Steel Pipe data

Does anyone have any steel pipe data in regards to hanging 3 1/2" concrete across a porch; I have old engineer reports for specific applications on homes I have built however I am sure there is data somewhere that gives acceptable spans with spacing requirements.

This porch is spanning approximately 7 feet; I did one similar about 2 years ago and I had to use 4" pipes at 6 inches on center. Cant believe the concrete contractor would even attempt something like this…

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