147. Use of gases underground.- The employer shall ensure at a construction site of a building or other construction work that- (a) petrol or liquified petroleum gas or any other flammable substances are not used, stored inside the tunnel except with the prior approval of the project engineer under rule 120; (b) after the use of the petroleum or liquified petroleum gas, or highly inflammable substances referred to in clause (a), all remaining petroleum or liquified petroleum gas or highly inflammable substances are removed immediately from such tunnel; (c) no oxy-acetelene gas is used in a compressed air environment in excavation or tunnelling work. | 
