Research was completed to develop guidelines for pipeline valve stem seals in CO2 rich applications such as for enhanced oil recovery (EOR) and carbon capture and storage (CCS). In particular, guidance was needed to ascertain when standard O-rings may be used, when a switch to rapid gas decompression (RGD) resistant O-rings is recommended and when O-rings should be replaced by more robust energized lip seals and/or by more robust seal materials.
The guidelines would interface with both NORSOK M 710 Rev. 3 and ISO 23936-2, and give specific details on procedures, steps and decisions that have to be taken when attempting to qualify seals for dense phase CO2 use. In order to develop these guidelines, well established sealing compounds having proven RGD resistance were selected for study, along with materials which were not known for their RGD resistance. RGD testing was performed on housed O-rings of each compound using CO2 rich applications.
The previous Phase I of the project was carried out with a decompression rate of 20 bar/min over 8 RGD cycles. In this Phase II of the project more severe 70 and 127 bar/min rates were used. Also, for the 20 bar/min rates the number of RGD cycles was increased to 50 to evaluate the seal materials. The report of the Phase I research report is available at no charge to members and for purchase by non-PRCI members through the PRCI website. The Phase II report is currently undergoing project team review.