Sandvik Steel has produced its first high-volume order for large diameter stainless steel tubes for gas lift risers (GLR). The tubes are to be used as centre tubes in a gas lift riser being produced by Kvaerner Oilfield Products. The total quantity is 17km of 101 mm outside diameter by 6 mm thick tubing (3.5″ ID) in super duplex stainless steel grade Sandvik SAF 2507. The tubes are joint-welded and coiled by Kvaerner Oilfield Products and subsequently installed in the GLR. The GLR systems are scheduled for delivery in 2003.
In addition to the long lengths with fewer or no welds and the handling benefits of coiled tubing, the use of large-diameter super duplex tubes has cost and weight saving advantages for riser tubing. For example, by using the high strength of super duplex SAF 2507 material, weight can be reduced by up to 75%, compared to ordinary stainless steel grade 316L. This translates into major savings through the reduction in required lift capacity of expensive flotation collars.
Similar cost and weight saving benefits can be obtained in flow line applications.
For the Bonga Field order, as well as approximately 250 tonnes of gas lift tubes, Sandvik is also supplying the control tubing for all the umbilicals – approximately 800 tonnes in grade SAF 2507.
