CORROSION PREVENTION AND CONTROL WORLDWIDE TABLE …

2 MAY 2016 MATERIALS PERFORMANCE

TABLE OF CONTENTSTANK PROTECTION CASE STUDIES

3 Chemically Bonded Phosphate

14 The Pros and Cons of Corrosion Barrier Linings

30 Corrosion Basics: Tank and Containment Linings

SPONSORED CONTENT TECHNOLOGIES

6 Anode SystemsThe Tank Corrosion Doctor

8 CosascoWireless Corrosion Monitoring in Tank Farms

10 DairylandUsing Decouplers to Improve Cathodic Protection System Performance in Storage Tank Applications

12 Electrochemical DevicesInnovative Products for Aboveground Storage Tanks

16 GMA GarnetAdvantages over other Abrasives

18 MATCORExternal Tank Bottom Cathodic Protection—State-of-the-Art Anode Technology

20 PolyCorpSelection Criteria for Corrosion-Resistant Rubber Linings

22 Rust-OleumThe Right Coating for the Right Job

24 Thorpe Plant ServicesThorpe Plant Services—FRP and Dual Laminate Specialists

31 MESAHeadline to come

REGULATIONS AND RESOURCES

26 Preventing Releases in Underground Storage Tanks

28 NACE International Education and Training for Tank Protection

29 NACE International Standards and Reports

TANK CORROSION CONTROLSUPPLEMENT TO MAY 2016

CORROSION PREVENTION AND CONTROL WORLDWIDE MATERIALS PERFORMANCE

About This Publication Corrosion is a leading cause of storage tank failures, but there are a wide variety of technologies and methods to effectively protect these structures. Technologies including cathodic protection, coatings and linings, chemical treatments, and leading-edge materials are serving to prolong the life of storage tanks and protect people and the environment from costly leaks. This publication provides a wide variety of resources for professionals charged with controlling the risk of corrosion on tanks.

materialsperformance.comEDITORIAL

MANAGING EDITOR-IN-CHIEF Gretchen A. Jacobson

EDITOR Kathy Riggs Larsen

TECHNICAL EDITOR Norman J. Moriber, Mears Group, Inc.

TECHNICAL EDITOR EMERITUS John H. Fitzgerald III, FNACE

CONTRIBUTOR Husna Miskinyar

GRAPHICS ELECTRONIC PUBLISHING Teri J. Gilley COORDINATOR

GRAPHICS DESIGNER Michele S. Jennings

ADMINISTRATION CHIEF EXECUTIVE OFFICER Robert (Bob) H. Chalker

GROUP PUBLISHER William (Bill) Wageneck

ASSOCIATE PUBLISHER Eliina Lizarraga

ADVERTISING SALES MANAGER Diane Gross [email protected], +1 281-228-6446

ASSISTANT SALES MANAGER Claudia Archer [email protected], +1 281-228-6497

ACCOUNT EXECUTIVES Erica R. Cortina [email protected], +1 281-228-6473

Brian Daley [email protected], +1 281-228-6455 Pam Golias [email protected], +1 281-228-6456 Jody Lovsness [email protected], +1 281-228-6257

Leslie Whiteman [email protected], +1 281-228-6248

ADVERTISING COORDINATOR Brenda Nitz [email protected], +1 281-228-6219

REGIONAL ADVERTISING SALES The Kingwill Co. REPRESENTATIVES Chicago/Cleveland/ New York Area– [email protected], +1 847-537-9196

NACE International Contact Information Tel: +1 281-228-6200 Fax: +1 281-228-6300 E-mail: [email protected] Web site: nace.org

EDITORIAL ADVISORY BOARD Zahid Amjad Walsh University Raul A. Castillo Consultant Irvin Cotton Arthur Freedman Associates, Inc. David D. He PG&E Jerry Holton Specialty Polymer Coatings USA, Inc. W. Brian Holtsbaum Corsult Associates (1980), Ltd. Russ Kane iCorrosion, LLC Ernest Klechka CITGO Petroleum Corp. Kurt Lawson Mears Group, Inc. Lee Machemer Jonas, Inc. John S. Smart III John Smart Consulting Engineer Jack Tinnea Tinnea & Associates, LLC L.D. “Lou” Vincent L.D. “Lou” Vincent PhD, LLC

3TANK CORROSION CONTROL SUPPLEMENT TO MP MATERIALS PERFORMANCE MAY 2016

CORROSION PREVENTION AND CONTROL WORLDWIDE MATERIALS PERFORMANCE

A variety of industrial facilities with struc-tures constructed of carbon steel (CS)—from pipelines, processing equipment, to tank farms and wastewater treatment plants in global economic sectors that include oil and gas, infrastructure, utili-ties, transportation, production, manu-facturing, and government—are at risk of corrosion. The large amounts of CS exposed to atmospheric conditions or harsh processes can be particularly sus-ceptible. The challenge with CS is that as soon as it is fabricated, it begins to corrode. This article describes an inor-ganic spray-on protective coating tech-nology developed by scientists with EonCoat, LLC (Raleigh, North Carolina) that provides corrosion protection to metal through a chemically bonded phosphate ceramic (CBPC) that bonds with the surface of a substrate to form an impenetrable ceramic. A case study is included that describes use of the coat-ing for protection of diesel tanks. This technology is a recipient of a 2015 MP Corrosion Innovation of the Year Award.

Chemically Bonded Phosphate Ceramics Provide Corrosion Protection for Storage Tanks

Stopping Corrosion, Minimizing Downtime

While many industries fight corro-sion due to rain, humidity, or proximity to a marine environment, some companies must combat it in harsher conditions where caustic chemicals may be present, such as the inside of some industrial storage tanks. Polymer coatings and rubber-type linings have long been used as physical barriers to keep corrosion promoters such as water, oxygen, and other aggressive substances away from steel substrates. This works until the coating or lining is scratched, chipped, or breached and corrosion pro-moters enter the gap between the substrate and coating, and become trapped.

“Often you can’t see the corrosion until you flake off the paint [and see] if there is corrosion under the surface,” says Bobby Hobbs, a job foreman at DC Metal Con-

struction (Ennis, Texas), a privately owned company specializing in steel construction and industrial plant building projects.

Stainless steel (SS) resists corrosion, and tank bottoms and other equipment at high risk for corrosion are sometimes constructed of SS for that reason; however, SS can cost up to six times as much as CS. When a large wastewater treatment facil-ity in Texas sought to control corrosion in a number of CS equalization tanks, the facility chose to have DC Metal Construc-tion coat the tank interiors with the CBPC coating. Wastewater can be very corrosive to CS, and traditional barrier coatings can-not reliably withstand it. The CBPC coating is inorganic, so there are no volatile organic compounds (VOCs), hazardous air pollut-ants (HAPs), or odor. This means that the coating can be safely applied in confined spaces.

Tank Protection Case Studies

Application of the CBPC coating to the interior of the CS equalization tank at a wastewater facility. Photo courtesy of EonCoat.

4 MAY 2016 MATERIALS PERFORMANCE TANK CORROSION CONTROL SUPPLEMENT TO MP

The CBPC coating technology utilizes two components—a food-grade acid phos-phate and a water-based slurry that con-tains base minerals and metal oxides (such as magnesium oxide [MgO])—that are combined and sprayed onto a metal surface with a plural spray system. An acid-base exothermic reaction occurs at the surface of the metal, which forms a hard, two-layer ceramic coating that is chemically bonded to the metal in about 5 min. The initial

application phosphates the steel in the pres-ence of an alkali and creates an amorphous (and contiguous) layer of iron-magnesium phosphate that is less porous than the crys-talline layer created by typical phosphating. This iron-magnesium phosphate barrier is chemically bonded to the steel, is highly resistant to corrosion, and is permanent. Corrosive elements cannot corrode or break through this amorphous layer.

On top of this passive layer, a 20-mil (508-µm) thick layer of ceramic made almost entirely of inhibitive pigments is formed. In the unlikely event that both the ceramic and the passive layer are breached, the ceramic layer will continually leach phosphates onto the surface of the metal. This phosphate does two things to stop corrosion and prevent further corrosion: it combines with any iron oxide to form iron phosphate, which arrests corrosion, and it also acts as a catalyst to create misawite (a hydrogen, oxygen, and iron compound). If a layer of misawite forms on the surface of steel, it creates a barrier that reduces the rate of further corrosion by many orders of

magnitude. This self-healing feature makes it virtually impossible for corrosion pro-moters such as oxygen and moisture to pen-etrate the coating. The ceramic shell resists corrosion, fire, water, abrasion, chemicals, and temperatures up to 400 °F (204 °C).

“Unlike traditional methods, the corro-sion-resistant coatings for mild steel have a double layer of protection,” says Hobbs. “The tough, outside ceramic coating will not chip like paint and takes sandblasting to remove. The chemically bonded layer stops corrosion and will not allow corro-sion promoters to spread.”

The CBPC coating has been rigorously tested by independent third parties. It has undergone thousands of hours without corroding in an ASTM B1171 salt spray test. To determine how the coating would per-form under a more aggressive corrosion test, a CBPC-coated steel sample, gouged down the center with a scribe, was tested for corrosion resistance using a seawater corrosion test developed by NASA. The test consists of continuous cycles of four hours of exposure to seawater spray (an average of

A CBPC-coated steel coupon (left) and a steel panel coated with another corrosion-resistant coating (right) after 45 days in an ASTM B117 salt fog test chamber. Photo courtesy of EonCoat.

Merck Pharmaceuticals fuel tank roof coated with the CBPC coating. Photo courtesy of EonCoat.


14 gal (53 L)of seawater are sprayed on the samples) followed by four hours of exposure to simulated sunlight (426-nm light waves) in a test chamber. Additionally, NASA per-formed 18 months of outdoor testing on the CBPC coating at its Corrosion Testing Lab at Kennedy Space Center, Florida as part of the first stage of a validation project for environmentally preferable coatings for its launch facilities. The coating advanced to the second stage of the validation project. The coating was also included in testing by the Edison Welding Institute for the Federal Railroad Administration (FRA) Rail Base Corrosion and Cracking Prevention study.2

After experiencing good results with the coating in the CS equalization tanks, DC Metal Construction coated the inside of a clarifier tank at the Texas wastewater facil-ity as well. “In the five steel tanks we have sprayed…in the past six years, we have had no corrosion issues, and no need for patching,” says Hobbs. “From the results we are getting, I believe the corrosion-resistant coating can add decades of low-maintenance, usable life to carbon steel tanks and other structures.”

The CBPC coating is applied as a sin-gle-coat system using a two-part spray gun. Heating the material as it is sprayed is not required. The coating dries to the touch in 5 to 10 min and cures in about an hour. “After appropriate tank preparation, we found that if we spray…in the morning, the tank can be returned to service the same day because it applies in one coat and dries quickly,” says Hobbs. “Quick return to service like this can be particularly important in production- focused industries like oil and gas. Since the corrosion-resistant coating has no VOCs, HAPs, or odor, we were able to spray during work hours, so the facility could stay in full production in adjacent areas while we coated the tanks,” he adds.

Case Study—Merck Pharmaceuticals

The aggressive production schedule of Merck Pharmaceuticals requires that pro-duction facilities be powered at all times and fully operational. To achieve this, Merck uses large tanks filled with diesel fuel to power generators that feed the facil-

ity. Merck had used a traditional three-part system of inorganic zinc, epoxy, and ure-thane to coat the fuel tanks, which eventu-ally showed signs of corrosion.

To prevent the costly time loss of repeated paint applications, Merck chose the CBPC coating with a topcoat to protect its assets and provide an environmentally sound corrosion-resistant solution. What is typically a two-week job to coat the tanks was shortened to five days. The surface preparation was less time consuming, flash rust did not need to be removed, and there was no need to wait for the coating to dry overnight prior to applying a topcoat. The application occurred in June 2014 when temperatures exceeded 95 °F (35 °C) in direct sunlight.

Source: EonCoat, LLC; Web site: eoncoat.com.

References 1 ASTM B117, “Standard Practice for Operating

Salt Spray (Fog) Apparatus” (West Consho-hocken, PA: ASTM International).

2 “Rail Base Corrosion and Cracking Preven-tion,” U.S. Department of Transportation Federal Railroad Administration, DOT/FRA/ORD-14/27, July 2014.

Chemically Bonded Phosphate Ceramics Provide Corrosion Protection for Storage Tanks

MPCIOYA ad (Jay is writing new copy, Teri's ads are old)


The Tank Corrosion Doctor

Anode Systems Company

“Cancer of Steel” is my definition of tank corrosion. Tanks, like humans, have a life cycle from young, to middle age, to old. As they age, tanks develop iron stains, rust, scale, and pits. Tanks, like humans, get sick. Coatings are the first line of defense against the sickness of corrosion. Coating a tank is like washing your hands to prevent a cold or the flu. Over time, coatings can become brittle, crack, and peel off. They lose their ability to protect the underlying steel. Installing anodes on tanks is like taking pills to reduce a fever or cold symptoms. They are like chemo in treating cancer.

Impressed current cathodic protection (CP) is like radiation for bare tanks. With enough cancer-fighting electrons from anodes, a tank can live a long, normal life. Magnesium and impressed cur-rent anode systems can put corrosion into remission. They will not have to be patched or have new bottoms installed. Corrosion prevention is the key to extending the life of a tank.

When choosing a doctor, you want one with a good educa-tion and experience. Mr. Schmoldt received degrees in geolog-ical engineering and geology in the 1970s from the University of Missouri at Rolla. Mr. Schmoldt began his career in corro-sion protection in the 1960s and 1970s working for Schmoldt Engineering in Bartlesville, Oklahoma. His internship was spent on construction crews every summer installing surface and deep well rectifier systems nationwide. He has worked for many ancestral oil and gas pipeline companies to today’s pipe-line companies. In 1984, he formed Anode Systems Company in Grand Junction, Colorado. In the last 32 years, Anode Systems has pioneered new and innovative solutions to protecting pota-ble water storage tanks, produced water lease tanks, under-ground storage tanks (USTs), and gasoline, diesel, chemical, and underground propane tanks. This specialist has 40 years of experience in installing and 32 years designing 556 UST anode systems and can write reports that tank owners understand.

Anode Systems sponsored the first UST seminar in Colo-rado in 1987. Anode Systems gave the first class on corrosion prevention on underground propane tanks in 1993. Anode Sys-tems sponsored its first seminar on corrosion protection for produced water tanks in 2010. Since 1987 Anode Systems has conducted 84 classes or seminars in 22 states to tank owners on CP design, testing, repairs and maintenance of CP systems.

ANODESYSTEMSCOMPANY

124 N. 22nd Ct.Grand Junction, CO 81501

+1 970-260-2775anodesystems.com

Hans Schmoldt, NACE Cathodic Protection Specialist #4162.

Anode Systems can diagnose whether your tank has a cold, the flu, or cancer. Remember, there are many causes of cancer and there are many causes of corrosion. Anode Systems makes house calls to wherever your tanks are located. From Alaska to Florida and from the East Coast to the West Coast. Mr. Schmoldt will utilize his education and expertise to engineer cost-effective CP solutions. He personally intends to actively pursue this work through 2025.


Cosasco

Wireless Corrosion Monitoring in Tank FarmsCorrosion of oil/fuel or chemical tanks presents a significant risk to both the environment and local communities. Tank farms are often located in suburban areas or near environmentally sensi-tive areas where the effects of a leak can be devastating. Seepage of flammable liquids into watercourses produces potentially explo-sive vapors, leading to deadly fires.

Typically, storage tanks require monitoring for corrosion both internally, caused by corrosive water coalescing in the bottom of the tank, and externally, caused by contact with water-bearing backfill materials resulting from water seeping under the tank floor.

It is normal practice to protect the internals of tanks by several different methods:

• A chemical treatment, either continuous injection of an inhibitor, or using slow release solid chemical, periodically dropped through the tank roof.

• The tank floor and the shell are coated with corrosion- resistant epoxy resin paint. In case of small "holidays" or localized damage, it is often further protected by a sacrifi-cial cathodic protection (CP) system.

To mitigate external corrosion, there are several methods available: • Most commonly, the underside of tank plates are protected

by a combination of epoxy coating and an impressed cur-rent CP system. The presence of a protective membrane can also provide additional corrosion protection.

• Other methods include corrosion inhibitor impregnated membranes and vapor dispersed inhibitor pumped under the membrane from below.

All of these methods require corrosion monitoring to evalu-ate whether they are working efficiently or if further measures are required to prevent or slow down corrosion attack on the structure of the tank.

Challenges• Older tank farms often have inadequate monitoring sys-

tems with no integrated data management, limiting data quality and access.

• Aging tanks require an increased focus on safety and envi-ronmental regulations.

• Loss of produced fuel decreases profits.

SolutionHistorically, retractable electrical resistance (ER) probes are

inserted into the lower part of the tank wall to provide monitor-ing internally and, for external monitoring, Cosasco’s underground

11841 Smith AvenueSanta Fe Springs, CA 90670

+1 (562) [email protected] • cosasco.com

620HD ER probes are installed under tank bottoms. These were read with a handheld device.

The new ER 300 Series Wireless Transmitter makes upgrading to a fully automated data collection system more affordable, with-out the costs of cabling. With WirelessHART7 and ISA100 Wireless communication options, ER Wireless Transmitters can be easily integrated with existing process monitoring systems. The ER Wire-less Transmitter connects to a 620HD and 3500 probes via a probe adapter. Metal loss measurements are transmitted back to a Gate-way and onto a server with Cosasco Data Online software.

Benefits• Comprehensive monitoring and protection systems provide

the best method of ensuring the integrity of storage tanks.• Monitoring both internally and externally encompasses the

areas most at risk from corrosion.• External corrosion monitoring provides information on the

performance of the impressed current CP system. • Internal monitoring provides information on the perfor-

mance of chemical and sacrificial CP systems inside the tank.• Wireless communication removes the need to visit the site

to record the data, reducing travel time to remote areas and providing the most up-to-date corrosion data.

• Seamless integration with WirelessHART7 and ISA100 Wireless Protocols.

The New Age of

Tank Farm Monitoring

Wireless data reduces risk and increases profitabilityCosasco customized wireless corrosion monitoring systems provide total protection for your tank farm, ensuring the safest operation and longevity of your storage system.

Internal and External Corrosion Monitoring

Evaluate effectiveness of Impressed Current CP System

Reduce risks with data delivered to your desktop

Seamless integration with WirelessHART7 and ISA100 Wireless process systems

For more information: [email protected] or visit www.cosasco.comUSA (800) 635-6898 Intl: +1 (562) 949-0123


Using Decouplers to Improve Cathodic Protection System Performance in Storage Tank Applications

Dairyland Electrical Industries

Dairyland decouplers are often associated with common indus-try applications such as alternating current (AC) mitigation and insulated joint protection, however they can also provide significant performance improvements for cathodic protection (CP) systems in a wide variety of applications, including on storage tanks.

Facility Grounding Systems Can Compromise Tank CP

Typical storage tanks are electrically bonded to local grounding systems to provide lightning protection. In addition, most tanks have electrical equipment such as motor-operated valves, pumps, and instrumentation that must be grounded for AC fault protection. Numerous connections can establish a bond between the tank and facility grounds, including grounding conductors of AC-powered equipment, metal conduit, metallic instrumentation shields, piping, and other bonds or directly connected ground rods. These ground-ing systems, since they are bonded to the tank, are also protected by the CP system and thus demand CP current well in excess of what would otherwise be required to protect the tank alone.

As a result, users can have difficulty achieving sufficient CP voltage levels to prevent corrosion, supply excessive CP current from an oversized design, or cause interference between structures.

Dairyland Decouplers Provide Simultaneous Overvoltage Protection and CP Isolation

Dairyland products address tank facility CP problems by acting as an isolation device in the affected bonds and grounds, yet meet overvoltage safety requirements. When installed in series in the grounding conductor of AC-powered equipment and in other bonds between the tank and facility grounding system, Dairyland products block passage of direct current from CP systems while providing safety grounding in the event of an AC fault or lightning strike. Sim-ilarly, decouplers should also be applied to other potential paths for CP current such as conduit and instrumentation shielding that is bonded to the protected tank. Dairyland decouplers and overvolt-age protectors are UL and C-UL certified for providing an “effective ground-fault current path” as defined by the U.S. National Electrical Code, and other codes. The result is an effective CP system that is unaffected by the site grounding systems.

PO Box 187 Stoughton, WI 53589

+1 [email protected] • dairyland.com

Properly applied Dairyland decouplers and over-voltage protectors can dramatically improve the performance of CP systems in tank facilities.

Most tanks also have piping that may create a bond to other tanks or pipelines, unless insulated joints are utilized. Although very effective at blocking CP current, insulated joints can be dam-aged by AC faults and lightning. Dairyland decouplers can be used to protect insulated joints during these events while maintaining isolation of CP current.

Product Selection for Hazardous Locations

Many tank facilities are formally classified as hazardous loca-tions and appropriate decoupler products must be selected based on these classifications. The most common hazardous location desig-nations are Division 2 or Zone 2, where explosive gases or vapors are not typically present, and Division 1 or Zone 1 locations, where such gases may be commonly present. Dairyland’s products are the only solid-state decoupling devices in the world certified for use in areas classified as Division 1 or Zone 1, and an array of Division2/Zone 2 certified products are also offered. Dairyland maintains an audited ISO 9001 quality system and extensive product certification.


Innovative Products for Aboveground Storage Tanks

Electrochemical Devices, Inc.

For its more than 30 years participation in the corrosion control industry, Electrochemical Devices, Inc. (EDI) has always asked the question, “How can we improve upon what’s out there?” The unparalleled success of the innovative products we have pro-vided over that time includes what we offer for aboveground stor-age tanks (ASTs).

About 20 years ago our first offering was the Model AT Lin-ear Anode System. Because we recognized that very long anode wires can be difficult to control and install, we reasoned that this could be solved by making shorter lengths joined together with the underwater connectors used in some of our other products. This enables us to make 15-m (50-ft) anodes that can be shipped from stock in a week or less. Each anode consists of a copper-cored titanium flat wire coated with mixed metal oxide in parallel with a #14 AWG shunt wire, all protected in a flexible mesh sleeve. Each length has a pin connector on one end and a socket connector on the opposite end so they can be mated either to additional anode sections to form an anode string or to a power feed cable. The con-nectors include a SureLock mechanical fitting to ensure mechani-cal and electrical integrity of the joint, and it installs quicker than all other systems. A calculator on our Web site allows a cathodic protection (CP) designer to determine what materials are needed for a given tank diameter.

Monitoring an AST bottom is challenging. The sand bed starts out very dry and gets even drier as the CP system operates. As a result, reference electrodes placed in this arid environment may only provide reliable potentials for a year or less before they dry out internally. An accurate embedded reference electrode is neces-sary during commissioning to ensure that the tank bottom is ade-quately protected. For subsequent corrosion monitoring, the use of electrical resistance (ER) probes has proven to be effective in these environments. EDI is working with an established manufacturer of ER probes to develop our Model SU Tank Monitoring System. It consists of both a reference electrode for commissioning and a high sensitivity ER probe for long-term monitoring in a common hous-ing. Because copper ions diffusing from the reference electrode can plate out on the ER sensor, affecting its accuracy, a steel ring is added to attract them before they reach the probe.

An alternative way to accurately measure tank bottom poten-tials is to pull a reference electrode through a perforated pipe placed in the sand beneath the AST. Our Model UT Undertank Ref-erence Electrode is designed for this purpose. A complete potential

PO Box 789Middlefield, OH 44062

+1 [email protected] • edi-cp.com

Model AT linear anode system is easier and faster to install than any other system.

profile can be taken across the tank bottom. Contact to the electro-lyte is through an all wood membrane that is resistant to breakage and will not clog with salts or dry out as rapidly as ceramic mem-branes. When not in service, the reference electrode can be stored indoors and easily calibrated before its next use.

Go to our Web site edi-cp.com to get complete information on these products.

electrochemical devices, inc.


Maria Silva, Belzona Polymerics, Ltd.

When selecting a protection system suitable for corrosion, we need to look at the total expenditure as well as the cost of a unit. This can include cover-age rate, length of downtime, and costs of application based on the sys-tem’s simplicity or difficulty. Selection and maintenance of a corrosion pro-tection system, which considers more aggressive environments comprised of elevated temperature immersion service with relatively corrosive acids or alkalis and some degree of erosion or abrasion, can contribute to the op-erating expenditure. These environ-ments can be common in piping and process vessels in the oil and gas up-stream and downstream sectors as well as petrochemical, chemical, and mineral processing industries. Chemi-cals such as sulfuric acid (H2SO4) and hydrochloric acid (HCl) in combination with seawater and erosive slurries can quickly eat away at the base metal, which is typically carbon steel.

The Pros and Cons of Corrosion Barrier Linings

The industry has moved away from base metals with high corrosion allowances to the application of a corrosion protection sys-tem that is able to extend the lifetime of the asset to an average of 20 to 30 years. Material selection for protecting the base metal can include a variety of options—exotic alloys, metallic cladding, epoxy and rubber linings, and other coatings. Following are descrip-tions of some of the technologies available and how they are used to the best advantage.

Glass LiningsGlass-lined steel performs well in a vari-

ety of operating conditions and offers excel-lent resistance to corrosion. Its anti-adhe-sive properties make it very suitable for use in the chemical and pharmaceutical industries. It provides superior corrosion resistance to acids, alkalis, water, and other chemical solutions (with the exception of hydrofluoric acid [HF] and hot concentrated phosphoric acid [H3PO4]). As a result of this chemical resistance, glass lining can serve for many years in environments that would quickly render most metal vessels unser-viceable. Its costs, however, are directly proportional to the protection it provides in extremely aggressive environments. Glass is not as effective against alkalis at higher tem-peratures. An increase of 10 ºC (18 ºF) can double the rate of attack on glass-lined steel. In addition, glass linings are very suscepti-ble to impact damage and the repairs can be very costly. For milder service conditions, a glass-flake technology can be considered.

Glass Flake-Containing Coatings

Glass flakes have been used to improve both barrier properties and reinforcement in anticorrosive coatings since the early

1970s. Due to their good chemical and ero-sion resistance, glass flake-based coatings are used in a variety of industrial sectors. Although glass flake is impervious to mois-ture vapor and gas diffusion, it does not pres-ent a continuous barrier in a resin matrix. The resin carrier, therefore, plays a very important role (i.e., glass flake cannot turn a poor resin film into an excellent coating, although it may substantially improve it).

Vinyl ester is one of the more common resins used with glass flake. It offers ben-efits in terms of cost savings, but also has several drawbacks. The polymerization process involved in the curing process of glass flake systems leads to shrinkage, causing the bond line to be permanently stressed. Adhesion is also found to be infe-rior to that of an epoxy-based system. The vinyl ester system can be brittle and easily damaged during inspection or mainte-nance. The cure mechanism, inhibited by atmospheric oxygen, can lead to significant coating voids that lead to failure, particu-larly in decompression situations. This has been confirmed by a test sponsored by a global group of energy and petrochemical companies. Vinyl ester glass flake systems, therefore, can be quite suitable for pipeline protection or storage tanks, but are not ideal for use in pressurized equipment.

Organic Epoxy CoatingsEpoxy coatings such as ceramic-filled,

modified epoxy novolac, or high-molecu-lar-weight polymer composites, have been on the market for many years and are con-tinually modified with new raw materials to improve features such as temperature resis-tance, abrasion resistance, adhesion, and sprayability for ease of application. Ceram-ic-filled epoxies are widely used for ero-

Tank Protection Case Studies


sion-corrosion protection. The limitations of these coatings are temperature resis-tance and sprayability. Both of these issues have been addressed by the introduction of modified epoxy novolac, which is able to continuously resist immersion tempera-tures up to 160 ºC (320 ºF), and high-mo-lecular-weight polymers, which offer supe-rior erosion resistance while being spray friendly. There are some risks associated with the use of epoxy coatings, mainly due to applicator error and incorrect coating specification. Both can be addressed with appropriate training and guidance pro-vided by the material manufacturer. Where epoxy coatings are limited in terms of tem-perature and chemical resistance, polytet-rafluoroethylene (PTFE)-based coatings can be used.

PTFE CoatingsPTFE coatings are widely used in situa-

tions where superior corrosion resistance is required. Fluoropolymers are the materials of choice for the process industry, serving as linings for vessels, piping, pumps, valves, columns, column internals, hoses, expan-sion joints, seals, and gaskets. They provide durable, low-maintenance alternatives to exotic metal alloys, as well as thermal sta-bility for use at high temperatures. Because they do not react with the process liquids, they prevent product contamination. PTFE is electrochemically, biochemically, enzy-matically, and virtually chemically inert. The coatings’ important, useful properties are retained at temperatures up to 200 ºC (392 ºF) with no more than 15% loss of chemical resistance, which means that PTFE has the highest retention rate of its chemical properties of any known plas-tic-like material.

Unfortunately, PTFE comes with a number of unfavorable properties when used with corrosive materials, and it is important to understand these in order to manage them. Because of a lack of intermo-lecular forces, the material is soft and easily abraded, and erosion is a potential concern as well as creep or cold flow under load. PTFE is also difficult to repair if damaged, as this cannot be done in situ.

Recoating a Petrochemical Plant Reactor

The maintenance manager of a polyole-fin petrochemical plant based in Ferrara, Italy was searching for a new coating sys-tem for the plant’s reactor, which operated between 70 to 80 ºC (158 to 176 ºF) and processed salt, caustic, and titanium tetra-chloride (TiCl4). The original hot-applied PTFE lining required maintenance due to localized disbondment caused by minor abrasion of the titanium compound. As a result, the plant was facing a long down-time, between two and four weeks, because it was not possible to conduct an in situ repair.

The maintenance manager wanted to keep the downtime to an absolute mini-mum and ultimately decided to replace the PTFE with a 100% solids modified epoxy novolac system designed for elevated tem-perature immersion up to 160 ºC. The lin-ing was hand applied onto the reactor in April 2015, and it was returned to service within four days. An added benefit is the

servicing of the lining. The modified epoxy novolac system is applied at ambient tem-peratures and adheres well to metal and itself, so it can be repaired in situ when necessary.

In September 2015 the reactor was opened for inspection. If the lining was going to fail due to poor chemical resis-tance, this first inspection would have revealed visible signs of degradation. As the lining was found to be fully intact, its durability was not questioned. Moreover, plant maintenance was able to save time by steam-cleaning the reactor, which was not previously possible with the PTFE lin-ing. The savings realized from reduced downtime, along with simplified cleaning and maintenance protocols, significantly outweighed the initial cost of material. The plant is now looking at replacing the lining on other reactors, as well as protecting new reactors with the same 100% solids modi-fied epoxy novolac system.

The reactor recoated with a modified epoxy novolac system.

The reactor with the modified epoxy novolac system after six months in service.


Advantages Over Other Abrasives

GMA Garnet

GMA Garnet abrasive is composed of natural Almandite garnet grains that are known for their natural hardness, durability, and abrasive characteristics.

It is a cost-effective alternative to silica sand, mineral slags, and steel grits as the perfect symbiosis of grain size, density, and hardness/durability creates the optimum abrasive efficiency and lowest abrasive consumption (lb/ft2) at the highest production rates ( ft2/hr).

Low DustingBlast cleaning using GMA Garnet provides significantly lower

dust emissions due to its inherent material toughness and rapid setting (high specific gravity). This ensures minimum disruption and danger to adjoining operations and improves operator visibil-ity and safety.

High ProductivityVery fast cutting is achieved with speed and the large number

and shape of grains impacting the surface. The acceleration and speed of a grain in an air stream is a function of the inertia and hence the size of the grain. Smaller grains accelerate much more readily and impart higher impact energy to surfaces resulting in a superior cleaning rate—usually twice the ft2/hr of conventional abrasives.

Low ConsumptionThe unique grain size enables many more active grains to

impact the surface and greatly reduces abrasive consumption.

Superior Surface QualityGMA Garnet grains clean deep into the cavities and pitted areas

down to the bare metal, thoroughly removing all rust, soluble salts and other contaminents. The blasted surface is free of embed-ment and rogue peaks and troughs. SA3 White Metal is effortlessly achieved. Surface profiles ranging from 1 to 4.5 mils (determined by the mesh size utilized) are also easily achieved along with a much greater number of peaks per unit area.

Improved Health & Safety and the Environment

GMA Garnet is non-toxic with no silicosis hazard or risk of con-tamination from leachable heavy metals or radioactive substances. Disposal volumes are greatly reduced as a result of lower consump-tion and recyclability.

1800 Hughes Landing Blvd., Ste. 350The Woodlands, Texas 77380

Tel: +1 832-243-9300Fax: +1 832-243-9301

[email protected]

RecyclabilityGMA Garnet is suitable for multiple usages and can be recycled

five times or more without losing its superior cutting ability. Special garnet recycling systems are available upon request. These add up to natural clean and cost-effective blasting.

Being environmentally inert, GMA Garnet meets all Occupa-tional Health and Safety requirements and achieves the highest quality of processing standards in respect to mineral purity and the stringent requirements of ISO 11126-10, SSPC AB-1, QPL mil spec 22262-b, and all sizes are California CARB approved.

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External Tank Bottom Cathodic Protection—State-of-the-Art Anode Technology

MATCOR

External corrosion of tank bottoms is a significant problem for tank owners. Corrosion professionals tasked with protecting these structures should consider multiple factors. One thing is clear: proper installation of an impressed current cathodic protec-tion (CP) system plays an important role in reducing corrosion and extending the service life of the tank bottom.

For new tank construction (and many tank bottom replacements), state-of-the-art corrosion prevention requires clean, chloride-free sand bedding combined with a dedicated impressed current anode CP system directly under the tank. The use of oil sand, crushed stone, asphalt, or other materials directly under the tank bottom should be avoided, as these hinder effective CP. The vast majority of new tank construction projects utilize mixed metal oxide (MMO) impressed current anode systems. MMO anodes offer long life, low cost, and design flexibility, making this type of system the best choice for tank owners and system designers.

Two primary CP configurations are used in tanks worldwide. The field-erected anode grid configuration was an early application of MMO anodes for tank bottoms and has a large global installed base. This system utilizes MMO ribbon anodes field cut into strips and laid out in parallel. Titanium ribbon conductor bars are also field cut and laid perpendicular to the MMO anodes. The MMO rib-bon and titanium conductor bars are field tack welded at the inter-sections. Separate power cables are then tack welded to the tita-nium conductor bars and the cables are fed back to a junction box.

A newer design to protect tank bottoms is a system of linear anodes in concentric rings. The key advantage of a concentric ring anode system is that there is no field cutting or welding—the anode rings are supplied factory assembled, tested, and ready to be laid into position prior to backfilling. The anode is typically backfilled within a pre-packaged tube filled with a high-quality carbon back-fill. This enhanced backfill protects the anode during installation, keeps the anode weighted and in place, improves performance, and reduces system resistance. It can also reduce depolarization caused by oxygen generation, which can impact CP system performance. For tank replacements where there is very little space between the tank bottom and the anode, a sand backfill can replace the carbon backfill to help ensure that the anode does not short due to contact with the tank bottom.

The grid system continues to be specified by many, however the factory-assembled concentric ring system should be strongly con-sidered. There is only one opportunity to properly install the CP sys-

+1 [email protected]

matcor.com

tem prior to field erection of the tank. Once installed and the tank is erected, there is no access or ability to go back and repair the system. A design that eliminates field cutting and welding of the anode and the anode-to-cable connections significantly improves system reli-ability. With the concentric ring system, all anode segments are fac-tory assembled and tested, with no field connections or welds. This greatly reduces installation time and helps ensure a long, reliable life.

Tank Edge

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*Number of Rings Varies with Tank Diameter

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Selection Criteria for Corrosion- Resistant Rubber Linings

Polycorp

Natural and synthetic rubber linings have been used extensively to protect tanks, pipes, and equipment from corrosive service con-ditions. As the industry has developed and matured, the range of products has expanded significantly, giving companies a wide variety of materials to choose from. As the global leader in the supply of rubber linings for corrosion protection, Polycorp has over 100 formu-lations to match the harshest of conditions. Selection of the optimal lining material for a given application is critical for protecting tanks from corrosive materials.

Rubber linings have a number of distinct advantages when used for corrosion protection. These include:

• Elastic nature of the material allows for flexing of the metal substrate

• Curing after application results in a “seamless” lining• Linings can be relatively thick—providing greater

protection and longer service life• Extremely cost effective• Decades of service history

Given the extensive range of products available, Polycorp engi-neers are always available to assist customers in choosing the best product for their application. In order to make the best recom-mendation, information is required on all operational conditions. Examples include:

• Temperatures—minimum, maximum, and normal operat-ing range

• All chemicals present• Potential chemical reactions in the tank• Operating pressures• Maintenance and cleaning practices• Indoor or outdoor location of the tanks• End use of the product such as food or pharmaceutical

With the correct information, Polycorp engineers can rec-ommend the best product for the application—ranging from our industry leading natural rubber linings to synthetics such as butyls or neoprenes or our unique TriflexTM range.

For more information, contact: Dennis Nolan, [email protected].

33 York St. West Elora, Ontario, Canada

+1 519-846-2075 • [email protected] • poly-corp.com

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Rubber Linings for Corrosion and Abrasion Protection

Polycorp designs and

manufactures the highest

quality Protective Linings

made from uncured natural

and synthetic rubber. We

help customers manage

the risk associated with

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accidental release.

Polycorp linings are used to protect railcar and truck tanks,

holding vessels, process equipment, and pipes, from a wide

range of acids, alkalis and abrasives. Our customers benefit

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of proven performance in the protective linings industry.

Contact us for answers to your corrosion and wear

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INNOVATION / QUALITY / SOLUTIONS / TECHNICAL SUPPORT+1-519-846-2075 / +1-800-265-2710 / www.poly-corp.com


The Right Coating for the Right Job

Rust-Oleum Corporation

In the center of the Northern Pacific Ocean, Midway Atoll (better known as Midway Island) became famous during WWII because of the major battle fought there between the Japanese Imperial Navy and the U.S. Navy in June, 1942. It was latter said that the battle was the turning point of the war in the Pacific. The U.S. Navy maintained Midway as a large and significant base during the years after the war. In the 1990s, the base was retired and the island was given back to the wildlife. It functions now mainly as a wildlife preserve that is home to an estimated 1.5 million birds, mostly Albatross, as well as endangered species of seals and turtles. There is a small group of personnel stationed there to maintain the airstrip, which basically functions as an emergency landing strip for trans-Pacific commercial aviation.

Rust-Oleum Noxyde Was Chosen for the Job.

Noxyde is a high build, water-based elastomeric coating that provides ultra-rugged protection in aggressive environments. It is well known for its use on suspension bridges for coating the main cables and suspender ropes. The flexibility of the coating along with the excellent adhesion and corrosion protection make it ideal for that type of dynamic environment. Additionally, it is suitable for use in many areas where steel needs to be protected from atmo-spheric corrosion, especially in coastal environments. Noxyde meets the requirements for ISO-12944 C5-M High and can tolerate surface chloride contamination up to 10 µg/cm2.

Noxyde has been tested in both independent laboratory and real world applications and has shown its performance over a min-imally prepared surface is equal to the performance of an inorganic zinc/epoxy system on an abrasive-cleaned substrate. The mini-mum surface preparation requirements for a Noxyde application is SSPC-SP3 Power Tool Cleaning or High Pressure Water Cleaning with a minimum 5,000 psi, to a cleanliness grade of SSPC WJ-4 Light Cleaning. The ability to need only minimum surface preparation when using Noxyde has shown to reduce total job cost significantly, in most cases by 50-65%.

The tanks on Midway Island were prepared by high-pressure water cleaning, then coated with two coats of Noxyde and a water- based acrylic finish. The recommended dry film thickness (DFT) for Noxyde is 7-9 mils, therefore the three-coat system had a total DFT of 16-21 mils. The use of this high build system resulted in superior adhesion and extended corrosion protection of the tanks, and dramatically reduces the leachability of lead from the previous coating that would affect wildlife now inhabiting the island.

11 Hawthorn Parkway Vernon Hills, IL 60061

+1 847-367-7700 rustoleum.com

Aviation fuel storage tanks on Midway Atoll coated with Noxyde.

INDUSTRIAL BRANDS

NOXYDE®

THE POWER OF

FOR UNRIVALED CORROSION PROTECTION

Rust-Oleum® Noxyde® Elastomeric Acrylic Coating provides ultra-rugged protection in aggressive environments. This heavy-duty, water-based formula provides high build coating for flexible durability on new or minimally prepared steel, metals and concrete.

FEATURES & BENEFITS • Resists corrosion, rust and water – even in severe marine environments;

10-year warranty available*

• Minimal surface preparation formula saves time and money

• Single-component, self-priming, high-build coating

• Performs like zinc/epoxy coatings without the need to abrasive-blast cleaning

• 200% elasticity *Contact your Rust-Oleum representative for further details

PROTECTION:The combined elasticity, adhesion and strength of Noxyde makes it an ideal industrial coating for corrosion protection of tanks, structural steel, cladding and bridges.

ADHESION:Noxyde offers excellent adhesion which allows for it to be used over most high pressure water cleaned surfaces. The adhesion properties of noxyde minimize rust creep even if the coating is damaged.

Noxyde Competitive System

NOXYDE®

THE POWER OF

FOR UNRIVALED CORROSION PROTECTION

Rust-Oleum® Noxyde® Elastomeric Acrylic Coating provides ultra-rugged protection in aggressive environments. This heavy-duty, water-based formula provides high build coating for flexible durability on new or minimally prepared steel, metals and concrete.

FEATURES & BENEFITS • Resists corrosion, rust and water – even in severe marine environments;

10-year warranty available*

• Minimal surface preparation formula saves time and money

• Single-component, self-priming, high-build coating

• Performs like zinc/epoxy coatings without the need to abrasive-blast cleaning

• 200% elasticity *Contact your Rust-Oleum representative for further details

PROTECTION:The combined elasticity, adhesion and strength of Noxyde makes it an ideal industrial coating for corrosion protection of tanks, structural steel, cladding and bridges.

ADHESION:Noxyde offers excellent adhesion which allows for it to be used over most high pressure water cleaned surfaces. The adhesion properties of noxyde minimize rust creep even if the coating is damaged.

Noxyde Competitive System


Thorpe Plant Services— FRP and Dual Laminate Specialists

Non-metallic materials such as fiberglass reinforced plastics (FRP) and dual laminates have been successfully used for over 50 years for storage of many corrosive compounds at elevated tem-peratures. These include various acids and acid chlorides and other chemicals. Many non-metallic composites have proven their reliability when used in harsh environments for tanks, scrubbers, vessels, piping, and ducts in various industries such as petrochem-ical, power generation, wastewater treatment, chlorine production, pulp and paper, etc.

When viewing composites as an engineering material, FRP remains superior in corrosive environments. In addition to its resistance to corrosion attack, FRP also has excellent strength to weight ratio. For example, an FRP laminate can be 1/6th to 1/3rd the weight of steel while providing up to a 32,000 psi ultimate ten-sile strength in contact molded laminates and up to 60,000 PSI ultimate hoop tensile strength in filament-wound applications. In addition, FRP material is naturally non-conductive and does not require cathodic protection or corrosion inhibitors like many other materials.

FRP and dual laminates can significantly reduce maintenance costs when compared to other materials. Non-metallic materials will not rust, which provides excellent protection from exterior ele-ments. With proper inspection and preventive maintenance, along with the proper operational controls, non-metallic equipment will far exceed the lifespan of many other materials and systems.

Choosing SuppliersChoosing a supplier can be a daunting task for the inexperi-

enced buyer or engineer, as not all suppliers are created equal. We recommend a single source, turnkey contract as the best way to assure a successful project and long-term reliability. The most important step is to ensure the supplier you choose has experience in your application. The important criteria include:

1. Technical and engineering capabilities2. Manufacturing quality3. Field erection/installation capabilitySuppliers should also be evaluated by their technical knowledge

and capabilities. Outsourcing the key technical and engineering components often leads to a poor design due to miscommunica-tions and involvement of others who are not as close to the needs of the application.

Manufacturing quality standards should be closely scrutinized. ASME offers accreditations to shops that can properly execute their

6833 KirbyvilleHouston, TX 77033+1 713-644-1247ThormePME.com

high standards and maintain that environment on a day-to-day basis. ASME RTP-1 is considered by many to be the best available control technology for FRP design, fabrication, and testing. This covers designs for tanks and process vessels from +/-15 psig design pressure. When vessels require additional design pressure, ASME offers Section X Class II authorizations to cover vessels from full vacuum to +250 psig design pressure.

Failures commonly occur at field joints and tie-ins due to unqualified installers erecting and maintaining equipment, mate-rials, and processes they are not familiar with.

Thorpe Plant Services, Inc. performs all three key components with complete turnkey capability. We work closely with the major material suppliers for the proper material selection and perform all engineering calculations internally. Thorpe is dually accredited to ASME RTP-1 and ASME Section X, Class II, assuring we maintain a vigorous quality control program that is unparalleled in the indus-try. Our field services offices are spread across North America and provide experienced crews familiar in non-metallic corrosion- resistant materials and equipment to assure the best quality instal-lation. We can provide shop manufactured vessels and equipment up to 57 ft in diameter using our patented (1978) ring-oblation pro-cess, with almost endless possibilities on height.

Winning TogetherThe Thorpe Plant Services team remains committed to helping

your company find the right solution, while providing you with the safest, most cost-effective and maintenance-free equipment possible.

24 MAY 2016 MATERIALS PERFORMANCE ABOVEGROUND & BELOWGROUND TANK SUPPLEMENT TO MP

Thorpe Plant Services

www.ThorpePME.com

FRP & DualLaminate TankSpecialists

Thorpe Plant Services, Inc. is proud to presentSTRAND® fiberglass reinforced plastic and dual laminatetanks and products. The world’s leading manufacturerof custom FRP/Dual Laminate tanks and products withover 400,000sf of manufacturing space across the USA.Thorpe utilizes state-of-the-art engineering software,materials, equipment, and design principals, as well asindustry leading QA/QC procedures, to meet growingprocess and environmental demands from both publicand private industrial clients for the most corrosiveenvironments.

Why FRP/Dual Laminate Tanks?• Economical benefits compared to field install alloy tanks – Less labor & freight, smaller crane needs, faster to erect/install

• Safer to assemble than steel tanks – minimalelevated work

• Corrosion resistant throughout the FRP structure

• Exterior paint not required – no “UV” derogation

• Easy to repair if damaged

• Good insulator on temperature and static electricity

Thorpe Service and Product Offerings• Turnkey FRP & Dual Laminate Specialists – Engineering and Design – Manufacture – Field erect/install

• Developer of oblation technology (Patented 1978)

• Dually accredited – ASME RTP-1 – ASME Section X, Class II

• Custom designs

• Tanks, pressure vessels, scrubbers, piping, ducts andstructural components

• Shop and field erected FRP vessels, piping, ductsand equipment

• Full line of U.S. made FRP flanges, fittings andaccessories

• Manufactured with premium grade resins:vinyl ester, furan and phenolics

• Thermoplastic and fluoropolymer liners for moresevere corrosive environments


In the United States, according to the U.S. Environmental Protection Agency (EPA), petroleum or hazardous sub-stances are stored in ~566,000 under-ground storage tanks (USTs). These USTs are located at hundreds of thou-sands of facilities across America. Con-tamination of groundwater, the drinking water source for almost half of all Amer-icans, is the greatest potential threat from leaking USTs, which are one of the leading sources of groundwater con-tamination.1 U.S. UST regulations re-quire owners and operators to design, construct, and properly install UST sys-tems in accordance with industry codes and standards, and according to manu-facturers' instructions. UST owners and operators must follow correct filling practices and protect their USTs from spills, overfills, and corrosion. Addition-ally, owners and operators must report the existence of new UST systems, sus-pected releases, UST system closures, and keep records of operation and maintenance.

Preventing Releases in Underground Storage Tanks

All USTs installed after December 22, 1988 must meet one of the following per-formance requirements for corrosion pro-tection:2

• Tank and piping are completely made of noncorrodible material, such as fiberglass-reinforced plastic.

• Tank and piping made of steel have a corrosion-resistant coating and cathodic protection (CP).

• Tanks made of steel are clad with a thick layer of noncorrodible material (this option does not apply to piping).

• Tank and piping can be installed without additional corrosion pro-tection measures provided that a corrosion expert has determined that the site is not corrosive enough to cause the equipment to have a release due to corrosion during its operating life, and owners or oper-ators must maintain records that demonstrate compliance with this requirement.

• Tank and piping construction and corrosion protection are determined by the implementing agency to be designed to prevent the release or

threatened release of any stored regu-lated substance in a manner that is no less protective of human health and the environment than the options listed above.

UST systems installed before December 22, 1988 must be protected from corrosion. These USTs must meet one of the corro-sion protection requirements listed previ-ously or meet one of the following upgrade options (or be properly closed): interior lining, CP, or internal lining combined with CP. Prior to adding CP, the tank integrity must be ensured using one of the following methods:

• The tank is internally inspected and assessed to ensure that the tank is structurally sound and free of corro-sion or holes.

• The tank has been installed for less than 10 years and uses monthly mon-itoring for releases.

• The tank has been installed for less than 10 years and is assessed for corrosion holes by conducting two tightness tests—the first occurs prior to adding CP and the second occurs three to six months following the first operation of CP.

• Alternative integrity assessment: The tank is assessed for corrosion holes by a method that is determined by the implementing agency to pre-vent releases in a manner that is no less protective of human health and the environment than those listed previously.

Upgrading bare metal piping is accom-plished by adding CP. Metal pipe sections and fittings that have released product as a result of corrosion or other damage must be replaced. Piping entirely made of (or enclosed in) noncorrodible material does not need CP.

Regulations and Resources


Underground Storage Tank Requirements Strengthened to Improve Leak Prevention and Detection

In July 2015, to strengthen federal UST requirements so prevention and detection of petroleum releases from USTs are improved and help ensure all USTs in the United States meet the same release protection standards, the EPA made several revisions to the 1988 UST regulation and the 1988 state program approval (SPA) regulation.3

Changes to the regulations include:• Adding secondary containment

requirements for new and replaced tanks and piping

• Adding operator training require-ments

• Adding periodic operation and main-tenance requirements for UST systems

• Addressing UST systems deferred in the 1988 UST regulation

• Adding new release prevention and detection technologies

• Updating codes of practice• Updating state program approval

requirements to incorporate these new changes.

Beginning on April 11, 2016, when installing or replacing tanks and piping, owners and operators must install second-ary containment, which means the tank and piping must have an inner and outer barrier with an interstitial space that is monitored for leaks, and includes contain-ment sumps when those sumps are used for interstitial monitoring of the piping. Inter-stitial monitoring must be used as release detection for these new or replaced tanks and piping. Automatic line leak detectors are still required for new and replaced pres-surized piping.4

Under-dispenser containment (UDC) for all new dispenser systems must be installed beginning on April 11, 2016. UDC contain-ment is containment underneath the dis-penser system designed to prevent leaks from the dispenser and piping within or above the UDC from reaching soil or groundwater. UDC must be liquid-tight on its sides, bottom, and at any penetrations. It must allow for visual inspection and access to the contained com-ponents or be periodically monitored for leaks from the dispenser system.4

The docket for the UST regulation is EPA-HQ-UST-2011-0301-0450 and can be accessed at regulations.gov.

Corrosion Protection for Underground Storage Tanks: An Overview

According to the EPA,2 unprotected underground metal components of the UST system—tanks, piping, and metal components such as flexible connectors, swing joints, and turbines—can corrode, and holes caused by corrosion can lead to product releases. Corrosion can begin as pitting on the metal surface, and holes may develop as corrosion continues and pits become deeper. Over time, even a small

corrosion hole can release a significant amount of product. All metal UST system components that are in contact with the ground and routinely contain product must be protected from corrosion. The two com-mon methods used for protecting metal components from corrosion are isolating the metal component from the corrosive environment and CP.

Tank LiningsA structurally sound tank interior may

be lined with a thick layer of noncorrodible material, as long as the lining material and application method comply with applicable industry codes. The lining used must also meet the same federal requirements as for repaired tanks (40 CFR 280.33). (Flexible inner liners [bladders] that fit inside a tank do not meet the tank interior lining require-ments.) Tanks using only an interior lining for corrosion protection must pass an inter-nal inspection within 10 years and every five years after that to make sure that the tank and lining are sound. Records of these inspection results should be kept.

Cathodic ProtectionA CP system—either a sacrificial anode

or impressed current system—is another


option for protecting USTs from corro-sion. Sacrificial anodes can be attached to a coated steel UST for corrosion pro-tection; however, the coating must be a suitable dielectric material (i.e., a coating that electrically isolates the UST from its environment and meets applicable indus-try codes. An asphaltic coating is not con-sidered a suitable dielectric coating). Sac-rificial anodes are more electrically active than the steel UST. Because these anodes are more active, the attached anode is sac-rificed while the UST is protected. Depleted anodes must be replaced for continued cor-rosion protection of the UST.

An impressed current CP (ICCP) system uses a rectifier to convert alternating cur-rent (AC) to direct current (DC). This cur-rent is sent through an insulated wire to the anodes, which are buried in the soil near the UST. The current then flows through the soil to the UST system and returns to the rectifier through an insulated wire attached to the UST. The UST system is pro-tected because the current going to the UST system overcomes the corrosion-causing current normally flowing away from it.

Federal regulations require that the field-installed CP systems at UST sites be designed by a corrosion expert. Within six months of installation and at least every three years thereafter, the CP system must be tested by a qualified CP tester. An ICCP system must be inspected every 60 days to verify that the system is operating. Additionally, within six months of a repair to any cathodically pro-tected UST system, the CP system must be tested. The results of the last two tests must be kept to prove that the sacrificial CP system is working. Results of the last three 60-day inspections must be kept to verify the ICCP system is on and operating properly.

Tank Lining Combined with Cathodic Protection

Appling both an interior lining and CP is another option for upgrading existing tanks. Combining the two corrosion protection sys-tems has several advantages: the USTs receive greater corrosion protection and the con-dition of the interior lining does not require periodic inspection. While these advantages can amount to significant cost savings over using an interior lining alone, the CP system

must periodically be tested and inspected to ensure it is working properly. Records of these tests and inspections must be kept.Source: U.S . Environmental Protection Agency, Web site: epa.gov.

References1 “Underground Storage Tanks (USTs),” EPA,

https://www.epa.gov/ust (April 13, 2016).2 Underground Storage Tanks (USTs), Release

Prevention for Underground Storage Tanks (USTs), “Corrosion Protection,” EPA, https://www.epa.gov/ust/release-prevention-under-ground-storage-tanks-usts (April 13, 2016).

3 Underground Storage Tanks (USTs) “Revising Underground Storage Tank Regulations-Re-visions to Existing Requirements and New Requirements for Secondary Containment and Operator Training,” EPA, https://www.epa.gov/ust/revising-underground-stor-age-tank-regulations-revisions-existing-re-quirements-and-new (April 13, 2016).

4 Underground Storage Tanks (USTs), Sec-ondary Containment and Under-Dispenser Containment - 2015 Requirements, EPA, https://www.epa.gov/ust/secondary-con-tainment-and-under-dispenser-contain-ment-2015-requirements (April 13, 2016).

5 Underground Storage Tanks (USTs) Laws & Regulations, “Industry Codes and Standards for UST Systems,” EPA, https://www.epa.gov/ust/underground-storage-tanks-usts-laws-regula-tions#code (April 13, 2016).

NACE International Education and Training for Tank Protection

NACE International offers comprehensive education, training, and certification programs to grow and enhance the careers of cor-rosion professionals worldwide. Most of these programs apply to tank and piping corrosion, helping operating companies comply with critical regulations and standards, effectively design and pro-tect assets, and avoid risk to personnel and environmental liability by using trained and certified corrosion professionals. Visit nace.org/training-education for complete information on the following programs.

General Corrosion ProgramGateway courses intended for individuals new to the corrosion industry and skill enhancement opportunities for experienced professionals.

Coating Inspector ProgramThe Coating Inspector Program (CIP) trains coating profession-als to properly inspect the surface preparation and application of a protective coating system on a variety of structures in any industry.

General Coatings ProgramA variety of training courses provide the technical proficiency for coatings and linings application.

Cathodic Protection ProgramThis program is designed to build an in-depth understanding of testing, evaluating, and designing both galvanic and impressed cur-rent cathodic protection systems.

Pipeline Industry ProgramThe Pipeline Industry Program addresses internal corrosion, reme-diation technology and field techniques for carrying out integrity assessments, implementation, and management of integrity man-agement programs.

Online TrainingOnline training provides a valuable and cost-effective method for continuous education and overall productivity enhancement that provides students with an easy to use and convenient way to learn industry and technology specific corrosion solutions.


Standards and Reports

Industry Codes and Standards for Corrosion Prevention of Storage Tanks

Corrosion is a leading cause of storage tank and piping failures. Government regulations often require that industry codes and standards be followed (where applicable) to ensure that a storage tank system is properly designed, constructed, installed, and main-tained. For example, all U.S. underground storage tank systems must be designed, constructed, and protected from corrosion in accor-dance with a code of practice developed by a nationally recognized association or independent testing laboratory. Current government regulations should be reviewed to determine if a code of practice is required to be followed in order to meet regulatory requirements.

NACE International StandardsNACE No. 10/SSPC-PA 6, Fiberglass-Reinforced Plastic (FRP) Linings Applied to Bottoms of Carbon Steel Aboveground Storage Tanks

NACE SP0169, Standard Practice: Control of External Corrosion on Underground or Submerged Metallic Piping Systems

SP0177-2014 ( formerly RP0177), Mitigation of Alternating Current and Lightning Effects on Metallic Structures and Corrosion Control Systems

SP0178-2007 ( formerly RP0178), Design, Fabrication, and Surface Finish Practices for Tanks and Vessels to Be Lined for Immersion Service

SP0187-2008 ( formerly RP0187), Design Considerations for Corro-sion Control of Reinforcing Steel in Concrete

SP0188-2006 ( formerly RP0188), Discontinuity (Holiday) Testing of New Protective Coatings on Conductive Substrates

RP0193-2001, External Cathodic Protection of On-Grade Carbon Steel Storage Tank Bottoms

SP0196-2011 ( formerly RP0196), Galvanic Anode Cathodic Protec-tion of Internal Submerged Surfaces of Steel Water Storage Tanks

SP0205-2010 ( formerly RP0205) Design, Fabrication, and Inspection of Tanks for the Storage of Petroleum Refining Alkylation Unit Spent Sulfuric Acid at Ambient Temperatures

SP0285-2011 ( formerly RP0285), Corrosion Control of Underground Storage Tank Systems by Cathodic Protection

SP0288-2011, Inspection of Lining Application in Steel and Concrete Equipment

SP0298-2007 ( formerly RP0298), Sheet Rubber Linings for Abrasion and Corrosion Service

SP0388-2014 ( formerly RP0388), Impressed Current Cathodic Protection of Internal Submerged Surfaces of Carbon Steel Water Storage Tanks

SP0294-2006 ( formerly RP0294), Design, Fabrication, and Inspec-tion of Tanks for the Storage of Concentrated Sulfuric Acid and Oleum at Ambient Temperatures

RP0391-2001, Materials for the Handling and Storage of Commercial Concentrated (90 to 100%) Sulfuric Acid at Ambient Temperatures

SP0177-2014 ( formerly RP0177), Mitigation of Alternating Current and Lightning Effects on Metallic Structures and Corrosion Control Systems

NACE International Test Methods

TM0101-2012 Measurement Techniques Related to Criteria for Cathodic Protection of Underground Storage Tank Systems

TM0174-2002, Laboratory Methods for the Evaluation of Protective Coatings and Lining Materials on Metallic Substrates in Immersion Service

TM0177-2005, Laboratory Testing of Metals for Resistance to Sulfide Stress Cracking and Stress Corrosion Cracking in H2S Environments

TM0187-2011, Evaluating Elastomeric Materials in Sour Gas Envi-ronments

TM0296-2014, Evaluating Elastomeric Materials in Sour Liquid Environments

NACE TM0497, Measurement Techniques Related to Criteria for Cathodic Protection on Underground or Submerged Metallic Pip-ing Systems

TM0499-2009, Immersion Corrosion Testing of Ceramic Materials

NACE International Reports

07174—Risk Based Assessment of Underground Pipelines and Stor-age Tanks

02321—Corrosion Protection of Storage Tanks

07044—Failure of Above Ground Storage Tanks

08058—Prevention of External (Soil Side) Corrosion on Storage Tank Bottom Plates by Cathodic Protection System

06541—Large Diameter FRP HCl Storage Tanks

05107—Report on Corrosion Probes in Soil or Concrete


Corrosion Basics

Tank and Containment Linings

Some of the most critical uses of protec-tive coatings involve service conditions that require the use of coatings as linings. They may be the same coatings that are used in atmospheric or underground service, but they are usually specially formulated for three specific purposes: 1) To protect the substrate (steel, alumi-

num, concrete, or other materials) from attack by the liquid being stored inside the tank or temporarily stored inside a containment structure

2) To protect the liquid being stored from contamination by the substrate

3) To restore structural integrity to an old tank, while meeting the requirements for protection of the substrate from cor-rosion and the liquid in storage from contaminationAll coatings are permeable to some

degree. The choice of coatings as tank lin-ings requires a much greater knowledge of the properties of the liquid being stored and the ability of the coating to withstand per-meation by that liquid than would typically be required for any coating being applied in atmospheric service.

Choosing a Tank or Containment Lining

Few project managers have an in-depth knowledge of the suitability of various tank linings when placed in immersion of aggressive, penetrating liquids. It is possi-ble to review the product data sheets of sev-eral global scope and specialty scope man-ufacturers to get a general idea of which linings might work in a given situation. However, this approach is risky in that the product data sheets, of necessity, must be quite general in nature. There are three rec-ommended alternatives that will provide choices with better chances of success in a given application:1) Comparative side-by-side testing of can-

didate systems in a laboratory program that simulates, to the best extent pos-

sible, the service conditions expected in that particular tank. This takes time but can provide very good indications of a lining’s resistance to permeation by a particular liquid for a given period of time at a stated storage temperature.

2) If time does not allow for comparative laboratory testing, the candidate coat-ing manufacturers can be requested to provide their chemical suitability tables for the products that are being consid-ered for a particular tank. Although this normally is limited to specific testing for specific time frames such as 30 and 60 days, it often provides reliable guide-lines about the performance character-istics of each product. In addition, these suitability tables normally include some very valuable precautions regarding immersion based on the pH, tempera-ture, etc., of the chemicals. Some very valuable information is normally avail-able about cleaning chemicals, proce-dures, and recovery times between dif-ferent cargoes.

3) Review selected case histories of tank linings used in similar services. This can be very valuable as it provides lon-ger-term results. However, when doing so, the project tank and containment linings manager must be careful to con-firm that the service conditions are truly similar to the expected service condi-tions. He or she must also be careful to confirm that the product shown in the case history is still formulated the same as it was when that case history was conducted. Volatile organic compound requirements have caused changes in products to achieve higher volume solids that can, and have, drastically altered the chemical resistance of some products. This article is adapted from The Pro-

tective Coating User’s Handbook, Louis D. Vincent (Houston, TX: NACE International, 2010).


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CORROSION PREVENTION AND CONTROL WORLDWIDE TABLE …