NEC3 ECC: Option C, what should the formal process be for warranties transferring to the Employer from the Contractor?

e.g. Contractor procuring Equipment such as a 412kV High Voltage Transformer to be installed and commissioned by the Contractor.

Does the OEM warrenty for the transformer stay with the Contractor until the defects period expires then automatically transfer to the Employer? If so, what is the formal paperwotk that has to be in place for an auditable trail to enable the Employer to go directly to the OEM to claim under the warranty.