X80 Grade
To meet these particularly challenging line pipe conditions, Vallourec has developed the X80 grade. Thanks to its unique engineering, the X80 allows wall thickness to be reduced by up to 20% compared to standard X65 line pipe grades at similar design pressures.
One line pipe x80 design for mild and intermediate sour conditions
Over the last 10 years, Vallourec has developed and optimized the X80 in close collaboration with end users as well as with engineering, procurement and construction (EPC) partners to deliver proven performance in the mild and intermediate sour environments of NACE regions 1 and 2.
Seamless pipe body:
- Resistant to Mild and Intermediate Sour environments (NACE Regions 1 & 2).
- Hardness below 290 HV10 (as per DNV-ST-F101).
- Average toughness 300J at -30°C.
- Range: OD 219.1-406.4 mm (NPS 8-16’’), WT up to 40 mm (1.57”).
- Possible use of grade X80 for Mechanically Lined Pipes to withstand the most corrosive environments.
Girth welds:
- Resistant to Mild and Intermediate Sour environments (NACE Regions 1 & 2).
- Hardness in Heat Affected Zone (HAZ) below 300 HV10.
- No SSC cracks at pH 5.0 / 2 psi H2S / 85% SMYS (NACE TM0177 Solution B) when testing four-point bend specimens with root left intact as per NACE TM 0316.
- Fatigue results in air exceeding BS 7608 class E target curve.
- Fatigue results in mild sour condition at pH 5.9 / 0.1 psi H2S (NACE Region 1) comparable to X65.
The weldability of the x80 is widely recognized by epcs and proven in tests and in the field.
- All welding can be performed using Gas Metal Arc Welding process at a minimum preheating temperature of 125° C.
- Hardness Survey proves structural integrity as per DNV-ST-F101 (Vickers method, 10 kg load).
- Overmatching is achieved with an optimized combination of filler material and pre-heat temperatures.
An operator was planning an offshore project with a riser made of 41 mm-thick pipes in X65 steel.
This would require the use of buoyancy modules in what is known as a steel lazy wave riser ( SLWR) configuration.
By replacing the X65 grade with X80, the operator was able to reduce the wall thickness of the riser pipe to 32 mm. This, in turn, eliminated the need for buoyancy modules.
Thanks to this steel catenary riser configuration (SCR), the X80 helps to lower project installation costs. The reduced wall thickness helped the operator eliminate more than 2,000 tons of steel production, which translated to cost savings of around $2 800/ton.
In addition, installation time was shortened by a full 12 days, saving up to 3,500 metric tons of CO2 emissions, as estimated along the entire value chain (i.e. from the raw material supply to the transport to final destination), according to the EPD International PCR 2012:01 standard (2012).
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