No longer able to crawl through welded vents.

code/ATMOSPHERICS/components/unary/unary_base.dm

@@ -9,6 +9,8 @@
 
 	var/datum/pipe_network/network
 
+	var/welded = 0 //defining this here for ventcrawl stuff
+
 	New()
 		..()
 		initialize_directions = dir

code/ATMOSPHERICS/components/unary/vent_pump.dm

@@ -40,8 +40,6 @@
 	var/internal_pressure_bound_default = INTERNAL_PRESSURE_BOUND
 	var/pressure_checks_default = PRESSURE_CHECKS
 
-	var/welded = 0 // Added for aliens -- TLE
-
 	var/frequency = 1439
 	var/datum/radio_frequency/radio_connection
 

code/modules/ventcrawl/ventcrawl.dm

@@ -81,7 +81,7 @@ var/list/ventcrawl_machinery = list(
 	var/atom/pipe
 	var/list/pipes = list()
 	for(var/obj/machinery/atmospherics/unary/U in range(1))
-		if(is_type_in_list(U,ventcrawl_machinery) && Adjacent(U))
+		if(is_type_in_list(U,ventcrawl_machinery) && Adjacent(U) && !U.welded)
 			pipes |= U
 	if(!pipes || !pipes.len)
 		to_chat(src, "There are no pipes that you can ventcrawl into within range!")