«FICHA TÉCNICA Título Segurança e Higiene Ocupacionais - SHO 2012 - Livro de Resumos Autores/Editores Arezes, P., Baptista, J.S., Barroso, M.P., ...»
Uncertainty exists where the all possible consequences of an event are unknown, the probability of either the hazards and/or their associated consequences are uncertain, or both the consequences and the probabilities are unknown (Holton, 2004; Kaliprasad, 2006; Cleden, 2009). To move from an uncertain situation, there is a need to improve the level of knowledge about the hazard situations, their probabilities and possible impacts; this process is referred as risk assessment. The result of risk assessment is used to provide information to aid decision making on the need to introduce risk reduction measures.
In spite of abundant number of tools, techniques and methodologies to apply risk management, there are still some difficulties to address uncertainties associated with decision making during different phases of a project life cycle.
Furthermore, in most decision making models, there isn't a clear distinguish between the key components of risk management process e.g. risk, uncertainty, hazard, and feeling threat. This study is an attempt to present and evaluate an efficient model to provide an appropriate decision making approach under the uncertain situation.
2. RESEARCH METHODOLOGY
Reviewing the relevant literatures including basic concepts of risk and uncertainty, risk management processes, hazard identification and risk assessment techniques, including academic journals, articles and books.
Presenting an uncertainty decision making model to provide an appropriate decision making approach and establish an effective risk management process Applying the presented decision making model to risk and uncertainties associated with an Oil Field Development Project and evaluating its effectiveness These steps enable the researcher to evaluate the effectiveness of the presented uncertainty decision making model in the real case study and find out its weaknesses and strengths.
2.1 The Uncertainty Decision Making Model The uncertainty decision making model defines the hazard and risk clearly and shows the relation between variables, hazard, feeling of threat, uncertainty situation and risk assessment process trough the decision making situation. At the first stage of decision making process all related variables which affect the defined goals should be identified (e.g.
technological, environmental, political, and economical variables). These variables in general could cause potentials for failures (hazard situations) such as loss of capital investment, reputation, productivity, assets, human life, environmental pollution, etc. The hazard situation could in turn results in a feeling of threat and an urgency to act against an uncontrollable and uncertain situation by finding some alternatives and try to make proper decisions.
The lack of knowledge about the alternatives causes the decision makers to face an uncertain situation. To move from an uncertain situation, there is a need to improve the level of knowledge about the alternatives by quantification of uncertainties. In order to quantify the uncertainties, each alternative should be evaluated by estimating the relevant risk probabilities and consequences, calculating risk and comparing weakness and strengths of different alternatives, this process is referred as risk assessment. The result of risk assessment is feedback to the decision maker as a decision support to choose the best option among the all alternatives.
2.2 The Case Study An oil field development plant is selected as a case study to apply the presented model and assess related risks and uncertainties during the basic design phase of the project in order to demonstrate the efficiency of the model. This case study was selected due to importance of oil field development plants after oil and gas extraction from the reservoir. For more explanation, these types of plants play a great role in crude preparation and relevant preliminary treatments prior to transmission to refineries.
Occupational Safety and HygieneInternational Symposium on
3. RESULTS AND DISCUSSIONThe presented decision making model is applied in the case study to evaluate the effectiveness of the model. The main goal is to design an oil field development plant in a safe and environmental friendly manner that can be safely operated and minimize the costs of failure as well as maintenance. Therefore safety consideration shall be coupled with any decision made over the period of plant design. The cause and effect diagram is developed to identify all key variables which may cause hazardous scenario of fire, explosion, and toxic material release. Three major categories are identified as the major causes of hazard situation in the oilfield development plant which are technical causes, organizational causes, and political issues. The main reasons for technical causes based on reviewing the accidents in process industry are, piping system failure, contaminations, material selection, corrosion, and heat transfer. The organizational failures are happened by poor human performance in managerial level or operator’s level and also poor knowledge sharing.
Moreover, main oilfields are located in unstable political areas like Middle East, Africa, and Latin America. So, this industry is very sensitive to geo-political events in hydrocarbon producing areas. Unstable political situation and sanctions affects the safety of process plants by imposing limitations on supply of required materials and facilities, selection of vendors, and avoiding foreign licensor’s to be companies’ joint ventures.
This hazard situation in turn results in feeling of threat to act against an uncontrollable and uncertain situation.
Consequently, identification of hazards is essential at the early stage of design for assessing the safety level. Not all hazard identification methods are suitable for all phases of project life cycle. The appropriate method for each stage of project will differ in respect to the available information as well as the level of detail that decision makers need. In respect to the available information and documents at the basic design stage of the investigated case study, HAZOP study had been carried out at final stage of basic design phase to identify hazardous scenarios. Between the identified scenarios
based on the HAZOP study, the following hazard scenarios had been selected for further analysis and risk assessment:
Scenario I: Fire/Explosion due to leakage of gas and crude oil as a result of damage to 1 st stage separator Scenario II: Loss of hydrocarbon due to rupture of flow line Scenario III: Rupture of production tube due to High pressure on upstream of well These scenarios are chosen between other identified scenarios due to their high likelihood or their major consequences.
Once the hazard scenarios are identified based on the HAZOP study; the fault tree analysis is developed for each hazard scenario in order to estimate the probability of undesirable scenarios. The consequence analysis for each investigated scenario should be developed to estimate the impact of the hazards on health, safety, environmental, and economical consequences. In this study the qualitative consequence analysis is developed to estimate the impact of hazard scenarios.
According to the estimated number in probability estimation and consequence estimation, the risk level is developed based on the semi-quantitative risk ranking matrix.
The result of risk evaluation shows risk level of scenario I & III are at unacceptable risk level, and Scenario II is acceptable but is required more investigation to reduce the level of risk to the tolerable level. The management team should develop required modification to reduce the risk level either by decreasing the probability or consequences.
Furthermore, there are some uncertainties due to different variables (technical, organizational, and political) which may affect the risk level considerably. The required considerations and appropriate actions to reduce or mitigate the associated uncertainties due to the key variables are explained in the main text in detail for each hazard scenario.
4. CONCLUSIONS The implementation of this model in the selected case study proves that the model has the ability to support decision makers and managers to take an appropriate action by addressing the key variables which may cause potential for failures (hazard situation). The success of this model is associated with addressing all key variables related to the defined goals or unwanted event. The process of variable identification should be performed by expert’s backgrounds and knowledge along with developing a systematic method. Some methods such as, checklists, fishbone diagrams, brainstorming sessions can be applied to identify all key variables properly. On the other side, the management intention and openness to the expert’s judgments and analysis is vital to consider all related variables during the decision making process.
The novel aspect of this model is that, all key components of risk management process are addressed clearly. Typically, in most decision making models, there isn't a clear distinguish between risk and hazard. But this model define the hazard and risk clearly and shows the relation between hazard, feeling of threat, and risk assessment process trough the decision making situation. Additionally, the presented model is general and could be applied to all types of decision making processes under uncertainty situation.
5. REFERENCES Sutton, I. (2010). Process Risk and Reliability Management- Operational Integrity Management (1th ed.). Elsevier Science Ltd.
Holton, G.A., (2004). Perspectives: Defining Risk. Financial Analysts Journal, Vol. 60, No. 6, pp. 19-25, November/December 2004 Kaliprasad, M., CCE., (2006). Proactive Risk Management. Cost Engineering, Vol. 48/No. 12 Dec, 2006 Cleden, D., (2009). Managing Project Uncertainty. Aldershot, Hants, England; Burlington, VT: Ashgate, c2009.
Ergonomia na construção civil Ergonomics in construction Bolonha, Tiagoa; Almeida, João b; Figueiredo, João P.b; Ferreira, Anab a Licenciado em Saúde Ambiental, firstname.lastname@example.org; b Escola Superior de Tecnologia da Saúde de Coimbra, Rua 5 de Outubro, Apartado 7006, 3040-854 Coimbra. Portugal, email@example.com
1. INTRODUÇÃO A Construção Civil (CC) apresenta actualmente um elevado índice de emprego nacional (69%, em Maio de 2011), representando um papel de relativa importância social e económica para o país (1)(2). A mão-de-obra na construção apresenta-se mediante um conjunto diversificado de especialidades (pedreiros, ladrilhadores, estucadores, pintores, carpinteiros, etc), provenientes quer de zonas rurais quer de zonas urbanas estando sujeita a situações de trabalho diversas (2) (4). O processo produtivo de uma obra de CC é realizado ao ar livre, expondo os trabalhadores aos diversos efeitos temporais. O trabalho é na sua grande percentagem efectuado manualmente, conferindo ao trabalhador esforços físicos de cariz elevado (4). No desenvolver das suas actividades os trabalhadores adoptam posturas incorrectas, movimentos repetitivos, manipulam cargas de peso e dimensão elevados, factores que proporcionam a curto ou longo prazo problemas sérios para a saúde, em sinergia com o ruído a que estão expostos provenientes da utilização de muitas das máquinas e equipamentos, como por exemplo as betoneiras, martelos eléctricos, máquinas de reboco projectado, rebarbadoras e berbequins (5).
A introdução da ergonomia como ferramenta de estudos visando a melhoria da qualidade de serviços na CC torna-se num grande desafio. A dificuldade da aplicação de resultados, face à diversidade de tarefas e a precariedade e improvisação encontradas dentro do ambiente de trabalho proporcionam um conjunto de barreiras que dificultam o desenvolvimento de ideias e planos para o alcance na qualidade de serviços e produtos (6).
Dentro da CC, diversos motivos somam-se para proporcionar o aparecimento de lesões no sistema músculo-esquelético (SME) (5). Deste modo, objectivou-se, com este estudo, identificar/avaliar os riscos ergonómicos associados a posturas de trabalho e movimentação manual de cargas (MMC) num conjunto de actividades envolvidas no processo construtivo de uma obra e verificar a aplicabilidade do método de análise ergonómica RULA e OWAS neste sector de actividade.
2. MATERIAL E MÉTODOS De todo o conjunto de empresas de CC existentes em Portugal Continental, foram estudadas como população-alvo as empresas da região centro do país, com recurso à técnica de amostragem não probabilística. O tipo de amostragem foi por conveniência, tendo sido estudados 11 estaleiros, para uma composição da amostra constituída por 44 trabalhadores. O estudo aplicado foi de nível II, do tipo descritivo-correlacional. Quanto à sua natureza o estudo foi prospectivo. A natureza do estudo consiste na identificação dos riscos ergonómicos a que os trabalhadores da CC estão expostos durante as várias fases de execução de uma obra. Com a finalidade de abranger todas essas fases, foram efectuadas um conjunto de avaliações em diversas actividades, nomeadamente o ladrilho, a cofragem, a utilização de martelo eléctrico, o reboco projectado, a alvenaria e a movimentação manual de cargas.
Para proceder à recolha de dados, utilizou-se um questionário semi-estruturado que se centrou numa descrição dos trabalhadores, nomeadamente dados antropométricos, idade, profissão, anos de experiência na CC, formação sobre MMC, queixas a nível músculo-esquelético, ocorrência de acidentes de trabalho (AT) e ainda a percepção dos trabalhadores a respeito das actividades mais dolorosas. Após a recolha de dados referente aos trabalhadores, foi retida toda a informação pertinente, com recurso a fotos e filmagens, check-list elaborada com base nos métodos Ovako Working Analysis System (OWAS) e Rapid Upper Limb Assessment (RULA).
Após a colheita de dados, os mesmos foram trabalhados no software Ergolândia 3.0 e no software estatístico SPSS 17.0.