(a) Except as provided in paragraphs (b) and (c) of this section, the provisions of this part apply to any porcelain enameling facility which discharges pollutants to waters of the United States or introduces pollutants into a publicly owned treatment works.

(b) Any existing porcelain enameling facility which prepares or coats less than 1600 m²/day and which introduces less than 60,000 1/day of wastewater into a publicly owned treatment works is not controlled by the pretreatment standards for existing sources established by this regulation. Such facilities must comply with the provisions of 40 CFR part 403.

(c) This part does not apply to the porcelain enameling on precious metal basis material.

(d) When wastewaters from coating cast iron are cotreated with wastewaters from coating steel, the limitations for coating steel contained in § 466.11 may be applied to the entire wastestream.