The piping must be cleaned and should be free of dirt, rust, scale, tools, rags, etc. prior to engine start-up. It is required that all customer supplied piping be cleaned and flushed with muriatic acid (pickling) to remove all welding slag and foreign material(1). After the "pickling" process, the pipe is very susceptible to corrosion, since its natural preservation has been removed. It is imperative that the piping then be rinsed to neutralize the acid and that it be "preserved" immediately after the cleaning process.Ideally, the piping should be brought to site and loosely assembled, disassembled, sent out to be pickled, and then reassembled on site. Although this seems expensive and time consuming at first thought, it prevents having to do the same after the engine start-up.