No turn signals,no flashers keep
Presuming that the maximum load that the indicators can draw is with the hazzards on, this would be 4 x 21w bulbs, maybe 2 x 6w repeaters. Throw in another 10w load for the relay its self and the dashboard indicator and your total load is about 110 watts.
110 watts / 12 volts says that your load is 9.2 amps tops. So a 10 amp fuse should be man enough. You might want to see what happens with a 15 amp fuse, but that's probably pretty much overkill. The lid of your fuse box SHOULD have the fuse ratings for each of the positions in the box imprinted on it.
I would suggest that the bottom line here is that if you are popping 15 amp fuses, you probably have a short somewhere.
Thoughts about how to fix this. While the usual effect of a bulb blowing is for it to fail OPEN circuit (The fillament in the bulb that lows burns out and there is nothing there), very rarely, when a bulb blows, it goes SHORT circuit (Part of the fillament will burn and cause the electrodes it hangs from to get welded together). This is a possible cause for a short.
Your first action should be to see if the fuses blow when you turn left, or right, or both. Chances are that it will only be on one side.
Now you have identified the side that the problem is on, remove the front and rear indicator bulbs (if it has repeaters in the wing and you can get this bulb out too, do so. Now engage the indicator again. Does the fuse still blow? (you will probably hear the relay clicking wildly because it has no bulbs to fire up, this is not important, the integrity of the fuse is.
If you have got this far, either start putting bulbs back, one at a time and seeing if the fuse pops. At the moment that the fuse DOES pop, you have found the faulty bulb. Or, if you got as far as the fuse surviving with the bulbs out, you may just want to replace all the bulbs on that side. Unimportant how you go about this, so long as you have a few spare fuses.
IF however removing all the bulbs on the affected side still blows fuses when you engage the signal, then you have a short somewhere in the wiring. Favorite places are in the wiring loom between the bulb holder and the point where the wires are wrapped in black tape. Cherck for chafing of a wire. If you find some and the wire core is exposed, simply tape it up with insulating tape to fix it.
Hope this helps. Please drop a note on this thread and let me know how you get on and if you need further help.
If it does