42 conducting feasibility studies and consultation concerning engineering, construction and installation of gas pipe-lines, oil pipe-lines, casings and forms of metal for oil wells, hoops, jackets, metal frames, metal pipes, tubes, casings and pipe-lines of metal, offshore drilling metal platforms, equipment and works for prospecting and exploiting liquid or gaseous hydrocarbon fields, in seas, rivers, streams, and generally any water planes and waterways and onshore, namely, floating or non-floating drilling rigs, excavating machines, silage machines, beating machines, pile drivers, welding machines, derricks, lifting and handling apparatus, hoist elevators, landing stages, boat machines, drainage machines, apparatus for treating ore and hydrocarbons, blowers for compression, exhaustion and transport of gases, automatic handling machines, cofferdams, protecting walls, hulls, bulkheads, frames and framework not of metal, rigid pipes not of metal, for prospecting and exploiting liquid or gaseous hydrocarbon fields, and of landing-stages and pipes in seas, rivers, streams and generally any water planes and waterways and onshore