CPV code 45253000 designates Construction work for chemical-processing plant in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
45253000 sits under 45250000 (Construction works for plants, mining and manufacturing and for buildings relating to the oil and gas industry) and groups 8 more specific sub-codes. When classifying a tender, choose the narrowest code that still covers the full subject of the contract.