Measurements were conducted to quantify the permeation of artificial seawater into various polyurethanes and polyethylene as a function of time and temperature. Both weight gain from water absorption and an electrical current between pairs of wires embedded into the polyurethanes were measured over a period of several months at 50°C. Water was absorbed into all materials, including polyethylene, but there was no increase in the current between wire pairs embedded in the polyurethanes, indicating that the water that was able to permeate was pure water of high resistivity whereas the charged ions in the seawater were not able to permeate to the wires.

The author first discusses the life of Dr. Robert Baboian, a leader within the corrosion and electrochemical field; a contributor to ASTM G5, Standard Reference Test Method for Making Potentiodynamic Anodic Polarization Measurements; a leader within ASTM International, NACE International (formerly the National Association of Corrosion Engineers), the International Organization for Standards, and the Electrochemical Society; a world-renowned corrosion researcher and promoter; the recipient of many awards in his field; and a good friend to many in the corrosion field throughout the world. The author then discusses the importance and history of the development of ASTM G5, a seminal work of ASTM Committee G01 on Corrosion of Metals. Finally, the apparatus, test procedure, and acceptance criteria for this standard are summarized.

Specimen blanks of additive-manufactured nickel Alloy 625 and Ti-6AI-4V were produced by the laser powder-bed-fusion process (L-PBF) with the principal test axis in both the Z direction (parallel to the build direction) and the X-Y direction (perpendicular to the build direction). The high cycle fatigue and corrosion fatigue properties of these metals were measured using R. R. Moore rotating cantilever fatigue tests, both in air and with a salt water drip on the test sections. Testing was conducted in order to determine the fatigue and corrosion fatigue limits of these materials at 10(8) cycles. The fatigue limit for L-PBF Alloy 625 material at 10(8) cycles in air was roughly 48 ksi (331 MPa), independent of build orientation. This is similar to the air fatigue limit of wrought material. The corrosion fatigue limit for L-PBF Alloy 625 material at 10(8) cycles in salt water was roughly 39 ksi (269 MPa), which was also independent of build orientation and slightly below the values for wrought material and values obtained by other investigators. The fatigue limit for hot isostatic pressed L-PBF Ti-6AI-4V material at 10(8) cycles in air was roughly 90 ksi (620 MPa), independent of build orientation. This is significantly better than the air fatigue limit of wrought material. The corrosion fatigue limit for L-PBF Ti-6AI-4V material at 10(8) cycles in salt water was roughly 78 ksi (540 MPa), which was also independent of build orientation, better than values for wrought material, and comparable to values obtained by other investigators. The fatigue crack growth rate behavior in air was characterized and compared with information available in the literature.

The mechanical, metallurgical and corrosion properties of Alloy 625 produced using the laser powder bed fusion (L-PBF) manufacturing process were investigated and compared with typical performance of the alloy produced using conventional forging processes. Test specimens were produced near net shape along with several demonstration pieces that were produced to examine the geometric complexity that could be achieved with the process. The additively manufactured specimens exhibited strength, fracture toughness and impact toughness that was equal to or better than properties typically achieved for wrought product. There was no evidence of stress corrosion cracking susceptibility in 3.5% NaCl solution at stress intensities up to 70 ksi-in1/2 after 700h exposure. The microstructure was equiaxed in the plane of the powder bed build platform (X–Y) and exhibited a columnar shape in the Z direction although there was not any significant evidence of anisotropy in the mechanical properties.

Currently, the launch tubes of ballistic missile submarines are protected from corrosion by coating over a chromate-containing wash primer. To comply with environmental and worker protection regulations it is desirable to replace this legacy coating system with a system that does not contain chromates. The launch tube coatings must withstand both a seawater immersion which occurs immediately after launch as well as the physical stresses of the launch itself. While the performance of the legacy system is well known, there is a concern that the long term performance history of the candidate replacement non-chromate coating systems under these conditions is not known. Standards developed for chromate-containing coatings and their non-chromate replacements address material composition, installation, and performance, but these standards don’t address the specific combination of environmental and physical conditions of the launch system. A test program was developed to compare the critical performance characteristics of the coating between the legacy and various candidate coating systems. Overall performance of fourteen coating systems produced by various manufacturers, and designed to represent a variety of different coating chemistries, was determined based on coupon test data generated in two phases: an initial phase addressing easier-to-test critical attributes and a second phase involving more costly testing which only tested those systems that performed as good as, or better than, the legacy system in the first phase. The data generated were used to rank the order of the overall coating system performance. The test conditions, performance results and ranking details are presented.

Abstract This book is a thorough review of corrosion control methods for steel structures, with a major emphasis on painting. The contents include chapters on the corrosion of steel, surface preparation, paints and paint coatings, pain application, specialist coating and applications, metal coating, writings effective specifications, quality control of coating operations, designing for corrosion control, maintenance painting, control methods other than coatings, coating defects and failures, the selection of coating systems, protective systems for different situations, and testing of coatings.

Description This significant new ASTM publication is specifically aimed at cathodic protection in seawater. It summarizes the latest criteria and philosophies for designing both sacrificial and impressed cathodic protection systems for structures vehicles in seawater. Seven peer-reviewed papers cover: • A new approach that allows for the formation of calcareous deposits in a more accurate fashion than older, traditional methods • Physical scale modeling of ICCP systems used by the U.S. Navy and how the results are translated into actual ship design • Formulation and performance of aluminum anodes in various environments • A protection design example for a geometrically complex warf structure • Practical experiences involving deep water structures, such as offshore oil platforms • Boundary Element computer modeling--latest technology for predicting cathodic protection current distribution and magnitude • Preventing corrosion of space shuttle solid rocket boosters during ocean recovery This volume is a valuable technical reference tool for designers of marine cathodic protection systems and evaluators of designs performed by others.

Mixtures of piping materials have been used in several piping systems during ship retrofitting. The use of dissimilar alloys may initiate galvanic corrosion of the more anodic, electronegative member which could lead to piping failures. Several control methods have been applied which may introduce secondary corrosion and require periodic inspection and replacement. This study involved several newer galvanic corrosion control methods (cathodic protection, barrier coatings, bi-electrode), which were used in mockup piping tests to monitor their effectiveness. These newer methods may provide alternative galvanic corrosion control techniques that may allow selective use of mixed piping systems with a minimization of shutdowns for removing, inspecting, and replacing system components.

Electronics cooling and environmental control systems are required in enclosed manned spaces such as the inside of spacecraft or submersibles. Because egress from such spaces may not be possible in a short time frame, coolant leaks must have minimum toxicity. For this reason, propylene glycol coolants are preferred over the traditional ethylene glycol coolants. Corrosion inhibitor formulations are well developed for ethylene glycol coolants, but there is concern that the inhibitor suite for propylene glycol systems may not be as mature. In particular, coolant systems with a mixture of aluminum and copper can develop heavy metal ion corrosion of the aluminum due to precipitation of copper ions from solution onto the aluminum. This type of accelerated corrosion of aluminum does not require electrical contact with copper, as is the case for galvanic corrosion, nor is significant coolant conductivity required for corrosion to occur. This paper presents a study of the ability of a commercial inhibited propylene glycol coolant to prevent heavy metal ion corrosion of aluminum when copper is also present in the coolant system. The inhibited propylene glycol’s performance is compared to that of reagent propylene glycol without inhibitors, a mature ethylene glycol inhibited coolant, and to tap water. The inhibitor suite in the inhibited propylene glycol was found to be as effective in controlling heavy metal ion corrosion as that of the inhibited ethylene glycol coolant, while uninhibited reagent propylene glycol was ineffective in controlling heavy metal ion corrosion.

During a recent renovation of the USS Constitution, extensive corrosion was discovered in bands around a number of copper treenails used to hold the wooden planks and strokes to the frames. Four treenails were evaluated at the Carderock Division, Naval Surface Warfare Center. Chemical and metallurgical analysis was conducted on the copper treenails, and x-ray diffraction analysis was performed on corrosion products and scrapings from near the treenails. The corrosion was found to be caused by metal ion concentration cells between areas in the wood and areas between wooden pieces, enhanced by the presence of microbiologically-generated sulfides. The treenails were determined to be at least 125 years old. The attack is likely to continue, and little can be done to mitigate the problem short of changing the treenail material or coating them before insertion, both of which would be very expensive and historically inaccurate. Since the rate of attack is fairly low, on the order of 1-mil/yr, no action is recommended short of performing ultrasonic inspections and replacing badly corroded treenails whenever there is access to the treenail heads during future restorations.

The effectiveness of two commercially available vapor phase corrosion inhibitors (VCIs) and one industrial desiccant wheel (DEW) dehumidifier are evaluated for the corrosion protection of advanced double hull (ADH) compartments on naval ships. Small-scale ADH compartments were constructed to simulate the environmental conditions likely to be encountered in service. The three simulated environments of interest were (1) air filled, sealed compartments, (2) compartments with a leak allowing humid air ingress, and (3) compartments with a seawater spill or leak. Commercial grade steel weight loss coupons and galvanic couples of steel/copper-nickel 90-10 (UNS C70600), steel/stainless steel 304 (UNS S30400), and steel/aluminum alloy 6061-T6 (UNS A96061) were installed in each box, along with atmospheric corrosion probes, thermocouples, and relative humidity probes. The test chambers were exposed to the marine environment on test racks located approximately 200 feet from the ocean in Dania, Florida. Six and 12 month weight loss, corrosion rate, temperature and humidity data are presented along with visual observations. Of the three corrosion control methods under test, the dehumidifier is providing the best environmental and corrosion control. The VCIs show promise under well sealed conditions, but the two formulations under test are unable to provide long-term protection under the severe air leak and seawater spill/leak test conditions.

Duplicate galvanic couples with a 1:1 area ratio were constructed from all combinations of the following materials: type 304L stainless steel, 90/10 copper-nickel, 70/30 copper-nickel, nickel-aluminum bronze, silicon bronze, and copper. In addition, duplicate panels of each of these materials were cathodically protected with either anode grade zinc or iron. Exposures were conducted in natural seawater flowing at 5-ft/s for 375 days while monitoring galvanic current and couple potential. Major changes in galvanic currents tended to occur within the first 120-days exposure, although drift to lower currents was observed over the entire test period. Couple potentials were highly variable over the entire exposure period, but major potential drift tended to occur within the first 120 days. The highest current densities for couples not including zinc or iron were for all of the 304L couples, particularly those with silicon bronze and copper, nickel-aluminum bronze coupled to silicon bronze or copper, and 70/30 copper-nickel coupled to silicon bronze or copper. Current densities for all other couples were below 1 mA/ft2, and should result in low total currents for reasonable anode/cathode area ratios.

Electrochemical impedance spectroscopy (E.I.S.) techniques can provide information about the condition of protective coatings on steel marine structures. Currently, an expert is required to interpret the data produced from an E.I.S. measurement, classifying the coating as good or poor, or identifying the data as bad. This limits the use of E.I.S. techniques to experienced operators. If the E.I.S. technique is to be used for production by inexperienced operators, measurements must be classified automatically. This investigation uses artificial neural networks (ANN) to develop an automated E.I.S. data classifier. ANNs were trained with a large data base of measurements on known good or poor coatings, including some bad data. The ANNs were tested with E.I.S. data not included in the training set. A variety of measurement signal processing schemes and network structures were evaluated. ANNs were developed which can accurately determine if the coating is good or poor, and whether measurement problems produced bad data.

Because of the difficulty in assuring full-time electrical isolation of dissimilar metal piping, alternate methods of coping with the galvanic corrosion must be used. Use of short, electrically-isolated piping sections between the dissimilar metals can reduce galvanic corrosion by increasing the electrical resistance of the seawater path through which the galvanic current must flow. This objective of this project was to determine the magnitude and distribution of galvanic corrosion of 70/30 copper-nickel piping when coupled to alloy 625 piping, to determine the efficacy of various lengths of isolated separator pipes made of either alloy, and to determine the amount of stray current corrosion that could occur on the separator piping as a function of pipe material. The presence of separators of any length in 2-inch pipe lowered the amount of galvanic corrosion between copper-nickel and alloy 625, with a 50-60% reduction in metal loss using 3-ft (1-m) separators. A further reduction of another 30-50% was achieved by increasing separator length to 10-ft (3-m). The use of copper-nickel separators generally resulted in higher metal losses than the use of alloy 625 separators. The effect of the separator was maximum under low flow conditions, and alloy 625 separators are more effective than copper-nickel separators. Smaller diameter copper-nickel pipe experienced higher corrosion rates than pipe of equal diameter to the alloy 625 pipe to which they were coupled. Linearity of potential profile through the separators was an accurate indicator of whether stray current corrosion was taking place.

The question answered in this study is whether the demand on a cathodic protection system will change when the protected pipe material is changed from copper-nickel to alloy 625. Two piping mockups were designed to simulate a probable geometry for a cathodically-protected piping system. Each mockup consisted of a 20-foot (610-cm) length of nominal 2-inch (5-cm) diameter piping with a zinc anode for cathodic protection inserted in the discharge end of each. one mockup was made with 70-30 copper-nickel pipe and the other with alloy 625 pipe. Protection currents and potential profiles inside the pipes were measured over a six-month exposure period in natural seawater flowing at 7-ft/s (210-cm/s). The total protection current and sacrificial anode consumption for alloy 625 pipe was half that for copper-nickel pipe. This means that replacing copper-nickel pipe with alloy 625 pipe in areas close to cathodically-protected heat exchangers or hulls will result in a more conservative design for the cathodic protection system than was the case for the original copper-nickel piping.