www.buyheatshrink.com heat guns are UL and CSA approved.
Take a look at VT-1100 heat gun. It is a durable and economical product. It can be used for variety of purposes such shrinking a tube, removing varnish, melting adhesives and loosening rusted bolts.
I have seen workers using head guns for the above mentioned purposed when I used to work for a switchgear company.