RTJ Grooves corroding in wet CO2 environment
RTJ Grooves corroding in wet CO2 environment
(OP)
The service is wet CO2 containing gas on oil field. Because of the pressure class, RTJs are chosen ahead of the compressor scrubbers as per piping code. Piping is SS and scrubber itself is CS. The ring gasket is SS. (Sequence: piping SS, Gasket ring SS, spacer, SS, gasket ring SS, vessel flange CS) Corrosion has been found in the troughs of the RTJ on the vessel flange causing the joints to leak. Two postulates are out there: wet CO2 condensing in the crevises and causing the corrosion in the CS troughs or galvanic corrosion between the SS piping and gasket and the CS steel causing accelerated corrosion in the trough on the vessel flange.
Has anybody else experienced this problem with RTJs on oil fields? Would this be a reason to override the B31.3 requirement for RTJ for the pressure class and specify flat gaskets instead? This would eliminate the crevice corrosion possibility and would also insulate the joint against galvanic corrosion.
On another vessel, we have found that placing a CS spacer between the SS piping and the CS vessel (sequence: piping SS, gasket ring SS, spacer CS, gasket ring SS, vessel flange CS) causes the CS spacer to preferentially corrode instead of the vessel flange. This is cheaper (obviates the reworking of the vessel flange) and is somehow predictable (one looks out for leaks at the piping side of the spectacle blind). Is this a good solution?
It has also been suggested to use CS gasket rings instead of SS ones. I do not favour this alternative, because I fear that the CS gasket could fail catastrophically because of both postulated corrosion mechanisms.
I would appreciate your views.
Has anybody else experienced this problem with RTJs on oil fields? Would this be a reason to override the B31.3 requirement for RTJ for the pressure class and specify flat gaskets instead? This would eliminate the crevice corrosion possibility and would also insulate the joint against galvanic corrosion.
On another vessel, we have found that placing a CS spacer between the SS piping and the CS vessel (sequence: piping SS, gasket ring SS, spacer CS, gasket ring SS, vessel flange CS) causes the CS spacer to preferentially corrode instead of the vessel flange. This is cheaper (obviates the reworking of the vessel flange) and is somehow predictable (one looks out for leaks at the piping side of the spectacle blind). Is this a good solution?
It has also been suggested to use CS gasket rings instead of SS ones. I do not favour this alternative, because I fear that the CS gasket could fail catastrophically because of both postulated corrosion mechanisms.
I would appreciate your views.





RE: RTJ Grooves corroding in wet CO2 environment
You might want to look at this gasket as it seals inside the RTJ groove. Pikotek has applied for full approval from API for this gasket.
http://w
Pikotek now has backup from Enpro, Garlock gaskets, so the engineering assistance should be there in spades.
RE: RTJ Grooves corroding in wet CO2 environment
I think this should be a common problem and I wonder whether there are also other solutions other than a different, non-standard gasket technology? On the plants I know, this would mean a large scale gasket change-out and long trial periods.
RE: RTJ Grooves corroding in wet CO2 environment
I would contact Pikotek directly with any concerns. There have probably been some progress that I'm not aware of as Enpro saw fit purchase the company.
RE: RTJ Grooves corroding in wet CO2 environment
Steve Jones
Materials & Corrosion Engineer
http://www.pdo.co.om/pdo/
RE: RTJ Grooves corroding in wet CO2 environment
= = = = = = = = = = = = = = = = = = = =
Still trying to help you stop corrosion.
formerly Trent Tube, now Plymouth Tube
eblessman@plymouth.com
or edstainless@earthlink.net
RE: RTJ Grooves corroding in wet CO2 environment
Ed, at one of the vessels a CS spectacle blind is in fact the sacrificial equipment (at the glycol contacter I have mentioned above). This blind has leaked through the groove before and it is being watched. If an SS weld overlay is put on at the flange, will the problem not be re-located to another point in the scrubber? Or can dissimiliar metal corrosion be solved that easily?
RE: RTJ Grooves corroding in wet CO2 environment