Api Task Group

API SC6 BALLOT ITEM 6A-_____ 30 June 2011

Clarification Of Requirements For Standard Size Tensile Test Specimens

Proposal:

Revise Section 5.6.4.1 to read as follows:

Paragraph 5 - “ASTM A370 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.”

Revise Section 5.7.4.1 to read as follows:

Paragraph 6 - “ASTM A370 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:

In the current edition of API 6A / ISO 10423, Section 5.6.4.1 and Section 5.7.4.1 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 for tensile testing.

“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 of 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, so this change does not impose something that is not a standard practice.

My Files\2011\API SC6 Summer Meeting\Agenda Item 7 - 6A Tensile Testing\API Ballot-Tensile Test-Haeberle.docx