3.7 ... Direct contracting without competition (single source) may be an appropriate method under the following circumstances:
(a) An existing contract for goods or works, awarded in accordance with procedures acceptable to the Bank, may be extended for additional goods or works of a similar nature. The Bank shall be satisfied in such cases that no advantage could be obtained by further competition and that the prices on the extended contract are reasonable. Provisions for such an extension, if considered likely in advance, shall be included in the original contract.
(b) Standardization of equipment or spare parts, to be compatible with existing equipment, may justify additional purchases from the original supplier. For such purchases to be justified, the original equipment shall be suitable, the number of new items shall generally be less than the existing number, the price shall be reasonable, and the advantages of another make or source of equipment shall have been considered and rejected on grounds acceptable to the Bank.
(c) The required equipment is proprietary and obtainable only from one source.
(d) The contractor responsible for a process design requires the purchase of critical items from a particular supplier as a condition of a performance guarantee.
(e) In exceptional cases, such as in response to natural disasters.