Urea Incident Database: Share for Safety

Authors: Jo Eijkenboom and Mark Brouwer UREAKNOWHOW.COM

 

Incidents happen in the chemical Industry. Many of these incidents do not surface but one should be aware of the fact that every incident has a learning factor and may avoid another incident in the future. UreaKnowHow.com has a Urea Incident Database in which the incidents are described and welcomes everybody to share an incident, anonymous or not in order to avoid a new incident. Sharing incidents will increase the safety of the industry.  Avoiding incidents is of key interest for all stakeholders in the industry.

History shows that organizations do not have a memory. Incidents often repeat themselves and often are not shared. UreaKnowHow.com is an internet platform facilitating communication between all urea plants worldwide with the target to improve safety and performance in the urea industry. UreaK.nowHow.com has estab­lished an Incident Database to facilitate the shar­ing of incidents.

UreaKnowHow.com’s Urea Incident Database currently contains more than 45 incidents, rang­ing from severe explosions with casualties to near misses. We are also aware of the fact that because most incidents are not reported, the da­tabase cannot be considered a complete collec­tion of all incidents. This Urea Incident data­base describes incidents and near misses as far as known and reported. It also gives a possibil­ity to anonymously report incidents. We hope and trust this database will avoid future inci­dents in our industry. This Urea Incident Data­base can be found on the UreaK.nowHow.com Round Tables.

We urge all urea producers worldwide to share more frequently their incidents and near misses to fellow urea plants for the benefit of all. This Incident Database is the right place to file an irregularity. This paper will finally provide an example of such a success story. Find below the list of the incidents described in the UreanowHow.com Urea Incident Database to date March 2015:

 

  1. Incident 14-001: Fatality during bot bolting
  2. Incident 13-001: Fatal liquid NH3 pipeline leak
  3. Incident 12-001: Failure of bends in HP car- bamate gas lines
  4. Incident 11-003: Rupture HP gas hoe
  5. Incident 11-002: Fire
  6. Incident 11-001: Dismantling pressure gauge of HP flush pump
  7. Incident 10-004: Lump falling dlown from prill tower
  8. Incident 10-003: Corrosion HP NH3 line due to back:flow
  9. Incident 10-002: Twisted Butterfly Valve
  10. Incident 10-001: Fire in compressor section urea plant
  11. Incident 09-002: HP gas pipeline ruptured
  12. Incident 05-002: Rupture HP flange connec­tions
  13. Incident 09-001: Accident during Prill tower construction
  14. Incident 05-001: Urea Reactor explosion
  15. Incident 04-001: Failure Reactor 200 mtpd
  16. Incident 02-002: Two people suffocate due to welding gas
  17. Incident 02-001: Casualties during prill tow­er cleaning
  18. Incident 01-002: Casualty valve mainte­nance
  19. Incident 00-001: Catastrophic failure of a weld-o-let
  20. Incident 98-002: NH3 leak in urea plant
  21. Incident 98-001: HP Pump NH3 leak
  22. Incident 97-001: Fire in Cooling Water Tower
  23. Incident 95-001: Urea Reactor explosion
  24. Incident 93-001: NH3 leak in urea plant dur­ing shutting down
  25. Incident 92-003: HP NH3 pump NH3 leak
  26. Incident 92-002: NH3 gas explosion N113 pump
  27. Incident 92-001: Urea Reactor explosion
  28. Incident 91-001: HP stripper explosion
  29. Incident 90-001: Reactor explosion
  30. lncident 87-001: Urea Melt splashes on per- son
  31. Incident 79-00 I : Reactor leak
  32. Incident 78-001: Urea Reactor Leak
  33. Incident 77-001: Urea Reactor explosion
  34. Incident 74-001: HP scrubber explosion
  35. Incident XX-012: Anhydrous NH3 Sam­pling procedure benchmarking
  36. Incident XX-011: Leak in liquid NH3 pipe­line
  37. Incident XX-010: CO2 can ignite a flamma­ble mixture
  38. Incident XX-009: Leak in liquid NH3 pijpe­line
  39. Incident XX-008: Fall of scaffold from height
  40. Incident XX-007: Explosion CO2 vent pipe ex CO2 compressor
  41. Incident XX-006: Leak HPCC tube causes corrosion tubesheet
  42. Incident X:X-005: Collapsed wooden Cool­ing Towers
  43. Incident XX-004: Rupture Urea Reactor due to Nitrate SCC
  44. Incident XX-003: Severe nitrate SCC Urea reactor
  45. Incident XX-002: Severe corrosion HP NH3 pipeline
  46. Incident :XX-001: Rupture HP CO2 line

Overlooking all incidents, one can conclude that the safety risks in a urea plant are related to:

  • High pressures
  • Corrosive properties of ammonium­carbamate
  • Ammonia release
  • Atmospheric corrosion, Corrosion under insulation

Analyzing more in detail the incidents of the UreaKnowHow.com database shows that some 35% of the incidents are related to the high pres­sure equipment, some 40% to high pressure pip­ing, valves and accessories, and some 25% to others such as cooling towers, prill towers and compressors.

It is our firm belief that fairly simple measures and adhering to some critical points of attention can avoid a significant part of these incidents. In this paper we will summarize these critical points for high pressure equipment and high pressure piping and valves for each phase of the lifetime of a urea plant.

Note the significant difference between equip­ment and piping when one considers corrosion inspection:

  • High pressure equipment is designed in such a way that all parts in contact with the process can be inspected during a turnaround and all urea producers do these inspections. Con­versely most of the high pressure piping can­not be inspected from the process side as it is simply not accessible. Inspection techniques of pipe line systems also have its limitations.
  • When manufacturing High Pressure equip­ment, welds are executed in a workshop under ideal conditions, while many welds in high pressure piping are executed in the field. Of­ten these welds are done in difficult positions and under difficult circumstances that impede the required and necessary quality.
  • It is not yet common practice to perform corrosion inspections to high pressure piping, valves and accessories on a regular basis. Al­so the execution of the inspection of a piping system is time consuming, and the interpreta­tion of the inspection results is not that simple.

General measures and attention points to avoid / minimize high pressure equipment and piping incidents in urea plants

During the design and engineering phase one should pay attention to:

  • Correct choice of materials of construction according to licensor’s specification; or bet­ter, choose a more corrosion resistant materi­al of construction in certain cases
  • Design avoiding crevices and dead legs. In­stall a state of the art leak detection system (active system with a continuous analysis) in equipment with a loose liner or at other areas where it is needed.
  • Specify application of adequate coating sys­tems in case of risk of atmospheric corrosion (chlorides, nitrates and sulphides)
  • Specify adequate insulation/tracing system to avoid ingress of moisture and condensation of gas phases
  • Lay-out of grass root plant with location of cooling towers opposite prevailing wind direc­tion

During the fabrication, construction, storage and shipping phase one should pay attention to:

  • Quality control of materials of construction according to licensor’s specification. The use of Positive Material Identification (PMI) tech­niques in this stage is unavoidable
  • Guidance and control during manufacturing of equipment and erection of plant
  • Choose qualified and experienced fabricators.
  • Maximize prefab welding of high pressure piping and make use of qualified and experi­enced welders
  • Guidance and control during application of coating and insulation systems
  • Guidance and control during pressure testing and flushing of equipment
  • During storage and transport/shipment in a chloride-containing atmosphere the equipment should be inerted with nitrogen

During operation and maintenance phase one should pay attention to:

  • Proper operation within the windows of licenser’s manual
  • Perform regular inspections based on Risk Based Inspection philosophy to be able to set up predictive maintenance programs for example for HP piping one can consider to in­spect high pressure carbamate gas lines for condensation corrosion and weld-o-lets for higher corrosion rates.
  • Perform maintenance/repair according to specifications
  • Continuous monitoring to be performed on addition of oxygen in CO2 supply
  • A continuous check on proper functioning of Leak Detection System
  • The blow down steam/condensate of HP heat exchangers to be monitored on conductivity, pH and chloride content
  • In case of any doubt analyze end product for Nickel content
  • Proper inspection/maintenance of insula­tion/tracing systems to avoid ingress of mois­ture and condensation of gas phases
  • In case of a leak, stop the plant and repair the leak

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