Cathodic ProtectionRequirements forMilitary Projects

Michael A. Wallace, P.E.Electronics EngineerNACE Cathodic Protection SpecialistEngineering Division

US Army Corpsof EngineersMobile District

Office: 251-694-4068FAX: 251-694-4057michael.a.wallace@sam.usace.army.mil

CESAM-EN-DR109 Saint Joseph St.Mobile, AL 36602-36301-800-543-2021

Corrosion is a major Economic, Environmental,and Safety Problem which adversely affects our Nation, as well as many of our military facilities.

Impact of Corrosion

Corrosion is the deteriorationof a material, usually a metal, because of a reaction with itsenvironment.

What is Corrosion?

Typical Corrosion Cell

TUBERCULAR BUILDUP OF

RUST

Types of Corrosion Cells

• Dissimilar Metal Cell• Concentration Cell• Differential Aeration

Cell• Stray Current Cell

• Stress Cell• New Pipe and Old

Pipe Cell• Motion Cell• Combination Cell• Temperature Cell

Corrosion Control mustbe properly addressed duringthe design, installation, and subsequent operation of systems adversely affectedby the corrosion process.

Corrosion Can Be Controlled

Corrosion Control Methods

• Protective Coatings• Design• Environmental

Control• Material Selection• Cathodic Protection

Protective Coatings

• Normally first line of defense against corrosion: provides barrier between a corrosive environment and the structure.

• No coating is perfect and consists of holidays (voids) often resulting from improper application and/or damage.

• Cathodic Protection often used in conjunction with coatings to protect the holidays or voids in the coating system.

An electrical method ofmitigating corrosion on metallic structures that areexposed to electrolytes suchas soils and waters.

Cathodic Protection:

Sacrifical Cathodic Protection

Magnesium or Zinc

Impressed Current CP

Standards and Laws

• NACE International Standards (National Association of Corrosion Engineers)

• 40 CFR Part 280 - Underground Storage Tanks (UST)

• 49 CFR Part 192 - Transportation of Natural Gas and other Gas by Pipeline

• 49 CFR Part 195 - Transportation of Hazardous Liquids by Pipeline

• Individual State Environmental and Safety Laws

Military Criteria

• ETL 1110-3-474, Cathodic Protection• TM 5-811-7, Cathodic Protection• MIL-HDBK-1004/10, Electrical Engineering,

Cathodic Protection• MIL-HDBK-1136, Maintenance and Operation

of Cathodic Protection Systems (Draft)

Military Criteria (Cont.)

• Guide Specifications (Army)– UFGS 13110A Cathodic Protection System

(Sacrificial Anode)– UFGS 13111A Cathodic Protection System

(Steel Water Tanks)– UFGS 13112A Cathodic Protection System

(Impressed Current)

ETL 1110-3-474 requires CP & Coatings regardless of soil or water resistivity for:

• Natural Gas and propane piping

• Liquid fuel piping• Oxygen piping• Underground storage

tanks (UST) systems• Fire protection piping• Steel water tank

interiors

• Ductile or cast iron pressurized piping under floor slab

• Underground heat distribution & chilled water piping in metallic conduit

• Other structures with hazardous products

Designer Qualifications

• Design must be accomplished by qualified personnel. ETL 1110-3-474 requires the following:– All pre-design surveys, designs, and acceptance surveys

must be by a “Corrosion Expert.”– “Corrosion Expert” is a NACE Certified Corrosion

Specialist, CP Specialist, or registered Professional Corrosion Engineer.

– “Corrosion Expert” must have a minimum of 5 years experience in CP design and experience must be type specific.

Advantages of Adequate Corrosion Control

• Extended Coating and Structure Life yielding Cost Savings

• Protection of Environment

• Improved Public and Employee Safety

• Avoidance of costly Litigation resulting from non-adherence to Laws and Regulations

Upstream View of Rupture Crater

Carlsbad, NM Explosion

Lively, TX Explosion• Gas Explosion - killed

2 Teenagers• Oil Company did not

maintain CP system and falsified records to OPS

• Jury awarded over 300 million dollars to Plaintiff

Removed & Leaking UST

Tank Wall Completely Penetrated Due to Pitting Corrosion

Corrosion of Steel H Piling Embedded in Concrete

MacDill AFB, Florida

Summary

• Corrosion is costly and its effects can cause harm to our environment, as well as to human life.

• Cathodic Protection can effectively control corrosion.

• Cathodic protection is required by many laws and regulations and must be designed by qualified personnel.