Are bellows seals only for globe valves?

They are common on globe and some gate designs; confirm availability per size and class.

Is packing always unacceptable for emissions?

No — many projects accept qualified packing systems. Follow the datasheet leak class.

When datasheets limit fugitive emissions, stem sealing becomes a line-item decision between bellows seal and enriched packing.

Topic	Bellows seal	Packed gland
Stem seal	Metal bellows primary barrier	Packing rings (graphite / PTFE)
Emissions	Often preferred for zero-leak stem goals	Can meet ISO packing classes with live loading
Cost / lead	Higher	Usually lower
Failure mode	Bellows fatigue if misapplied	Packing wear / adjustment
RFQ cue	Bellows seal globe/gate	Live-loaded packing + leak class

Paste the fugitive-emission or TA-Luft / ISO class clause on the inquiry.