major potential hazards in urea plants v6 090917 · problem of a valve in an ammonia line ... to...
TRANSCRIPT
Revision Hazard & Initiating Event Consequences Safety Study Reference Link C L R Sponsor 1 Sponsor 2 Sponsor 3 Sponsor 4 Sponsor 5 Sponsor 6 C L R
1V4, 1
August 2017
Human error to solve a vibration problem of a valve in an ammonia line
NH3 release to atmosphere Commissioning Feed HP NH3 valve Incident Database Incident 93-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=962
Major Unlikely (8) High 8 Prepare Standard Operating Procedures for operators and for start up and shut down phase. Perform vibration analysis on critical pipelines.
Major Rare (5) Moderate 5
2V4, 1
August 2017
NH3 leak due to a sight glass failure during start up
16 people injured Commissioning Feed NH3 pumps Incident Database Incident 15-002 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1189
Major Moderate (11) High 11 Several recommendations are included in: http://www.ureaknowhow.com/ukh2/library/1190-2017-ureaknowhow-com-top-10-revamp-tools.html
Several recommendations are included in: http://www.ureaknowhow.com/ukh2/library/1190-2017-ureaknowhow-com-top-10-revamp-tools.html
Moderate Rare (3) Moderate 3
3V4, 1
August 2017
High pressure in suction line due to operating the melt pump with hot condensate and no / low flow conditions leading to steam formation
Sight glass damages Commissioning Finishing Melt pump HAZOP Catastrophic Unlikely (10) High 10 Perform commissioning of melt pump with cold condensate, find alternative methods to test instrumentation. Apply a BUNGARTZ melt pump.
Catastrophic Rare (7) High 7
4V4, 1
August 2017
Tank damages due to vacuum created in tank
Major damage Commissioning Recirculation Atmospheric storage tanks
Incident Database Incident 15-003 & 03-001
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1273
Major Unlikely (8) High 8Be aware that condensing steam / gases by a cold stream can easily create vacuum, install a water seal on a tank as a 3" vent stack of 100 m height could not compensate the vacuum pressure in this incident
Major Rare (5) Moderate 5
5V4, 1
August 2017
Boiler explodes due to explosive mixture in boiler
3 casualties and 5 people injured Commissioning Utilities Steam boiler Incident Database Incident 16-003 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1392
Catastrophic Unlikely (10) High 10
Boilers, furnaces and reformer to be charged with fuel gas only when furnace draft fans are put into operation. Standard operating procedure to be modified accordingly. Fuel gas line leak test to be strictly done with nitrogen. Proper interdepartmental communication to be ensured between maintenance supervisor and control room and work area to be cleared of contract workman before initiating start up activities.
Catastrophic Rare (7) High 7
6V4, 1
August 2017
During construction of prill tower, accident occurred from high elevation
12 casualties, plant construction on hold
Construction Finishing Prill tower Incident Database Incident 09-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=272
Catastrophic Unlikely (10) High 10 When working at high heights take care of extra security to avoid falling down. Inspect condition of carrier equipment
Catastrophic Rare (7) High 7
7V4, 1
August 2017
Rupture of HP stripper due to fabrication defect
12 casualties, 71 mln US$ financial loss
Construction Synthesis Stripper Incident Database Incident 90-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=278
Catastrophic Moderate (12) Intolerable 12 Assure a proper design and experienced and qualified fabricator for HP urea vessels. Perform quality control during fabrication.
In case of a leak stop the plant. Catastrophic Rare (7) High 7
8V4, 1
August 2017
Crystallisation of carbamate and clogging upstream or downstream safety valve
High pressures than design leading to potential damage and carbamate / NH3 release
Engineering Carbamate Safety valves HAZOP
2008 Meessen Stamicarbon Urea
Plant Safety - A Review
Catastrophic Moderate (12) Intolerable 12 Trace pipeline upstream safety valve, trace body of safety valve and flush body and downstream pipeline of safety valve (best solution is LESER Flush safety valve)
Catastrophic Rare (7) High 7
9V4, 1
August 2017
Clogging of safety valve or other blow off devices upon activation due to solid formation of CO2 in blow off lines
Pressures increase above design pressure, damage
Engineering Feed CO2 compressor HAZOP
2008 Meessen Stamicarbon Urea
Plant Safety - A Review
Major Moderate (11) High 11Avoid stagnant lines at inlet (L/D<3) or provide tracing and insulation. Check that upstream temperature is above mentioned treshhold value (discharge 3rd and 4th stage downstream cooler are critical areas). Threshhold value at 80 bars is abt 45 degC and at 140 bars is abt 80 degC.
Major Rare (5) Moderate 5
10V4, 1
August 2017
Damage of carbon steel pressure bearing wall due to leakage of protecting sleeve in nozzle
Not clear but possibly bad design and thermal stresses
Engineering Synthesis HP Equipment Incident Database Incident 03-002 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1454
Catastrophic Unlikely (10) High 10Pay attention in the detailed design and fabrication and inspection of nozzles of HP urea equipment. Install a proper leak detection system for loose liners. Perform corrosion inspections at regular intervals and pay attention to leaks in the urea plant.
In case of a leak stop the plant. Catastrophic Rare (7) High 7
11V6, 3
September 2017
Drain line ruptures due to corrosion/erosion
Large loss of containment Engineering Synthesis Drain system Incident Database Incident 09-003 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1474
Catastrophic Unlikely (10) High 10 Better design of drain system with double block and bleed possibilities. Be aware that drain valves easily pass. Apply high quality vendor and higher alloy materials (duplex).
In case of a leak stop the plant. Catastrophic Rare (7) High 7
12V6, 3
September 2017
Isolation valve fails during maintenance
11 casualties, 10 injured Maintenance Feed HP pump Incident Database Incident 92-002, N&S 2017 Fatima
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=280
Catastrophic Unlikely (10) High 10Install double block and bleed for isolation valves of HP NH3 and carbamate pumps or install blind plates, do proper maintenance on these block valves, limit number of people at these locations during maintenance, wear personal protection. Apply high quality vendor and higher alloy materials.
Catastrophic Rare (7) High 7
13V4, 1
August 2017
Explosion due to atmospheric corrosion of ammonia pipeline, erosion from process side
Six fatalities and 25 people injured Maintenance Feed Ammonia pipelines Incident Database Incident 13-001 and XX-009
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=818 and http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=903
Catastrophic Moderate (12) Intolerable 12Do regular corrosion inspections. Colour ammonia lines for easy recognition. Assure proper quality of welds. Assure proper condition of insulation.What can be cause for erosion from process side, catalyst particles ? Any experience from others ?
In case of a leak stop the plant. Catastrophic Rare (7) High 7
14V4, 1
August 2017
NH3 leak due to loosening packing ring of stuffing box HP reciprocating pump
3 people injured Maintenance Feed HP Pumps Incident Database Incident 98-001 and 07-001
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=924 and http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1425
Catastrophic Moderate (12) Intolerable 12Perform proper (also preventive) maintenance on HP pumps, stuffing boxes have a limited lifetime Also check wear and tear of other related parts also like the condition of for example threads. Involve high quality and experienced companies.
Catastrophic Unlikely (10) High 10
15V4, 1
August 2017
NH3 pipeline weld joint fails Heavy ammonia leak Maintenance Feed NH3 piping Incident Database Incident 08-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1404
Catastrophic Unlikely (10) High 10
Corrosion-fatigue resulting from combined action of an alternating stresses and corrosive environment. On line sealing of leakages either from pipes or weld joints should be avoided. Contrary to pure mechanical fatigue, there is no fatigue limit load in corrosion-assisted fatigue. Much lower failure stresses and much shorter failure times can occur in a corrosive environment. OMIFCO has decided not to do online sealing for any developed leakages on ammonia pipe lines. Consider Boreal NH3 detectors.
Assure sufficient isolation possibilities (remotely controlled block valve) to limit ammonia emissions. In case of a leak stop the plant.
Major Rare (5) Moderate 5
16V4, 1
August 2017
Leaking flange of CO2 line One person passes out Maintenance Feed CO2 compressor Incident Database Incident XX-014 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1455
Major Moderate (11) High 11CO2 is heavier than normal air and can collect at lower elevations reducing oxygen content to dangerous low levels. A proper CO2 detector should be present. Flange leakages are to be checked after a start up. Personal should be aware of the risks of CO2.
Major Rare (5) Moderate 5
17V4, 1
August 2017
Acetic acid used for cleaning enters lube oil system of CO2 compressor via nitrogen network
Severe damage to bearings/seals Maintenance Feed CO2 compressor Incident Database Incident 09-005 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1476
Major Unlikely (8) High 8 Perform risk analysis also for maintenance activiities, do not trust check valves to stop flow completely. Consult expert companies.
Major Rare (5) Moderate 5
18V6, 3
September 2017
During cleaning or maintenance activities heavy lumps can fall down causing casualities
several casualties during several incidents
Maintenance Finishing Prill tower / Granulation
Incident Database Incident 02-001 and 10-004
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=273 and http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=907
Major Likely (13) Intolerable 13 Working in a prill tower or granulator with urea lumps is dangerous: clean first maximum amount from outside. Make use of wet cleaning (refer to Nagarjuna paper)
Take care of proper protection Moderate Rare (3) Moderate 3
19V4, 1
August 2017
While trying to open clogged melt line, melt splasht out of 3-way valve or flange
one person injured (40 days in hospital) while wearing good personal protection
Maintenance Finishing Urea melt line Incident DatabaseIncident 87-001 and XX-015 and
XX-016
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=329 and http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1457 and http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1460
Moderate Moderate (9) High 9
Do not compromise on safety: Flush drain lines of urea melt lines twice per shift to ensure drain line is clear, perform job safety analysis to identify unsafe situations (e.g. no escape path close to 3-way valve, work with safety watches at risky situations. Be careful when heating up urea melt lines as gasses occur and pressures increase. Avoid overheating of urea melt lines, pay attention to no flow conditions. Apply a reliable melt pump.
Do not compromise on safety: Wear always the right and full cover personal protection.
Minor Rare (2) Low 2
20V4, 1
August 2017
Julla falls down from 10 m height due to shearing of pinion of electrical winch
3 persons were badly injured and 2 fatalities was reported
Maintenance Finishing Prill tower Incident Database Incident XX-008 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=896
Catastrophic Unlikely (10) High 10 Second holding of the julla to be made foolproof Catastrophic Rare (7) High 7
No:Hazard Scenarios Hazard Reference Information Mitigated Risk RankingSupport from our Sponsors
Ref No. Prevention measures reducing Likelihood Mitigation measures reducing Consequences
Risk Register of Major Potential Hazards in Urea Plants V6: September 3, 2017
Project phase Plant section Equipment itemUnmitigated Risk Ranking
Ref No.
21V4, 1
August 2017
Granulator door jammed close unexpectedly
One person injured Maintenance Finishing Granulation Incident Database Incident XX-017 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1461
Moderate Moderate (9) High 9 Mechanically secure the granulator doors in open position even when inspecting the granulator through open doors.
Moderate Rare (3) Moderate 3
22V4, 1
August 2017
Miscommunication during maintenance job
One injured Maintenance Finishing Reclaimer Incident Database Incident XX-018 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1504
Moderate Moderate (9) High 9 Apply the safest possible procedure even if it takes more time Moderate Rare (3) Moderate 3
23V4, 1
August 2017
People enter a pipeline (confined space) while welding was performed and welding gas was applied (inerts) leading to asphyxiation
Two casualties Maintenance Plant Confined spaces Incident Database Incident 02-002 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=925
Catastrophic Unlikely (10) High 10 Apply proper precautions when entering confined spaces, measure oxygen, use a safeguard Catastrophic Rare (7) High 7
24V4, 1
August 2017
Crane collapses during maintenance job
One casualty Maintenance Plant plant incident Database Incident 15-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1140
Moderate Unlikely (6) Moderate 6 Apply proper preparation procedures when using a crane, do a risk analysis Moderate Rare (3) Moderate 3
25V4, 1
August 2017
Sight glass ruptures One casualty and 2 people injured, all in one case
Maintenance Plant Sight glass Incident Database Incident XX-013 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1303
Catastrophic Likely (14) Intolerable 14Several recommendations. Refer to Round Table discussion (refer to: http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1303). Apply non-cavitating BUNGARTZ pump.
Several recommendations. Refer to Round Table discussion (refer to: http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1303). Apply non-cavitating BUNGARTZ pump.
Insignificant Unlikely (2) Low 2
26V4, 1
August 2017
Backflow from synthesis (discharge HP carbamate pumps) to recirculation (suction side) as during flushing mode the XPV (LPV) in the discharge is opened while people are in the area
Potential toxic ammonia release and/or high temperature/pressure carbamate release (SIL 2)
Maintenance Recirculation HP carbamate pumps
HAZOP
2008 Meessen Stamicarbon Urea
Plant Safety - A Review
Major Moderate (11) High 11 Add position indicators on main blockvalves in order that XPV can only be opened in case pump is running or in case both pumps are stopped and blockvalves are closed
In case of a leak stop the plant. Major Rare (5) Moderate 5
27V4, 1
August 2017
Asphyxilation / unconsious while working on tank
one casualty, one person injured Maintenance Recirculation Atmospheric storage tanks
Incident Database Incident 16-002 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1336
Catastrophic Unlikely (10) High 10 Pay attention that vapours can escape from vents from the tank while working on top of the tank. Perform a job safety analysis.
Catastrophic Rare (7) High 7
28V4, 1
August 2017
Vent line of ammonia water tank explodes during grinding
One casualty and one injured Maintenance Recirculation Tanks Incident Database Incident XX-020 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1513
Catastrophic Moderate (12) Intolerable 12Assure proper blinding (spectacle blinds, double block and bleed) when doing maintenance or inspections on a equipment item. Perform a risk analysis before starting the job. Apply proper winterising measures
Catastrophic Rare (7) High 7
29V4, 1
August 2017
HP butterfly valve twists leading to leakage
Unsafe situation plus in ammonia plants risk for fire
Maintenance Synthesis HP piping Incident Database Incident 10-002 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=333
Moderate Moderate (9) High 9 Pay proper attention to the installation of high pressure butterfly valves between flanges with lens gaskets, consider the new BHDT design for these valves
In case of a leak stop the plant. Moderate Rare (3) Moderate 3
30V4, 1
August 2017
Pressure gauge ruptures after HP flush pump is put in operation due to malfunctioning pressure control valve
Unsafe situation Maintenance Synthesis HP flush pump Incident Database Incident 11-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=388
Moderate Unlikely (6) Moderate 6 Assure proper functioning of pressure control valve and relief valve In case of a leak stop the plant. Moderate Rare (3) Moderate 3
31V4, 1
August 2017
Reactor ruptures due to bad maintenance practice of closing the manway cover
One person injured due to toxic ammonia (double long transplantation)
Maintenance Synthesis Urea Reactor Incident Database Incident 01-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=515
Catastrophic Unlikely (10) High 10 Apply proper maintenance procedures and experienced and qualified services companies. Apply the right gaskets. Treat high pressure urea vessels as critical equipment
In case of a leak stop the plant. Catastrophic Rare (7) High 7
32V4, 1
August 2017
Rupture of valve due to high pressure pocket during maintenance
In one incident one casualty, in another case one person injured
Maintenance Synthesis HP piping Incident Database Incident 01-002 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=662
Moderate Likely (11) High 11 Be aware that high pressure lines / valves can contain high pressure pockets and apply proper maintenance procedures taking this into account.
Wear proper personal protection. Moderate Rare (3) Moderate 3
33V4, 1
August 2017
Rupture high pressure flange connection
Large ammonia emission, complaints from neighbours
Maintenance Synthesis HP piping Incident Database Incident 05-002 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=946
Catastrophic Unlikely (10) High 10
Carbon steel is not corrosion resistant and corrosion rate is very high. The installation of all equipment in the HP loop must be performed only by specialists with the right material. An independent check must be performed on all flanges in the HP section to check all dimensions. Grooves have been made in the carbon steel flange to allow the carbamate to escape
In case of a leak stop the plant. Catastrophic Rare (7) High 7
34V6, 3
September 2017
Rupture of weldolet after trial to stop leak by installing a clamp
Four casualties and 4 people injured
Maintenance Synthesis HP piping Incident Database Incident 00-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=292
Catastrophic Moderate (12) Intolerable 12
Assure the quality of the applied materials fulfils the minimum requirements; Apply higher alloy materials (25-22-2 or duplex). Assure the quality of the installation and welding services. Apply better designs for weldolets with no dead volume. Pay attention to the right location of the weldolet (avoid gas phase). Perform proper inspections and testing during installation and after repair procedures (hydrotest, X-ray test of weld-o-let). Perform regular corrosion inspections of critical areas especially in plants older than 20 years. Never apply a clamp on a carbamate containing pipeline.
In case of a leak stop the plant. Catastrophic Rare (7) High 7
35V4, 1
August 2017
During hot bolting gasket fails One casualty Maintenance Synthesis HP piping Incident Database Incident 14-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1016
Catastrophic Unlikely (10) High 10 Never apply hot bolting at high pressures In case of a leak stop the plant. Catastrophic Rare (7) High 7
36V4, 1
August 2017
Failure of flanged head connection of a urea reactor
Major damage Maintenance Synthesis Urea Reactor Incident Database Incident 10-005 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1276
Catastrophic Moderate (12) Intolerable 12Avoid a design with a cooling jacket, apply a proper vacuum based leak detection system with an accurate and reliable ammonia detector. Never flush leak detection circuits with steam or condensate or water.
In case of a leak stop the plant. Catastrophic Rare (7) High 7
37V4, 1
August 2017
Leaking flange connection in high pressure pipeline
Risk of corrosion of carbon steel flanges, bolts and nuts, loss of integrity
Maintenance Synthesis HP piping HAZOP Catastrophic Likely (14) Intolerable 14 Apply right torques and high quality materials. Use clean bolts and nuts which are both in good condition. Do not reuse lens rings.
In case of a leak stop the plant. Major Rare (5) Moderate 5
38V6, 3
September 2017
Failure of wooden structure of cooling water unit in some 15 Indian plants
Significant damage and production loss
Maintenance Utilities Cooling water unit Incident Database Incident XX-005 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=516
Minor Moderate (6) Moderate 6 Check design of wooden structure and avoid large weights at higher elevations, do proper quality control, perform proper corrosion inspections
Minor Rare (2) Low 2
39V4, 1
August 2017
Fire due to leakage CO2 compressor lube oil
Production loss, fire could be snuffed out before further damage
Operational Feed CO2 compressor Incident Database Incident 10-001http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=309&p=7446#p7446
Major Unlikely (8) High 8 Install fire detectors, cameras. Install oil system besides compressors / turbines. Minor Unlikely (4) Moderate 4
40V4, 1
August 2017
Large uncontrolled NH3 emission in case suction line of HP NH3 pump fails due to unwanted backflow scenario
As NH3 booster pump from NH3 plant keeps running, NH3 emission can be very large (SIL 3)
Operational Feed NH3 pumps HAZOP
2008 Meessen Stamicarbon Urea
Plant Safety - A Review
Catastrophic Moderate (12) Intolerable 12 Install fast closing XEV to stop supply of NH3 from boosterpump or stop booster pump automatically. Wear personal protection when working on NH3 equipment
Minor Moderate (6) Moderate 6
41V6, 3
September 2017
A rupture disc on NH3 system opened without proper noticing
Large ammonia emission, complaints from neighbours
Operational Feed NH3 heat exchangers
Incident Database Incident 98-002 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=764
Moderate Unlikely (6) Moderate 6 Apply NH3 detection system for leaks of rupture discs as these do not close again after damage
Minor Unlikely (4) Moderate 4
42V4, 1
August 2017
Fire / explosion during blow off due to icing and hydrogen ignition
Damage plus possible casualties Operational Feed CO2 compressor Incident Database Incident XX-007 and XX-010
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=658 and http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=970
Major Unlikely (8) High 8 Lower explosion limit of hydrogen is 4 vol%, are these levels possible. Is fire possible ? Anybody has experience ?
43V4, 1
August 2017
Anhydrous ammonia splashes during sampling
One person injured Operational Feed NH3 piping Incident Database Incident XX-012 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1131
Moderate Moderate (9) High 9 Apply proper sampling procedure. Perform job safety analysis. Wear sufficent personal protection Minor Rare (2) Low 2
44V5, 17 August 2017
Backflow from corrosive carbamate from synthesis to carbon steel NH3 and CO2 feed lines
Failure HP piping, large ammonia leak
Operational Feed HP piping Incident Database Incident 16-004 and 10-003
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1428 and http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=467
Catastrophic Moderate (12) Intolerable 12
Two checkvalves in series with different design and high quality. Do not apply a design with vanes. Check valves to be installed in vertical line. Install a flushing connection upstream check valve to flush away solids. Install a fast closing MOV from DCS (some plants apply buffer vessel in CO2 supply line). Apply the specbreak upstream this MOV. Pay attention also to bypass / start up lines.
In case of a leak stop the plant. Catastrophic Rare (7) High 7
45V5, 19 August 2017
Backflow from carbamate from synthesis causing reverse flow of HP centrifugal carbamate pump
Damage HP carbamate pump (SIL 2)
Operational Recirculation HP carbamate pumps
HAZOP Moderate Moderate (9) High 9
Two checkvalves in series with different design and high quality. Do not apply a design with vanes. Check valves to be installed in vertical line. Install a flushing connection upstream check valve to flush away solids. Install a fast closing XV which acts on TSHH in the line to the synthesis (some plants apply two XV in series).
In case of a leak stop the plant. Moderate Rare (3) Moderate 3
46V6, 3
September 2017
Failure of separator of CO2 compressor causing wet corrosive CO2
Pipe failed during clamping Operational Feed CO2 compressor Incident Database Incident 16-006 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1438
Major Unlikely (8) High 8The pipe was replaced by stainless steel. The efficiency of the liquid separator was improved. Do not apply clamps when the condition of the pipe is not clear. Apply experienced CO2 compressor vendors.
In case of a leak stop the plant. Major Rare (5) Moderate 5
47V4, 1
August 2017
CO2 breakthrough with ammonia recycle.
Internal corrosion, possible damage
Operational Feed NH3 buffer vessel HAZOP http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=7&t=1519
Catastrophic Unlikely (10) High 10 Stainless steel liner with ammonia leak detection system or stainless steel vessel. In case of a leak stop the plant. Catastrophic Rare (7) High 7
48V4, 1
August 2017
Gas pipeline ruptures Fire and plant shut down Operational Plant Piping Incident Database Incident 11-002 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=451
Moderate Moderate (9) High 9 Apply high quality materials. Perform corrosion inspections of pipelines based on risk based inspection
In case of a leak stop the plant. Moderate Rare (3) Moderate 3
49V4, 1
August 2017
Several scenarios lead to high pressure in the recirculation
Potential toxic ammonia release and /or high temperature /pressure carbamate release
Operational Recirculation Recirculation HAZOP
2008 Meessen Stamicarbon Urea
Plant Safety - A Review
Major Moderate (11) High 11 Safety valve plus high pressure switch to realise the required Probability of Failure on Demand. The high pressure switch activates synthesis blocking situation. Apply a reliable pressure measurement.
Minor Rare (2) Low 2
50V4, 1
August 2017
Rupture of column due to hydrogen explosion
Major damage Operational Recirculation
MP scrubber, LP absorber and atmospheric
absorber
HAZOP Incident 00-002 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1446
Major Moderate (11) High 11Install a hydrogen converter in CO2 feed, use ammonia feed from atmospheric pressure (no dissolved H2 and CH4), be aware of flushing with condensate which can increase H2/NH3 ratio (larger explosive area). Apply an explosion dome or 7 times higher design pressure.
Insignificant Rare (1) Low 1
51V6, 3
September 2017
Hot fluid splashes (this risk is high with process fluids which easily crystallise)
Injuries Operational
Recirculation, evaporation and
waste water treatment
sample valves HAZOP Moderate Moderate (9) High 9 Make use of Tyco (Yarway) sample valves with no dead volume at inlet side Moderate Rare (3) Moderate 3
52V4, 1
August 2017
Rupture of reactor due to active corrosion due to weld defect in weld clip to liner
Rupture of reactor leading to severe damage to the plant, 10 people injured inside and 90 people outside the battery limits
Operational Synthesis Urea Reactor Incident Database Incident 92-001http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=267&p=1188#p1188
Catastrophic Moderate (12) Intolerable 12
Proper active vacuum based leak detection system for loose liners with a reliable and accurate ammonia detector in operation, procedure to shut down the plant in case a leak is identified, apply a full penetration weld, proper quality control of critical welds, proper design of clip so that proper welding is possible, use high alloy welding material, include clip welds in corrosion inspection program
In case of a leak stop the plant. Catastrophic Rare (7) High 7
53V4, 1
August 2017
Rupture of HP CO2 line due to corrosion under insulation
Unplanned shut down of the plant Operational Synthesis HP piping Incident Database Incident XX-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=268
Moderate Moderate (9) High 9Insulated carbon steel at concerning temperatures has to be protected by a coating system or personal protection can be applied. Insulation should be in good condition. Regular inspections for atmospheric corrosion at critical areas is recommended. Be careful with flushing water.
In case of a leak stop the plant. Moderate Rare (3) Moderate 3
54V4, 1
August 2017
Significant wall thickness reduction of HP NH3 line due to atmospheric corrosion
Repair during turnaround Operational Synthesis HP piping Incident Database Incident XX-002 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=269
Major Moderate (11) High 11Apply a protective coating system on the pipeline also in the area of the clamp. Apply a glass fibre tape between the pipeline and the clamp. Avoid wetting of the pipeline during flushing the floor. Apply Good Practice when guiding a pipeline through concrete floors.
In case of a leak stop the plant. Major Rare (5) Moderate 5
55V4, 1
August 2017
Rupture of or cracks in pressure bearing wall due to atmospheric corrosion (Nitrate stress corrosion cracking)
Repair during turnaround or new reactor required
Operational Synthesis Urea Reactor Incident Database Incident XX-003 and XX-004
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=270, http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=275
Catastrophic Moderate (12) Intolerable 12
Regular corrosion inspections also for atmospheric corrosion is recommended. Take care of a proper aluminum cover sheeting to avoid ingress of water contaminated with nitrate and/or urea (especially at critical locations like supports, insulation rings). In case of risk of nitrate (or urea) contamination carbon steel equipment and piping operating at temperatures in between -10 and +240 oC have to be coated. The angle iron insulation support ring should be fixed on the carbon steel shell in area with a lower stress level. Consider a shelter on top of HP vessels.
In case of a leak stop the plant. Catastrophic Rare (7) High 7
56V4, 1
August 2017
Rupture of reactor due to stress corrosion cracking of carbon steel pressure bearing wall due to flushing of leak detection system with water and bad design leak detection holes in multi layer vessel
4 casualties, 32 injured Operational Synthesis Urea Reactor Incident Database Incident 05-001 and 95-001
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=276
Catastrophic Moderate (12) Intolerable 12
Flushing leak detection systems with steam or condensate can introduce substances leading to stress corrosion cracks in the pressure bearing carbon steel wall. A proper sealing (design) is required between the leak detection holes and the first carbon steel layer. The same is valid for the nozzles of a high pressure urea equipment item.
In case of a leak stop the plant. Catastrophic Rare (7) High 7
57V6, 3
September 2017
HP carbamate gas line ruptures due to strain induced intergranular cracking (SIIC)
Unsafe situation, large ammonia emission, plant shut down
Operational Synthesis HP piping Incident Database Incident 09-002 and 12-001
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=404 and http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=927
Major Moderate (11) High 11
Apply proper tracing and insulation so that condensation will be avoided (dew point typically higher than 160 degC), apply stainless steel with small grain size or apply higher alloy material (25-22-2 or duplex). Perform corrosion inspections for HP gas lines and weldolets. End of lifetime for 316L UG high pressure gas lines is some 30 years.
In case of a leak stop the plant. Major Rare (5) Moderate 5
58V4, 1
August 2017
HP NH3 pipelines ruptures due to backflow of corrosive carbamate
Unsafe situation Operational Synthesis HP piping Incident Database Incident 10-003 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=467
Major Moderate (11) High 11
Pay attention to high quality materials, proper design and installation of checkvalves, Install two checkvalves in series with different design, Pu spec break of pipe upstream fast closing Motor Operated Valve, Install flushing connection upstream checkvalves so that any solids can be flushed away from checkvalves.
In case of a leak stop the plant. Major Rare (5) Moderate 5
59V4, 1
August 2017
Rupture of urea reactor due to cracks in carbon steel behind the liner
Significant part of plant was destroyed, plant never started up again, no casualties
Operational Synthesis Urea Reactor Incident Database Incident 04-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=550
Catastrophic Moderate (12) Intolerable 12 Avoid any contamination in space between loose liner and carbon steel. Do not flush a leak detection system with water
In case of a leak stop the plant. Catastrophic Rare (7) High 7
60V4, 1
August 2017
Rupture of urea reactor due to defect in titanium liner
Massive damage and long period forced shut down
Operational Synthesis Urea Reactor Incident Database Incident 90-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=618
Catastrophic Moderate (12) Intolerable 12Apply an active leak detection system with an accurate and reliable ammonia detector. Perform corrosion inspections at regular intervals. Choose higher alloy material of conctruction for protective layer
In case of a leak stop the plant. Catastrophic Rare (7) High 7
61V4, 1
August 2017
Several scenarios lead to high pressure in the synthesis
Potential toxic ammonia release and /or high temperature /pressure carbamate release (SIL 3)
Operational Synthesis Synthesis HAZOP
2008 Meessen Stamicarbon Urea
Plant Safety - A Review
Catastrophic Moderate (12) Intolerable 12 Safety valve plus high pressure switch to realise the required. Probability of Failure on Demand. High pressure switch activates synthesis blocking situation. Apply a reliable pressure measurement.
Minor Rare (2) Low 2
62V4, 1
August 2017
Tube rupture leads to high pressure on steam or cooling water side
Pressure on steam or cooling water side will be higher than design, damage with realease of carbamate and toxic ammonia
Operational Synthesis HP Heat Exchangers
HAZOP
2008 Meessen Stamicarbon Urea
Plant Safety - A Review
Catastrophic Moderate (12) Intolerable 12
Sometimes steam side is protected by a rupture disc, but spurious activation has led to a large release. Steam side are also typically protected by a safety valve, which also blows off at tube rupture. Analysis has shown this safety valve is sufficient and blow off needs to be located to safe loaction (suitable for large ammonia release). In case of cooling water on shell side a rupture disc remains necessary (assure safey location of blow off).
Minor Rare (2) Low 2
63V4, 1
August 2017
Steam supply to the HP stripper during blocking in situation
Pressure higher than design, damage (SIL 3)
Operational Synthesis Synthesis HAZOPDieltjes SIL
Classification in Urea Plants
Catastrophic Unlikely (10) High 10Safety valve plus high pressure switch to realise the required Probability of Failure on Demand. Switch activates synthesis blocking situation (closing steam supply). Apply a reliable pressure measurement.
Minor rare (2) Low 2
64V4, 1
August 2017
Failure of the tube to tubesheet weld
Carbamate entering the steam / cooling water side, potential risk of corrosion of carbon steel tubesheet
Operational Synthesis HP Heat Exchangers
Incident Database Incident XX-006 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=880
Catastrophic Moderate (12) Intolerable 12 Apply a conductivity measurement to detect leak. Do not expand tubes in the tubesheet during fabrication of the heat exchanger.
In case of a leak stop the plant. Minor Rare (2) Low 2
65V4, 1
August 2017
Failure of pressure bearing wall due to leak in overlay welding
Urea / carbamate leaked through insulation
Operational Synthesis HP Equipment Incident Database Incident 78-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=883
Minor Moderate (6) Moderate 6 Perform corrosion inspections during turnaround. Apply higher alloy materials for repair or replacement of protective layer in HP equipment
In case of a leak stop the plant. Minor Rare (2) Low 2
66V4, 1
August 2017
Failure of HP scrubber due to hydrogen explosion
Major damage Operational Synthesis HP scrubber Incident Database Incident 74-001 and 00-002
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=884 and http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1446
Catastrophic Moderate (12) Intolerable 12
Install a hydrogen converter in CO2 feed, use ammonia feed from atmospheric pressure (no dissolved H2 and CH4), monitor H2 content downstream hydrogen converter, never close inert valve, be aware of flushing with condensate in HP scrubber which can increase H2/NH3 ratio (larger explosive area). Apply an explosion dome HP scrubber
Insignificant Rare (1) Low 1
67V4, 1
August 2017
Failure of urea reactor due to no proper leak detection system
Major damage Operational Synthesis HP Equipment Incident Database Incident 77-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=885
Catastrophic Likely (14) Intolerable 14 Install a vacuum based leak detection system with a reliable and accurate ammonia detector. In case of a leak stop the plant. Catastrophic Rare (7) High 7
68V4, 1
August 2017
Massive leak in urea reactor due to no proper leak detection system
Damage of carbon steel pressure bearing wall
Operational Synthesis HP Equipment Incident Database Incident 79-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=886
Catastrophic Likely (14) Intolerable 14 Install a vacuum based leak detection system with a reliable and accurate ammonia detector. Pay attention to a proper design of the nozzles of HP equipment.
In case of a leak stop the plant. Catastrophic Rare (7) High 7
69V6, 3
September 2017
Failure (SIIC) of pipe in bends of 316L UG high pressure gas lines
Large release of ammonia Operational Synthesis HP carbamate gas lines
Incident Database Incident 12-001http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=927
Catastrophic Moderate (12) Intolerable 12Perform corrosion inspections during turnaround, secure sufficient tracing and insulation of gas lines to avoid condensation corrosion, apply small grain size material, apply higher alloy materials (25-22-2 or duplex).
In case of a leak stop the plant. Catastrophic Rare (7) High 7
70V4, 1
August 2017
Hot fluid splashes, balloon collapses during sampling at high pressure section
Injuries Operational Synthesis sample valves HAZOP Moderate Moderate (9) High 9 Make use of the BHDT Zero Dead Volume HP Sampling Valve Moderate Rare (3) Moderate 3
71V6, 3
September 2017
HP scrubber ruptures due to not commissioning all leak detection holes
Major damage Operational Synthesis HP Equipment Incident Database Incident 98-003 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1364
Catastrophic Unlikely (10) High 10 Asssure the correct and complete installation of a leak detection system to all leak detection holes. In case of a leak stop the plant. Catastrophic Rare (7) High 7
72V4, 1
August 2017
Cracks from outside in carbon steel pressure bearing wall due to dripping of carbamate from a leaking flange
Major damage Operational Synthesis HP Equipment Incident Database Incident 94-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1365
Major Unlikely (8) High 8 Avoid that leaking carbamate can drip on high pressure urea equipment. In case of a leak stop the plant. Major Rare (5) Moderate 5
73V6, 3
September 2017
Stripgas entered reactor during blocking in causing active corrosion
Damage of carbon steel pressure bearing wall Operational Synthesis HP Equipment Incident Database Incident 13-002
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1348 Catastrophic Unlikely (10) High 10
During blocking in monitor the vessel temperatures for any heat increases. If the temperatures increase by more than 20F, the synthesis loop must immediately be drained. Assure positive isolation of CO2 when the loop is blocked in by monitoring loop pressure. Ensure operators close the isolation valve downstream of HIC-1201. Modify the Urea Plant startup procedure to include lab analysis of the stripper bottoms for metals found in the stainless steel liner, specifically Ni as it will be dissolved in the solution. The first sample must be taken within 12 hours of startup and the second 24 hours later. If the values are stable or decreasing, no action is required. If the values are increasing, the plant will be shut down and drained.
In case of a leak stop the plant. Catastrophic Rare (7) High 7
74V4, 1
August 2017
Failure of titanium level pipe due to corrosion (hydrogen enbrittlement below fouling)
Large emission of carbamate / ammonia
Operational Synthesis HP Equipment Incident Database Incident 16-005 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1436
Catastrophic Unlikely (10) High 10Be aware of fouling as below fouling active corrosion can occur or with titanium as material hydrogen enbrittlement (hydrogen is formed with carbamate corrosion reaction without oxygen present)
In case of a leak stop the plant. Catastrophic Rare (7) High 7
75V4, 1
August 2017
Severe damage of liner Replacement of liner Operational Synthesis HP Equipment Incident Database Incident 12-002 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1439
Catastrophic Moderate (12) Intolerable 12 Assure a proper active vacuum based leak detection system with a reliable and accurate ammonia analyser
In case of a leak stop the plant. Catastrophic Rare (7) High 7
76V4, 1
August 2017
Rupture of reactor due to stress corrosion cracking of carbon steel pressure bearing wall due to cooling jacket
Stress corrosion cracking Operational Synthesis Urea Reactor Incident Database Incident 64-001 and 59-001
http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1443 and http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1444
Catastrophic Unlikely (10) High 10Do not apply cooling jackets for HP urea equipment. Do not flush leak detection systems with water. Take care of proper insulation of HP equipment so that water / moisture cannot enter. Build a shelter on top of HP equipment.
In case of a leak stop the plant. Catastrophic Rare (7) High 7
77V6, 3
September 2017
Liner bulges and ruptures due to too high pressure behind the liner or due to draining the synthesis
Severe damage of liner and extensive repair
Operational Synthesis HP Equipment Incident Database Incident 09-004 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1475
Minor Moderate (6) Moderate 6 Be aware that pressure difference over liner is very limited. Apply a vacuum based leak detection system. Be careful with draining, install a vacuum pressure measurement in synthesis
In case of a leak stop the plant. Minor Rare (2) Low 2
78V4, 1
August 2017
Chloride from atmosphere (cooling water effluent, marine atmosphere) entering the steam condensate system via atmospheric steam condensate tank
Chlordes causing chloride stress corrosion cracking in for example the falling film high pressure carbamate condenser or high pressure scrubber in gap between tubes and tubesheet
Operational Synthesis HP Heat Exchangers
HAZOP Catastrophic Moderate (12) Intolerable 12 Assure always a higher pressure than atmospheric pressure in atmospheric steam condensate tank, check conductivity on steam side of HP heat exchangers leaks in tubes or tube-tubesheet welds
Catastrophic Rare (7) High 7
79V4, 1
August 2017
High vibrations of discharge line HP reciprocating carbamate pump
High pressure carbamate line rutpures, hot carbamate sprays around, luckily nobody got injured
Operational Synthesis HP Pumps Incident Database Incident XX-019 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1510
Catastrophic Unlikely (10) High 10Pay proper attention to the the welding and installation of discharge pipelines of high pressure pumps. In case of severe vibrations, stop the plant and improve the installation, consider dampeners in case of reciprocating pumps. Install vibration detectors on vibration sensitive pipelines
Catastrophic Rare (7) High 7
80V4, 1
August 2017
316L UG HP pipeline at inlet of reactor (conventional plant) ruptures due to erosion corrosion close to thermowell
Luckily no injuries, unplanned shut down and repair
Operational Synthesis HP pipeline Incident Database Incident 09-006 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1515
Catastrophic Moderate (12) Intolerable 12Also take into consideration erosion corrosion caused by turbulence of internals in piping and vesselsApply better grades of materials like 25-22-2 or duplex.
Catastrophic Rare (7) High 7
81V6, 3
September 2017
316L UG liquid outlet line HP NH3 stripper leaks due to relatively high temperature and as a consequence higher corrosion rates
Carbamate / ammonia can injure people
Operational Synthesis HP Piping HAZOP Catastrophic Moderate (12) Intolerable 12Replace pipe by better material like 25-22-2 or duplex. Perform regular corrosion inspections. Apply continuous corrosion measurement (EMERSON Permasense). Refer to: http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?t=1525
Catastrophic Rare (7) High 7
82V4, 1
August 2017
Explosion / damage of motor Major damage Operational Synthesis, Hydrolyser
HP pumps, hydrolyser pump
Incident Database Incident 16-001 http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=1294
Major Unlikely (8) High 8 Pay attention to proper alignment, perform regular and preventive checks on condition (vibrations) of heavy duty centrifugal pumps
Major Rare (5) Moderate 5
83V4, 1
August 2017
Fire in cooling water unit due to leak in heat exchanger
2 mln US$ financial loss and 55 days out of operation
Operational Utilities Cooling water unit Incident Database Incident 97-001http://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=298. Minor safety risk but catastrophic financal risk
Minor Unlikely (4) Moderate 4 H2 and NH3 analyser in each cooling water cell (FFBL) Minor Rare (2) Low 2
84V6, 3
September 2017
Explosion ammonia water tank due to combining NH3 and urea plant drain system
Damage the vessel, pipeline and instrumentation around it. No casualties.
Operational Waste water treatment
Ammonia water tank Incident Database Incident XX-022 https://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?t=1553
Minor Moderate (6) Moderate 6 Separate drain and vent system for ammonia and urea plant. Prepare proper Standard Operating Procedures for draining and venting for start-up and normal cases in both ammonia and urea plants.
Minor Rare (2) Low 2
85V6, 3
September 2017
316L UG High Pressure gas line ruptures due to condensation corrosion and dead end design
Large ammonia emission, plant shut down, no casualties
Operational Synthesis HP carbamate gas lines
Incident Database Incident 11-003
https://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?f=33&t=945&p=5045#p5045
Major unlikely (8) High 8
Avoid dead ends. Apply proper tracing and insulation so that condensation will be avoided (dew point typically higher than 160 degC), apply stainless steel with small grain size or apply higher alloy material (25-22-2 or duplex). Perform corrosion inspections for HP gas lines and weldolets. End of lifetime for 316L UG high pressure gas lines is some 30 years.
In case of a leak stop the plant. Major Rare (5) Moderate 5
86V6, 3
September 2017
High Pressure reactor offgas line leaks from weld defect
Ammonia detectors alaram, plant shut down, no casualties
Operational Synthesis HP carbamate gas lines
Incident Database Incident 15-004 https://www.ureaknowhow.com/ukh2/round-table/viewtopic.php?t=1555
Major Moderate (11) High 11
Apply proper tracing and insulation so that condensation will be avoided (dew point typically higher than 160 degC). Apply stainless steel with small grain size or apply higher alloy material (25-22-2 or duplex). Perform corrosion inspections for HP gas lines and weldolets. End of lifetime for 316L UG high pressure gas lines is some 30 years.
In case of a leak stop the plant. Minor Rare (2) Low 2