SUPERIOR WASTEWATER CORROSION PROTECTION COATINGS PROVEN BEST BY PERFORMANCE TEST

Transcription

1 SUPERIOR WASTEWATER CORROSION PROTECTION COATINGS PROVEN BEST BY PERFORMANCE TEST

2 S.W.A.T. TESTING EVOLVING WASTEWATER CONDITIONS PROMPT IMPROVED TEST STANDARDS CONvENTIONaL wastewater TEST procedures and OLD COaTINGS TEChNOLOGIES are CONSIDERED INaDEquaTE for TODay S much more ExTREmE CORROSIvE wastewater headspace ENvIRONmENTS. That was the premise that launched a new, more comprehensive and conclusive test developed by Tnemec in conjunction with a coalition of wastewater experts, coatings formulators and testing agencies. The purpose of the initiative was to evaluate previously unrepresented exposure conditions, thereby ensuring more valid, reliable results. The main difference between the Severe Wastewater Analysis Test (S.W.A.T.) and a standard immersion test (acid contact test) is that the latter totally omits the damaging impact of sewer gases an invisible polymer destroyer.

3 TROUBLING EFFECTS OF ThREATENING FACTORS 1970 Clean Air Act mandated sealing of open wastewater tanks, which caused H 2 S to become trapped, increasing the buildup and corrosive effects of sulfuric acid, carbon dioxide and methane. Recent initiatives by sewer districts to cut costs through consolidation spawned regional treatment plants and caused wastewater to travel farther distances and be retained longer in collection systems, allowing higher concentrations of H 2 S and other damaging gases Clean Water Act demanded pre-treatment to eliminate harmful heavy metals, but as a result, bacteria (otherwise held in check by the presence of the metals) began to flourish and acted as a catalyst to create septic sewer gases. 3 BLISTERING CONDITIONS Corrosive gases badly blistered and stripped the coating from this concrete wastewater lift station. It then proceeded to degrade the structure, resulting in very costly repairs and downtime. FIELD CORRELATION STUDY SUPPORTS S.W.A.T. FINDINGS Tnemec conducted a year-long field study in seven different wastewater locations around the United States. Test sites were selected because of their highly corrosive environments and elevated hydrogen sulfide levels (>500 ppm), which commonly emanated from the septic sewage. One particular site was a manhole within a mixed-use development in Texas. Technicians prepared several samples (steel panels and concrete cylinder coupons) by coating them with various formulations and compositions. Then the samples were hung in the headspace for more than three years and evaluated regularly. After the prolonged exposure in most locations, results mirrored and corroborated S.W.A.T. findings. All but the Tnemec Perma-Shield coatings revealed a significant drop in impedance (a measure of permeation resistance) and ultimately became blistered and cracked, losing their protective qualities altogether.

4 S.W.A.T. TESTING NEW S.W.A.T. OFFERS MOST CONVINCING DEMONSTRATION OF CORROSIVE GASES LIquID phase S.W.A.T. was the first to examine the presence and effects of hydrogen sulfide in a sewer headspace. More recently, in an effort to further enhance and refine protocols, Tnemec expanded S.W.A.T. a commercially available liquid/vapor test. This new version of the protocol examines additional gas exposures, including carbon dioxide (CO 2 ) and methane (CH 4 ), which are also responsible for causing vapor phase significant deterioration of coatings, linings and underlying steel, ductile iron or concrete substrates. S.W.A.T. s accelerated simulations, conducted over 28 days, are representative of actual field conditions. That is why this analysis is so important. It is used as a true basis for understanding the full spectrum of wastewater corrosion and for identifying new solutions and standards of performance. The Tnemec accelerated S.W.A.T. protocol requires a controlled chamber environment held at a constant 150 F (66 C) temperature in which test samples are exposed to replicated septic conditions of sewage headspace environments. acknowledged INNOvaTION In recognition of pioneering research work on S.W.A.T., Tnemec received the 2012 Reader s Choice Corrosion Innovation of the Year Award from Materials Performance magazine, published by NACE International. It was chosen from among 64 nominations by 17 different countries. SEvERE wastewater analysis TEST - S.w.a.T. AQUEOUS SOLUTION: 10% sulfuric acid, brine (saltwater) containing 0.4% NaCI PURGE GAS: 500ppm H2S, 10,000 ppm CO2, 5,000 ppm methane TEMPERATURE: 150 F (65 C) TOTAL ELAPSED TEST TIME: 28 Days TIME UNDER TEST CONDITIONS: 28 days with 20 gas purges and 60 immersion cycles IMMERSION SChEDULE: The specimens were immersed in the sulfuric acid solution for 15 minutes, three times each working day, Monday through Friday. The rest of the time, the specimens were positioned in the vapor space above the sulfuric acid solution.

5 COmpaRISON: SERIES 436 S.w.a.T. and field RESuLTS field ExpOSuRE SERIES 436 (S.w.a.T.) 12 INITIaL 1 year 2 years SERIES 436 (field TESTING) 10 EIS LOG Z (0.1 hz) INITIaL 10 DayS 20 DayS 28 DayS SEvERE wastewater analysis TEST COmpaRISON: polyamide EpOxy S.w.a.T. and field RESuLTS polyamide EpOxy (S.w.a.T.) 12 INITIaL field ExpOSuRE 1 year polyamide EpOxy (field TESTING) 10 EIS LOG Z (0.1 hz) INITIaL 10 DayS 20 DayS 28 DayS SEvERE wastewater analysis TEST BEfORE after LAGUNA BEACh WET WELL REhAB After 30 years of operation, Bluebird Sewer Pump Station in Laguna Beach, CA, required heavy restoration to a severely deteriorated concrete wet well. Hearing of Tnemec s advanced Perma-Shield coatings system, the consulting engineer specified it for the project. After extensive surface preparation, Series 218 MortarClad was trowel-applied to fill voids and resurface the corroded concrete. Series 436 Perma- Shield FR (fiber-reinforced) was then spray-applied to a dry-film thickness of mils DFT. The fiber reinforcement offered greater film strength in combination with excellent gas permeation and corrosion resistance. After one year, the wet well was inspected for signs of wear. Series 436 was in perfect shape, and Laguna Beach city officials were extremely satisfied.

6 PERMA-SHIELD DEFINITIVE ANALYSIS REVEALS ThE SUPERIORITY OF PERMA-ShIELD EvEN with ThE ExCELLENT ChEmICaL RESISTaNCE Of SOmE EpOxy COaTINGS, INCREaSINGLy SEvERE wastewater ENvIRONmENTS are STILL attacking SuBSTRaTES, CauSING CRaCkS, BLISTERING, BaRRIER penetration and SuBSTaNTIaL premature failures. In most cases, the coatings resistance is compromised by the permeation of corrosive microscopic gas molecules. Years ago, Tnemec recognized that all-new coating formulations with improved permeation resistance needed to be developed. After repeated trials, testing and screenings of multiple formulations, the Perma- Shield product line emerged as a very effective solution. To verify this fact, currently used coatings of various compositions were evaluated using S.W.A.T., along with Tnemec Perma-Shield products. An independent lab conducted the tests. Electrochemical Impedance Spectroscopy (EIS) a widely accepted scientific method of measurement was used to determine coating penetration and degradation. Baseline EIS measurements were established and then taken at three more 10-day intervals during S.W.A.T. exposure. Even though most of the coatings exhibited excellent initial permeation resistance (high impedance), virtually all of them, with the exception of Perma-Shield, began showing significant drops in impedance within the first 10 days. Obvious visual signs of corrosive damage soon followed. Only Perma-Shield prevailed.

7 PERMA-ShIELD PRODUCTS ARE AT ThEIR BEST IN ThE WORST CONDITIONS Innovative Perma-Shield coating products, developed specifically for the harshest wastewater environments, have been subjected to the most damaging of all possible gases, acids and bacteria. These are substances which, if left unchecked, can eat away at steel and concrete in as little as months to a few years. SERIES 431 This newest, high-performing Perma- Shield PL lining, used primarily in ductile iron and steel pipe and fittings, is a modified-ceramic epoxy with much greater chemical and abrasion resistance than conventional ceramic epoxy. SERIES 434 An epoxy mortar used for wastewater system repair/restoration that has excellent adhesion and permeation resistant properties in a trowel applied version. Now, with a decade of proven performance behind the Perma-Shield System, there s no question about its superior protective qualities. Perma-Shield products provide greater barrier permeation resistance, longerlasting corrosion protection and overall superior performance. SERIES 435 The spray applied, thick film epoxy retained 100% impedance (permeation resistance) from day one and throughout the accelerated 28-day test cycle. SERIES 436 For more durable, lasting substrate protection and permeation resistance, this fiber reinforced epoxy lining performs well in repeated tests. S.w.a.T. EIS analysis: permeation SERIES 431 SERIES 434 SERIES 435 SERIES 436 a (polyamide EpOxy) INITIaL ImpEDaNCE final ImpEDaNCE B (polyamine NOvOLaC EpOxy) C (polyamide EpOxy COaL TaR) COaTING ImpEDaNCE, LOG Z (Z IN OhmS-Cm 0.1 hz) poor GOOD ExCELLENT

8 PERMA-SHIELD SLUDGE TREATMENT Dewatering Sludge holding Digestors COLLECTION Gravity sewers Sewer interceptors Lift stations Manholes COMMON APPLICATIONS PERMA-ShIELD

9 PRIMARY TREATMENT Covered clarifier Anoxic basins headworks Screening structures Lift structures Grit chambers Influent channels Flow-measurement facilities Equalization tanks REAL-WORLD APPLICATIONS ShOW PERMA-ShIELD ADVANTAGES AT WORK S.W.A.T. and field tests are very important in serving as reliable indicators of actual performance. However, nothing is as indicative of how coatings and linings will perform as real-world situations. Perma-Shield has been specified for many different severe wastewater applications, and, in virtually every case, the products have done an outstanding job of enduring what are, without question, some of the most aggressive and destructive conditions of any, regardless of industry or type of corrosive threat. The basis of this success is Tnemec s unrivaled commitment to continual product development and innovation aimed at finding solutions to the most difficult challenges.

10 PERMA-SHIELD BEfORE hall STREET SLUDGE holding TANK As if smashed by sledgehammer blows, chunks of concrete were missing from the walls of two Concord, New Hampshire, sludge tanks. All of it was damage caused by severe exposure to sewer gases. Just two years before, the tanks had been repaired using a conventional, acrylic-modified cementitious resurfacer and coal tar epoxy. But it wasn t enough to prevent the extensive chemical attack. Delamination occurred swiftly. Frustrated by previous efforts, the Concord wastewater treatment plant chose Perma-Shield because of its proven performance in H 2 S-rich environments. The restoration began with surface abrasive blasting. A parge coat of resurfacing mortar was used to patch major holes. Then, a layer of Series 434 Perma-Shield mortar, designed especially for H 2 S permeation resistance, was troweled and backrolled at 125 mils DFT. A final coat of Series 435 Perma-Shield modified polyamine epoxy lining was spray applied at mils DFT. Conclusion: Today s much more aggressive wastewater environments demand a higher performance solution. after

11 KEY BENEFITS SEWER GAS PERMEATION RESISTANT SULFURIC ACID RESISTANT ABRASION RESISTANT RAPID RETURN TO SERVICE INCREASED FILM ThICKNESS WIThSTANDS ThERMAL CYCLING ROBINSON STREET LIFT STATION Due to excessive substrate penetration and biogenic sulfide corrosion, the Springdale, Arkansas, Water & Sewer Commission was forced to close this lift station for major overhaul. Based on product research, they decided to use a Tnemec Perma-Shield coatings system for its reliable protection and value in minimizing asset life-cycle costs. Cast-in-place concrete was first blasted and then resurfaced with Series 218 MortarClad. Series 434 Perma-Shield H 2 S was trowel applied and backrolled to tighten the surface. Finally, a topcoat of Series 435 Perma- Glaze, specially formulated for superior resistance to destructive sewer gases, was roller applied at mils DFT. The sewer district engineer was so impressed by the result, he added Tnemec as an approved vendor on their Master Specification List for future projects.

12 INNOVATION IN EVERY COAT Tnemec Company Incorporated 6800 Corporate Drive kansas City, missouri TNEmEC1 fax: tnemec.com published Tnemec instructions and pricing are subject to change without notice. Contact your Tnemec technical representative for current technical data, instructions and pricing. warranty information: The service life of Tnemec coatings will vary. for warranty, limitation of seller s liability and product information, please refer to Tnemec Data Sheets at or contact your Tnemec technical representative. printed in usa. Tnemec Company, Inc hw2.5m613 BROSwaT