fabrication and erection of structures of various types on contract basis. On 13th September 1988, the petitioner entered into a turn key contract with Bharat Petroleum Corporation Ltd. (for short “BPCL”) for fabrication, assembly and erection of waste water treatment plant. The activities involved in the contract were procurement, supply, fabrication, transportation of various components, making of civil construction and erection of waste water treatment plant and commissioning it. By that plant, water polluted with oil, bacteria and chemicals and deficient in oxygen was required to be treated to remove oil, neutralize bacteria and harmful chemicals and supply oxygen to the water and and treat it before it was discharged in the pipeline. On 26th June 1990, the Superintendent of Central Excise (the respondent no.4 herein) issued a notice to the petitioner alleging contravention of provisions of Rule 9(i) read with Rules 52-A, 173-B, 173-C, 173-F, 173G of the Central Excise Rules. In the notice, it was alleged that the petitioner had fabricated/manufactured the waste water treatment plant in the premises of BPCL valued at Rs.5,32,37,123/- without payment of central excise duty thereon. The notice further alleged that the waste water treatment plant fell under chapter heading no.8419.00 on which excise duty was payable. The notice further alleged the plant came into existence in unassembled form as per the drawings and designs approved by the BPCL before the same was installed and