1. INTRODUCTION

Process transfer and weighing in the areas liquid catalyst are potentially exposed to ergonomics hazards in the chemical process industries. Previous studies investigating work-related musculoskeletal disorders (MSDs) in this industry have shown that the chemical processing industry continues to develop. The Ministry of Manpower noted that the 1,075 companies based on 2015 Central Bureau of Statistics (BPS) data had increased by 97 during the previous three years. The most common health problems that lead to disabilities in Indonesia are back and neck pain. From 2006 to 2016 data from the Global Burden of Disease study (GBD) increased by 24.8% which ranked first compared to other health problems. (Silva et al., 2016). Ergonomic interventions can be carried out on suspending agents by designing and adding assistive devices such as conveyors, adjustable jacks and ergonomic working methods (Yadi et al., 2018).

Observation in the work activities involving manual material handling at the transfer station, as well as weighing liquid catalyst raw materials (Perbuthyl ND-75, Perhexyl PV-75 and Percmyl ND-75) at Company X, a material hazard to human health, namely irritation of the skin, eyes, nose and mucous membranes. Also, workers have the potential dangers of slipping due to liquid on the floor, limited workspace, cold temperatures and awkward work postures, which can increase the risk of work-related musculoskeletal disorder (WMSDs). Another study reported the most prevalent symptoms in lower back, knees, upper back, neck, and shoulders in a group of petrochemical workers (Choobineh et al., 2013).

The goal was to create an ergonomic work design in order to reduce hazards throughout the work environment, as well as to reduce the risk of work posture to prevent WMSDs from occurring at the liquid catalyst transfer and weighing workstations at chemical processing industries. Some studies revealed a correlation between poor workstation design and development of MSD (Yadi et al., 2018;Lin and Chan, 2007). Poor working conditions in the areas liquid catalyst transfer and weighing workstations warranted adequate ergonomics considerations. So, in working conditions improvement, taking risk factors, redesign tools and work method of these regions essential.

2. METHODS

2.1 Study Design

Study design to develop manual material handling tools using People, Object, Environtment, Message & Media Service (POEMS) framework, and Social, Physical, Identity, Communication and Emotional (SPICE) development. The more optimal work posture design was simulated by using CATIA software with the aim to reduce the RULA score. The assessment of the risk levels for posture and work complaints was conducted for Rapid Upper Limb Assessment (RULA) (McAtamney and Corlett, 1993). To make a work system design in the workstation, the process of removing and weighing the catalyst at Company X used design thinking stages Vianna et al., 2012).

The following are the stages of the design used in this study:

People: describes stakeholders involved in observing research and participation, their involvement with each other, and relationships between stakeholders in the process of moving and weighing in the area of liquid catalyst;

Objects: describes what artefacts exist in the research observation area, their relevance to stakeholders, and how these objects influence stakeholder relations in the process of transferring and weighing in the area of liquid catalyst;

Environment: stakeholders in the surrounding environment, and what stakeholders do in moving and weighing activities in the area of liquid catalyst;

Message & Media: describes the media used to deliver and convey information and understand the message conveyed in the process of transferring and weighing in the area of the liquid catalyst;

Services: describes services or assistance facilities located at observation sites that help carry out the transfer process and weigh in the area of the liquid catalyst.

Social: explain the things needed to build relationships with other individuals in the process of moving and weighing in the area of liquid catalysts;

Physical: describes the facilities needed to assist activities in the process of transfer and weighing in the area of liquid catalyst;

Identify: how to describes what is needed to dare to define itself in the process of moving and weighing in the area of liquid catalyst;

Communication: how to explain what information is needed by the process of transferring and weighing in the area of liquid catalyst;

Emotional: how to explain emotional and psychological needs.

2.2 Manual Appointment Activities

The following are work activities carried out at the liquid catalyst raw material station (Perbuthyl ND-75, Perhexyl PV-75 and Percmyl ND-75):

3. RESULTS

3.1 People Object Environtment Message & media Service (POEMS)

User observations and worker behaviour at the transfer station and weighing of the liquid chemical catalysts used the POEMS framework:

Figure 1 is some documentation from the observation process at the liquid chemical catalyst weighing station and transfer process.

Figure 1(a) shows the process of weighing liquid catalyst raw material, Figure 1(b) shows the process of transferring liquid catalyst raw material that has been/will be weighed, Figure 1(c) shows the manual transfer process using a manual pump.

3.2 Interview and Medical Examination Data

Most of the workers in this section convey complaints of illness due to repeated physical work activities. Tools are needed that can facilitate the transfer of liquid catalyst raw materials, there is a need to practice good and right way to lift weights. Rotations between other workstation should occur, so as not to get bored while working.

The company doctor said that most workers use assistive devices in the form of waist support straps. This tool was provided to reduce the risk of bad posture while performing the physical activity.

Information from HSE management requires training for employees in the transfer and weighing section to find the right and correct appointment method. It is essential to evaluate the tools that have been implemented.

3.3 Social Physical Identification Communication Emotional (SPICE)

In this stage, data from observation and interview are process due to determine the state of the needs of workers in the workstation of weighting and transferring liquid catalyst raw materials. Data processing through needs finding, which defines the needs of workers at the station and is analyzed based on the results of observations and interviews using SPICE. Table 1 showed processing of SPICE data.

Based on the identification of needs using SPICE, there are three needs statements obtained:

Based on the three needs statements above, we choose a statement as a reference for developing solutions. The selected needs statement is the first statement because of the impact of lifting activities and weighing liquid catalyst raw materials in the form of risk of MSDs.

3.4 Rapid Upper Limb Assessment (RULA)

Increasing work posture analysis use mannequins in CATIA software, by simulating the mannequins in the activities of pushing and pulling liquid catalyst containers, and pouring and filling the liquid catalyst into the container.

RULA method is used to assess work postures that are most at risk to workers at weighing station of chemical catalyst raw materials. RULA Score 7 for assessment work activity existing with RULA method, it means to investigate and change immediately show in Figure 2 (a), and analysis of adjusting work posture using CATIA software on redesign posture, the RULA value drops to 3 show in Figure 2 (b). That is means there is a significant reduction in the risk of awkward work postures being a safe work posture.

3.5 Integrated Ergonomics Work System Design

Such Integrated work system design is anticipated to lead to better work design, method, and work posture on how to improve injury prevention and to the development of more effective programs for people with musculoskeletal disorders.

Integrated system design takes into account the following factors: first, the replacement has been designed by replacing and modifying the manual transportation method with conveyors and trolleys, so as to minimize transportation activities, while the weighing process is done by replacing conventional weighing. The semimechanical system so that it can eliminate transportation activities in the activity of adding or reducing heavy material and accuracy is better than before. Second, a combination and adaptation, a solution that can be developed from a combination of elements and adaptation are to design a tool that will be used to facilitate the transfer of container that are used as weighing media. Trolleys are developed by modifying them so that they can be adapted to container, while semi-mechanical devices are developed to eliminate manual activity when moving catalyst fluid to the container during weighing. Third, modification, reducing the risk of MSD suffered by workers, can be done by designing work methods to improve ergonomic work posture by complementing the need for conveyor equipment and modifying the semi-mechanical weighing method. Fourth, put other uses and arrange, adjust the movement of container from starting to be moved from the storage area to the weighing place until returning to the storage area so that the process is integrated. the last, elimination, elimination of manual material transfer methods.

The design of an integrated ergonomics work system is a work station design that functions to facilitate activities on the workstation by weighing liquid catalysts. The design of this design uses several aspects that are considered in making the design of integrated work systems as follows:

3.5.1 Adjustable conveyors

The conveyor serves to facilitate the transfer of goods from the storage area to the weighing point, as well as from the weighing point to the place where the raw material is mixed in the mixing tank or to the storage area again.

3.5.2 Modification of Trolley

Trolleys serve to simplify the process of transferring liquid catalysts during weighing and/or as a means of transportation from the ground floor to the upper floors.

3.5.3 Semi-mechanical Weighing

Semi-mechanical scales function as a liquid catalyst weighing device, to move the liquid catalyst raw material in accordance with the formula needed from one container to another container.

The integrated work system design was made using the help of CATIA software so that the user profile needs could be adjusted with a safe working posture at the workstation. The design focused on transfer movement problems and weighing motions of liquid catalyst raw materials, by exploring the needs of newly designed prototypes.

Figure 3 show about existing condition on weighing and transfer workstation, and Figure 4 show about components of an integrated works system design included (a) conveyor aids, (b) trolley, and (c) semi-mechanical modifications of the equipment in the weighing process at the transfer station, and the weighing of liquid catalyst raw materials.

4. DISCUSSION

The results of the POEMS framework show the importance of identifying users and workers behaviours. The first step was to provide an overview of the scope of the work that was to be designed. Interviews with various resourceful persons reinforced the necessary improvements that will be included in the work system. One of these is related to work postures that can cause WMSDs. The work system will be able to indicate whether occupational health improves among the workers through this new system. The use of ergonomic interventions in the workplace allows for a reduction of the risk of MSDs and prevents adverse effects on health (Polajnar et al., 2010;David, 2005;Genaidy et al., 1994). From the observation process at the liquid chemical catalyst weighing station and transfer process has been identified potential MSDs of the process of weighing liquid catalyst raw material, the process of transferring liquid catalyst raw material that will be weighed, and the manual transfer process using a manual pump.

Based on structured and comprehensive design, companies need to develop efforts to prevent WMSDs by fully supporting equipment that could help ease the difficulties of physical work. Early interventions must be made to prevent fatigue and the discomfort of workers from developing into injuries. Empower workers to be more responsive to the risks of WMSDs, mainly through education and training in ergonomic working principles, to increase productivity and efficiency in the workplace. Intervention design is not only to reduce risk but also to optimize work productivity (Niven and McLeod, 2009). Prevention of WMSD is, will continue to be, one of the main challenges of working in the chemical industry plant. The contribution to addressing this challenge is to conduct further research and intervention studies so that the results can be most effective.

The results of the identification of needs according to SPICE identified many factors by workers, these can be used as information reinforcements in the analysis of the developed design. These factors are also valuable as an integrated amplifier in the system that will be develop in the design. Ergonomic is heavily involved in the design of interventions in the workplace (Kaewboonchoo et al., 2016).

An assessment of the risk level of posture as well as work-related complaints was conducted using RULA. The results of the work posture analysis demonstrated a decrease of three in the value pertaining to risk of work posture in the new design. Improving work posture is very useful in the effort to reduce instances of awkward posture. Based on the design plan that was formed, it is necessary to add auxiliary equipment to the workstation to transfer and weigh the liquid catalyst raw material in the form of conveyors, trolley modifications and semi-mechanical modifications. These modifications were based on the results of interviews, observations and other additional information about the health status of the workers. The design results should be integrated and could be beneficial for the health of the workers. Changes in working conditions must be implemented immediately to protect the workers, and installing appropriate equipment will improve the quality of the worker's lives (Sahu et al., 2013).

Integrated work system design is usually associated with the reduction ergonomic hazard, especially musculoskeletal disorders. The critical factor that identifies a health issue as being ‘ergonomic’ is that the injury arises because the way the environment and equipment are arranged requires people to adopt postures, movements, apply force and read the material, in conditions that are potentially damaging to health in order to complete what is expected of them in the normal course of their work (Niven and McLeod, 2009).

At workstations transferring and weighing liquid catalyst raw materials can be carried out by several interventions: First, technical intervention, by engineering physical hazard exposure during transfer, lifting and weighing. Second, administrative intervention, focusing on changing tasks or design work such as job rotation. Third, behavioural intervention, focusing on improving fitness or strength and improving work methods.

5. CONCLUSIONS

The need ergonomic work design at the transfer station and the weighing of liquid catalyst raw the materials, this can be achieved by increasing human resources through training, diseminating information of occupational health, and work rotation.

The design of integrated work tools at the transfer station, as well as and the weighing of liquid catalyst raw material is in the form of adding work aids: (a) conveyors, (b) trolley modifications, and (c) semi-automatic weighing mechanisms.