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Serviceability of copper naphthenate-treated poles
2000 - IRG/WP 00-30214
Copper naphthenate-treated poles in service were inspected for deterioration, penetration, retention, and serviceability. The study to date has included poles in all hazard zones in the United States. Poles installed by 12 different utilities and eight different treating companies are included in the survey. Both southern pine and Douglas-fir poles and distribution and transmission poles are included in the survey. Only two of the surveyed poles were considered failures, indicating that properly treated copper naphthenate poles are performing satisfactorily.
H M Barnes, M H Freeman, J A Brient, C N Kerr Jr


Performance of boron and fluoride based rods as remedial treatments in Douglas-fir poles
1995 - IRG/WP 95-30070
Boron and fluoride are widely used for remedial internal treatments, but their use in North America has been limited. Recently, however, interest in these chemicals has increased as the result of concerns about the risks of fumigant usage. The performance of boron or a boron/fluoride combination was assessed in Douglas-fir poles over 1 to 3 year periods. Both chemical formulations diffused well through the wetter, groundline zone of the poles, although the initial release rate of the boron in the fused borate rods was somewhat slower than that found with the combination. Chemical levels in the groundline zone remain above those required for control of active fungal attack. Chemical levels above the groundline varied widely reflecting the moisture variations present and highlighting the need for adequate moisture to produce uniform diffusion.
J J Morrell, P F Schneider


Preliminary modelling of methylisothiocyanate movement through Douglas fir transmission poles
1988 - IRG/WP 3466
Methylisothiocyanate is a volatile solid that is the active ingredient of several registered and experimental wood fumigants. Information on the sorption and diffusion of this chemical in Douglas-fir heartwood and sapwood was used to develop a two-dimensional model of fumigant movement within a single horizontal cross-section of a transmission pole. The model indicated that dry wood (14% MC) strongly sorbed MIT, which resulted in lower rates of MIT movement. Conversely, it was predicted that wetter wood (22 or 40% MC) held MIT less strongly and had a more rapid rate of chemical movement. In addition, predictions suggest that the presence of an oil-treated peripheral shell had a strong influence on loss of fumigant from the surface of the pole, but had little effect on concentration which developed in the heartwood zone. The results indicate that MIT movement can be effectively modeled. Further studies are underway to account for longitudinal movement of MIT in the model and to simulate extended time periods.
A R Zahora, P E Humphrey, J J Morrell


Feasibility of using biological control agents to arrest and prevent colonization of Douglas fir and southern pine by decay fungi
1988 - IRG/WP 1345
The use of microfungi to control basidiomycetous decay has been evaluated in Europe for many years, where it has produced mixed results against Lentinus lepideus Fries, the fungus presumed to be the major cause of decay in Scots Pine poles. In the United States, remedial decay control has been largely chemical, with little use of alternative decay control strategies. Increasing restrictions on chemical usage have stimulated renewed interest in biological decay control. In our tests, a European biological control, BinabÒ,was evaluated for its ability to prevent or arrest attack of southern pine sapwood or Douglas fir heartwood by 5 Basidiomycetes commonly isolated from poles in service. Lentinus lepideus was included as a comparison. In general, BinabÒ performed well against Lentinus lepideus and the other brown rotters, but was unable to completely eliminate most of the test fungi. In addition, the biological had little effect on white rot fungi, which are an important component of the microflora in decaying poles. The results suggest that biologicals will not be suitable for remedial decay control without supplemental treatments that favor growth and activity of the biocontrol agent.
J J Morrell, C M Sexton


Effect of kerfing on performance of Douglas-fir utility poles in the Pacific Northwest
1990 - IRG/WP 3604
Preservative treatment produces an external layer of protection in Douglas-fir poles, but the development of deep checks as the wood dries after treatment can permit entry by fungi and insects. A variety of remedial treatments can arrest this decay; however, it is far more efficient to prevent checking. Kerfing represents one potential method for limiting the development of deep checks. In previous studies, examination of kerfed poles after 20 years in service revealed that only 2% contained viable decay fungi in the kerfed zone, while over 20% of similar non-kerfed poles contained viable decay fungi. Recently, over 5,000 kerfed and non-kerfed Douglas-fir poles ranging from 0 to 25 years in age were inspected. The presence of internal decay in these poles was generally low in comparison with previous reports. Several explanations are proposed for these differences.
J J Morrell


Sterilization to limit pretreatment decay: Internal temperature during kiln drying of Douglas-fir poles
2001 - IRG/WP 01-40206
Sterilization to limit pretreatment decay: Internal temperature during kiln drying of Douglas-fir poles. Fungal colonization of poles following peeling has been the subject of considerable concern among electric utilities. While the presence of fungi does not, in itself constitute a risk, the survival of these fungi through the conventional treating processes could allow them to continue to degrade the pole once it is placed in service. Previous research has shown that pressure treatments in heated, oil-based solutions expose the poles to sufficient heat to eliminate established decay fungi. Many treaters in North America are shifting towards kiln drying to reduce treatment times, but there is little data on the internal temperatures in poles during conventional kiln treatments. In this report, we describe field tests to monitor internal temperatures in Douglas-fir poles during treatment. In general, temperatures did not reach the generally accepted lethal target temperature for eliminating fungi from wood (67°C for 75 minutes), but the times when temperatures were between 60 and 65°C approached 40 hours in some charges. Prolonged exposure to these elevated temperatures should also eliminate established decay fungi. The results suggest that internal temperatures during kiln drying reach levels that should eliminate the risk of pre-treatment decay fungi surviving the treatment process.
J J Morrell, P G Forsyth, K L Levien


Effects of air-seasoning on fungal colonization and wood strength of Douglas fir poles
1987 - IRG/WP 1315
Air seasoning economically reduces the moisture content of Douglas fir poles before pressure treatment with preservatives. Advanced decay in poles in service has resulted when decay fungi (Basidiomycetes) colonized poles during air-seasoning and survived the treatment process. These problems have led to recommendations to severely limit this practice. To determine the role of these fungi in peeled and unpeeled Douglas fir poles during air-seasoning in the Pacific Northwest, we identified many of the fungi involved, measured their effect on wood strength, and studied methods for limiting fungal colonization. Over 90 percent of peeled poles air-dried for more than 1 year contained decay fungi, suggesting that air-seasoning in the Pacific Northwest might pose some hazard; however, no significant strength losses were noted in poles dried 1 to 2 years. Poles seasoned for 3 years began to show significant strength losses, but these strength values fell within suggested design parameters for Douglas fir poles. Although Douglas fir poles are colonized by decay fungi as they dry, our results indicate that these fungi do not cause serious damage for at least 2 years. On the basic of these results, we recommend that poles be air dried no longer than 3 years in the Pacific Northwest. We also emphasize the importance of heating air-seasoned wood adequately during the treatment process to kill any fungi present.
J J Morrell, M E Corden, R D Graham, B L Kropp, P Przybylowicz, S M Smith, C A Sexton


Distribution of boron from fused borate rods in Douglas-fir transmission poles
1996 - IRG/WP 96-30112
The diffusion of boron from fused borate rods (disodium octaborate tetrachydrate) was monitored over 42 months in CCA-treated Douglas-fir transmission poles. The boric acid equivalent was estimated by the curcumin/salicylic acid color test on increment cores removed from the poles. Moisture content of the poles was quite variable but was always above 20 percent. The percent of increment core length showing boron was also variable with time of sampling from individual poles and between poles. Diffusion of boron increased until 18 months then decreased slightly at 30 and 42 months. Boron was almost always detected downward from the treatment holes at a distance of 25 cm. Likewise, boron was usually detected laterally from the insertion hole at a distance of 7.6 cm. Movement of boron upward from the insertion holes was often nil and not exceeding 5 cm. Thus, because of the variable penetration of boron in the Douglas-fir heartwood, untreated areas are present that are susceptible to decay.
T L Highley, F Green III, W F Finney


Borate diffusion from fused borate rods in douglas-fir transmission poles
1994 - IRG/WP 94-30042
Pressure-treated utility poles have given many years of excellent service, but their lifetime is often shortened by internal decay of the untreated heartwood center, particularly in refractory species, such as Douglas-fir. This paper reports the distribution of boron from fused borate rods installed in CCA-treated Douglas-fir transmission poles. The boric acid equivalent was roughly monitored by the curcumin/salicylic acid color test on increment cores removed from poles at 6 and 18 months after installation of fused borate rods. The percent of increment core length showing boron at 18 months was 2.5 times greater than at 6 months. Boron was almost always detected downward from the treatment at a distance of 25 cm (10 inches). Movement of boron upward from treatment holes was not as good, rarely exceeding 5 cm (2 inches). The increment core length showing boron did not always correlate with moisture content but when the moisture content was greater than 40%, the total core length with boron was greater than 80%.
T L Highley, W Finney, F Green III


Metal Migration from Douglas-fir Poles Treated with Ammoniacal Copper Zinc Arsenate According to Best Management Practices
2010 - IRG/WP 10-50272
The potential for migration of metal components from ammoniacal copper zinc arsenate treated (ACZA) poles was examined using pole sections treated using Best Management Practices. Copper and zinc levels were highest in runoff collected following the first rainfall events, then declined. Copper and zinc levels in runoff averaged 20 ppm and 5 pm respectively. The metal levels were then used to predict the amount of metal loss when poles were stacked in different configurations that altered exposed surface area. Tight stacking reduced total metal losses, although metal levels would still rise well above background within 150 mm of the surface beneath the poles if no dilution occurred into the surrounding soil. The results illustrate the potential for managing poles to reduce metal losses in storage.
J J Morrell, C S Love, C Freitag


Incidence of soft rot attack on preservative treated Douglas-fir poles: a preliminary survey
2014 - IRG/WP 14-10818
Occurrence of soft rot decay in Douglas-fir poles treated with ammoniacal copper zinc arsenate (ACZA) or pentachlorophenol in oil was studied. Soft rot was less prevalent in poles treated with penta, but some soft rot was found in approximately 20 % of poles examined. Soft rot was more common in poles treated with ACZA, and, when present, was found in almost 20% of the cells examined. The potential impacts of this damage are discussed in relation to future inspection procedures for these poles.
P Torres Andrade, J J Morrell


Potential for migration of boron from fused boron rods used as internal remedial treatments of utility poles
2014 - IRG/WP 14-50301
The distribution of boron in Douglas-fir utility poles and in the surrounding soil was assessed over a 54 month period following application of fused boron rods. Boron levels in the wood never reached the levels that might be predicted if diffusion were to produce a uniform chemical distribution, nor did levels in the soil suggest that boron was becoming more concentrated. The results suggest the need for further studies to better delineate boron distribution in wood and to better understand the rate at which bron moves from wood and intro the surrounding soil.
M Konkler, C Freitag, C S Love, J J Morrell, J Renfroe


Migration of copper from copper naphthenate treated Douglas-fir poles during storage
2014 - IRG/WP 14-50302
Preservative migration from treated wood products has raised concerns among regulators, especially when the biocides move into surface waters. In most cases, chemical levels are well below the acceptable minimum level, but can become a concern if large quantities of treated wood are stored in one location. One such case would be a location where utility poles are stored for use in emergency repairs. The potential for preservative migration from copper naphthenate treated poles in storage was evaluated over a 2 year period. Copper was always present in rainfall runoff from the poles at levels mostly ranging from 2 to 12 ppm. Neither rainfall amount nor the interval between rainfall events had a large effect on copper levels in runoff, suggesting that metal migration could be modeled using the extent of wood surface exposed to precipitation. The data were used to model three different storage scenarios and these results were used to predict copper levels at various depths in the soil beneath stored poles. The results can be used to manage pole storage to minimize migration.
C S Love, C M Freitag, J J Morrell


Boron dual-treatments for Douglas-fir utility poles: Tracking boron migration over time
2019 - IRG/WP 19-30739
The potential for using boron pressure-treatment prior to over-treatment with conventional, heavy-duty wood preservatives to limit internal decay in-service was investigated in two field tests on Douglas-fir utility poles. Pole sections were pressure-treated with disodium octaborate tetrahydrate (DOT) and then over-treated with either pentachlorophenol or copper naphthenate in oil. Alternatively, poles were treated with a mixture of DOT and ammoniacal copper zinc arsenate in a single treatment. The pole sections were installed in the field and monitored for changes in boron content over time. Boron levels immediately after treatment were extremely high in the outer 25 mm of poles in both tests and declined sharply away from the surface. Field exposure for one to five-years resulted in some boron losses near groundline, but overall levels near pole surfaces remained well above the fungal protection threshold. Diffusion did occur further inward, but there was still a steep boron gradient from the pole surface five-years after treatment. Results are discussed in the context of Douglas-fir heartwood resistance to boron diffusion compared with other wood species and the potential for long-term retention of chemical within the heartwood.
J Cappellazzi, M J Konkler, J J Morrell


Application of radio frequency heating to accelerate fixation of CCA in treated round-wood
1999 - IRG/WP 99-40133
The potential of radio frequency heating to accelerate the fixation of chromated copper arsenate (CCA) in treated round-wood was assessed. Pre-dried Douglas-fir and western red cedar round-wood sections were pressure treated with CCA in a pilot plant retort, after which they were placed individually in a pilot radio frequency (RF) chamber. Based upon the color reaction of chromotropic acid with hexavalent chromium and the quantitative assessment using diphenyl carbazide, fixation was achieved in less than 6 hours. During heating, the temperature at various locations inside the pole sections was monitored by fiber-optic thermocouples. The moisture profiles before, and after fixation, were also recorded. Further studies will examine other benefit of RF heating, including a) sterilization, and b) rapid drying of round-wood with minimum check formation.
Fang Fang, J N R Ruddick


Treatability of plywood containing intermountain Douglas fir veneers
1982 - IRG/WP 3203
Eighteen sheets of plywood were obtained which contained intermountain Douglas-fir veneers from two regions of British Columbia. Following pressure treatment with chromated copper arsenate (CCA type C) and ammoniacal copper arsenate (ACA) the preservative penetration and retention in individual veneers was assessed. It was concluded from the study that the intermountain Douglas-fir veneer could not be adequately penetrated by either CCA or ACA, although the degree of penetration achieved with ACA was better than that recorded for CCA. The preservative retentions measured were generally in excess of that required for plywood to be used in the preserved wood foundation system.
J N R Ruddick, A Walsh


Effect of a penta emulsion on the service life of Douglas fir, heartwood posts
1978 - IRG/WP 3112
C S Walters


Movement of boron from fused boron rods implanted in Southern pine, Douglas fir, red oak, and white oak timbers
1995 - IRG/WP 95-30061
This paper reports the distribution of boron from fused boron rods installed into six-inch (15.2 cm) square timbers of Douglas-fir, Southern Pine, red oak and white oak exposed aboveground. The composition and size of rods was: sodium borate and sodium borate-copper oxide (8.5 x 100 mm²); sodium borate-copper, sodium borate and boric oxide-copper oxide (12 x 76 mm²). The boric acid equivalent was roughly monitored by the curcumin/salicylic acid color test and the presence of copper was detected by the chrome azurol-S reagent. One year after installation of rods, movement of boron was determined by application of curcumin dye to increment cores removed at various distances from the site of boron rod installation. A portion of a sodium borate treated Southern Pine timber was also analyzed by spraying curcumin dye on sawed longitudinal and transverse sections. At 2 years, one foot sections were removed from all timber species, sawed as above, and boron and copper detection reagent sprayed on the sawed surfaces. Movement of copper from rods in all timbers was virtually nil. Both transverse and longitudinal movement of boron from rods was greatest in Southern pine which also had the highest moisture content. Movement of boron was next best in red oak. There was little movement of boron away from the rods in white oak and Douglas-fir.
T L Highley, L Ferge


Long-term effectiveness of fumigants in controlling decay in Douglas fir waterfront timbers
1986 - IRG/WP 3364
The persistence, movement, and effectiveness of chloropicrin and Vapam (sodium N-methyl dithiocarbamate) in large, horizontal Douglas fir timbers were evaluated 7 years after fumigation. Chloropicrin prevented reestablishment of decay fungi; reinvasion occurred in some Vapam-treated timbers. Residual fungistatic effect was detected up to 1.2 m from the fumigation site in chloropicrintreated timbers but not in Vapam-treated timbers.
T L Highley


Sequential exposure of borate treated Douglas-fir to multiple Formosan subterranean termite colonies in a 40-week field test
1993 - IRG/WP 93-10006
Douglas-fir boards (ca. 74.5 g) pressure-treated with disodium octaborate tetrahydrate (DOT) retentions of 0 (controls), 0.88, 1.23, 1.60, or 2.10% (weight/weight) DOT were sequentially exposed to four active field colonies of Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), in an above-ground field test. Samples were placed in contact with each colony for 10 weeks, with oven-dry weight losses determined between exposures, for a total termi exposure period of 40 weeks. Feeding activity differed among termite colonies, with the control wood samples having mean weight losses of 1.3-15.1% of their initial weight during each individual 10-week termite exposure. The two lower borate retentions (0.88 and 1.23% DOT) were virtually equal efficacy, with mean wood weight losses during each individual 10-week exposure ranging from 1.2-4.6%. Feeding was negligible at the two higher borate retentions, with mean wood weight losses from termite feeding during each 10-week period ranging from 0.7-1.3% with 1.60% DOT, and 0.3-0.9% with 2.10% DOT. Total cumulative wood weight losses over the 40 week exposure were: 10.2% (0.88% DOT), 8.7% (1.23% DOT), 3.6% (1.60% DOT), and 2.4% (2.10% DOT).
J K Grace, R T Yamamoto


Effect of fatty acid removal on treatability of Douglas-fir
1993 - IRG/WP 93-40008
Treatment of Douglas-fir with chromated-copper-arsenate (CCA) poses a major challenge. Several hypotheses based on the anatomical aspects as well as chemical reactivity of the preservative formulations with cell wall constituents and deposits have been proposed. Techniques to prevent pit aspiration or slow fixation reactions have, however, not significantly improved treatment. The presence of high molecular weight fatty acids have been reported to be responsible for higher hydrophobicity in some wood species. These acids can react with Cu+2/Cr+3 ions to form insoluble metallic soaps, thereby immobilizing Cu/Cr and increasing wood hydrophobicity by a mechanism similar to that employed in paper sizing. The effect of fatty acids on treatability was explored by removing these components via several extraction methods. In general, extracted wood had higher gross solution absorptions and chemical retentions, but preservative penetration was largely unaffected. The results suggest that removal or disruption of fatty acids can improve treatability of Douglas-fir heartwood.
S Kumar, J J Morrell


Studies on the biological improvement of permeability in New Zealand grown Douglas fir
1983 - IRG/WP 3231
This report outlines progress towards optimizing conditions for water storage of New Zealand grown Douglas fir with the aim of improving permeability to water-borne preservatives, in particular CCA. Small scale laboratory tests are in progress but the need to scale up to potential commercial applications is being considered. Mixed populations of bacteria isolated from 10 week water sprinkled Douglas fir are being used to inoculate green, sterile timber. Environmental parameters such as pH, temperature and nutrient status are controlled to evaluate optimum conditions of growth, enzyme production and pitmembrane degradation leading to permeability improvement.
K J Archer


Treatment of Douglas fir heartwood with disodium octaborate tetrahydrate (Tim-BorÒ ) to prevent attack by the Formosan subterranean termite
1991 - IRG/WP 1487
Toxicity of disodium octaborate tetrahydrate (Tim-BorÒ) to Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), and termite feeding on treated Douglas-fir heartwood were evaluated in laboratory and field tests. Feeding on filter papers impregnated with Tim-BorÒ solutions reduced but did not eliminate termite gut protozoan populations. In a forced-feeding laboratory assay, Douglas-fir heartwood treated to Tim-BorÒ retentions ³0.35% BAE drastically reduced termite feeding and resulted in 100% termite mortality within three weeks. Gradual and significant mortality (49%) after four weeks of feeding at 0.16% BAE suggests that this or lesser concentrations may be useful in baits for remedial termite control. After 162 days of field exposure to an active Coptotermes formosanus colony in an accelerated field test, moderate feeding was noted at 0.65% BAE (13.6% weight loss) and 0.73% BAE (16.9% wt. loss), and only slight damage (2.5% wt. loss) at the highest retention field tested of 1.02% BAE. These results indicate that Tim-BorÒ provides protection from Formosan termite attack, but that some cosmetic damage occurs even at high retentions. This cosmetic damage is unlikely to create a structural hazard, but additional field evaluations are needed to determine the treatment requirements for timbers visible to the consumer.
M Tamashiro, R T Yamamoto, J K Grace


Development of decay in untreated, second-growth Douglas-Fir using two exposure techniques in North Queensland
1997 - IRG/WP 97-20110
The results of two exposure techniques for evaluating the development of wood decay in untreated, mill-run lumber from second-growth Douglas-fir containing both sapwood and heartwood are presented. Nominal 50 mm by 100 mm by 2.5 m (2 in. by 4 in. by 8 ft) lumber, No 2 and better, was obtained from a production run in a mill that was processing second growth, Coastal Douglas-fir in western Oregon, USA. Untreated wood members were kiln dried, then shipped to Queensland. At the Timber Research Laboratory, Indooroopilly, Queensland, two units for above-ground exposure were fabricated from each 2.5-m (8-ft) untreated member. A 600-mm (2-ft) length was cut from each end of each member. One 600-mm section was transversely bisected, forming two, 300-mm (12in.) units; the other 600-mm section was used in a separate study. The middle 1200-mm (4-ft) length was used as one exposure unit. These shorter members were then milled to form a joint with a 100-mm (4-in.) overlap. Two holes were drilled through the overlapping portions, and the two sections were bolted together. The identity of the 1200mm length and the end-matched lapped jointed section was maintained throughout the exposure. Both units were positioned on a horizontal support approximately 1 m above ground in an open field near Innisfail, Queensland. As units were installed in the field, all cut surfaces inside the joint and at the ends were brush coated with a commercially available (in Australia) copper naphthenate emulsion containing 1% copper. Decay was first detected after 2 years of exposure and it advanced rapidly during the third year. The pattern of results suggests that the weathering of the upper, exterior surface and the retention of a high moisture content by the 50-mm-thick wood, when wetted, is more important in predisposing wood to decay than is end-grain absorption of moisture. Decay ratings for the 1200-mm members were equivalent to those observed with the lapped joints. The two types of units are of equal utility in demonstrating the potential for decay in a wood material that has natural susceptibility to decay.
J Norton, S Kleinschmidt, R C De Groot, D Crawford


Migration of Metals from Douglas-fir Lumber Treated with ACZA or Pentachlorophenol Using Best Management Practices: Preliminary Tests
2005 - IRG/WP 05-50224-4
The potential for migration of preservative components from ammoniacal copper zinc arsenate (ACZA) and pentachlorophenol treated Douglas-fir lumber in non-soil contact exposure was assessed in a simulated rainfall device. Metal levels from ACZA treated wood were elevated for the first 30 minutes of rainfall and then declined sharply. Repeated cycles of rainfall led to declines in initial metal losses suggesting that surface metals were gradually depleted from the wood. Penta losses were also initially high, but then declined at rates related to rainfall level. The results suggest that preservative losses from treated wood in above ground exposures can be predicted.
J J Morrell, Hua Chen, J Simonsen


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