bids are invited for custom bid for services - fabrication and erection of support structures--transportation, fabrication, erection, levelling, alignment, welding and painting of pipe supports, saddles, columns, pipe bridges, approach ladders, service platforms as per following scope of work:- 1) collection of steel structurals and plates from issue deptt./ stores, transportation to site of work and safe custody of material 2) all the supporting columns, structures, pipe saddles, pipe bridges, platforms and ladders saddles etc. shall be fabricated and erected as per drawing provided by the executing deptt. and as per site condition. 3) procedure for welding of sections of structural segments as per laid down guidelines in the drawing shall be followed. 4) the fabricated columns to be properly erected and aligned over the base plates on foundation bolts. care to be taken during erection work