40 CFR 65.82: Design requirements.

(a) The owner or operator shall equip each transfer rack with either one of the following equipment:

(1) A closed vent system which routes the regulated material vapors to a control device as provided in § 65.83(a)(1) and (2).

(2) Process piping which routes the regulated material vapors to a process or a fuel gas system as provided in § 65.83(a)(4), or to a vapor balance system as provided in § 65.83(a)(3).

(b) Each closed vent system shall be designed to collect the regulated material displaced from tank trucks or railcars during loading and to route the collected regulated material to a control device as provided in § 65.83(a)(1) and (2).

(c) Process piping shall be designed to collect the regulated material displaced from tank trucks or railcars during loading and to route the collected regulated material vapors to a process or a fuel gas system as provided in § 65.83(a)(4), or to a vapor balance system as provided in § 65.83(a)(3).

(d) Each closed vent system shall meet the applicable requirements of § 65.143.

(e) If the collected regulated material vapors are routed to a process or a fuel gas system as provided in § 65.83(a)(4), then each owner or operator shall meet the applicable requirements of § 65.142(c).