**Minnesota Construction Specification 214---Cathodic Protection for
Buried Metal Structures**

**1. Scope**

The work shall consist of furnishing and installing all material
necessary to provide cathodic protection for metal structures as shown
on the drawings.

**2. Material specification**

Anodes and connections shall conform to the requirements of Material
Specification MN-306.

**3. Installing anodes**

The anode metal shall be centered in the packaged backfill just prior to
installation. Anodes may be placed either horizontally or vertically and
shall be deep enough to have at least three (3) feet of earth cover.
Unless otherwise specified the anodes shall be saturated with a minimum
of five (5) gallons of water after being placed, and prior to being
backfilled. Moist, fine-grained earth material shall be used to backfill
around the anodes. Compaction shall be to the density of the surrounding
fill and shall be accomplished by means of hand tamping or manually
directed power tampers or plate vibrators. The fill shall be placed in
layers not exceeding four (4) inches prior to compaction.

**4. Attaching anode to pipe**

The lead wire from the pipe shall be attached to the pipeline by a
powder welding process. The area of damaged pipe coating and the weld
shall be repaired as specified in Section 6.

Unless otherwise specified, the lead wires from anodes shall be
connected to the header wire by a powder weld, brazed or silver
soldered. The connection shall be made waterproof and tightly wrapped to
a minimum thickness of 24 mils of vinyl plastic electrical tape. Prior
to wrapping, the connection shall be thoroughly cleaned to remove all
foreign material and moisture.

**5. Testing stations**

A testing station shall be installed as shown on the drawings for each
anode bed installation. The anode lead or header cable from the anode
bed and the lead wire from the pipeline shall be placed in a galvanized
metal conduit between the ground surface and the test box.

The test box shall be a metal, weatherproof device. The leads shall be
connected to a terminal post or block or be connected with a split bolt
connector. The electrical circuit shall be insulated from the test box.

**6. Repair of damaged coatings**

Any damage to the zinc coating shall be repaired by thoroughly wire
brushing the damaged area, removing all loose and cracked coating,
removing all dirt and greasy material with solvent, and painting with
two coats of zinc dust-zinc oxide primer conforming to the requirements
of Federal Specification TT-P-641, Type III, or zinc dust paint
conforming to the requirements of Military Specification MIL-P-21035. If
the coating is damaged in any individual area larger than 12 square
inches or if more than 0.2 percent of a total surface area of a length
of pipe is damaged, the length will be rejected.

Bituminous coating damaged by welding or breaks or scuffs in bituminous
coatings that are less than 36 square inches in area shall be repaired
by the application of two coats of hot asphaltic paint or a coating of
cold-applied bituminous mastic. The repair coating shall be at least
0.05 inches thick after hardening and shall bond securely and
permanently to the connection and the pipe. The material shall meet the
physical requirements for bituminous coatings contained in the
references cited in Material Specifications 551 and 552. Whenever
individual breaks exceed 36 square inches in area or when the total area
of breaks exceeds 0.5 percent of the total surface area of the pipe, the
pipe will be rejected.

Polymeric or pitch resin coating damaged by welding of coated pipe or
pipe fittings and breaks or scuffs in polymeric or pitch resin coating
that are less than 36 square inches in area shall be repaired according
to the manufacturers recommended repair procedure. Surfaces to be coated
must be clean and dry. The repair coating shall be at least 0.010 inches
thick after hardening and shall bond securely and permanently to the
pipe. The material shall meet the physical requirements for polymeric or
pitch resin coatings contained in the references cited in Material
Specifications 551 and 552. A plastic or vinyl repair coating shall be
similar and equal in quality to Scotch-Clad Protective Coating 1706,
manufactured by 3M Co., 3M Center, St. Paul, Minnesota. If the repair
coating thickness is not measured, six coats shall be applied allowing
30 minutes drying time between coats. Whenever individual breaks exceed
36 square inches in the area or when the total area of breaks exceeds
0.5 percent of the total surface area of the pipe, the pipe will be
rejected.

**7. Construction details**