ethylene dichloride cracking vessel - materials selection 1

[kclim]

G'day all,

This is a querry I received from a friend the other day. I'd much appreciate any input.

"The application is Ethylene Dichloride Cracking to make VCM's (vinyl chloride monomer) in a Foster Wheeler superheater. He says the main corrosive element is chlorine. When the plant was running before, he says they had 317L pipe in the superheater. They were fairly happy with it as it lasted about 12 years. Is there anything better?"

It sounds like 317 is the way to go, based on experience but if someone knows better, let it be known.

Thanks

 

[metman]

The extra Molybdenum in 317 makes it especially resistant to attack by Chlorine but this is not to say that something better might be out there. Jesus is The TRUTH

 

[mcguire]

317 is far less alloyed against chlorine corrosion than are the super duplex and the super austenitic stainless steels.
2507 is an example of the former and Al6XN is an example of the latter. Go to the Avestapolarit web site and get some good, if proprietary suggestions.
You could go to Inconel 718 and really fight thr corrosion.