Gentlemen,
ASME B31.4 (para 404.4.7.2) explicitly prohibits "Metallic Gaskets" in Class 150 flanges with the exception of spiral wound & ring types. Question: Are flexible graphite-coated corrugated metal gaskets (CMGs) considered "metallic gaskets" by code?
I always thought these corrugated metal-core gaskets with compressible coatings were more for thermal cycling applications (e.g. heat exchanger flange joints), not line or pump flange joints. Some of my co-workers are disagreeing.
For years we've used only spiral wound gaskets for all oil & gas pipeline flange joints. Now one client is stating they prefer flexible graphite-coated CMGs on Class 150 flanges only with crude oil pipelines (for their NGL lines they still prefer spiral wounds ... go figure).
Any feedback would be much appreciated.
ASME B31.4 (para 404.4.7.2) explicitly prohibits "Metallic Gaskets" in Class 150 flanges with the exception of spiral wound & ring types. Question: Are flexible graphite-coated corrugated metal gaskets (CMGs) considered "metallic gaskets" by code?
I always thought these corrugated metal-core gaskets with compressible coatings were more for thermal cycling applications (e.g. heat exchanger flange joints), not line or pump flange joints. Some of my co-workers are disagreeing.
For years we've used only spiral wound gaskets for all oil & gas pipeline flange joints. Now one client is stating they prefer flexible graphite-coated CMGs on Class 150 flanges only with crude oil pipelines (for their NGL lines they still prefer spiral wounds ... go figure).
Any feedback would be much appreciated.
