Difference between ABS EQ70 and CCS EQ70 steel plate

ABS EQ70 and CCS EQ70 are both extra-high-strength quenched and tempered steel plates specifically engineered for the most demanding marine and offshore applications, particularly those requiring excellent toughness at low temperatures. They are certified by two major classification societies-ABS (American Bureau of Shipping) and CCS (China Classification Society)-and represent the higher toughness tier within the 70 kgf/mm² strength class, designed for structures operating in extremely cold environments.

ABS Grade EQ70 is certified by the American Bureau of Shipping. The designation "EQ70" indicates a minimum yield strength of 690 MPa (100 ksi) and a tensile strength range of 770-940 MPa (112-136 ksi) . The "E" signifies the Charpy V-notch impact test temperature of -40°C (-40°F) , requiring minimum average energy of 41J (transverse) or 62J (longitudinal) . These plates are manufactured using quenched and tempered (QT) processes to achieve their exceptional combination of strength and toughness . Typical applications include offshore drilling rigs, platforms, jack-up rig legs, ship hulls, floating production storage and offloading vessels (FPSOs), and critical marine structures requiring superior strength and durability in harsh environments.

CCS Grade EQ70 is certified by the China Classification Society and serves as the direct equivalent to ABS EQ70 in the Chinese classification system . According to classification society standards, CCS EQ70 shares identical mechanical property requirements with its ABS counterpart: minimum yield strength of 690 MPa and tensile strength of 770-940 MPa . It belongs to the same product family as AQ70, DQ70, EQ70, and FQ70 series for shipbuilding and offshore applications, with each letter representing a different impact test temperature. Like ABS EQ70, CCS EQ70 requires Charpy impact testing at -40°C with similar energy requirements.

Key Differences:
The primary distinction between these two grades lies in their certifying authority and the corresponding quality control system. ABS EQ70 complies with American Bureau of Shipping rules and is recognized internationally, particularly in projects requiring ABS certification for offshore platforms and vessels destined for ABS-classed fleets . CCS EQ70 complies with China Classification Society rules and is typically specified for offshore structures built in Chinese shipyards or for projects under Chinese classification .

From a technical perspective, these steels are considered interchangeable, and major manufacturers can produce plates certified by both societies simultaneously . The choice between them is typically determined by the flag state of the vessel, shipyard preferences, or specific project requirements. Both grades must be supplied with mill test certificates (MTC) bearing classification society surveyor signatures and can be produced with through-thickness properties (Z25, Z35) for improved resistance to lamellar tearing in highly stressed joints.

Chemical Composition

CCS EQ70 Extra high Strength Chemical Composition in Tempering and Quenching

Mechanical Property

CCS EQ70 Extra high strength property in tempering and quenching