Why are O-rings used for sealing the valve stems of 6D piping valves?
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As the title suggests, my understanding is that in 6D, it is required to have a grease injection port at the valve stem location; is this O-ring sealing structure adopted for manufacturing reasons? Please ask an expert to help clarify this, thank you.
Typical 6D ball valve stem seals consist of two layers of sealing elements: one is an O-ring, and the other is a graphite packing. Under normal conditions, the sealing performance of O-rings is very good. In addition to its conventional function of providing medium-mouth sealing, the graphite filler is also used for sealing purposes in fire protection designs.
Of course, it’s because the O-ring has good sealing properties.
Are there any other considerations for choosing an O-ring besides its good sealing performance? The 6D specifications do not specify any requirements regarding the packing; the drawings provided also show a packing box structure, rather than an O-ring structure.