Supplier of custom engineered and prefabricated treated timber products, utilizing Copper Naphthenate as a wood preservative.
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Home Page: http://www.wheeler-con.com E-Mail: info@wheeler-con.com Info Request: Click here for form |
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INTRODUCING COPPER NAPHTHENATE
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A Report by Kenneth A. Johnson, P.E. |
Decisions are sometimes forced on decision makers, or at least chance provides opportunities for change that would not necessarily have been considered if not imposed on them. Such was the case for Wheeler Lumber when their wood treating plant burned to the ground in a devastating fire on March 16, 2003. The treating plant was part of their large fabrication and treating facility located at Whitewood, South Dakota. Fortunately, nobody was injured nor was any other part of the vast facility damaged by the fire. The treating and wood fabrication facility has been at its present location along Interstate Highway 90 since 1959 when a massive forest fire burned the original facility that was located near Deadwood, South Dakota. The devastation caused by the fire forced Wheeler's Management Team to make many decisions that will affect how Wheeler conducts its business over the next several decades. The basic question was not “If to rebuild”, but rather “What to rebuild?” As tragic as this event was, it was looked upon as an opportunity to build a state-of-the-art treating facility. Construction has been completed. The first charge of treated timber from the new plant was produced in March. One of the most basic questions to be answered was which preservative or preservatives to be included in the new facility. Wheeler's long and successful history with Creosote as its primary preservative weighted heavily in the ultimate decision of selecting Copper Naphthenate as the primary wood preservative. The primary concern in selecting a wood preservative is its efficacy in protecting the wood from insects and decay. After studying all of the scientific data and the long-term monitoring of the performance of in-use structures, Wheeler is convinced that Copper Naphthenate will provide the same level of protection as the other preservatives it has used in the past. There were many factors debated that led to the final decision. In the final analysis, it was the long-term future of pressure treated timber for engineered wood structures that dictated the choice of Copper Naphthenate. This paper presents many of the factors and supporting information on which the decision was based. Wheeler’s management feels an obligation to its loyal and long-term clients to provide this information on which its decision was made. Obviously, in any debate there are two sides to every issue; creosote and pentachlorophenol are still excellent wood preservatives and Wheeler's fire did not change their effectiveness. Wheeler's decision is based on their collective judgement about the future of the Wood Treating Industry. WHAT IS CuNap? The short answer is: Copper Naphthenate (CuNap) is an approved, effective, oil-borne wood preservative. The long answer is basically the rest of this paper. Copper Naphthenate was developed in the Scandinavian Countries at the turn of the last century. It has been used as a preservative for a variety of wood and textile product over the years. If you have ever been in the military and spent any time in a tent, you have smelled CuNap. It has been used as a preservative for canvas used in tents for decades. A review of literature indicates that it has been used in many applications including field boxes, beehives, benches, flats, fenceposts, water tanks, canvas, burlap, ropes, nets, greenhouses, utility poles, crossarms and wooden structures in ground contact and above ground contact. It was used to extend creosote during World War II. Copper Naphthenate was introduced into the American Wood Preservers’ Association (AWPA) Standards in 1949 and has been there since. Copper Naphthenate has been marketed under a number of trade names over the years, including Perm-8, Cop-R-Nap, CuNap, Cunapsol, Cuprinol, and M-Gard. Of these the most common is Cuprinol, dating back to the Danish of over a century ago, meaning, “copper in oil.” Wheeler has selected the firm of Osmose as the source for the preservative, as manufactured by Merichem. This selection of Osmose and Merichem is based on their long and excellent reputation for supplying quality products and providing good service. They have an excellent web site at www.merichem.com that we encourage you to visit. This site contains full-text versions of many of the technical papers about Copper Naphthenate. Copper Naphthenate is generally prepared by reacting copper or copper salts with napthenic acid or with sodium Naphthenate. The most common commercial methods of producing NcNap are direct metal, melt (fusion), or double decomposition methods. Naphthenic acid is a by-product of petroleum refining and contains a mixture of monocarboxlic acids that have a cyclopentane and cyclohexane groups with an acid number ranging from 150 to 300. Naphthenic acid is recovered commercially from kerosene, jet fuel, and diesel fractions during petroleum refining. The concentrate delivered by rail car to Wheeler's plant contains 8% copper contained in an oil carrier. This concentrate is diluted with No. 2 oil to form the working solution that will contain approximately 1% copper depending on the specifications for the product being treated. The use of CuNap as a commercial wood preservative in the United States has been limited, but recent environmental concerns with CCA, Penta, and Creosote has stimulated its use. CuNap has been accepted as a wood preservative for several decades and has been employed in nonpressure treatments of wood and other products, but has not been extensively used in pressure treatments of wood products, presumably, because of cost. Copper Naphthenate is becoming the preservative of choice by many specifiers where environmental concerns are important. |
* Treating Process The actual treating process is very similar to the process for treating with pentachlorophenol. The timber will be dried to below the fiber saturation point, which is approximately 28 - 29% depending on the species, before being placed in the treating cylinder, sometimes called a retort. Figure No. 1 contains a graphic representation of a typical treating cycle. Once the door of the cylinder has been closed and sealed some initial air pressure is introduced in the cylinder, this helps to kick-out the excess preservative at the completion of the treating cycle. Next, the cylinder is filled with the heated working solution. The pressure phase of the cycle is maintained for one to several hours depending on the species and the controlling specification. After the completion of the press period the cylinder is emptied of the working solution and a vacuum is established in the cylinder. Next the material in the cylinder is subject to live steam for two hours. |
 Figure No. 1 • Graphic representation of the typical treating cycle for Copper Naphthenate. |
After the steaming another vacuum is drawn and the material remains in the cylinder for another hour for a drip period. Once the treating cycle is completed in the cylinder the charge is removed from the cylinder and is placed over a drip pad where it remains for additional time. Wheeler Lumber is a member of the Western Wood Preservers Institute (WWPI) and as such follows the Best Management Practices (BMP) published by WWPI. ATTRIBUTES The concentrate is a liquid with a dark blue-green color. Wood treated with CuNap will take on several different shades of light to dark brown depending on the species and the treating cycle used. It will look very much like wood treated with penta. Photograph No. 1 shows a typical timber bridge constructed with Copper Naphthenate treated timber. Photograph No. 2 is a close-up view of the curb and railing system of Copper Naphthenate treated wood. |
 Photograph No. 1 • Profile view of a timber bridge treated with Copper Naphthenate |
 Photograph No. 2 • Close-up of the curb and railing system of a bridge treated with Copper Naphthenate. |
Copper Naphthenate treated wood shortly becomes dry to the touch. There are several other attributes or characteristics of wood that can be altered by the treating process. The following is a short list of some of the effects resulting from treating with CuNap: |
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| * Leachability | ||
Standard wooden blocks, when treated with CuNap, were tested in accordance to AWPA Standard M-11. Results of these test indicated slight leachability of the preservative system. Preliminary indications are that the Copper Naphthenate is tightly bound to the wood substrate, which may be both chemical and physical, including copper lignin bond formation. |
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| * Conductivity | ||
Published test results show that there is no increased conductivity of wood when treated with Copper Naphthenate in an oilborne preservative system. |
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| * Resilience | ||
Tests using Southern Pine and Douglas Fir as compared to standard preservative systems found no significant difference between in resilience with wood treated with other preservatives using P9 Type Oil as carrier. Standard Duration of Load Factors can be used in the design process. |
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| * Corrosivity | ||
The corrosivity of the Copper Naphthenate in treated wood offers no significant increase compared to untreated wood or preservative treated wood using other oilborne preservative systems. Test comparing the corrosivity of the biocide dissolved in either No. 2 fuel oil or medium aromatic treating oil have indicated no significant corrosiveness from the treating solution. |
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| * User Friendly | ||
Wood treated with Copper Naphthenate does not have any photo-toxicity associated with some oil-borne preservatives. Construction workers and utility linemen prefer to work with products treated with Copper Naphthenate. |
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| EFFICACY | ||
The most important attribute of any wood preservative is its effectiveness in preventing damage from insects and fungi. Determination of length of serviceability that will, in many cases, out-last the person designing or specifying the treated wood becomes a very important issue. There are three general methods used to determine the efficacy of a wood preservative. |
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* Laboratory tests * Field plots of stakes * Monitoring in-service components |
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The first two methods are designed to accelerate the effects of time. It is well understood that the deterioration potential for wood is directly related to temperature and the rainfall and humidity at the location of use. Figure No. 2 contains a map of the United States indicating the various Deterioration Potential zones. The U. S. Forest Products Laboratory at Madison, Wisconsin maintains test plots in the gulf coast region and at the Canal Zone in Panama where the environmental conditions are most favorable for insect and decay damage to wood. |
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The results of these ongoing tests are periodically published. These publications by the U.S Department of Agriculture’s Forest Product Laboratory document the performance of treated members. A typical test plot contains stakes treated with different preservatives at varying amounts of retention of the preservative. The treated stakes are divided into two groups, one set is placed in a gulf coast test plot and the other identical set of specimens is placed in the test plot at Madison, Wisconsin. Additionally, untreated stakes of the same material and size are also placed in each test plot. The performance of the stakes is checked periodically and the data analyzed and published by scientists. The results are published in a document entitled Comparison of Wood Preservatives in Stake Tests published by the U.S. Department of Agriculture, U.S. Forest Service. That paper has an index of the various tests, listed by the wood preservative used. As can be seen in a portion of the index in Figure No. 3, stakes treated with different preservatives are placed in the same test plot. Copper Naphthenate and creosote, coal tar treated stakes were both placed in Test Plots 16 and 17. This provides for a direct comparison of the two preservatives under identical environmental conditions. |
 Figure No. 2 • Map of the United States showing the Deterioration Potential Zone as determined by the American Wood-Preservers’ Association. |
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 Figure No. 3 • A portion of the Index of the publication Comparison of Wood Preservatives in Stake Tests - 1995 Progress Report, published by the U.S. Department of Agriculture, indicating that several different preservatives are used in the same test plot. |
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A portion of Table No. 16 is shown in Figure No. 4. The interesting aspect is that this particular test plot was established in 1946, and this particular Table was the results after 46 years of service in Saucier, Mississippi. The results of field tests such as that one are used and cited in peer-reviewed publications for use by interested parties. |
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 Figure No. 4 • A portion of Table 16 from the Comparison of Wood Preservatives in Stake Tests - 1995 Progress Report showing the performance of three preservatives. |
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Figure No. 5 shows Table No. 3 from a paper by Rodney C. De Groot, Forest Products Laboratory, which published in a book entitled Wood Protection Techniques and the Use of Treated Wood in Construction, by the Forest Products Research Society. That Table indicates the Service Life of preservative treated pine post in a U.S. Forest Service Mississippi post study. The indicated service life of posts treated with Copper Naphthenate was 42 years, which equaled the longest service life of all preservatives and was longer than most in that study. Additionally, there are thousands of Copper Naphthenate treated components and structures that have been in service for decades and have established Copper Naphthenate as a preservative equal to other established preservatives. It is no accident that the service life of all of the different preservatives are very comparable, the science of wood preservation has advanced to the point where the amount of preservative retention necessary for long-term performance can be readily determined. The type of tests necessary to verify the efficacy of wood preservatives have been documented and published by the American Wood Preservers Association in their Standards. Wheeler Lumber is satisfied with the evidence that Copper Naphthenate when properly applied in a pressure treatment process will provide the level of protection to wood that its customers have come to expect. Treated timber structures that have been well engineered, properly treated and installed in accordance with plans should provide close to a century of trouble-free service life. |
 Figure No. 5 • TABLE 3 from a paper by Rodney C. De Groot published in the book Wood Protection Techniques and the Use of Treated Wood in Construction by the Forest Products Research Society. |
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REGULATIONS The following is a summary of a review of the regulatory status of Copper Naphthenate by Environmental attorney, Walt Talerek, Esq. The complete review is available for viewing and downloading from the web site of Merichem Company at www.merichem.com. Copper Naphthenate is an EPA-registered, non-restricted use (general use) wood preservative. EPA regulations and product labels do not require applicators of copper naphthenate wood preservatives to be certified. (However, some states may require applicator certification for Copper Naphthenate for the wood preservatives typical use patterns.) Copper Naphthenate wood preservatives are not restricted-use pesticides under 40 CFR section ß 152.170 because: |
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They (CuNap wood preservatives) are not Toxicity Category I acute toxicants; | ||
| * | They do not cause significant subchronic, chronic or delayed toxic effects; and | ||
| * | They do not pose a serious hazard to man or the environment. | ||
Copper Naphthenate wood preservatives are not the subject of an EPA special review under 40 CFR section ß 154.7, nor will they be in the future, because: |
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| * | They do not pose a risk of serious acute injury to humans or domestic animals; and | ||
| * | They do not pose a significant risk of inducing oncogenic, heritable genetic, teratogenic, fetotoxic or reproductive effects in humans. |
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Copper Naphthenate wood preservatives are reviewed under the Resource Conservation and Recovery Act (RCRA). Pursuant to those regulations, Copper Naphthenate wood preservatives wastes are not federal hazardous wastes because: |
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| * | Copper Naphthenate wood preservation wastes are neither listed (from specific or non-specific sources) nor characteristic hazardous wastes. See 40 CFR Part 261. |
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| * | EPA's 12/6/90 wood preservative wastes listing rule does not apply. |
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| * | Copper and Copper Naphthenate are not regulated under the Toxicity Characteristic (TC) and are not Appendix VII constituents of concern. |
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In summary of the regulatory status, Copper Naphthenate is an EPA-Registered, nonrestrictive, relatively non-toxic, wood preservative. From a regulatory standpoint, Copper Naphthenate is an attractive wood preservative because EPA imposes minimal requirements on wood preservers who use it. Furthermore, when compared to each restricted use wood preservative, Copper Naphthenate enjoys some if not all of the following advantages: |
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| 1. | EPA does not require applicators of Copper Naphthenate wood preservatives to be certified; |
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| 2. | EPA does not regulate Copper Naphthenate wood preservative wastes as hazardous wastes; |
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| 3. | EPA does not regulate Copper Naphthenate emissions from wood-treating plants as hazardous air pollutants; only the solvents that they are diluted with are regulated; |
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| 4. | Copper Naphthenate is not a regulated toxic substance to which Clean Air Act (CAA) accidental release prevention requirements apply; |
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| 5. | Copper Naphthenate is neither a Clean Water Act (CWA) nor a Comprehensive Environmental Reporting, Compensation and Liability Act (CERCLA) hazardous substance for which spills have to be reported; and |
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| 6. | Copper Naphthenate is not an Emergency Planning and Community Right-to-Know Act (EPCRA) extremely hazardous substance for which emergency release notification requirements apply. |
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SPECIFICATIONS The principal source for specifications regarding the actual preservatives and their proper application in the process of wood preservation is the American Wood-Preservers’ Association (AWPA). The AWPA is an international, nonprofit, technical society founded in 1904 to provide a common forum for exchange of technical information between industry, research and user of treated wood. Since that beginning the AWPA has become the foremost authority on the technical aspect of the wood preservation. As stated earlier, Copper Naphthenate was included in their Standards in 1949 and has been an accepted wood preservative since. Almost all other public and private agencies that specify treated wood either for design or for purchase use AWPA Standards for the source document for their specifications. The American Association of State Highway and Transportation Officials (AASHTO) Specifications for Preservatives and Pressure Treatment for Timber is designated as AASHTO M 133-03. It contains no detailed technical specification, but states: |
“Wood products shall be treated in accordance with AWPA C 14, or the following standards set forth by the American Wood Preservers’ Association. In the case of conflict, AWPA C 14 shall govern.” |
State Highway Departments and Departments of Transportation generally do one of two common approaches to specifications for treated timber. Some make reference in their specification directly to AWPA, others make reference to AASHTO M 133, which as shown above, make reference to AWPA. The paper path may vary from State to State, but ultimately they all make reference to AWPA for the source document. Figure No. 6 contains a Table showing the current AWPA Commodity Standards and the new Use Category System (UCS). |
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 Figure No. 6 • A Comparison Chart indicating both the existing AWAP Commodity Standards and the New AWPA Use Category System (UCS) for many of the products used in engineered timber structures. |
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CURRENT USES Wood products treated with Copper Naphthenate have been and are currently being used for utility poles, farm products including fence posts, building poles and squares, and splash-planks and has been used for earth retaining walls and has been used for highway bridges. The U.S. Forest Service has used Copper Naphthenate exclusively in some Forest Regions for their structures. It has been used for other non-wood related uses such as textiles, rope of all kinds, fishnets, field boxes and hotbeds, beehives, and has been used for medicinal purposes in treating hoof rot and other conditions of livestock. ENGINEERED STRUCURES Wheeler Lumber's staff of engineers and wood technologists have investigated and researched the use of Copper Naphthenate for the treatment of the wide range of treated timber structures that Wheeler produces and have uncovered no physical reason or existing specification that would prevent the use of Copper Naphthenate. There is no reason why properly designed and fabricated heavy timber structures treated to the proper specification with Copper Naphthenate will not perform as well as structures treated with other approved wood preservatives. Copper Naphthenate can be used as the preservative for highway bridges, pedestrian bridges, drainage structures, bulk storage structures, retaining walls and railroad structures. SUMMARY When all aspects of selecting a preservative for engineered timber structures were considered, the choice was clear. Copper Naphthenate offered more advantages for the long-term serviceability and less risk in all environmental areas for all application of pressure treated timber in the construction of engineered structures. Wheeler Lumber, LLC has built its reputation on providing quality treated timber products over the past century and it is not going to offer any products that do not meet the standards that have established its reputation. |
| In conclusion, Copper Naphthenate is an excellent choice as a wood preservative because it: | |||
| * | Is a safe and effective wood preservative | ||
| * | Is noncorrosive to hardware and connectors | ||
| * | Has recognized performance/efficacy | ||
| * | Is an EPA General Use Pesticide | ||
| * | Has minimal worker exposure issues | ||
| * | Has No Federal disposal restrictions | ||
Wheeler Lumber LLC is proud to offer its complete line of Copper Naphthenate treated engineered timber structures to its customers. Wheeler Lumber, LLC will continue to stand behind its products and offer the same assurance of quality and integrity its customers have come to expect. |
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Manufactured By: Wheeler Lumber, LLC |