Singed is a tank. dont get me wrong he does huge damage in a sustained fight but you are the one who initates. NEVER FORGET THIS

There are a few different ways to use singed and as any good player you will bend and mold into what is needed for your team. these are some other builds i have used and still carried on. easily...

If the other team has a madreds -1 Warmogs +FoN
If you are carrying -1 Warmogs -GA +abbysal +rylais
If you are getting ripped up by ap -1 warmogs +abbysal or +FoN
If you dont need the resists due to runes, -GA +warmogs
If you are getting hurt my close range, -warmogs +sunfire
You should have no problem with ranged champions because they should always be your first target, getting them into the middle of a team fight drastically reduces their chance of doing any sort of significant damage and will more then likely make them a feeder.

The point of getting two catalysts at the start is so that you become unharrasable. they stack so you gain 600 health every lvl and it allows you to farm as many creeps as possible. Use your poisen effectivly as possible by running backwards and through the minion lines. If the other team is harrassing dont be afraid to flash and flip them, or if thier melee, throw them back into your teammate or poisen so they take as much damage as possible.

At lvl 8 with two catalysts and merc treads you should be able to tower tank with a partner, you will take some damage but as long as your ult is used you can move quickly in for the grab on the enemy champ. You will need to keep farming even if the enemy tower is destroyed, A farmed tank is always a good tank.

The point of singed is to keep them in your poisen so constant slows and making sure they follow in your poisen is a major factor in playing singed. use slow and flip together to keep them inside your poisen trail. with the runes and RoA they will die more then likely before they reach thier base.

remember you can also be a gaurdian to your teamates, try to avoid tossing enemy champs into weaker members of your team. especially if they are low on health. or use your slow to help kite the enemy team.

By the end of a 40 minute game you should have close to 300 creeps. As well if played correctly you should have over 10 kills with ease. remember that speed is your friend and its smart sometimes to throw the people who slow away from you so you can charge right up to thier carries. the other team members will chase you through, you are the tank get thier attention.

Vote if you enjoy this build, it is super easy to build and people will hate you for using it.
Purple for poisen cause if you forget to turn it on you are doing it wrong and will lose..

Happy Charging!