• total aluminum content Alt in the table.
• Unless required for smelting, elements not mentioned in this table should not be intentionally added to the steel without the purchaser\'s consent. The manufacturer shall take all appropriate measures to prevent elements that could impair the mechanical properties and suitability of the steel from being introduced through scrap or other materials used in the production process.

• long.=Longitudinal；tr.=transverse；ReL=Lower yield strength
• For high-quality carbon steel and alloy steel pipes with D ≥ 76 mm and S ≥ 14 mm, impact tests shall be conducted. The impact absorption energy values listed in the table refer to the requirements for full-size Charpy V-notch specimens. When using sub-sized impact specimens, the minimum Charpy V-notch impact absorption energy requirements for 10 × 7.5 or 10 × 5 specimens shall be reduced to 0.75 or 0.5 times the full-size specimen requirements, respectively.
• The hardness testing of steel pipes shall comply with the following provisions:
ⓐ For steel pipes with S ≥ 5.0 mm, Brinell hardness test or Rockwell hardness test shall be conducted;
ⓑ For steel pipes with S < 5.0 mm, Rockwell hardness test shall be conducted (if Rockwell hardness values are not specified in the table, this test is not required);
ⓒ Upon the purchaser’s request, through mutual agreement between supplier and purchaser, and as specified in the contract, Vickers hardness test may be performed in place of Brinell or Rockwell hardness tests. When Vickers hardness testing of steel pipes is specified in the contract, the values shall meet the requirements given in the table.
• According to the buyer\'s request, and upon mutual agreement between the supplier and the buyer, with notation in the contract, a hardness test may be conducted on the outer surface of the steel pipe, and the values should comply with the specifications listed in the table.