40 CFR §420.101

1. (a)The term recirculation means those cold rolling operations which include recirculation of rolling solutions at all mill stands.
2. (b)The term combination means those cold rolling operations which include recirculation of rolling solutions at one or more mill stands, and once-through use of rolling solutions at the remaining stand or stands.
3. (c)The term direct application means those cold rolling operations which include once-through use of rolling solutions at all mill stands.
4. (d)The term single stand means those recirculation or direct application cold rolling mills which include only one stand of work rolls.
5. (e)The term multiple stands means those recirculation or direct application cold rolling mills which include more than one stand of work rolls.
6. (f)The term cold worked pipe and tube means those cold forming operations that process unheated pipe and tube products using either water or oil solutions for cooling and lubrication.