Plan your management system
The ISO Navigator™ database hyperlinks the ISO 9000 principles and the ISO 9001 requirements; and explains them in plain English with practical guidance.
ISO 9001: Purchasing 7.4
The purchasing process is essential to any organization's ability to provide customers with products that meet their requirements. You should ensure that all purchased products conform to the specified purchase requirements that are generated by the design and development and the customer related processes.
It would be extremely uncommon for purchasing to be excluded from the quality management system. ISO 9001:2008 specifies three aspects to the purchasing process.