Bulk materials and tagged items

Tagged (engineered) items — pumps, vessels, instruments, packaged units — each carry a unique tag, a datasheet and usually a dedicated purchase order; they are known early, priced by quotation, and tracked one by one from requisition to installation. Bulks — pipe, fittings, flanges, cable, cable tray, structural steel, bolts, paint — are defined by specification classes and consumed in quantities that only emerge from take-off; they are bought in aggregated orders against the MTO and managed statistically, with growth allowances and surplus percentages instead of per-item tracking.

The split runs through everything downstream: estimating treats tagged items as quoted line items and bulks as measured quantities at rates; procurement runs different processes for each; and material control on site is an inventory problem for bulks and a chain-of-custody problem for tags. Most quantity surprises live on the bulk side — tagged items are hard to lose, but nobody ever discovers on site that a pump is missing; they discover that the fittings are.