Who is rdx

The second node node 2 connects nitration vessels 2 and 3. For this node, the parameters flow, temperature and reaction were analyzed. Table 6 is the result of the HazOp for this node. The pressure switch was not evaluated since its variation results from changing other parameters, making its analysis therefore redundant.

Possible variations in the mass flow were analyzed using keywords "none" and "less". All of them are related to errors in hexamine dosing and possible flaws in this operation. In order to minimize the occurrence of this event, implementing automatic control in this equipment is suggested. Regarding the parameter "flow", there is also the possibility of potential physical damage to the pipes, occurring in the guidewords "none" and "less".

In these cases, the implementation of a program of preventative maintenance or replacement of the pipelines, when necessary, is recommended.

In the case of increased flow "more flow" , venting the equipment in order to prevent overpressure and the consequent risk of explosion is recommended. For this, it is necessary to empty the tank. Draining is possible through bottom discharge valves. Variation in flow is identifiable by checking discharge into the emergency vessel, which may interrupt the chemical reaction.

This tank is connected to the output of all the reactors nitration vessel and boilers. When the temperature increases above the set points which are established from the safety limits of the reactions , the control system interrupts the supply of compressed air to the bottom valve, opening it the valve fails in the open position. In case of safety valve opening, the vessel contents flow into the dump tank emergency.

The tank normally is partly filled with water at room temperature. This water dilutes the acid and equalizes the temperature, thus stopping the reaction and preventing an explosion. The precautionary measure is to decrease or increase the flow of coolant brine according to the temperature increase or decrease, respectively. A final consideration is that, due to the nature of the reaction, a thermal explosion is very unlikely to occur, since the increase of flow would increase the rate in which NOx is released, creating an overpressure before a thermal explosion.

Analyzing the parameter "reaction", is relevant because the nitration step is essential for RDX production. In relation to this parameter, one identifies the possibility of occurrence of the following deviations: none, less and more. The suggested remedial measure is to regulate the flow into the tank for discharge in emergency depending on the nature of the deviation via regulating valves already existing.

The third node node 3 is located between the hexamine feeder and boiler 1. An analysis was made for flow, temperature and reaction. Table 7 is the result of the HazOp for this node. This process completes the conversion of hexamine into RDX. Nitrogen oxide gases are formed as by-products. These are released to another vessel to prevent encapsulation within the crystals of RDX in the form of acids.

Boiling safely completes the conversion of hexamine into RDX. Boiling also releases the nitrogen oxide gases. Decrease of flow is related to obstruction or crushing of the supply line. The reaction parameter may be increased or decreased depending on the increase or decrease of flow equipment.

As a solution to the differences observed in this node, it is suggested to carry out regular maintenance to prevent the clogging of pipelines and of feeder for hexamine, which is replaced when necessary.

Another measure is that it is necessary to interrupt the operation in case of overflow. Deviations in temperature are directly related to flow. Identification of these deviations can occur by inspection and by instruments thermal sensors. The main consequence of temperature deviations is decrease of yield and interruption of the manufacturing process. Over-temperature increases pressure in vessels and reaction rate. Control valves and exhaust valves are required.

The control valves operate integrated to sensors that measure temperature in the reactor and provide this information to a controller, which operates the valves to match set points. This safety system, if well stabilized, prevents any deviation in temperature.

Furthermore, as part of redundancy due to the explosive nature of the mix, as the temperature rises in this node, the control system enters a "state of alert". Dilution by water lowers the temperature, dilutes the acid thereby interrupting the reaction, and eliminates the risk of explosion. Reaction time may differ slightly due to variation in feeding hexamine and hence to temperature change in equipment boilers.

There is also a risk of losing the batch in an accidental fire. The forth node node 4 extends between the two boilers. Analyzed parameters are "flow", "pressure", and "temperature". Table 8 is the result of the HazOp for this node.

The reaction parameter was not considered here because there are no chemical processes before or after this node. Regarding interruption or flow reduction, there is the possibility of obstruction in the piping. To solve this problem it is suggested to implement maintenance programs and piping repair and replacement, as necessary. Deviations for flow can be identified by the presence of material in the emergency dump vessel.

In this situation, the risks involved and response mechanism are analogous to those in node 2. Pressure changes according to the flow from boiler 1 regarding the keywords "none," "less", and "more".

These keywords lead to variation in the flow of cold water feed water. To address this situation, one can establish a maintenance program for the boilers and install a pressure gauge for the control parameter.

The temperature node 4 may increase or decrease, depending upon the decrease or increase in the pressure in boiler 1 or variations in the flow of wastewater, respectively.

Temperature effects can be controlled with the implementation of instruments and a command and control system. The fifth node node 5 is positioned between the second boiler and the second heat exchanger.

Analysis of this node considers "flow", "pressure" and "temperature". Table 9 is the result of the HazOp for this node. Like node 4, there is no need to address the reaction parameter. No reaction occurs at this node. Flow interruption or reduction is due to obstruction in the piping, as well as the causes listed for flow increase.

Dosing accurately the hexamine can mitigate both deviations. Pressure at node 5 varies due to gas leakage. This is a case of pressure reduction, which may be caused by an increase in the generation of nitrogen oxide gases, as well as a decrease in the capability of releasing pressure.

Thus, there must be a pressure gauge at this point, and a pressure relief valve and enabling the discharge of nitrogen oxide gases. The increase or decrease in temperature at this point node 5 is related to decreased pressure or reduced inflow of cold water in the heat exchanger, as well as an increase in the pressure and inflow of cold water in the heat exchanger, respectively. These variations relates to the variation in the return flow of cooling water feed, as well as the flow of coolant water.

The consequences of temperature increase at this point node 5 do not generate events with potential major accidents or explosions, but can produce burns in the case of leakage. Inspection routines or changing the system for the return flow of chilled water and cold water feed will control temperature deviations.

The sixth node node 6 is located between the heat exchanger and vacuum filters. To study this node, the recommended parameters are "flow" and "temperature", since there is no chemical reaction near this node. It remains at atmospheric pressure. Table 10 is the result of the HazOp for this node. The consequence of these deviations is the changing of the load on the vacuum filter increase, decrease or lack of flow.

Correction of deviations to flow requires installation of a flow control valve between equipment, periodic maintenance and a flow meter in the piping.

Maintenance is a critical aspect for this node as well as the previous nodes. Further analysis of deviation in temperature at node 6 indicates that it relates to changes in the flow of cold water. Installing equipment for monitoring as well as for cooling or heating the product to be filtered can control these deviations. The seventh node node 7 is located between the vacuum filters and the output of RDX.

Flow is the only relevant parameter here since there is no chemical reaction and the flux between filters connection and product exit occurs in atmospheric pressure. Table 11 is the result of the HazOp for this node. The parameter, "flow", indicates the failure of production in previous equipment, which is critical in this node.

In order to identify the causes of deviation in the flow, one uses the keywords "none," "less", and "more". As a general rule, all deviation in flow relates to failure in vacuum filters clogged or damaged or obstruction of piping. Deviations for this node node 7 are observable through loss of product quality and operational variation of the exhaust system. A possible mitigation is to ensure maintenance of this equipment.

Addressing the HazOp results from a management perspective, operation of the control system around the same variables and set points is critically important.

This starting point provides the means to observe and address all possible and sometimes expected deviations. This integrated unit could be a PLC panel that monitors and controls all parameters relevant to the operation temperature, pressure and flow rates. In the RDX manufacturing unit, these valves should be installed along the pipeline to ensure safety. A possible suggestion for improvement of in-service units is to modernize the existing control panel to ensure the most accurate levels of control.

However, this intervention would require readjustment of the major part of the unit, making this option costly and sometimes financially unviable. During the study, some safety bypasses were plotted, but neglected for HazOp purposes. Usually a bypass is located in stretches of critical piping and valves between departure and arrival of fluids. These safety devices ensure operational continuity of flow since they provide an alternate path for process fluids.

They are, therefore, vital to solving the identified deviations in the parameter, "flow". This statement allows one to conclude that design engineers addressed the same issues discussed in this paper. Data loggers found in most RDX units offer redundant storage of measurements in addition to storage devices present in the control panel.

In the storage vessels, one solution to the problem of deviations in the flow is an emergency discharge system. In the first node, for example, in case of failure there is the alternative of pumping fluid into the HNO 3 vessel. Furthermore, from the analysis of the design of an RDX manufacturing unit, one should conclude that some equipment provides redundancy, most likely for predicting the occurrence of failures as discussed in this paper.

Action taken as a result of this analysis ensures, in some cases, the continuity of the process and in others, safe termination. Since many of the control measures suggested in response to the possible consequences listed in this study are already present in most RDX plants, there is the logical assumption that a HazOp-type study has occurred prior to project implementation.

However, absence of documentation of such studies in the open literature increases the relevance of this paper.

RDX manufacturing plants usually contain pneumatically controlled and powered equipment. This requires a source of compressed air. The compressed air system was not addressed as part of this work. Installation of electronic sensing and control devices in RDX plants should increase accuracy and precision of operational parameters.

However, these devices will not guarantee greater reliability in the safety system. This increases safety, since any loss of energy or another deviation will cause the valve to open, thereby discharging the reacting material into the dump vessel. These communication systems allow the transmission of broadband data through the electrical grid.

Thus would be allowed to monitor the unit for any computer, provided they are properly authorized, through Internet, favoring the monitoring of security conditions. Another advantage of the system is that its implementation requires no physical alterations on site, once the grid is already in place. This paper focused on the core issues of such a manufacturing unit, since the nodes were applied only at seven points, considered critical to the overall operation.

Upon conclusion of this particular HazOp, each node provided key information that should be considered when designing or operating any RDX nitration unit.

Those key aspects are consolidated in Table Furthermore, the results show that the guidewords used for selected nodes flow, pressure, temperature and reaction and their deviations made possible a complete diagnostic of the RDX nitration unit intrinsic risks.

This approach also made possible the analysis of types of detection, consequences of failure, and steps to be taken for each deviation identified. This study also indicates that a risk assessment had occurred on the unit examined in this study previously. This is evident mainly due to existence in the flowcharts of the required mitigation measurements such as safety valves, bypasses and control instruments.

Finally, it is important to mention that HazOp methodology does not quantify risk. For this reason, other tools for risk assessment should complement HazOp. Open menu Brazil.

Journal of Aerospace Technology and Management. Open menu. Text EN Text English. Table 1 Equipment list. Table 2 List of guide words. Table 3 Deviations and parameters. Table 4 Parameter used in each node.

Table 6 Node 2 — Connection between nitration vessels. Table 7 Node 3 — Connection between the nitration vessel and the boiler. Table 8 Node 4 — Connection between boilers. Table 9 Node 5 — Connection between boiler and heat exchanger. Table 10 Node 6 — Connection between the heat exchanger and the vacuum filter. Table 12 Study contributions and final results. Akhavan, J. Aven, T. Bachmann, W. Bisarya, R.

Boonthum, N. Chouhan, T. Crawley, F. Eckerman, I. Freeman, K. Galante, E. Gehlawat, J. Graf, H. Haddad, A. Held, M. Kennedy, R. Khan, F. Kletz, T. Leach, J. Lukasavage, W.

Mei, Z. Meyer, R. Rausand, M. Rossing, N. Rouhiainen, V. Sahar, N. Seccatore, J. Shimada, Y. Steen, R. Taylor, J. Urbanski, T. Publication Dates Publication in this collection Oct-Dec History Received 09 June Accepted 26 Sept This is an Open Access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Figures 1 Tables Node Node description Key equipment Recommendations 1 Array of vessels for waste and clean water for dilute HNO 3 Water vessels Installation of control valves to assure flow management.

Implementation of level and temperature instruments. Existing RDX toxicity and carcinogenicity data are 20 years old; federal agencies are working together to generate new environmental health data. Where can I get more information?

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