We are now getting up to the level where tanks are actually useful. Both of these flashpoints would be fairly difficult to do without having someone in the group built to soak damage. For the most part, these are pretty straightforward missions. Make sure to note that Battlelord Kreshan, last boss of Hammer Station, continuously spawns adds during the fight. Don't get overwhelmed. Also, the Prophet of Vodal in Athiss will vanish and summon indestructable, slow fireballs occasionally. Simply walk away from these and they will disappear shortly.
Here are some general tips for tanking at this level:
Don't stress over aggro: Before Flame Sweep, it is incredibly difficult to hold AoE threat when the DPS don't single target. Remember that silver-bordered "strong" mobs are the sort you routinely solo while questing. If a DPS pulls one of these off you it is not a big deal. They are easily soloable. Just keep the harder mobs on you and always STAY CALM. A panicking tank has led to many a group wipe.
Single target ability priority: Assuming infinite heat, your single target priority list should look something like this:
Rail Shot > Rocket Punch > Combust (Flame Burst debuff) > Explosive Dart > Flame Burst > Rapid Shots
Flame Burst's debuff should have as close to 100% uptime as you can afford. A free 4% damage reduction is nothing to sneeze at. Explosive Dart is an easily overlooked ability for single target because its damage is delayed. Surprisingly, it does more damage when it goes off than Flame Burst, so use it when the target will actually live for the duration.
AoE ability priority: AoE priority is very straightforward:
Death From Above > Combust (Flame Sweep debuff) > Explosive Dart > Flame Sweep
Death From Above to open. While Explosive Dart is both more threat/GCD and more threat/heat than Flame Sweep, it is delayed and will not provide snap aggro. If you need threat immediately (add spawns for example) use Flame Sweep over Explosive Dart. Remember that Flame Sweep does have quite a high heat cost so don't just spam it! If your DPS are single targeting a mob in a group, it is preferable for you to single target that mob as well. Your job is not to kill enemies, it is to hold aggro and keep your heat low enough that you can be flexible if something goes wrong. What I like to do in that kind of situation is simply replace Flame Burst in the single target priority list with Flame Sweep.
Channeled abilities: Flamethrower and Unload are of debatable value for a tank. When used optimially, they are two of the most heat efficient abilities available to tanks. Flamethrower beats out Flame Sweep by a lot if you can line up a couple targets, while Unload is considerably more damage per GCD than Flame Burst. The problem is that tanks suffer from pushback a lot. Everything is constantly wailing on us, greatly diminishing the value of channels. Don't dismiss these abilities out of hand, but use them sparingly and only when you can be sure of getting almost all the channel off. 25 heat is far too much to spend on a Flamethrower or Unload that only ticks once. Death From Above, while being a channeled ability, is basically only used during the pull so suffers minimally from pushback. It is also so damn strong that it would be worth using even if you only got one missile volley off.
Heat management: ALL OF THESE PRIORITY LISTS ARE ASSUMING INFINITE HEAT!!! In reality, you cannot always simply choose the highest priority ability. Keep tabs on your heat levels throughout everything you do. Most of the time you will find yourself choosing Rapid Shots over Flame Burst in order to keep your heat low enough to be able to Rail Shot, Rocket Punch, and Explosive Dart. 40 heat is the magic number, but it isn't a huge deal if you go a little over. I will go into heat management in much, much greater detail at level 50.
Now go forth and tank!