Selection of flange gaskets for liquid oxygen pipelines in air separation plants
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Dear fellow sailors, what type of gaskets are used in pipelines for liquid oxygen and liquid nitrogen at -196 degrees? How effective are metal-wound PTFE gaskets? I’m currently interested in Duralbar’s Durlon 9000. Has anyone used this type of filled modified PTFE material, and what are the results?
This PTFE-filled gasket is suitable for use at this temperature. . . But the key is to use flange connections less often. . .
We now manufacture the low-temperature gaskets for external flanges ourselves, by processing copper sheets and then wrapping them with PTFE; this method has been proven effective over many years.
It seems to be very low-cost; I’ve learned it, thank you
The worst-performing ones are gaskets made from domestic PTFE sheets (perhaps inferior brands were used), followed by PTFE wound gaskets; Durlon 9000 should be more durable!
Use Sigma 511 for low pressures, and wound gaskets with inner and outer rings for high pressures
A 5mm thick copper plate is cut to the desired size, then sent to a machine tool for machining of the inner and outer circles. Sealing grooves 0.5mm deep are created on each of the two end surfaces (in multiple layers), and finally, PTFE tape is wrapped around them – this yields excellent results. It is particularly suitable for low-temperature environments as well as situations involving frequent start-up and stop-off operations
Is 5mm a bit thick? Generally, gaskets are 3.5mm thick. Should the tape be inserted into the sealing groove or wrapped around the inner and outer circumferences?
Due to the incomplete information provided by the original poster, and in order to illustrate the level of pressure involved, I will share information on the use of gaskets in low-temperature oxygen environments both in China and abroad. Several major foreign gas companies such as AP, Linde, Air Liquide, and Praxair use modified polytetrafluoroethylene gaskets such as Fle*tallic’s Sigma 511 product, as well as RPTFE gaskets from other well-known foreign brands in low-temperature oxygen environments. It is worth noting that there are currently no successful cases of Chinese companies producing modified polytetrafluoroethylene materials； In recent years, domestic gas companies and equipment manufacturing firms have gradually begun to use modified PTFE gaskets to replace the previous pure PTFE gaskets as well as other types of seals. Regarding pure PTFE material as a sealing material, standard HG/T20606 specifies the operating temperatures for such materials. As for the scope of application and definitions related to EPTFE and RPTFE, I cannot fully agree with them. Feel free to discuss the above issues further; I hope this can help you.
I thought Klinger’s gaskets were being used!