Super Duplex 2507 - The Pinnacle of Corrosion Resistance

Exceptional properties of 2507

The PREN (Pitting Resistance Equivalent Number) of 2507 is typically above 40, versus 32-35 for 2205 and 24-28 for 316L. This high value reflects superior pitting corrosion resistance in chloride environments, including under conditions of temperature, chloride concentration and oxidation-reduction potential that 2205 cannot tolerate.

The yield strength of 2507 (550 MPa minimum) exceeds that of 2205 (450 MPa minimum), enabling the design of even lighter equipment for equivalent service pressure. In the offshore oil industry, this weight reduction can translate into savings of several tons on large equipment, with significant implications for fabrication, transport and installation costs.

Its resistance to chloride stress corrosion cracking is virtually complete under normal operating conditions, even at elevated temperatures where 2205 begins to present risks. This practical immunity is a decisive advantage for critical equipment that must operate without failure over long periods without inspection or maintenance.

Offshore and subsea applications

2507 is the reference material for many offshore and subsea applications. Seawater injection systems, used to maintain pressure in oil reservoirs and for offshore firefighting systems, are subjected to high-pressure seawater at moderate temperatures: ideal conditions for 2507 use. Piping, valves, fittings and pumps in these systems are commonly fabricated in this grade.

Offshore umbilicals, assemblies of tubes and cables connecting subsea equipment to surface installations, use 2507 tubes for hydraulic and chemical lines. These tubes must withstand external deepwater pressure (which can exceed 100 bar), internal service fluid pressure and the corrosive seawater environment for 20 to 30 years without possibility of easy replacement.

Desalination industry

Reverse osmosis seawater desalination is a growing application where 2507 is establishing itself as the reference material for high-pressure components. Reverse osmosis membranes operate at pressures of 60 to 80 bar with concentrated seawater. Pressure tubes, manifolds, valves and fittings in these systems are subjected to aggressive chloride corrosion under high pressure, conditions where 2507 offers unmatched durability.

High-pressure pumps in desalination installations, subjected to cavitation erosion and seawater corrosion under pressure, benefit from 2507’s resistance to both degradation mechanisms. The increased longevity of this equipment significantly reduces the operational costs of desalination installations, which represent considerable investments.

Petrochemical and acid industry

In the petrochemical industry, 2507 is used for equipment in contact with mixtures of chlorides, organic acids and sulfur compounds at moderate to elevated temperatures. Distillation columns, condensers, coolers and piping for certain specific petrochemical processes use this grade for its resistance to corrosive combinations that standard stainless steels cannot tolerate long-term.

Dilute and concentrated hydrochloric acid processing equipment, acid neutralization systems and equipment in the chlorine and vinyl chloride industry constitute other applications where 2507 is employed for its superior resistance to chlorides at high temperature and concentration.

Fabrication requirements and ADI Laval expertise

Fabricating super duplex 2507 is considerably more demanding than 2205 or 316L. The welding parameter control range is narrower, risks of harmful phase precipitation (sigma, chi) are higher, and post-weld quality procedures are more extensive. Welders must be specifically qualified for these procedures, and each critical weld must be examined by non-destructive methods (radiography, ultrasound or liquid penetrant depending on applicable standards).

ADI Laval has developed the expertise and procedures necessary to fabricate quality components in super duplex 2507. Our qualified welding procedures, welder qualifications and ISO 9001 quality management system ensure that each part fabricated in this material meets the strictest requirements of our clients in the oil, offshore and petrochemical sectors.