Darren ZettlerI would treat this no differently than any other situation where smoke or products of combustion or dust or dirt may cause a false alarm. If a building owner is going to do welding, soldering, or even sanding of drywall I expect them to take the proper precautions. These steps would include calling the fire department, the monitoring station and bypassing the area where the work is taking place on the fire alarm panel. Bagging of detectors may be an option also. A fire watch may also need to happen while the area is bypassed.
Smoke from a pipe or any other source, legal or not, can cause false alarms and I would treat it exactly like soldering, welding or drywall dust. The owner must take precautions to avoid the false alarm and notify all appropriate parties.
Too many false alarms can cause building occupants to become complacent and not react to a real fire alarm, therefore we must ensure owners do whatever they can to avoid false alarms.