CPC Subgroup
E21C 37/16 by fire-setting or by similar methods based on a heat effect (drilling by use of heat E21B7/14)
Full Title
Other methods or devices for dislodging with or without loading (breaking-down by means inserted in slits E21C27/14) > by fire-setting or by similar methods based on a heat effect (drilling by use of heat E21B7/14)