When the working procedures are considered according to the works performed in general in the cement sector, working in confined spaces also has an important place. All the processes within the structures such as crushers, separators, coal and raw mills, cyclones and furnaces fall into working in confined spaces. Sometimes we need to work in confined spaces once a week, sometimes once a month, sometimes once a year, however the main issue here is not related to how often, it is to access this area rather than how often, to work in this area and whether we can perform rescue operation in case of any unwanted situation. It is critical for our risk assessment and emergency action plan to be accurate, adequate and applicable so that all these can be practiced.
The confined space can be defined by three main questions according to the OSHA (Occupational Safety & Health Administration) definition in the USA.
1- Is it large and structured enough so that an employee can physically go in and perform assigned works inside?
2- Is it limited or restricted to enter and exit?
3- Is it not designed for continuous work?
If you can reply “Yes” to all three questions, then we need to ask a last question: “Does the working space include any serious health and safety risks such as atmospheric hazards, suffocation, opening etc.?” If you also reply “Yes” to this question, then the area you work in must be called as confined space requiring permission.
Prior to work to be performed in the confined space, the risk analysis must be definitely carried out, and a drill must be made with the equipment to be used before the actual work, testing the usage and operation of the equipment to be used. For the access section, which is the second step, it is required to look at whether the area to be entered is horizontal or vertical. Accordingly, various solutions can be considered for access and rescue purposes. Plants in Turkey often keep a tripod available for an emergency case. However, it should be kept in mind that in case of an emergency, it will take time for the tripod to be brought to the incident place and set up. For this reason, it is required to set up the tripod from the moment of entry into the space before the incident occurs. Another issue is that the tripod is not suitable for any kinds of spaces. For example, in a place where horizontal entrance is made, it will not be a very accurate approach to set up a tripod. Horizontal entrances are generally encountered in structures such as cyclone and mill. Another point to consider is to have a flat surface on which the legs of tripod press so that the tripod can be evenly set up. Finally, when a fall occurs and/or a situation occurs in which the employee loses his/her consciousness and needs to be rescued, the rescuer must make a physical move to get the victim to a safe place after he/she is hoisted by means of a tripod. However, as you can see the figures below, access and rescue can be performed by means of various solutions. In case of vertical entrances such as tank inlets, 5-pieces systems (Figure 1), horizontal entrance equipment (Figure 2) which can be used in horizontal inlets, or light and mobile systems that can be used for both vertical and horizontal entrances (Figure 3, Figure 4), can be selected according to its suitability by evaluating specially for every confined s pace entrance.
It is important to choose the harness that the employee will continuously remain tied to after the anchorage points selected for access during the access inside. For example, during welding work, any hole arising from a flame, which may occur on the harness, caused by the welding sparks reduces the protection of the safety belt. Therefore, it is recommended to use products having Nomex/Kevlar material, which is suitable for welding works.
After selection of the harness and anchorage point, the crane and/or self-retractable fall arresters must be selected depending on the work space to enable the person to work safely. Periodic maintenance is also critical for 3 groups mentioned above, which are used for access to confined space and rescue. In general, the shelf life of equipment containing textile materials is 10 years, but periodic checks determine its service life. As for the mechanical products (tripod, self-retractable fall arrester, etc.), there is no problem in terms of use as long as it passes through the periodic inspection. However, the manufacturer’s instructions must also be taken into account for all of these.
Whether an atmospheric hazard is present in the area to be entered and whether an extra atmospheric hazard is further created depending on the process to be performed (cleaning, painting, welding, etc.) should also be taken into consideration. Although ventilation is performed especially in places such as furnaces and cyclones, the gas values at all levels of indoor area should be read at both the entrance level and the specific distances, before entering. Pumped gas measuring devices (Figure 5) are preferred to measure the oxygen / chemicals inside the levels, generally before entering inside. Therefore, even in depths of 5, 10 and 15 meter, it is possible to provide reliable indoor measurement. However, one of the most important points in this phase is to carry out the correct and timely calibration of the gas measuring devices and the bump tests. According to gas measurements, if there is a need for respiratory protection, negative pressure (disposable dust mask, half/full face masks) masks can be used depending on to the risks inside as well as positive pressure masks can be used according to necessity.
According to the nature and content of the work, in some cases, self-contained breathing apparatus (SCBA) (Figure 6) can be used, while in some cases, back-up system supplied air respirators (Flite-COV) connected to compressor and/or special systems (Figure 7) can also be used. If we consider the general differences between them, SCBA systems is not convenient since the oxygen cylinder at the back occupies a large area for some places especially when entering a narrow area, whereas the cylinder attached in Flite-COV is a small cylinder fixed on the leg, and it does not create spatial problem. Besides, while the SCBA provides 45 minutes of fresh air, Flite-COV does not have a time limit since it is supplied from the compressor. Another difference is that a 10 or 15 minutes of back-up system for an emergency in case of Flite-COV is an opportunity for the user to escape in any unexpected situation.
Following the gas measurements, according to the risk analyses and the nature of the work to be carried out inside, other necessary personal protective equipment should be worn, and afterwards the work must be initiated. However, one of the most common problems is to communicate with people who use respiratory mask in a confined space. Because communication is usually provided by radio, but the voice of people having a mask on their face cannot be clearly transmitted through the radio. In such cases, it is also recommended to use systems (Figures 8 & 9) that can transmit the sound clearly to the radio by means of the microphone included in the positive pressure masks, provided that each space is assessed in its own way.
In the last stage of the rescue section, it is essential to comply with the emergency action plan and to keep the rescue teams together with all their equipment. In addition to the correct equipment, risk analysis and emergency action plan in confined space works, one of the most critical points is the fact that employees and persons guarding and observing the employees in confined space must have had the necessary trainings, and the drills of products to be used with such trainings shall be practiced.
