Ports https://github.com/tgstation/tgstation/pull/50497

code/game/objects/items/devices/transfer_valve.dm

@@ -13,6 +13,8 @@
 	var/mob/attacher = null
 	var/valve_open = FALSE
 	var/toggle = 1
+	var/ui_x = 310
+	var/ui_y = 320
 
 /obj/item/transfer_valve/IsAssemblyHolder()
 	return TRUE
@@ -235,3 +237,52 @@
 // eventually maybe have it update icon to show state (timer, prox etc.) like old bombs
 /obj/item/transfer_valve/proc/c_state()
 	return
+
+/obj/item/transfer_valve/ui_interact(mob/user, ui_key = "main", datum/tgui/ui = null, force_open = FALSE, \
+									datum/tgui/master_ui = null, datum/ui_state/state = GLOB.hands_state)
+	ui = SStgui.try_update_ui(user, src, ui_key, ui, force_open)
+	if(!ui)
+		ui = new(user, src, ui_key, "TransferValve", name, ui_x, ui_y, master_ui, state)
+		ui.open()
+
+/obj/item/transfer_valve/ui_data(mob/user)
+	var/list/data = list()
+	data["tank_one"] = tank_one
+	data["tank_two"] = tank_two
+	data["attached_device"] = attached_device
+	data["valve"] = valve_open
+	return data
+
+/obj/item/transfer_valve/ui_act(action, params)
+	if(..())
+		return
+
+	switch(action)
+		if("tankone")
+			if(tank_one)
+				split_gases()
+				valve_open = FALSE
+				tank_one.forceMove(drop_location())
+				tank_one = null
+				. = TRUE
+		if("tanktwo")
+			if(tank_two)
+				split_gases()
+				valve_open = FALSE
+				tank_two.forceMove(drop_location())
+				tank_two = null
+				. = TRUE
+		if("toggle")
+			toggle_valve()
+			. = TRUE
+		if("device")
+			if(attached_device)
+				attached_device.attack_self(usr)
+				. = TRUE
+		if("remove_device")
+			if(attached_device)
+				attached_device.on_detach()
+				attached_device = null
+				. = TRUE
+
+	update_icon()