Jamaica Energy Partners Doctor Bird Power Plant Engineering Report. Report No. 20140228-DG2_FR

DG #11 Failure

September 2013

Prepared By: Carlos Mohan

Executive Summary

Prior to the failure on Saturday September 08, 2013 at 0111hrs, DG#11 was taken offline to investigate and correct high cylinder liner temperatures on cylinders A2 and A3. The cylinder liner, piston and cylinder head were all replaced.On the morning of the failure, (September 08, 2013) unit was started at 0151hrs and began its running program. During the running-in program, at 20% loading, the unit experienced a catastrophic failure where cylinder A2 and B2 connecting rod and counterweight became separated from their respective cranks and exited through both sides side of the engine block.The failure resulted in extensive damages to the engine block in the cylinder liner, crankcase, tappets and camshaft areas, and a fire that caused severe damages to engine instrumentation system and control wiring for both DG#11 and DG #10, the engine room fire detection system, instrument and power cables for common engine support systems, and the two engine hall gantry cranes.The inspection and assessment of the failed components and a review of the operating data, trends and statements and interviews with personnel who were directly involved in the maintenance and operations work were carried out. This revealed that the root cause of this failure came from a combination of human and latent causes.

In order to reduce the likelihood of future failures, the following were recommended:1. Address the latent root cause of this accident by implementing and enforcing a handing over procedure for all shift personnel.2. Work orders should have clear close out comments at the end of a shift, and that personnel continuing with the same job along with the shift supervisor review these comments before continuing.3. Adherence to maintenance procedure MMP-11(Quality Assurance/Quality Control Section 3-A-1 QC/QA procedures) should be enforced.

IntroductionOn Sunday September 08, 2013 at 0149hrs DG#11was started and shutdown due to low HT water pressure, the unit was restarted at 0151hrs and synchronized at 0155hrs. The unit was at twenty percent of its running-in program at 0217hrs (3.415MW) when a loud grinding sound was heard followed by a loud explosion and a huge fire from the engine, the unit was immediately emergency stopped by the control room operator, DG#9 was also emergency stopped ( DG#10 was offline for maintenance work). The engine experienced catastrophic damages in the area of the A2 and B2 drive train and engine block area. The connecting rod and counterweight for both cylinders became detached from their respective crank and exited the side of the engine block, the resulting fire from the accident resulted in severe damages to the instrumentation and control system wiring for both DG#11 and DG#10 A-bank along with the plants fire detection system and the two engine room gantry cranes.

Investigative ActionsThe objectives of this investigation were to identify the cause of the failure of the connecting rod and counterweight fastening mechanism for cylinder A2 and B2, and to provide recommendations to prevent a recurrence of this kind of failure.The investigation examined the three main possible areas of the failure roots namely, Physical, Human and Latent roots, the investigative actions taken were:1. Analysis of the DG Set operating trends to identify if there were any abnormal operating conditions that could have contributed to the failure.2. Thorough review of written statements of submitted by Operations and Maintenance personnel who were directly involved with the unit during the period of maintenance custody and the period of startup by the Operations personnel prior to the failure.3. Examination of the failed components, particularly the fracture faces of these components, with the aim of identifying the nature of the forces involved. Determining if there were possibly defects in material that precipitated the failure. In the absence of laboratory type equipment to perform full metallurgical analysis a fair degree of accurate determination was able to be arrived at.4. Analysis of the DG Set operating trends to identify if there were any abnormal operating conditions that could have contributed to the failure.

Findings

The following were the findings from the different aspects of the investigation:1. The written statements submitted by plant operations and maintenance personnel revealed that there is no standard procedure driven protocol that exist that governs the way jobs are handed over from on shift to another. Interviews carried out further revealed that the techniques employed for the handing over of jobs vary across shifts.

2. There were no consistency in updating the comments in the work orders by shift personnel at the end of their shift, and there were no enforcement on the path of the shift supervisors to ensure that this is done.3. Examination of the trends for the different engine operating parameters did not reveal any abnormalities; they were consistent with normal operation of a unit leading up to the twenty percent point in a running-in program.4. The practice of not running a nut onto a stud to its full threaded run without carrying out any immediate plan to carry out tensioning of that stud was not done. This was left for relieving shift to be done for cylinder A25. Shift supervisor for the afternoon shift to which the day shift handed over to failed to ascertain and communicate the total status of the work being done on the DG set, this led to his Mechanical Technicians taking over the job making their own assessment and assumptions of what was completed and what was outstanding.6. Physical examination of the failed connecting rod studs fractures revealed with a fair degree of accuracy that the four studs from the A2 cylinder failed from fatigue, which could most likely be due to under tensioning, the studs from the cylinder B2 displayed signs of plastic deformation at point of fracture. Only three of the total of four counterweight studs from the two cylinders, A2 and B2, were found and the examination of these indicates that they possibly failed as a result of mechanical impact to the counterweight.

AnalysisThe deformation of the studs for the connecting rods and counterweight were carefully analysed with a view to determine the cause of failure, connecting rod studs for cylinder A2 showed signs of failure consistent with fatigue, those however from cylinder B2 showed signs of failure from impact.The counterweight studs failure faces were all consistent with that caused by external mechanical impacting forces.The displacement of the cam section for cylinder A2 occurred as a result of one of the counterweight exiting the engine coming in contact with it.The A2 connecting rod studs may not have been tensioned as per specification, and thus initiated the failure, the result of this been a detached A2 connecting rod from the crank that gave way quickly and coming in contact with connecting rod and counterweight for cylinder B2. The forces involved in this collision coupled with the level of unbalance on the crank may have caused further failure of the A2 counterweight.

ConclusionHaving analysed all available data and information pertinent to the failure of Diesel Engine #11 drive train A2 and B2 against the three main possible areas of failure roots a number of anomalies were identified, the possible physical root contribution when analysed revealed that the actual failure mechanisms for cylinder B2 and A2 counterweight were all externally drive, while that of cylinder A2 connecting rod studs were human induced and did not point to any defect in the material.For the human root, the investigation concluded that there were inappropriate human actions that contributed to the failure. The failure investigation as far as the Latent root revealed that anomaly as far as non-adherence to procedure and the lack of other relevant procedures to guide and control the flow of effective communication existed.This investigation concludes that the root cause of this failure was a combination of human and latent causes.

Appendix

Historical Trends

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Failed Components

Failed counterweight studs

Remainder of stud in main bearing housing

Statements

INCIDENT REPORTNAME: Gregory BartleyDATE: September 07, 2013TOPIC: DG #11 A2/A3 Drive Gear Failure

When I took up shift at 1600hrs from Newton Burke, I was made aware of the status of the plant inclusive of the work been carried out on DG #11, the list included Investigate reported high liner temperatures on A2, A3 Change A-Bank charge air compensator (bellow) before turbo compressor Repair oil leak at A2 crankcase door relief valve Change O-ring on the rocker box covers and hand wheels Investigate and correct cause of B-bank turbine wash failure Lubricate fuel pump racks; grease control arms and linkages Replace B6 straight pipe Replace A8 vertical exhaust gas bellows Inspect and service instrumentation motors and controls on lube oil separator unitI was then told of the work that was conducted, which was that both A2 and A3 liners were replaced, A2 piston replaced and torqued, A8 vertical bellows was removed but not replaced, was then told that none of the other works scheduled for the morning shift was attempted, then I called Phillip Martin informing him of the work to be done just in case he saw Troy Simms before I did.I then read the shift summary and proceeded to the change room where I saw mechanics Ricardo Newsome and Garron Palmer getting ready to leave I told them they should not leave as the scope of work left to be completed on DG #11 is a lot, for it to be returned by midnight, they insisted they had to leave.Mechanic Michael Morris was the only one I saw at the time for the present shift so I told him to proceed to DB2 DG#11 where there is an A8 vertical bellows to be installed, he then left. I then went in search of Stefan pitters whom I was told was working on ALOF #1, I found him and told him that he should proceed to DG #11 to render assistance I also made my way there, on the way I met Troy Simms where I informed him of the work to be done including replacing A3 piston and cylinder heads for both cylinders along with pressure testing of the injectors, I also told him that I would be seeking assistance for the completion of the job, Craig Bernard the fourth of the mechanics was present from the earlier shift working along with R. Newsome and G. Palmer and continued through to the present shift.I then got back to the office and made a call to the maintenance supervisor Giovanni Valentine informing him of the situation he then told me he would call out Martel Lynch and Miguel Gordon he later called back to say he got them and they will be coming in, M. Gordon arrived and called I then made my way to the stores to facilitate the location of the parts needed for the job, I then made my way to DB2 where I did a sump clearance on DG #11 after the cleaning of the sump was done on this shift no foreign particles found I then instructed the control room operator Phillip Martin that when the HT pipe work was completed then water should be added a liner underside inspection done and then lube oil can be addedAt 2200hrs I handed over the shift to Dawin Brown with most of the work from prior list completed save for the completion of the A-Bank charge air compensator (bellow) which was far advanced.