A railway administration may, on the request made by the consignee or endorsee, allow weighment of the consignment subject to such conditions and on payment of such charges as may be prescribed and the demurrage charges if any:
     Provided that except in cases where a railway servant authorised in this behalf considers it necessary so to do, no weighment shall be allowed of goods booked at owners risk rate or goods which are perishable and are likely to lose weight in transit:
     Provided further that no request for weighment of consignment in wagon-load or train-load shall be allowed if the weighment is not feasible due to congestion in the yard or such other circumstances as may be prescribed.