Your search resulted in 16 documents.
Introduction to a field demonstration of various instruments and methods for the detection of defects in poles
1984 - IRG/WP 2228
Detection of defects in standing poles by X-ray techniques
1980 - IRG/WP 2132
The application of X-ray techniques to wood pole inspection procedures has been evaluated. Internal defects were accurately identified using X-ray inspection methods. These methods and their possible influence on the safety and economic aspects of wood pale utilization are discussed.
W D Gardner, R S Johnstone, W Pitt
Non-destructive testing for the detection of defects in poles (letter to members of Sub-group 5 of WG II)
1982 - IRG/WP 2171
Report on a field demonstration of methods for detecting defects in wood poles
1984 - IRG/WP 2232
P I Morris, H Friis-Hansen
Washboard effect: A surface deformation of spruce resulting from vacuum-pressure impregnation with water-borne preservatives
1987 - IRG/WP 3450
The washboard effect has been observed in sawn spruce after both commercial and laboratory based preservative treatments and is of increasing economic importance. The effect is defined as a specific phenomenon at the wood surface. It is distinct from internal collapse in the wood, but it may occur in association with internal collapse damage. Experimental investigations on the causes of washboarding and preliminary results indicate that a combination of several factors induce the effect. At treating pressures below about 10 bar washboarding appears to develop with post treatment drying of the wood whereas with higher pressures it will occur during the impregnation cycle. Further research has been started to develop measures to minimise the problem.
H Willeitner, R J Murphy
Summarized comparison of four techniques for detecting defects in poles
1979 - IRG/WP 2126
Since our discussions in open session of Working Group II at Peebles, a number of workers in Australia have collaborated in comparing the efficacy of X-ray, sonic testing, or resistivity measurements for detecting internal defects in poles. The purpose of this circular is to draw to your attention some of the results, in summary form. No attempt has been made to compare techniques. More detailed accounts may be published at some future time by the individual workers concerned. Forty condemned eucalyptus telegraph poles were assessed by traditional inspection methods (hammer sounding and boring), X-ray scanning, Resotest Pole-Check sonic tester, and Shigometer resistivity technique. The work was planned and carried out by Messrs Johnstone and Gardner (Forest Commission of N.S.W., Wood Technology and Forest Research Division), Messrs McKitterick and Seaman (Telecom Australia) and Dr. Thornton of this Division who collaborated in examining 22 of the poles with the Shigometer. The results are summarised in the Table and some of the more interesting poles are shown in the figures. Unfortunately, details of the X ray scanning are not available for dissemination at this stage and therefore they have been omitted from the Table. For interpretation of the data obtained with the Shigometer, Dr. Thornton has combined the instrument's readings with application of it's probe to detect sound wood, i.e. less than 40 mm of sound wood remaining together with readings which suggest the presence of internal defects results in the pole being condemned. Note also in the case of the Resotest Pole-Check a suspect reading means that the poles should be re-assessed by traditional boring and sampling. Dr. Thornton and I wish to stress that we believe the instruments used in this study are valuable as aids to the linesman/pole inspector; we consider that no system should be put forward as the sole indicator of whether a pole has failed or not.
A simple non-destructive means of testing poles in situ
1982 - IRG/WP 2167
A novel device for detecting internal defects in wooden poles
1989 - IRG/WP 2329
The diagnosis of internal defects caused by termites and decay in hardwood transmission poles has been investigated using a novel Automatic Feed Drill (AFD) pole testing device. Internal defects were recognised by changes in drill feed-rate as the automatic air-driven drill traversed its 100 mm working stroke. The instrument is portable, simple to operate and recognises defects instantaneously. Tests carried out on pole material in the laboratory and the field showed that the instrument gives quick and accurate measurements of internal collapse and weakness in wood at the groundline zone.
R A Eaton, R S Johnstone
Premature failure of treated timber in wharfs in Papua New Guinea, attributed to defects in design
1991 - IRG/WP 4158
The performance of timber in wharfs in Papua New Guinea has been monitored for a number of years. Premature failure of wharf structures was found in many cases to be due to defects in design rather than ineffective preservative treatment. Above-water timbers were found to be prone to severe checking followed by decay. Protection for the end grain of pile tops and the limiting of radial checking in them was found to be vital. Removable metal caps and stout metal bands sized to give a snug fit around the circumference of the pile were found to give the best protection. Major areas of decay or marine borer attack were most common where other structures were attached to the piles in such a fashion that the "envelope" of treated sapwood was breached. In order for treated timber to perform satisfactorily in wharfs, care has to be taken at the design stage. Any post-treatment machining should be undertaken with suitable tools and remedial treatment or protective measures will be required. A list of recommendations for the use of treated timber in wharfs in the tropics is given, relating to the preparation of wood, the construction of the wharf and the protection of vulnerable parts of the installed wharf. The question of good and bad design, and its effect on service life of wharf timbers requires further investigation. The author requests colleagues with information relating to this to contact him.
S M Cragg
The influence of the location of a wood defect on the modulus of elasticity determination in wood durability testing
2004 - IRG/WP 04-20287
This study investigates the influence of the location of a wood failure in stakes upon elastic changes observed in beech specimens with the resonance vibration technique. Natural failures were simulated by artificially created defects at different locations of the test stake. The results indicate that the location of an attack in a stake is important for the measurement outcome. When the attack is located at far ends of a stake, the detected faults are underestimated. Higher losses of modulus of elasticity were recorded with notches in comparison to bore hole defects. The non-destructive vibration approach (dynamic MOE) applied in durability testing offers advantages compared to conventional static techniques.
L Machek, H Militz
Structural defects in CCA treated timber fence posts: A case study.
1997 - IRG/WP 97-40084
Since 1983 an environmental improvement programme has been in progress in the city of Dundee. This programme included the erection of rail and pale timber fencing throughout the city. The timbers had been pressure treated with CCA prior to painting with 2 coats of an exterior wood stain finish. However, the larger dimension timber fence posts (100 x 125 x 1500 mm3) regularly developed severe checks/shakes in service. These defects raised questions regarding the continued use of timber as a fencing material by the municipal authoritiy due to concerns relating to the long term efficacy of preservative treatment and timber durability. Statistical models generated from visual and physical measurements of aged post timbers recovered from field sites in the city indicated that a reduction in the development of structural defects was associated with lower heartwood:sapwood ratios. The sites from which posts were recovered also influenced defect development indicating inconsistent timber quality specifications and/or pronounced variation in environmental conditions at each site. This paper highlights the problem of many municipal authorities who, through lack of available information, fail to implement specifications for treated timber components tailored to their specific requirements.
S Muhsin, D C R Sinclair, A Bruce, H J Staines
New approaches to practical evaluation method of bio-degradation of wooden construction - Non-destructive detection of defects using radar technique
2000 - IRG/WP 00-20214
There have been a number of researches and developments on the techniques and apparatus for the nondestructive evaluation of the biological deterioration in wood and wooden constructions, such as decay or insect attack in house, public buildings or in historically important architectures. As for the detection of the decay in wood, techniques using sound in audible or in ultrasonic frequency ranges, stress waves, heat wave and X- ray have been investigated, where the changes in the physical properties expressed in the wave form were related to decay. The change in the velocity, the attenuation or the frequency spectrum of these physical energy waves can be associated with the decrease of the specific gravity or the structural change due to decay. Some mechanical properties such as the boring resistance and the elastic properties of wood surface could be an indicator of decay. The dielectric property of wood and its relation to decay is also useful. Miller et al. (1989) applied a radar technique to diagnosing of standing trees. However the techniques previously developed are not always feasible. One of the possible reasons is that these physical or mechanical properties change not only on decay but also on other factors, such as the water content or the grain direction in wood. In addition, sometimes the techniques are less practical, strictly not non- destructive or too expensive. In practical maintenance operation of wooden constructions, visual inspection together with sampling method plays an important roll, however a specialized training is needed for the operator to get the skill of the diagnosing. In this study, to establish a practical evaluation method of bio- degradation in wooden construction, scanning using a newly developed portable radar apparatus was investigated. By comparing the results with other methods, a more practical method to evaluate the bio-degradation in wood was proposed.
Y Fujii, Y Komatsu, Y Yanase, S Okumura, Y Imamura, M Tarumi, H Takiuchi, A Inai
Alternatives to CCA-treated Pinus radiata as vineyard posts
2004 - IRG/WP 04-50212
An estimated 10 million trellis posts per year are used in Australian vineyards and about 75% of these are CCA-treated Pinus radiata. CCA-treated Pinus radiata posts are brittle and at times in short supply. Use of some products containing CCA is being restricted in Australia. Recently, plantation forestry has expanded rapidly for disposal of industrial and irrigation wastewater. Thinnings from these plantations are used as firewood, mulch or simply dumped. Thinnings could be treated and used as vineyard posts. Consequently, our research was conducted to investigate the alternatives to CCA and the suitability of plantation thinnings as vineyard posts. Results have shown a moderate, but not statistically significant, difference in bending strength between CCA and ACQ-treated debarked Pinus radiata posts, in favour of CCA. On average there was no significant difference in bending strength between PEC and ACQ-treated debarked posts of hardwood species (P = 0.54), although two species showed borderline significant differences in favour of ACQ. However, some hardwood species treated with ACQ had more posts rejected due to splitting compared with the same species treated with PEC. No ACQ or CCA-treated Pinus radiata posts were rejected because of splitting.
M Mollah, J Smith, K McCarthy, L J Cookson
Examination of power poles by computerized tomography
1980 - IRG/WP 2142
The technique known as computed axial tomography (CAT or CT) has become widely known because of the success it has achieved in medical imaging and diagnostics. It has now been used to give non-destructive crosssectional pictures of a variety of industrial objects, including wooden power poles, with a spatial resolution of about 1 mm (0.04 in.). It is obvious the benefits that would be derived from being able to locate and determine the location and extent of knots, surface checks, internal cracks or rot and penetration of preservative. The internal density and possibly straightness of grain may also be assessed.
J A Taylor, I L Morgan, H Ellinger
Evaluation effect of kiln schedule on Warp, Twist, Bow and surface checks in Poplar Wood
2011 - IRG/WP 11-40565
In this research, to establish a kiln-drying schedule for poplar (Populus nigra) lumber with 75 mm thickness that cut down from North Khorasan province in Iran, with three schedules T5-D2 (Forest Product Laboratory), T5-D3 and T8-D5 were adapted for drying the lumbers down to the final moisture content of 8±2%. primary dry bulb temperature each three schedules was adjusted at 49,49 and 54°C and the final dry bulb temperatures was adjusted at 71,60 and 82°C respectively. Quantity of defects including warp and surface checks of the lumber were measured before and after the drying process in each stage. In order to analysis the lumber defects for estimating the best schedule, quality control graphs were used. Results of investigation indicated that drying of poplar lumber by using of the three schedules was desired. However the first schedule (T5-D2) had better drying characteristics than the other schedules.
M. Akhtari, M.Arefkhani
Acceptance levels of surface disfigurement - tolerance to defects of coated wood
2015 - IRG/WP 15-20564
Service life planning (PSL) has become an important issue in performance based building and substantial progress has been made in recent years. The role of predicting the aesthetical service life of wooden building components has been underestimated for quite long time but is recently attracting more and more notice. It is influenced by numerous factors such as discoloration, fading, flaking, cracking, and in extreme deformation due to interior rot. However, still the acceptance of such superficial disfigurement is subjected to the subjective sensation of consumers and end-users. This study aimed on evaluating different ‘technically defined’ limit states of weathered coated wood surfaces with respect to the acceptance of users. Therefore different groups of users were addressed in the frame of a survey as well as two different commodity groups were looked at separately, i.e. wooden window joinery and claddings. A remarkably high percentage of respondents ranked color and gloss related deficiencies as high as technical defects of the coating and recommended maintenance measures even when the coating was still fully intact. Technical characteristics such as the formation of cracks and flaking need to be considered separately from optical and aesthetical parameters for the definition of acceptance levels of coating disfigurements and defects. Limit states need to get defined specifically for different building components since acceptance varied significantly as shown exemplarily in this study between windows and cladding boards. For service life planning the overruling role of the subjective sensation of the user necessitates careful consideration.
C Brischke, P Kaudewitz