Offering longer operational life in some of the most demanding offshore locations throughout the world, the new range of hyper-duplex wirelines from Sandvik is designed for efficient use in extreme chloride containing environments.
Sandvik SAF 2707 HD® is a high alloy duplex stainless steel with very high mechanical strength, specially developed for service in highly corrosive conditions and is particularly suited to aggressive, acidic, chloride-containing environments. The material displays excellent resistance to pitting and crevice corrosion, stress corrosion cracking and general corrosion. Its use can reduce well downtime, cut re-spooling operations and reduce the number of lines required, providing both cost and operational savings.
In general, wirelines are particularly at risk to pitting corrosion due to the environment in which they are used. However, Sandvik SAF 2707 HD, with a service temperature range of -50 degrees C to 280 degrees C (-60 degrees F to 540 degrees F), resists pitting in chloride environments at very high temperatures making it ideal for use in the most demanding well applications.
Introduction of the new material follows extremely successful trials carried out over a 6 month period with customers operating deepwater wells offshore. In Indonesia trials showed over 2½ times the running time, compared with UNS S32760, which means higher efficiency and less time wasted re-spooling. The demanding conditions included chlorides up to 15,000 ppm in 309 ºF and at 5000 psi (with 4% CO2 and no H2S). After long time usage the ductility of the wire was still good.
Sandvik has used the knowledge and expertise gained from producing its previous duplex grades to introduce a higher level of performance into the new grade. The generally accepted index for comparing resistance to pitting and crevice corrosion is the PRE value. Sandvik SAF 2707 HD has a minimum PRE value of 48.
The superior properties of the new steel, compared with other duplex stainless steels, make it a cost-effective alternative to super austenitic steels and nickel-base alloys in the most demanding applications such as hot tropical seawater.
Tensile strength and breaking loads of the new grade are very much higher than most stainless or high alloy wirelines. The greater strength also contributes to extended life expectancy with greater resistance to wear and mechanical damage along with better fatigue resistance.
Tested and certified in accordance with a minimum nominal tensile strength, Sandvik SAF 2707 HD (UNS S32707) has a proof strength around 90% of its tensile strength and resists permanent set of the wire even when handling high loads. Sandvik’s integrated production processes, from the steel melt right through to the finished product, results in a high quality product, guaranteeing consistent performance from batch to batch and delivery to delivery. It also means close control over material chemistry.
Sandvik SAF 2707 HD wirelines are currently manufactured and stocked in 0.108 inch and 0.125 inch diameters and in continuous lengths up to 30,000 feet.