Manual Sanding Research Articles

Hazards and Health Risks Encountered by Manual Sand Dredgers from Udupi, India: A Cross-sectional Study.

Globalization and urbanization have resulted in an increased demand on sand dredging. Legal and environmental restrictions on automated dredging have led to a rise in manual technique. The working techniques and environment involved in manual sand dredging may expose the workers to multiple work related disorders. To determine the health risks and occupational hazards involved in manual sand dredging. An assessment schedule was developed and content was validated by five experts for the study. A cross-sectional study was then conducted using this assessment schedule. Thirty manual sand dredgers were recruited from three randomly selected docks on Swarna riverbed in Udupi district, Karnataka, India. A detailed work and worksite assessments were conducted using systematic observation and close-ended questions. Work-related health risk evaluation included onsite-evaluation and self-reported health complains. The prevalence of musculoskeletal pain and discomfort was 93.34% with lower back (70%), shoulder (56.7%) and neck (46.7%) involvements being most common regions. Prevalence of sensory deficits at multiple site and ear pain was 66.6% and 76.6% respectively. All the workers recruited, complained of dermatological and ophthalmic involvements. Also, lack of health and safety measures like personal protective devices and security schemes were identified. This study shows a high prevalence of multiple work-related disorders and hazards involved in manual sand dredging, a highly demanding job in coastal Karnataka. Lack of health and safety measures were also identified.

Avaliação da Superfície de Lâminas Decorativas de Curupixá (Micropholis venulosa Mart. Eichler)

RESUMO O objetivo do trabalho foi avaliar a rugosidade e a molhabilidade da superfície de lâminas de madeira de curupixá (Micropholis venulosa) antes e após o processo de lixamento manual e aplicação de seladora. A rugosidade foi estimada usando-se um rugosímetro; para avaliar a molhabilidade utilizou-se um goniômetro. A rugosidade das lâminas submetidas a lixas de diferentes números de grão abrasivo (180 e 240) diferiu em relação àquelas não lixadas. No entanto, a rugosidade das lâminas lixadas com números de grão abrasivo 180 e 240 não apresentaram diferença significativa entre si, mesmo após a aplicação da seladora. Quanto ao ângulo de contato, o menor valor foi encontrado para as lâminas lixadas com o número de grão abrasivo 240 após a aplicação de seladora. Assim, a aplicação de lixa combinada com produto de acabamento melhora a qualidade de superfície das lâminas, implicando em melhor qualidade do produto acabado.

Hydrocarbon volume optimization using improved net-to-gross estimates through core-log calibration of the “Akar field,” Niger Delta

Net to gross (NTG) is an important parameter in evaluating the volumes of hydrocarbon in place (VHIP) in reservoirs, and proper evaluation of this parameter will lead to significant accuracy in the estimated reserves. The use of conventional petrophysical log evaluations often does not provide sufficient resolution for net sand analysis of reservoirs, especially in laminated reservoir rocks. The uncertainties associated with log-derived net-to-gross estimates arise from the petrophysical shale volume (Vsh) cutoffs used in deriving the net sand count over a reservoir interval. One way of improving the net-to-gross estimates is by using a model that calibrates log-derived net to gross to a core equivalent, which is the more accurate representation of net sand counts. In this study, a model for calibrating log-derived net to gross to a core equivalent based on genetic units and facies associations of reservoir rocks in three wells (wells 7, 36, and K008) was established. Ultraviolet core photographs show a good contrast between hydrocarbon-stained sandstones and shales, and combining it with white light-slabbed core images facilitated a manual net sand count of the core photographs on a bed-by-bed basis. Petrophysical shale volume (Vsh) cutoff derived from two volumes of shale indicators was applied to generate net sand counts, which were used to get log-derived net-to-gross values. Then, the net to gross from core images and petrophysical clay volume (Vsh) analysis were compared by facies associations, and this comparison yielded a reliable core-calibrated net-to-gross model, which reduces the uncertainties in net-to-gross values estimated from Vsh cutoffs. The results show that for the distributary channel sands, net to gross derived using Vsh cutoff results in an underestimation of net to gross by about 6–10 % when compared with the core-calibrated net to gross, while for the upper shoreface units, Vsh cutoff overestimates net to gross by about 7–10 % when compared to its core-calibrated equivalent.

Efficiency of Sanding Belts for Beech and Oak Sanding

The effects of wear on the performance of sanding belts were determined for European beech (Fagus sylvatica L.) and English oak (Quercus robur). These measurements are presented as a function of the defined sanding time of 480 min on a manual sanding belt machine. Sanding belt pressure on the piece surface (6600, 10400, 14700, and 18600 Pa), sanding direction (cutting speed vector with reference to wood fibers equal to 0°, 60° and 90°), wood hydrothermal treatment, and sanding belts from various manufacturers were the variables. The sanding belt wear was monitored by means of specific wood removal rate (g/cm2.min) in 20-min intervals by the means of reference samples with size of 50 x 50 x 50 mm, which were sanded for 1 min. The resulting curves for the sanding belts, as well as the statistical models of the wood removal rate, decreased as a function of the sanding time, described by the function y = a + b.e-ct. This work also describes the impact of wood species, optimum pressure, and grinding time on the characteristics to abrasion.

Estimation and Analysis of Sanding Length in Brush Sanding Specially Shaped Wood Products

Abstract Sanding is an important process in furniture production. Components with unconventional shapes are usually sanded by hand rather than by machine because heavy sanding makes machine sanding more difficult. However, manual sanding is inefficient and costly. Thus, a machine capable of sanding unconventionally shaped surfaces is needed. In this study, we defined the cumulative sanding length L of a brush sander and built a numerical simulation model of L to analyze the problem of heavy sanding during surface brush sanding of specially shaped wood products. Based on our analysis of the motion and sanding process of a sander roller, we propose that the sanding strip should be bent when sanding flat surfaces and straight when sanding bulging surfaces. We also analyzed the effects of specific sanding parameters and the causes of heavy sanding. This research shows the following results: L increases with increasing theoretical contact length, the radius and rotational speed of the sander roller are proportional to L, feed rate is inversely proportional to L, and the L of a bulging point is 7.5 times greater than that of a flat surface. This difference is the main cause of heavy sanding, which is, in turn, mainly caused by different sanding strip patterns used when various parts of the component are sanded. This study provides a theoretical basis for using surface brush sanding for specially shaped wood products.

Advanced Desander Removes Solids Without Deferring Well Production

Technology Update As oil and gas fields mature, production of sand and other reservoir solids can become an increasing and sometimes major impediment to hydrocarbon production and facility operations. These solids can move through the wellbore into process facilities, causing flow assurance problems that affect system integrity, export line transportation, cleaning, and disposal. As operators seek to optimize production from mature assets, solids management is likely to take on additional importance. Sand and solids production can also be a problem on some new wells. To address these issues, Stork Technical Services developed an advanced online desander (AOD) for managing separator solids, providing thermographic determination of sand accumulation, and enabling clean sand discharge to the sea, with no deferred production (Fig. 1). The system has been used successfully in eight deployments on the Hummingbird floating production, storage, and offloading system (FPSO), which supports Centrica’s Chestnut field, operated by Wood Group, in the United Kingdom North Sea. Risks of Sand in Production Vessels The presence of sand in production vessels reduces capacity and affects separation performance, which leads to deteriorating produced water quality and the carry-over of water in the oil phase. If not controlled, the sand can cause a separator to be taken offline and manually cleaned. This exposes facility crew members to process hazards and may damage downstream equipment. Conventional sand management techniques require a shutdown of 10 to 14 days for manual sand removal, resulting in a significant delay and additional expense. Following this, oil-on-sand discharge rules may limit disposal options and compel storage of some or all of the sand. The Online Desanding Technology The desander is designed to allow more operator uptime and to reduce costs, compared with traditional vessel entry cleanout methods. With the new technology, there is no need to shut down production, and the elimination of manual cleaning improves safety. In addition, the technology enables operators to change their approach to planned shutdown periods. Because the system allows a high degree of cleaning to take place before shutdown, the team of technical experts needed for a shutdown can be smaller and planning for it simpler. The system comprises a number of purpose-designed, integrated components including solids extraction, solids separation, and solids conditioning packages. A high-flow jetting unit with a recovered-liquid package recycles the separator water. The system complies with European Union hazardous area safety requirements and can be used in Zone 2 hazardous offshore environments.

Characterization and Control of Airborne Particles Emitted During Production of Epoxy/Carbon Nanotube Nanocomposites

This work characterized airborne particles generated from the weighing of bulk, multiwall carbon nanotubes (CNTs) and the manual sanding of epoxy test samples reinforced with CNTs. It also evaluated the effectiveness of three local exhaust ventilation (LEV) conditions (no LEV, custom fume hood, and biosafety cabinet) for control of particles generated during sanding of CNT-epoxy nanocomposites. Particle number and respirable mass concentrations were measured using an optical particle counter (OPC) and a condensation particle counter (CPC), and particle morphology was assessed by transmission electron microscopy. The ratios of the geometric mean (GM) concentrations measured during the process to that measured in the background (P/B ratios) were used as indices of the impact of the process and the LEVs on observed concentrations. Processing CNT-epoxy nanocomposites materials released respirable size airborne particles (P/B ratio: weighing = 1.79; sanding = 5.90) but generally no nanoparticles (P/B ratio ∼1). The particles generated during sanding were predominantly micron sized with protruding CNTs and very different from bulk CNTs that tended to remain in large (>1 μm) tangled clusters. Respirable mass concentrations in the operator's breathing zone were lower when sanding was performed in the biological safety cabinet (GM = 0.20 μg/m3 compared with those with no LEV (GM = 2.68 μg/m3 or those when sanding was performed inside the fume hood (GM = 21.4 μg/m3; p-value < 0.0001). The poor performance of the custom fume hood used in this study may have been exacerbated by its lack of a front sash and rear baffles and its low face velocity (0.39 m/sec).

Residential and Commercial Painters' Exposure to Lead during Surface Preparation

The California Painters Project was a 2-year intervention research project aimed at preventing lead poisoning among a group of residential and commercial painters in San Francisco, Calif. As part of this project 12 contractors invited project staff to conduct employee exposure monitoring. Twenty-five full-shift samples were collected, with 8-hr TWA results ranging from 0.8 to 550 microg/m3 (arithmetic mean: 57 microg/m3). Six of the 25 samples (24%) were above the Occupational Safety and Health Administration (OSHA) permissible exposure limit; all of these involved dry manual sanding or uncontrolled power sanding. Fifty-eight 30-minute task-specific samples also were collected. The arithmetic mean concentration results for heat gun use, wet sanding, and open flame burning were all under 10 microg/m3; the mean concentration for HEPA-exhausted power sanding was 33 microg/m3; dry manual scraping, 71 microg/m3; dry manual sanding, 420 microg/m3; and uncontrolled power sanding, 580 microg/m3. Analysis and modeling based on the 30-min results for dry manual sanding and uncontrolled power sanding indicate that painters' full-shift exposures often exceed 500 microg/m3 and the OSHA assigned level of protection for a half-mask air-purifying respirator. These results are cause for concern because both of these surface preparation methods are widely performed wearing half-mask respirators. The data show that HEPA-exhausted power sanding reduces paint dust exposure levels by approximately 80 to 90%. These tools should be more widely promoted as a safer alternative work method.