Stress Corrosion Cracking – Two Cases in a Row

February 19, 2009

The engineers at Reksolindo have an interesting inquiries for failure analysis suffered by different parts of equipment lately. Quitely different operation condition (high temperature and ambient temperature, medium and low carbon steel, marine atmosphere versus caustic feed water).  We are really satisfied for microscopy works that can catch the clear picture of lightning type-branched  small crack surrounding opening tip of main cracks below. The lightning  type and branched of small cracks which are believed in many literature [1,2,3]as the finger-print of stress corrosion cracking mode. And it was very clueful which made us more easier to find the contributing causes .

1. Chloride-SCC in an uncoated medium carbon steel bolt in marine atmosphere

Bolt

2. HAZ – Caustic SCC at 100-250 °C

plate-scc


Erosion Corrosion – Learning from Humber Estuary

January 27, 2009

Muhammad Abduh (abduh@reksolindo.co.id)

On 16 April 2001 a fire and explosion occurred at Humber Refinery following the catastrophic failure of an overhead gas pipe. Investigation was carried by The Competent Authority and the plant operator company by legislative mechanism under Control of Major Hazard (COMAH) Regulation 1999. Humber refinery was one of approximately 1000 major hazard site under this regulation. The competent authority consisted of Health and Safety Executive (HSE) UK and Environment Agency (EA).

p4363

The cause of the piping system failure was the erosion corrosion
of the 6-inches diameter pipe, known P4363, which carried the overhead line from the De-ethanizer (W413) to the heat exchanger (X452) in saturate gas plant (SGP) unit. The failure occurred down stream of a closely water injection point. Examination to thefailed elbow recovered from the damage site showed wall thickness thinning from 7-8 mm to a minimum 0.3 mm. When the pipe failed it burst open catastrophically causing a full bore type of release the pipe contents.

The water injection point was not the original design of the piping system. Water injection to the vapor stream between the top de-ethanizer column and the heat exchanger was addressed to solve the previous problem of salts or hydrates fouling in heat exchanger X452/3. An injection point was created in P4363 by piping water to an existing 1 inches vent point on the pipe without injection quill or dispersal device and made the water entering the pipe as a free jet.

Erosion-Corrosion
There are studies that noted the synergistic effect ofmechanical impingement and electrochemical corrosion result in greater rate of metal loss than the sum of the two mechanism ( S. Zhuo, N. Stack & R.C Newman)

The highest rate of erosion-corrosion occurred in stagnant region, immediately beneath the jet, where the particles impacted the surface at an angle of 90°, This critical erosion-corrosion region in a piping system are found at the outer side of elbow where the fluid impinges the wall directly at an angle 90°.

NACE 34101: Refinery Injection & Process Mixing
Points

One of the generic guidance to overcome the problem of erosion corrosion in refinery process is NACE 34101 which gas already published as recommended practice for the design consideration of  injection system.

RBI Regime was not Effective
This accident also has shown the effect of in-effective implementation of RBI for inspection management. RBI as a comprehensive method shall be supported with complete and adequate data. The ignorance of the operator company for the significant risk contribution of the injection system to the piping were resulted in the failure.

Similar Accidents:

1. Wilmington California United States – October 8,1992
2. North Rhine West Phalia Germany-  December 10,1991
3. Yokkaichi Mie Japan – May 2, 1997
4. Mina Al-Ahmadi Kuwait-  June 25, 2000


Heat Exchanger In- Service Damages

May 24, 2008

1. Excessive mineral deposits on the cooling water side of ammonia reactor effluent gas cooler.

2. Ice and fouling in a condenser tube.

3. Shell-side bacteria growth in cooling water heat exchanger

4. Fin Cooler tubes severly corroded

5. Deposits build-up on the inside of a heat exchanger tube

6. Plugged exchanger tube

7. Scaling on the inside diameter of a cooler tube

8. Deep Pitting in Exchanger Tubes

9. Cluster Pitting from Sour Glycol

10. Shell-side Pitting

11. Cooler Tube Rupture

12. Tube Failure Due to Thinning

13. Shell-side ruptured tube

14. Wall thinning led to this catastrophic failure of an exchanger tube

Image Source: Maverick Inspection

Book on Heat Exchanger Fouling: Heat Exchanger Fouling: Mitigation and Cleaning Techniques


The 50 Major Engineering Failures (1977-2007) Part-4

May 1, 2008

List of Engineering Failures Contributed by Material Failures, Corrosion, Design Flaw, and Construction Defect in Oil and Gas Production Facilities, Hydrocarbon Processing, and Oil and Gas Distribution

(Part 4 of 5) -Muhammad Abduh (abduh@reksolindo.co.id)

39. Roncador Brazil – March 15, 2001 (Tank Leaking, Offshore Platform, 2 killed, 8 missed, USD 515,000,000)

Figure Showing P-36 listing and arrangement of EDT

Official investigation report to the fire, explosion, and sinking to P-36 the largest offshore production facility said that the P-36 accident did not occur due to one single cause but was provoked by a series of factors. Chronology of the accident started from the failure of starboard emergency drain tank (EDT). Excessive pressure in Starboard EDT due to a mixture of water, oil, and gas, which caused rupture and leaking the EDT fluids into the fourth level of the column. The unexpected flow through the entry valve of the starboard EDT can be related with the blocking of the vent and the racket absence in the entry valve. The rupture of the EDT caused damage to other vital elements in the column including the sea water service pipe that initiating the flooding of this compartment and released gas to
and ignited explosion. (Source 1, 2, 3, Location)

40. Carson City California US – April 23, 2001 (Pipe Leaking, Refinery, USD 120,000,000/124,000,000)

A pipe segment leak resulted fire in a refinery coker unit. A report said that smoke from the fire rose to over 3,000 feet and the coker unit was shut down for approximately two months. The exact cause of pipe leakin is still under investigation. (Source, Location)

41. Rawdhatain Kuwait – January 31, 2002 (Pipe Leaking, Refinery, 4 killed,18 injured, USD 200,000,000)

A pipe leak resulted in major explosion at an oil gathering center killing four people and made 18 other severely injured. Three main facilities at the production site were destroyed. Production restored to its normal 500,000 bbl/day a month later. (Source)

42. Brookdale Manitoba Canada- April 14, 2002 (Stress Corrosion Cracking, Natural Gas Pipeline, USD 13,000,000)

A 36-inches diameter natural gas pipeline ruptured at a zone of near neutral pH stress corrosion cracking (SCC). Following the rupture the sweet natural gas ignited. Technical investigation report determined that pipeline ruptured due to overstress extension of pre-existing cracks. The cracks had initiated on the outside surface of the pipe and progressed in a mode of failure of transgranular SCC. The pipeline was constructed I 1970 by double submerged arc welded straight seam pipe by the accordance of API 5L Grade X65. (Source, Location)

43. Moomba Australia – January 1, 2004 (Liquid Metal Embrittlement, Gas Processing Plant, USD 5,000,000)

Figure showing failed HE Nozzle of Moomba Gas Plant (Courtesy of AON)

The gas was released that led to vapor cloud explosion. The gas released was caused by the failure of a heat exchanger inlet nozzle in the liquids recovery plant. The failure of the inlet nozzle was due to liquid metal embrittlement of the train B aluminium heat exchanger by elemental mercury. (Source, Location)

44. Skikda Algeria – January 19, 2004 (Liquid Metal Embrittlement, LNG Plant, 27 killed 72 injured, USD 30,000,000)

Figure showing destroyed Skikda LNG Plant

A report noted that the explosion was the consequence of a catastrophic failure in one of the cold boxes of Unit 40, which led to a vapour cloud explosion of either LNG or refrigerant. The most probable source of ignition was the boiler at the north end of Unit 40. The report concluded that the escaped gas was from the cryogenic heat exchanger. (Source, Location)

45. Humber Estuary Killingholme UK – April 16, 2001 (Erosion Corrosion, Refinery, USD 82,400,000)

Figure showing destroyed Humber Estuary Refinery (HSE UK)

On 16 April 2001 a fire and explosion occurred at Humber Refinery following the catastrophic failure of an overhead gas pipe. Investigation was carried by The Competent Authority and the plant operator company by legislative mechanism under Control of Major Hazard (COMAH) Regulation 1999. Humber refinery was one of approximately 1000 major hazard site under this regulation. The competent authority consisted of Health and Safety Executive (HSE) UK and Environment Agency (EA).


Figure showing failed elbow of Humber Estuary Refinery (HSE UK)

The cause of the piping system failure was the erosion corrosion of the 6-inches diameter pipe, known P4363, which carried the overhead line from the De-ethanizer (W413) to the heat exchanger (X452) in saturate gas plant (SGP) unit. The failure occurred down stream of a closely water injection point. Examination to the failed elbow recovered from the damage site showed wall thickness thinning from 7-8 mm to a minimum 0.3 mm. When the pipe failed it burst open catastrophically causing a full bore type of release the pipe contents.
The water injection point was not the original design of the piping system. Water injection to the vapor stream between the top de-ethanizer column and the heat exchanger was addressed to solve the previous problem of salts or hydrates fouling in heat exchanger X452/3. An injection point was created in P4363 by piping water to an existing 1 inches vent point on the pipe without injection quill or dispersal device and made the water entering the pipe as a free jet.

Similar Accident: Wilmington California United States 8 October 1992, North Rhine West Phalia Germany 10 December 1991,Yokkaichi Mie Japan 2 May 1997, Mina Al-Ahmadi Kuwait 25 June 2000. (Source, Location)


The 50 Major Engineering Failures (1977-2007) Part-1

April 25, 2008

List of Engineering Failures Contributed by Material Failures, Corrosion, Design Flaw, and Construction Defect in Oil and Gas Production Facilities, Hydrocarbon Processing, and Oil and Gas Distribution

(Part 1 of 5) – Muhammad Abduh (abduh@reksolindo.co.id)

As key chain in world energy supply, the industry within oil and gas production, hydrocarbon refinery, storage and distribution, and power plant industry strive to achieve the highest level of integrity and reliability of their facilities, structures, tool and equipment system. Industry stakeholders that ranging from oil and gas producer, engineering, procurement, contractors, material suppliers, and inspection companies from day to day improve the quality standards, discovering new tehcnologies, develop new techniques and methodologies in order to raise the engineering integrity for the improvement of safety for people , environment conservation, and securing economic investment.

Tak ada gading yang tak retak. As an ancient Indonesian proverb is also happened to engineering structure: there will be no design without flaw and there will be no construction without defect. Failures sometimes occur. In several cases the aftermath of failures have a significant impact to the people safety and economic risk. But industry gain a valuable experience each accident occurs. There always be opportunities to improve operation procedures, value perceptions, technical code revisions, and regulatory improvements.

This publication as a result of literature work is aimed is to develop an alternative engineering failure database associated with material failures,corrosion, design flaw and construction defect that lead to material failure in oil and gas production, hydrocarbon industry, oil and gas distribution network, and energy power plant.

1. Umm Said Qatar – April 3, 1977 (Weld Failure, Gas Processing Plant, 3 killed, US$ 76,350,000/179,000,000)

A tank containing 236,000 barrels of refrigerated propane at 45 °F failed at weld. Near-miss-accident a year earlier reported at similiar tank weld caused 14,000 barrels of propane released. The possible cause of weld failure was corrosion by the influence of sulphate reducing bacteria that remained inside the tank after hydrotest with seawater. The wave of liquid propane swept over the dikes before igniting a near tank contained 125,000 barrels of buthane. It took eight days to completely extinguished the fire. (Source, Location)

2. Abqaiq Saudi Arabia – April 15, 1978 (Corrosion, Gas Processing Plant, US$ 53,700,000/117,000,000)

A 22-inch pipe operated at 500 psig in gas transmission system corroded and releasing vapor cloud. The first ignition occured from a flare 1,500 feet downwind. The second ignition occured when jet whipped pipe section struck the vapor space of a 10,000 barrels spheroid tank. (Source, Location)

3. Ekofisk Norway – March 27, 1980 (Weld Failure, Offshore Platform, 123 killed)

Alexandra L Kielland Platform, a semi-submersible oil drilling platform located at Ekofisk field North Sea capsized during a storm. The platform supported by five columns standing on five 22 meter diameter pontoons. The five 8.5 diameter columns on the pontoons were interconnected by a network of horizontal bracings. The cracked bracing made five other bracing broke off due to overload, and the vertical column connected with the cracked bracings became separated from the platform. The platform subsequently became unbalanced and capsized.

The investigation showed that a fatigue crack had propagated from the double fillet near the hydrophone mounted to one of the horizontal bracing. Some cracks related to lamellar tearing were found in the heat affected zone (HAZ) of the weld around the hydrophone. Learning from this accident some countermeasures were undertaken including the amendment of the standards in for stability, motion characteristics, manueverability, watertight doors, and structural strength in Mobile Offshore Drilling Units (MODU) Code by the International Maritime Organization. (Source 1, 2)

4. Edmonton Canada – April 18, 1982 (Fatigue, Petrochemical Plant, US$ 21,000,000/33,000,000)

Vibration from the reciprocating compressor was believed causing transverse fatigue of 1/8 stainless steel instrument tubing. High pressure ethylene released causing a fire by static electricity ignition. Although the compressor building equipped with gas detection system the gas release was not accurately relayed to the control room. Automatic fail-safe valves functioned properly by blocking the flow of more ethylene which was up to 11,000 pounds of gas already released causing damage to this low density polyethylene plant. (Source)

5. Remeoville Illinois US- July 23, 1984 (Weld Failure, Refinery, 17 killed, US$ 191,000,000/273,000,000)

A vessel for monoethanolamine absorber was constructed ten years earlier with one-inch thick ASTM A516 Gr 70 steel plates rolled and welded with full submerged arc without post weld heat treatment. Just prior to rupture a 6- inches crack detected at circumferential weld and by the time operator close inlet valve crack spread to 24 inches. The area was already cleared for evacuation and when fire brigade arriving the explosion occured. This explosion created sequential fire and explosion within refinery plant. A boiling liquid expanding vapor exposion (BLEVE) occured in a alkylation unit vessel.
Technical investigation pointed that crack initiated at HAZ of welded shell of the column by hydrogen cracking, and progressed by the mechanism of hydrogen induced stepwise cracking (HISC). Test according to NACE procedure confirmed that material was susceptible to HISC. (Source 1, 2)

6. San Juan Ixhuatepec Mexico City Mexico – November 19, 1984 (Pipe Leaking, LPG Terminal, 650 killed 64,000 injured, US$ 19,940,000/29,000,000)

A 12-inches pipeline between cylinder and sphere storage ruptured. Initial blast caused a series of BLEVEs. The oustanding cause of escalation was the ineffective gas detection system and as a result of lack of emergency isolation. This explosion and fire is perhaps the most devastating incident ever. The high death toll was due to the proximity of the LPG terminal to residence complex. Until now there is no clear information about the cause of pipe rupture. (Source 1, 2)

7. Las Piedras Venezuela- December 13, 1984 (Hydrogen Embrittlement, Refinery, US$ 62,076,000/89,000,000)

A fracture occured in 8-inch line carrying hot oil from hydrode sulfurizer. Crack found in heat affected zone about 1 – 1/2 inches from weld. Hot oil at 700 psi and 650 oF sprayed and ignited at the hydrogen units. Fire causing sequential rupture of 16-inch gas line and successively blow torch to piping system in adjacent areas. Vibration analysis nine years earlier judged that the failed line was having excessive vibration and it strengthened the confidence that the hot oil line failed in fatigue dominantly due to hydrogen embrittlement. (Source)

8. Norco Louisiana- US May 5, 1988 (Erosion-Corrosion, Refinery, 4 killed, 20 injured, 4500 evacuated US$ 254,700,000/336,000,000)

An elbow at depropanizer column piping system in a fluid catalytic cracking (FCC) unit failed. A large vapor with estimated 20,000 pounds of C3 hydrocarbon cloud escaped from the failed elbow and ignited in FCC charge heater. The explosion of FCC unit was the most severe damage. A report pointed that the failed elbow suffering excessive locally thinning. The failed elbow was located downstream of the injection point where ammoniated water was added to reduce propanizer condensation or fouling.(Source 1, 2)

See also: Part 2, Part 3, Part 4, Part 5



Palembang Pipeline Leaking – Aging Pipeline to Raise Risk Exposure

April 6, 2008

Muhammad Abduh (abduh@reksolindo.co.id)

Pipeline transporting crude oil leaking on Saturday April 5, 2008. The line that served 265 kilometers TempinoSungai Gerong of Trans-Sumatran Pipeline, leaking at milepost KM 8.3 released about 5 barrels crude oil. The spill made a little environment disturbance to the surrounding villagers rice plant. Operator company had already mitigated the leaking 8 hours after the first report. Pipa Minyak Bocor di Palembang Apr-08

Fig. 1- Media Coverage of Palembang Pipeline Leaking 5 April 2008 (Metro TV, Kompas, Antara).

This leaking follows recent accidents reported in Indonesia pipelines are: Samarinda 4 April 2008 (Antara), Belawan 10 March 2008 (liputan6), Cilacap 9 March 2008 (Tempo Interactive), Tuban 21 January 2008 (Metro TV), Grissik-Singapore Subsea Pipeline 2007(Antara), Karawang 16 November 2007 (Antara), and Surabaya 24 May 2007 (Antara)

The leaking pipeline which was constructed in 1983, according to an authorized company man, reported to have a corrosion problem. Previous pipeline leaking from this area were reported in Sukarami March 4, 2004 and in Pangkalan Balai October 29, 2004. These pipeline accidents occurred in high consequence areas in the proximity of villagers rice plants and residential.

Pipeline Failure Consequence

Pipeline failures sometimes lead to significant impact to economic, environment, and human safety:

1. The Prudhoe Bay Oilfield Shutdown to shock United States Oil Production; 2. Oil tapping from leaking pipeline in some African nations to cause large fatalities; 3. Guadalajara Fuel Pipeline Explosion to create tremendous fatalities and infrastructure damage; and 4. Ghiselenghien Gas Pipeline Explosion to cause business interuption cost in a Belgium industrial park.

Figure 2 – Adeje and Lagos 2006 Pipeline Explosion Nigeria (National Geographic, 26 December 2006)

Figure 3- Pipeline Explosion at Ghislenghien Industrial Park Belgium 2004 (emergency-management.net)


Aging Pipeline and Risk Triangle

The pipeline accident in an aging system is likely to occurred. Global pipeline accident record summarized the cause of pipeline failure as follows:third party damage (31%-50%), corrosion material and construction defect (32%-41%), unknown and unclassified causes (6% – 25%). Muhlbauer risk triangle can be suggested to examine the probability of pipeline failure. The probability of failure is governed by three variables: exposure ,resistance, and mitigation. Aging pipeline raise the possibility of failure due to corrosion growth with time. Expanding line or unmaintained right of way raise the possibility of failure associated with time-independent third party damage.

Figure 3 – Muhlbauer Risk Triangle

The risk triangle proposed that to keep probability of failure constant or within acceptable limit, pipeline operator should raise the effort to mitigate the risk from pipeline aging with time and exposure to third party damage. These can be done by: 1. Intensively monitoring and assessing the pipeline condition; and 2. Performing more extensive public awareness program.

Pipeline Integrity Standards

Several integrity standards for pipeline (API 1160 for liquid, and ASME B31.8S for gas pipeline) has already provided systematic procedures for enhancing the integrity of pipeline. The guidelines cover: High Consequence Area Identification, Integrity Assessment (ILI, pressure testing, and direct assessment), Risk Assessment, Anomalies Classification, Repair Method, and Mitigation Option.

The Toolbox for Pipeline Integrity Program

1. Pipeline Risk Assessment one pioneered by Muhlbauer

2. Pipeline Inline Inspection (Intelligent PIgging)

3.Corrosion Direct Assessment several methodologies drawn for standards by NACE (external corrosion, internal corrosion, and stress corrosion cracking)

4. Several emerging non destructive inspection technique including long range UT, multi array sensor and field signature method.

The emerging methodologies and technologies for pipeline should be taken as an opportunity to raise the level of the integrity of pipeline and raise safety for people and environment.


Corrosion and the Shutdown of Alaska Prudhoe Bay Oil Field

March 27, 2008

Muhammad Abduh (abduh@reksolindo.co.id)

Nation biggest oil field of United States was shutdown after an indication of severe pipeline corrosion. The Trans-Alaskan Pipeline is one of the world largest oil pipeline. The line that is known for it zig-zag pattern to allow thermal expansion and earthquake movement. The pipeline was designed to allow 5 feet of vertical movement and up to 20 feet laterally. The pipeline which cost about USD 8 billion to build sits on top of 78,000 aboveground supports spaced 60 feet apart.
prudhoe-bay-pipeline-network.jpg

Figure 1 – Prudhoe Bay Pipeline Network (Source: USA Today, BP, EIA, CSI)

The sections aboveground are insulated and covered. Build in the 1970s after oil discovery at Prudhoe Bay in 1968. The pipeline is 48-inch diameter, 800 mile of line links Prudhoe Bay on the Arctic Ocean with a terminal at Valdes, the ice-freeport within the area. This pipeline serves Californian and some US West Coast Refineries, which accounts for roughly 20 percent of US oil annual production or 2,6% US national supply or about 400,000 barrels per day.

Trans-Alaskan Pipeline
Figure 2. Trans-Alaskan Pipeline

Oil spill was reported in March 2, 2006. US Department of Transportation ordered smart pig inspections responding the leaking report. The inspection record noted that the steel had corroded in 12 places on the eastern side of Prudhoe Bay up to 70-81% orginal thickness which was less than company standard. According to the company corrosion authority, the pipeline was designed for 25 year and at the time of leaking the pipeline was 29 years lasted. Company spent to fight corrosion USD 72 million at the year of leaking and USD 60 million previous year. The effort, according to the company man including corrosion inhibition, X-Ray runs, and ultrasonic tests.

Reference

1. BP: Pipeline shutdown could last weeks or months (USA Today)

2. BP to Shutdown Prudhoe Bay Oilfield (BP Global Press)

3. BP’s Prudhoe Bay Pipeline Shutdown Could Continue into Next Year (Guardian UK)

4. Oversight Hearing on BP Pipeline Failure (PHMSA DOT US)