I'm afraid you have the inputs reversed (i.e. you're trying to input water at the petroleum pipe, and petroleum at the water pipe). They are not interchangeable. Also note that sulphur is not a fluid but a solid object which has to be transferred by inserter, so your current attempt at piping it to...

The chemical plant at the top (the one that should be making sulfur) wont take in the petroleum or water that are going into the intake slots. Is there something that I'm missing that's breaking this or what?