Duvha powerstation turbine blowup: SA

Duvha coal-fired turbine exploded because of ‘operator error’ – finding:

  • Update Nov 25 2011 – The Duvha coal-fired power station’s turbine explosion happened because of an ‘operator’s fault’ which caused a 600 mW shortage, the investigation into the accident has revealed:  link: 

  • We already revealed this information in February 2011, based on a from a well-informed, close observer of this photographed turbine-explosion at the 3600MW fossil-fuel power station in Mpumalanga. The source wrote:“They were doing a test of the turbine overspeed protection system, and in short, the protection did not kick in. Conventional wisdom tells me that there should be a better way to test a protection system than to try and destroy the turbine and see if it feels like protecting itself, but that’s basically what they did. “…

“The turbine has a governor valve which controls the amount of steam coming into the turbine In order to keep it running at the right speed (3000 rpm for our grid frequency) and then it has a main isolation valve to shut the steam off completely. The protections systems (of which there are 3 independent systems, and a dude with his finger on the emergency button) are supposed to close this main isolation valve in a fraction of a second when the turbine overspeeds.

DUVHA coalpowerstation SA UNREPORTED ACCIDENT TURBINE1
TESTS OF 3000 RPM TO 4500 RMP OVERSPEED, all three systems failed – yet the guy who was supposed to push the manual-trip button wasn’t even at his post…

“So they get ready for the test, they dump a helluva lot of steam onto the turbine, speed starts going crazy, it went from 3000 RPM to 4500 RMP in ten seconds (they are generally only designed for 10 to 15% overspeed, all three protection systems should have kicked in by the time you get to 110%). Anyway, I don’t know why, but all three systems failed, and the dude with his finger on the manual trip button wasn’t at his post. So the result was a big bang, some fire and a lot of steam going where it shouldn’t go.”

DUVHA coalpowerstation SA UNREPORTED ACCIDENT TURBINE roof ———–

DUVHA has a shared turbine hall… all six units neatly placed in one long line without missile shields in between…

Scary thing is Duvha has a shared turbine hall. (picture below). All six units are placed in one long straight stripe, with no missile shield between them. And if you look at the third last pic you can see how big that shaft is, if that landed on another turbine it would have destroyed that too. They are very lucky they didn’t lose the entire station.” So anyway, what gets reported in the news? “Unforeseen maintenance” at one of the units at Duvha requires it to remain shut down for 18 months.” …  understatement of the century in my book. “

DUVHA coalpowerstation SA UNREPORTED ACCIDENT TURBINE DESTRUCTION

BELOW IS THE OFFICIAL SA GOVERNMENT VERSION OF EVENTS:

  • ‘Repairs to Eskom’s Duvha Power Station to Take Time”
    February 11, 2011 – Eskom has warned that a unit which burst into flames this week at Eskom’s Duvha Power Station during a routine test will take extensive time to repair. Eskom spokeswoman Hilary Joffe said Unit 4 of Eskom’s Duvha Power Station was “damaged last night in the course of a routine test. No one was injured but the unit is expected to take extensive time to repair,” she said. Joffe said the other five units of the 3,600 MW Duvha power station were running normally and the national grid remains in ‘green’ status, meaning that Eskom is generating enough power to satisfy the demand in the national grid. The incident happened when the 600 MW units at Duvha had been taken off load to perform a required turbine test.“This is a statutory test that is carried out in every power station. In the execution of the test, the protection of the unit failed, causing severe mechanical damage and starting a fire, which was brought rapidly under control by the power station’s fire team,” said Joffe. Eskom have since launched a “technical review “ of the incident. Eskom’s divisional executive for power-generation, Thava Govender, said: “The technical review is aimed at finding the cause of the unit failure, so that we may take appropriate action to prevent similar incidents in future.” Source: Nthambeleni Gabara at BUA News agency.
    http://www.netnewspublisher.com/repairs-to-eskoms-duvha-power-station-to-take-time/

About Adriana Stuijt
Retired South African-Dutch journalist formerly Sunday Times Johannesburg

37 Responses to Duvha powerstation turbine blowup: SA

  1. Just another example of how ESKOM continually lie to the paying public. You can bet your bottom dollar that nobody from the guy who had his finger up his @rse to the supervisor to the ops manager to the power station manager will be held accountable.
    This reinforces the public feeling that ESKOM should not be granted tariff increases as all it does is perpetuate a level of incompetance that is unpresedented in it’s history!

  2. Obi Wan Kenobi says:

    Massive Weapon.

  3. Bob says:

    I have seen these overspeed tests conducted before. There is an electrical and mechanical overspeed bolt on the turbine which are independant and designed to shut off the ESV (Emergency Stop Valve)when the turbine gets to about 3200rpm (electrical) and 3300rpm (mechanical). The guy with his finger on the button is the most important link here. Nevertheless – the trips are supposed to be independantly tested BEFORE the turbine is put into an overspeed condition to verify that they work. Clearly this was not done. As for the dude who was supposed to be at the manual trip button but wasn’t (sleeping maybe) is just plain stupidity, gross negligence and incompetance. Surely there should have been a verification that the guy had his finger on the button before the test was started???

  4. Daan says:

    Ek onthou ‘n soortgelyke insident by Koeberg toe daar ook n bout foutief was, en ook ‘n paar jaar gelede ‘n insudent by mosgass (Petro SA) waar)’n verkeerd klep oopgemaak is met so ‘n R45000000 ontploffingkie tot gevolg, Seker ook ‘n moer wat nie op sy plek was nie.! Waar was die moer wat hier in beheer was? Net so ‘n klein ongelukkie. Dis maar soos Afrika lyk , en as die nie vir ons was nie sou daai turbine nooi herstel word nie, net soos in Afrika. Alles wat breek word netso laat vaar. En dis n suurdeeg wat regdeur werk, kyk maar net hoe lyk munisipale water, paaie en rioolwerke, Alles is stukkend, “het gebreek” “ons wag vir goverment funds om reg te maak” So gaan dit ad infinitum. Wat soek sulke onbevoegde mense in beheer van sulke belangrike en duur toerusting?

    • croix says:

      Net die ‘pay’, Boet – net die ‘pay’.

    • Ouboet says:

      Ek wonder wat soek wit ingenieurs wat sukkel om werk te kry nog in die land. (Miskien is hulle bang ons maak dit reg en dan moet hulle ons werk gee?)

    • Johan says:

      Dit is vir my pateties indien dit waar is dat die operateur nie op sy pos was nie.Tydens enige toets op enige aanleg is dit van kardinale belang dat daar ‘n bevoegde paneel operateur is. In elk geval,tydens normale bedryf moet die gogga ook daar wees.

      @Daan- Los maar liewer die Mossgas voorval. Daar was nie ‘n verkeerde klep oopgemaak nie. Die regte kleppe was in bedryf gestel maar die aanvanklike gas/suurstof mengsel was nie van so ‘n aard dat ontbranding normaal kon plaasvind nie. Toe die korrekte balans gevind is was die toerusting met ‘n te groot gasmengsel gevul met die gevolg dat ‘n ontploffing plaasgevind het.O ja,die moer was op sy pos en het gereageer op wat die beheerpaneel se informasie oorgedra het!

  5. Wallace Cleland says:

    In the 60’s Kariba Power Station had an overspeed incident on one of its 120 meg.watt turbines.It was quite frightening.Fortunately the turbine operator managed to do the right thing to get the guide vanes closed quickly to the turbine and thus slow it down.The shaking and vibrations cause staff in the hall to head for the lift and road access in a stampede.

    I find it quite frightening thinking of a 600 meg.watt machine running away as you have describe here!

  6. Steven says:

    Dear Adriana Iread everything in the newspaper and have no comment about the accident.I would like to be part of rebuilding the plant, but need the name and fax number of the elecrical contractors please. Steven 0729410941

  7. Louis says:

    Worked for Eskom a number of years.Things changed,used to be one of the safest companies in SA

  8. Dave Houghton says:

    What a bunch of *ankers

  9. HENDRIK LODEWYK LOOTS says:

    Wys jou net het ook shutdowns vir eskom gedoen maar dit het te gevaarlik geword mense in beheer weet nie wat hulle doen nie

  10. croix says:

    No need to invest in new aircons then ??? Shame! It took but a minute to sort out the ‘airflow’ and it is permanent – without the need for any silly future maintenance! Absolutely brilliant!! I’m sure this will mean a reduction in Escom tariffs very soon?

  11. Andre says:

    Heng man dis jammer om my Unit so te sien. Ek was U4 B&I Eenheid Tegnikus gedurende die middel 90’s. Ons het altyd gespekuleer oor die soort van ding, maar ek moet se dit lyk erger as wat ek gedink het dit sou lyk.

  12. Ant says:

    Why should we have to fit the bill for gross incompetence. Surely Eskom has insurance in their equipment. Insurance should pay out, not the consumer. Or are they going to hide the fact that they insured, get the cash, then run off to Parliament to beg for a higher increase to fit the bill? (FRAUD!)

  13. TheRatKat says:

    insurance what insurance …. the operator was not at his post so no insurance payout … like everything else in this country …they are destroying it all ….so much for BEE and AFFIRMATIVE ACTION ….no more people with qualifications to do the right thing …. WELCOME TO THE NEW SA….. ALL YOU PEOPLE THAT VOTED FOR REFORM NOW YOU PAY THE PRICE …….

  14. P.Wilkinson says:

    Let job competence be paramount in employment choice, while addressing BEE quotas in a more evolutionary manner.
    No South African can afford the cost of these disasters!
    Let us not destroy the established infrastructure of our society in pursuit of social and financial “equality!”

  15. lamha says:

    When they built the turbine they probably couldnt be bothered to install the electrical or mechanical saftey devices, and the clown who was supposed to be manning the safety button was probably asleep like the rest of EFKOM. The entire Dhuva staff should be fired and replaced with real people!

  16. Shakiraj says:

    politics should not be involved in the incident. No one has the right to assume what the cause of the accident was unless they were directly involved in the accident or investigation. By the way this is not the only power station with a shared turbine hall. Please also remember that if there is an increase in electricity rates , that all management and employees of the station will be affected too.

    • Who posted this message? – registered name: Shakiraj IP: 82.145.210.143 z19-16.opera-mini.net
      E-mail : S.jappie@hotmail.com
      82.145.210.0 through 82.145.210.255
      Kuwait, Al Kuwayt

    • Now why would any person sitting at a fake address from Kuweit be posting a warning that ‘politics should not be involved’ in the horrendous blow-up described in the article above? The discussion at hand has nothing to do with politics – the engineers and ex-engineers who are commenting on this accident are commenting about the engineering and mechanical aspects of this explosion. Wonder who this mystery-person would be who seems to be wanting to steer this discussion away from the mechanical discussion?

    • roger says:

      give it to a black man

  17. shakiraj says:

    not sure whats up with the address but i live in south africa. My problem is not with the article but with the comments people have posted. How can someone just assume that every employee in eskom is incompetent. I have no intentions on steering away from the topic at hand. Dont get me wrong everyone has the right to their own opinion but it just disappoints me how one minded some south africans are…

  18. Theo Taylor says:

    Hi!
    What can an ordinary south african do to get the goverment to realise that they are basically destroying the country for all south africans and they need to urgently change their polocies?
    Regards.
    Theo

  19. Exzanian says:

    The burning question here is who exactly the operator was or was supposed to be? The Maintenance Engineer was heavily dependant on him/ her and no doubt the duty roster was checked and the Engineer satisfied that so and so had in fact clocked in…(I’ve scoured the net fruitlessly without any result. This story, if not muffled, does not have the lead one would expect given the enormity of the disaster) One has the sense that this will simply dissapear into the ether as so much else in SA nowadays, leaving the poor compliant tax payer dumbly forking out yet more of their hard earned money.

  20. Keith says:

    I was wondering if the person who left the bolt in the turbine in Kooberg was possibly banished ( and probably promoted…) to Mpumalanga and then decided to show his skills there????

    Its diheartning to see incompeternce wrecking infrastucture like this. To the really competant people still in escom, it must be extremely frustrating too…

  21. Fazal Abdool says:

    Where was the manual shutdown push-button located relative to the machine? Would the Operator have been exposed to the shrapnel from a turbine overspeed if he was standing at the push-button location? Did the procedure involve using a small manually operated bleed valve across the closed manual isolation valve to limit the maximum steam flow into the machine? Once the machine inertia is overcome, the manual block valve is left throttled, and steam flow slowly increased via a manual trim valve across the manual block valve. This would limit the maximum speed attainable by the turbine, and would avoid a runaway condition, as energy supply would be limited by the bypass valve position.

    • Manfred Hofmann says:

      Good Question, “where was the emergency push button?”
      But: If the “shrapnels” flying it’s to late to push any button.
      Example:
      Grootvlei P/Stn., Unit Nr.1 commissioning and hand over.
      As a Supervisor the execution of Quality & Safety on the electrical/C&I side was my responsibility.
      On the Turbine pedestal the stop button was installed before the turbine cover was mounted. this was done and the switch disappeared under the cover. Before that happened I issued a “non conformance” report, but to no avail. As a Master electrician (degree from Germany) one should think I would know the job.
      I did not sign the relevant paper, but good enough for the new Efkom people.
      The solution was simple:
      A square hole was cut in the cover to reach through with the hand ! — If the Operator could see it !—
      My general impression after some talks with some operators is that 80 % are not received -in my humble opinion – the utmost proper training and therefore not qualified enough to take important decisions to press any buttons !
      PS:
      In spit of a crippling shortage of (skilled or experienced) manpower e.g. Medupi & upcoming Kusile P/Stn’s I am since 2 years unemployed, – because I am ….. – ? / uncomfortable ? for some of the new bosses ?

      • amazing description. Most enlightening. Thanks Mr Hofman. I hope you are thinking of finding a job in a country which appreciates your skills and does not judge you by your skin colour. There are lots of job-ads for Master Electricians with a degree from Germany on websites all over the world.

  22. MrCyberdude says:

    It’s all guess work as to what happened without an official report, But I’ll give my 2cents worth.

    A requirement before all this normally happens is to ensure a string of checks are done and some basic checks are as follows in no particular order.

    1. Confirm the governors and emergency stop valves isolate or at least open and close fully.
    2. Remote control room operation of trip solenoid which trips the oil system that holds the spring stop valves open.
    3. Local operation of the hand trip which mechanically trips the same oil system.
    4. Mechanical overspeed units are bench tested and operate at 3000 +10% nominally ~3300. At no time is the Turbine speed to exceed 3400 under the assumption of maybe it will work with just a few more rpm.
    5. Ensuring the turbine does not increase in speed when the turbine control oil system is charged as steam admission is an obvious indication of passing emergency stop valves. This is prefered to be checked by slowly charging the boiler main steam legs via a smaller bypass if possible.

    If any of the turbine speed governor valves were passing badly and there were no emergency stop valves then this is also a recipe for disaster.

    All of this is also not a guarantee that any mechanical trip will work as I have seen these working only to find when doing the actual overspeed testing that the turbine pedestal block that they were attached to did not have the holes drilled in them to allow an oil flow path to the trip bolts.

    One old tried and tested way to do these tests normally involves using a small manually operated dead mans hand clamp with a fine screw valve on top. This allows governing oil to be finely adjusted at the front end of the turbine where the mechanical overspeed bolts are normally located and if the trigger is not held in the turbine steam admission valves cannot be opened.
    This of course could be manipulated if there is inadequate understanding, training or lack of safety culture. i.e. someone ties the dead man’s switch closed. This job is normally given to someone that fully understands the responsibility in hand (literally) and requires that there be a very visible live speed (not dampened) indication directly in front of the operator whose sole job is to control the speed. There is also another operator required to operate the mechanical hand trip lever if needed which directly isolates and drains the governor and emergency stop valves oil system.

    The entire overspeed procedure should be clear and concise and outline specific responsibilities of designated personnel and these people should not have more than one responsibility at a time.

    While I have read quite a few comments here about the operators being at fault which may be the case, more often than not in my experience these types of monumental mistakes like Chernobyl, Sayano–Shushenskaya, Fukishima and the like are cause by engineering design and engineers not being familiar with operating procedures, but most often by management taking shortcuts from manufacturer operating and maintenance instructions and lack of real industry training. All this smothered in a thick multi layer of budgets excuses.

    Owners are often very quick to blame operator error as they are often insured for exactly that. The absence of any official report (I haven’t looked to hard) floating around the ether-net gives the impression of major engineering input and resultant turbine blade output. :(

    MrCyberdude.

  23. NamaDirk says:

    I am waiting for Koeberg to blow up. It nearly did about two years ago. The “Seer” Niklaas van Rensburg has seen such events as princess Diana murder, Brett Kebble’s murder etc etc. No reason why his vision of Koeberg destroying the bay area will not come true. I don’t look forward to it nor relish it.

  24. Andrea says:

    My dad worked for Eskom for many years and he had some inside info:
    The guy who was supposed to be manning it was indeed a BEE position.
    The guy went on a tea break and was not at his post
    The emergency button is connected to a computer mainframe several meters away, behind glass.The ‘emergency button’ could have been pushed but: The computer was not even connected to the turbine, therefore no emergency button was available.
    There was insurance cover paid, but due to negligence not payable.
    This is the reason they say ‘human error’
    My dad is 83 year old and he is being asked to come in again to advise, as no one seems to know what’s going on, except for his old pre- 1990’s colleagues.

  25. TSETSE FROM SHONGOANE 1 says:

    At some points,we have to ensure that all people given responsibility are declared competent and are good to perfom accordingly so that we can avoid such incidents

  26. JC says:

    This incident actually happened Jan 08 2003, a turbine blade in the low pressure section failed.
    while running at 3000rpm.

  27. JC says:

    I guess not, this one happened in 2011. Wow two blown turbines in 10 years.

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