Zdas04,
I was just keeping it simple, but I've designed a number of similar systems and agree, Duplex is pretty rare, but the OP specifically stated he or she needs "a section of metallic piping" at a design pressure of around 240 bar.
How long or what diameter is unknown as is the amount of hydrocarbon - could be 5 %.
The RTPs around now are pretty good and the market seems to have consolidated to a couple of suppliers?
I was just asking about the well tubing for information.
Riley15 - You really need to find a materials engineer to give you an answer you can use to go and design and buy something and know what your fluid is and how much dissolved Oxygen and chlorides there are in it.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.