255.461 External corrosion control: protective coating.

(a)Each external protective coating, whether conductive or insulating, applied for the purpose of external corrosion control must:#

(1)be applied on a properly prepared surface;#

(2)have sufficient adhesion to the metal surface to effectively resist underfilm migration of moisture;#

(3)be sufficiently ductile to resist cracking;#

(4)have sufficient strength to resist damage due to handling and soil stress; and#

(5)have properties compatible with any supplemental cathodic protection.#

(b)Each external protective coating which is an electrically insulating type must also have low moisture absorption and high electrical resistance.#

(c)Each external protective coating must be inspected just prior to lowering the pipe into the ditch and backfilling, and any damage detrimental to effective corrosion control must be repaired.#

(d)Electrical tests appropriate for the type of coating shall be used on pipelines to operate at 125 psig (862 kPa) or more to detect defects in the coating which may not be revealed by a visual inspection. Where such tests are not practical, electrical tests, after installation, shall be conducted.#

(e)Electrical tests of pipe coating on distribution mains, other than those covered by subdivision (d) of this section, shall be conducted where practical.#

(f)Each external protective coating must be protected from damage resulting from adverse ditch conditions or damage from supporting blocks.#

(g)If coated pipe is installed by boring, driving or other similar method, precautions must be taken to minimize damage to the coating during installation.#