Flange selection for highly hazardous media equipment
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I designed a chlorine dryer. The medium is chlorine, anhydrous calcium chloride, the pressure is 0.35MPa, and the temperature is 50 degrees. According to the provisions of Appendix A of HG20583, the flange of equipment with highly toxic media must use tongue-and-groove surface, and the gasket must use wound gasket (304+flexible graphite). The reviewer looked at it and said that the 304+ flexible graphite wound gasket will be corroded by chloride ions, the flange was changed to a concave and convex surface, and the gasket was made of polytetrafluoroethylene. Is this statement correct? Thanks
The theoretical level of your reviewer must be very high. For the so-called "chlorine dryer", it is still necessary to distinguish whether the chlorine medium is "dry" or "wet".
Chlorine is a highly dangerous substance, and the sealing performance of the graphite gasket is questionable. The poster can take a look at this issue.~
I would like to ask about 2 units. The chlorine gas contains water and is dried with anhydrous calcium chloride. Is it okay to use concave and convex flanges and PTFE gaskets for this equipment? Thank you
My understanding is that Appendix A of HG20583 does not stipulate which type of equipment flange you choose. It is based on how you choose the type of equipment flange and the sealing surface. For highly toxic media and low pressure, we generally choose PTFE as the gasket material, and its performance is very good.
The level of your auditors is really high! But I suggest that specific matters should be discussed with the chemical process personnel! Process and equipment are a family, and the relationship should be closer. We should learn from each other.* !
Generally, concave and convex flanges are used. I will use a flange with a falcon groove.
Reinforced PTFE gaskets are recommended. Because pure PTFE has cold flow properties, the pressing force will decrease over time, affecting the sealing effect.
It is a matter of common sense that stainless steel is not resistant to chloride ion corrosion. Plastic King has good corrosion resistance, and the reviewer made a good point. Learn more from him * !
The audit is very strict, the stainless steel cannot come into contact with chlorine, and the pads should be replaced.