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taking place within a single piece of equipment. In a Urea reactor for instance the corrosion in the top is more than in the bottom part. This reduction in liner wall thickness should not mean automatically the end of the lifetime of a reactor. An in situ relining may extend the lifetime of the reactor again for many years. To allow an optimum repair with respect to quality, timing and down time of the Urea reactor it is important to make a good game plan and preparations should already be done prior to the turn around. In the HP Heat Exchangers the liner is not the critical factor. The heat exchanger tubes are the limiting factor with respect to the lifetime of the equipment and a replacement appears to be the most economical solution.
maintenance and repairs; lower OPEX costs 4. Lower APEX
included in the Stamicarbon Specification A4-71111 for welding of Safurex® liners.
4) Stress corrosion cracking Typically vertical HPCC 5) Strain induced intergranular cracking Typically Urea Reactor 6) Stern face attack Typically HPCC & Scrubber 7) Under deposit corrosion Typically HP Stripper
lyse the accuracy and reliability of the applied inspection method. Together with the introduction of Safurex®, a modified eddy current inspection technology was developed to assess the wall thickness of HP stripper HEX-tubes. After utilizing this inspection technology for a couple a years, the reported higher passive corrosion rates of Safurex® HEX-tubes were doubted, since Safurex® outperforms BC.05 material in all laboratory corrosion tests. Proper understanding of the modified eddy current inspection technology resulted in a more reliable and accurate inspection technique. By using this optimized procedure, the corrosion rate of Safurex® HEX-tubes is currently reported in the same order of magnitude as the BC.05 ones. Still a distinct advantage of Safurex® over BC.05 HEX tubes in HP strippers is the absence of active corrosion, which makes the use of the former far more favorable .
piping), cold pilgering (for heat exchanger tubes), hot and cold rolling (for plates) and forging (for bars).During the development of the HIP-ing method for Safurex®, it also became clear that its corrosion resistance was superior to that of non HIP-ed Safurex®. This opens opportunities to use the HIP-ed material in specific applications where higher corrosion resistance is needed. In this paper the development and achievements of this production route are presented as well as the first operational experiences. HIP-ed Safurex® is patented by Sandvik and Stamicarbon.
ger time. We also deal with how both Stamicarbon and Sandvik handle Safurex, how to deal with spare material and even spare equipment.
mance. And rightfully; we must see safety as a prime concern in order to protect ourselves and our neighbors from unwanted effects from our activities. Moreover, on the long run production without accidents will be a key factor in order to obtain and maintain acceptance of our activities by the rest of the society. In order to maintain this so called ‘license to operate’ it is of importance that our production processes are safe, but also we should be able to proof that our safety procedures and standards are up to ‘world class’ level. In this respect it is important to recognize that safety standards are continuously evolving. Things that were fully acceptable 100 years ago nowadays are completely unthinkable.
d our present update “The Stamicarbon Y2K update on explosion risk in urea plants
IS). To comply with internationally recognized standards, Stamicarbon introduced the concept of SIL in its standard design urea plants. This paper focuses on the risk graph method, which is a means of quickly assessing and screening a large number of scenarios resulting in loss of containment (LOC). A limitation of the risk graph method however is that it leaves some subjective elements in assessing the consequences (severity) of LOC scenario, whereas these consequences are increasingly important in the ever increasing capacities of urea plants and equipment. To overcome this limitation Stamicarbon developed a quick reference chart covering all sections of the urea plant that allows quick and objective assessment of the severity and SIL parameters. Further, the paper highlights SIL-equivalents for safety relief valves in crystallizing media and risk reduction by means of Safety Instrumented Systems (SIS).
roducts are highly corrosive. Risks discussed in this presentation: •Explosion •Loss of mechanical integrity
duction. At the same time, we must expect that society will focus even more on safety and environmental issues associated with fertilizers, such as Health and safety risks from working in fertilizer plants Major accident risks, to avoid disasters like the explosion in Toulouse Terrorist acts, using fertilizers for bomb-making Pollution risks from the manufacturing processes and from the use of fertilizers Climate change and the role of fertilizers and agriculture Use of limited energy and mineral resources, such as phosphates The public perception of Good Citizenship has changed over the years. Today, many people look upon the chemical industry as a burden to future sustainability. This perception will deepen if the industry has a poor safety and environmental performance. It is vital to perform well and to eliminate bad practices. Otherwise we must expect that much stricter regulations will be enforced upon the industry. In this paper I will focus on the 3 first bullet points above, those that are related to safety and product stewardship, with some practical advice on actions the industry should take in order to be in command and avoiding over regulation.
actices’ give guidelines about the necessity and sizing of emergency relief systems, aiming at protection of the plant under emergency conditions. Traditionally, disposal of the ammonia containing gases from such emergency relief systems (safety valves or rupture discs) from urea plants has been done as direct discharge into the atmosphere. Recently a study was conducted by Stamicarbon to see whether this practice is acceptable from a safety point of view, taking into account progressing insight gained in the subject of emergency relief in recent years.
to use this information to take corrective action and prevent recurrences. Stamicarbon has been recording major process safety incidents in urea facilities for 48 years, but because they are on the whole so few and far between it is questionable whether they provide sufficient input to identify common causes and inadequate protective measures for them to be corrected before a serious incident actually takes place. Near misses and lower-consequence incidents are increasingly thought of as the most important indicators of major accidents; therefore, we have expanded our database of major process safety accidents to include them in the interests of improving understanding of process safety. Besides our major incident database we also consult internet news channels and fertilizer industry associations to find more incidents within urea manufacturing facilities. But it has to be acknowledged that we will only hear about major events from these sources; lower-consequence incidents are unlikely to see the light of day. So we are left with lagging indicators instead of the leading indicators that are so badly needed! Also, incident databases at customers’ individual sites contain insufficient data points to uncover common causes. This is why urea manufacturers need to work together and build an incident database from which all can benefit. To enable the urea community to learn more from near misses and low-consequence accidents, Stamicarbon is launching a process incident sharing portal service for its customers. The service will contain the following: • Stamicarbon will host the HSE platform and subscribing members can access the posted HSE information at any time, free of charge. • Subscribing members will periodically receive a report by e-mail to learn about relevant accidents and near misses and possible improvements in terms of process design and operational practices. • Customers who report an incident or near miss to Stamicarbon can receive tailored HSE support under an applicable service agreement. • The incident report and other relevant HSE information that Stamicarbon considers appropriate to share with its customers can also be downloaded from the HSE portal. The procedure for reporting incidents is as follows. • To obtain access to the HSE portal the customer will first need to register on the Stamicarbon HSE portal http://hse.stamicarbon.com . • Customers will initially provide a rough description of their process safety event by filling out a simple incident notification form, which is designed to minimize their administrative effort. • Stamicarbon’s HSE engineer will contact the issuer of the notification to find out in detail exactly what happened. Further administration will be handled by Stamicarbon.
weld overlays) are in passive state
ase and thus the efficiency of the reactor will go down. However, by changing the internals of the reactor (using a different type of trays) the efficiency in the reactor can be improved. In the past two types of trays were used in Stamicarbon Urea plants: the conventional trays and the high efficiency trays. Now a new type of trays is introduced, which improves the efficiency of the reactor and thus results in savings of the high-pressure steam consumption. These trays are called the Siphon Jet Pumps. The first trays have successfully been installed in SKW Piesteritz. In this paper the Siphon Jet Pumps are introduced and several aspects around these trays are discussed.
gas lines was again AISI316L-UG, because there were still some such tubes in stock, dating from the time the plant was constructed.The affected areas showed evidence of stress corrosion cracking (SCC), but reduction in the wall thickness was also observed. This was attributable to condensation corrosion, which is normally observed in the gas lines. It was most severe in the heat-affected zones (HAZ) near the welds. The affected elbows were subjected to metallographic examination in Brazil as well as in Stamicarbon laboratory. This paper presents the investigations carried out on the elbows and piping removed from the urea synthesis gas lines in order to find the root cause of the leakages.
ia inside the process equipment is essential from a safety,environmental andeconomica lpoint of view
tripper performance. The stripper level indication (Radioactive type) LT-1043 got erratic at our plant and we sustained plant operation without this indication by: 1. Keep the plant load constant and avoid any changes in plant load. 2. Observe the stripper outlet temperature as this temperature will change with increase or decrease of the stripper bottom level. 3. Observe the steam consumption of the stripper as the steam flow will change with a change in the liquid level. 4. Observe the N/C Ratio and keep it constant. 5. Observe the downstream section pressure at constant plant load.