections) “b) test method: Perform tensile tests at room temperature in accordance with the procedures specified in ISO 6892-1 or ASTM A370. Perform a minimum of one tensile test. The results of the tensile test(s) shall satisfy the applicable requirements of Table 6.” • API 6A Table 6, column 2 (for bodies, bonnets, and end and outlet connections) “0,2% offset yield strength”.

  15. The Problem PROBLEM: • The yield strength acceptance criteria for bodies, bonnets, and end and outlet connections is limited to the 0,2% offset method yield strength values in Table 6. This is good! • However, for mandrel hangers it is up to the manufacturer to specify not only the yield strength in MPa (psi), but also the method of determining the yield strength. • Unfortunately, if the manufacturer does not specify the method of determining the yield strength, methods other than the 0,2% offset method may be used, and these may give higher or lower values than would be obtained if the 0,2% offset method were used.

  16. The Solution PROPOSED REVISION: • 5.3.5.2 PSL 2 to 4 tensile testing (for mandrel tubing hangers and casing hangers) “b) test method: Perform tensile tests at room temperature in accordance with the procedures specified in ISO 6892-1 or ASTM A370. Perform a minimum of one tensile test. The results of the tensile test(s) shall satisfy the manufacturer’s specified requirements. The 0,2% offset method shall be used for determination of the yield strength”. JUSTIFICATION: • A standardized method of determining the yield strength needs to be used for mandrel casing and tubing hangers.

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