Import and carrying of equipment all over India for quality certification of customer products

Client is based out of Chennai and has obtained GSTN in TN. They are planning to import certain quality testing equipment which is generally taken to the customer places, located all over India, for quality assurance certification of the customer's products. Request experts to please provide the precautions/ documentations to be undertaken while transporting the quality certification machinery to customer places.

Also, it should be possible for the client wants to import the equipment directly to a customer place, say in Gujarat, for quality testing and then move the equipment back to TN? What documentation/ precautions would be necessary? Many thanks in advance to the experts.