Went even farther in consolidation of trinary atmospherics.

- We can eliminate any overridden methods at all on flipped trinary devices by making a `mirrored` and `tee` variable!  This allows us to do things like flip them without delete/spawning.
- T-Valves are also basically trinary.  Sadly they are not a subtype, so to share code with them I have to put it into an outside proc.  But still worth it.

code/ATMOSPHERICS/components/trinary_devices/trinary_base.dm

@@ -3,6 +3,9 @@
 	initialize_directions = SOUTH|NORTH|WEST
 	use_power = 0
 
+	var/mirrored = FALSE
+	var/tee = FALSE
+
 	var/datum/gas_mixture/air1
 	var/datum/gas_mixture/air2
 	var/datum/gas_mixture/air3
@@ -25,15 +28,7 @@
 	air3.volume = 200
 
 /obj/machinery/atmospherics/trinary/init_dir()
-	switch(dir)
-		if(NORTH)
-			initialize_directions = EAST|NORTH|SOUTH
-		if(SOUTH)
-			initialize_directions = SOUTH|WEST|NORTH
-		if(EAST)
-			initialize_directions = EAST|WEST|SOUTH
-		if(WEST)
-			initialize_directions = WEST|NORTH|EAST
+	initialize_directions = get_initialize_directions_trinary(dir, mirrored, tee)
 
 /obj/machinery/atmospherics/trinary/update_underlays()
 	if(..())
@@ -55,6 +50,23 @@
 	if(old_stat != stat)
 		update_icon()
 
+/obj/machinery/atmospherics/trinary/attackby(var/obj/item/weapon/W as obj, var/mob/user as mob)
+	if (!istype(W, /obj/item/weapon/wrench))
+		return ..()
+	if(!can_unwrench())
+		to_chat(user, "<span class='warning'>You cannot unwrench \the [src], it too exerted due to internal pressure.</span>")
+		add_fingerprint(user)
+		return 1
+	playsound(src, W.usesound, 50, 1)
+	to_chat(user, "<span class='notice'>You begin to unfasten \the [src]...</span>")
+	if (do_after(user, 40 * W.toolspeed))
+		user.visible_message( \
+			"<span class='notice'>\The [user] unfastens \the [src].</span>", \
+			"<span class='notice'>You have unfastened \the [src].</span>", \
+			"You hear a ratchet.")
+		new /obj/item/pipe(loc, make_from=src)
+		qdel(src)
+
 // Housekeeping and pipe network stuff below
 /obj/machinery/atmospherics/trinary/network_expand(datum/pipe_network/new_network, obj/machinery/atmospherics/pipe/reference)
 	if(reference == node1)
@@ -93,10 +105,7 @@
 // Get the direction each node is facing to connect.
 // It now returns as a list so it can be fetched nicely, each entry corresponds to node of same number.
 /obj/machinery/atmospherics/trinary/get_node_connect_dirs()
-	var/node1_connect = turn(dir, 180)
-	var/node2_connect = turn(dir, -90)
-	var/node3_connect = dir
-	return list(node1_connect, node2_connect, node3_connect)
+	return get_node_connect_dirs_trinary(dir, mirrored, tee)
 
 /obj/machinery/atmospherics/trinary/atmos_init()
 	if(node1 && node2 && node3)
@@ -191,4 +200,58 @@
 
 	update_underlays()
 
-	return null
+	return null
+
+// Trinary init_dir() logic in a separate proc so it can be referenced from "trinary-ish" places like T-Valves
+// TODO - Someday refactor those places under atmospherics/trinary
+/proc/get_initialize_directions_trinary(var/dir, var/mirrored = FALSE, var/tee = FALSE)
+	if(tee)
+		switch(dir)
+			if(NORTH)
+				return EAST|NORTH|WEST
+			if(SOUTH)
+				return SOUTH|WEST|EAST
+			if(EAST)
+				return EAST|NORTH|SOUTH
+			if(WEST)
+				return WEST|NORTH|SOUTH
+	else if(mirrored)
+		switch(dir)
+			if(NORTH)
+				return WEST|NORTH|SOUTH
+			if(SOUTH)
+				return SOUTH|EAST|NORTH
+			if(EAST)
+				return EAST|WEST|NORTH
+			if(WEST)
+				return WEST|SOUTH|EAST
+	else
+		switch(dir)
+			if(NORTH)
+				return EAST|NORTH|SOUTH
+			if(SOUTH)
+				return SOUTH|WEST|NORTH
+			if(EAST)
+				return EAST|WEST|SOUTH
+			if(WEST)
+				return WEST|NORTH|EAST
+
+// Trinary get_node_connect_dirs() logic in a separate proc so it can be referenced from "trinary-ish" places like T-Valves
+/proc/get_node_connect_dirs_trinary(var/dir, var/mirrored = FALSE, var/tee = FALSE)
+	var/node1_connect
+	var/node2_connect
+	var/node3_connect
+
+	if(tee)
+		node1_connect = turn(dir, -90)
+		node2_connect = turn(dir, 90)
+		node3_connect = dir
+	else if(mirrored)
+		node1_connect = turn(dir, 180)
+		node2_connect = turn(dir, 90)
+		node3_connect = dir
+	else
+		node1_connect = turn(dir, 180)
+		node2_connect = turn(dir, -90)
+		node3_connect = dir
+	return list(node1_connect, node2_connect, node3_connect)