check this
hxxp://pt.scribd.com/doc/14830059/Estimators-Piping-ManHour-Manual-5th-Edition&ei=ISe-UabIGZGf7gbCv4GoCA&usg=AFQjCNHMplquDza8eVEX7AXcDKc POIzlqA&sig2=97lJeSa4nMgFUeJ_bgd6qQ&bvm=bv.4788377 8,d.ZWU