In VOC service
In VOC service means that the piece of equipment contains or contacts a process fluid that is at least 10 percent VOC by weight. (The provisions of 60.485 specify how to determine that a piece of equipment is not in VOC service.)
40 CFR § 60.481
As used in this subpart, all terms not defined herein shall have the meaning given them in the Act or in subpart A of part 60, and the following terms shall have the specific meanings given them.