Ep 47 Piper Alpha

This week we have a very special guest. Alonzo joins us to talk about Piper Alpha. A deep sea oil rig (5:35) exploded and sank over the course of 80 minutes (7:50). There were alot of failures that led to the explosion (28:00), some of which we may still be learning.


Piper Alpha

Episode Summary

Hi and welcome to Failurology; a podcast about engineering failures. I’m your host, Nicole

And I’m Brian. And we’re both from Calgary, AB.

We also have an extra special guest joining us today, Alonzo, who is also an engineer in Calgary .

Hi everyone, happy to be here!

Alonzo, can you tell us a little bit about yourself and your history with Piper Alpha?

I am a Geomatics Engineer with an energy company here in Calgary. How I got to know about the Piper alpha disaster is that about 5 years ago I was asked to do a safety presentation for a cross disciplinary group at my company. I do talks on a semi-regular basis. Now, this team was creating a very important process and I was asked to start that meeting with a talk on an incident where the process was poorly executed. And that is how I came across piper alpha. Piper alpha is a sad reminder on how a flawed and poorly executed process can have disastrous consequences. So it was especially relevant to that team on how important a well thought out and properly executed process is necessary to ensure a job is done safely. Especially in the energy industry.

Do you mind if we share a link to your presentation in our show notes?

Of course. I actually updated the original presentation for Failurology and your audience.

Excellent! Thank you. The presentation includes some maps and visuals that are really helpful to understand where everything was in the North Sea. We will throw a link in the shownotes.


As always, we do want to take a second to thank our Patreon subscribers! For less than the cost of your university calculator, you can hear us talk about more interesting engineering failures! That’s right, just $5 a month for double the content, including more train and plane tangents. We even did an extra bonus episode on the harrowing tale of Trans American Flight 209 that was featured in the 1980 documentary Airplane!.

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Before we get to the failure, I do have something I want to plug. European listeners, I will be in Dublin presenting at ShipItCon on Friday September 2nd. Yes, in person, presenting, on software related engineering failures.

Now on to this week’s engineering failure; the Piper Alpha.

  • An offshore oil platform in the North Sea 190km NE of Aberdeen Scotland in 144m of water

    • Built as 4 modules separated by firewalls

    • The initial layout had the most dangerous platform operations taking place furthest from personnel areas.

  • Operated by Occidental Petroleum (Caledonia) Ltd and began production in 1976

    • The operation was a joint venture of four companies who obtained an oil exploration license in 1972. They discovered the Piper oilfield in 1973.

    • They started with 250,000 barrels per day and later increased to 300,000 barrels per day

  • It was initially used as an oil platform, but converted later to add gas production in 1980 - this conversion is important for later so keep it in mind. Nicole, tell us some more about Piper Alpha and the platforms that were operating in the North Sea.

  • There were three platforms from Piper, Claymore and Tartan oilfields which were connected to the Flotta oil terminal via a series of pipelines.

    • A pipeline ran from the Claymore and Tartan rigs to Piper Alpha

    • And then a 750mm pipeline ran 206km from Piper Alpha to Flotta

  • In late 1988 the rig was undergoing major construction, maintenance and upgrade work - it was not processing gas at this time, only oil


  • Evening of July 6, 1988

  • Deadliest offshore oil industry disaster to date - one of the costliest man made catastrophes ever

  • Of the 226 on board, 167 men died

  • Cost 1.7 billion pounds (3.4 million USD), not to mention that Piper Alpha was 10% of North Sea production. So if you add in the loss of tax revenue, the cost is even greater.


  • July 6 - 12-6pm - Worker took out a pressure safety valve for liquid natural gas pump A for routine maintenance. The pump was one of two pumps that displaced the liquid natural gas for transport to the coast. He couldn’t finish the work before shift change at 6pm and filled out a permit stating the pump could not be activated.

    • Place a blind flange (flat plate) on the open ended pipe - hand tightened only

    • He didn’t tell anyone on the next shift (which was common on Piper Alpha) and somehow that no copies of that permit, #23434, were ever seen by the next shift - important to note that the valve and pump were in different areas so it wouldn’t be immediately obvious to someone standing at the pump that the valve was missing

    • Permit for the safety valve was never seen by the next shift

  • 7pm - fire fighting system is put under manual control - had an automatic system that was controlled by diesel and electric pumps - the diesel pumps sucked sea water in to fight fires, and since divers were in the water at the time, the pumps were turned to manual mode to protect the divers.

    • There were 4 intakes for these pumps that were at the 40m depth level and included caged intakes - even though turning them off was a part of the safety protocol, they weren’t seen as a risk to divers unless the divers were within 3-5m of the intake

    • An audit completed before the explosion recommended the procedure be revised to leave the fire fighting system in automatic mode unless the divers were working close to the intakes, rather than going to manual anytime divers were in the water, which was 12 hours per day.

    • The nearby Claymore platform had adopted this procedure of only changing the fire fighting system to manual when the divers were close to the intakes.

  • 9:45-9:55 - pump B is blocked - the power supply of all construction depended on this pump.

    • Workers went through maintenance documents to see if they could start pump A, but they didn’t find the valve permit

    • From what I read, it seems like they did actually look for permits. They didn’t just open the fridge and look for 2 seconds and decide there was nothing to eat.

  • 9:55pm - pump A is restarted and the hand flange doesn’t hold and gas starts spewing out at high pressure, drawing attention and triggering alarms, but it ignited and exploded before anyone could react.

    • The explosion blew through a firewall made of 2.5m x 1.5m panels that were bolted together. One of the panels ruptured another liquid gas line and created another fire

    • Piper Alpha was designed for oil production not gas and the firewalls were only designed for oil fires and couldn’t handle the gas explosion

    • The conversion also broke the safety protocol of keeping dangerous operations furthest from personnel areas

    • A production first mentality and negligent safety culture meant they never retrofitted the walls for gas operation

  • 10:04pm - The control room and radio room were next to the production modules and evacuated shortly before they were destroyed. There was no protocol for an emergency without the control room.

    • First explosion knocked out electricity which also knocked out alarms, lighting and the PA system

    • The fire suppression was in manual mode and had to be operated from the control room which was evacuated. The gas alarms didn’t function properly.

    • The rest of the crew were not warned of the unfolding disaster, costing them valuable time to evacuate safely.

  • 10:05pm - nearby search and rescue stations were alerted and a plane and helicopter set out for piper alpha

  • 10:06pm - The fire ruptured another pipe in another section and 1200 barrels of oil spilled onto the deck and ignited almost immediately creating a black plume of smoke.

    • The smoke prevented a helicopter from landing and from people reaching the lifeboats. Smoke killed a lot of the men that night.

  • 10:20pm - the tartan gas line ruptured at Piper Alpha - a 19km 450mm diameter gas pipeline connecting Tartan Alpha (another offshore drilling platform) to Piper Alpha

    • This released 10-30 thousand square metres of highly flammable contents at high pressure every second, igniting a massive fireball

  • 10:30pm The Tharos - a large semi-submersible fire fighting, diving/rescue and accommodation vessel arrived at Piper Alpha, but its water cannon was so powerful it would injure or kill anyone hit by the water so they had to use it with extreme caution. The Tharos was equipped with a hospital and set up a triage area on the helideck to receive injured survivors

    • Google MSV tharos to see what it looks like. It is essentially a platform.

  • 10:55pm - another pipeline fails and explodes, shooting flames 90m into the air. The explosion destroyed a rescue vessel (and FRC), killing all but one of the crew and survivors. At this point, the Claymore rig stopped pumping oil. They probably should have stopped during the first mayday call 50 minutes earlier.

  • 11:18pm - the claymore gas line ruptured - another nearby platform - further than tartan

    • Neither Claymore or Tartan shut down production, Claymore waited at least 1 hour

    • Piper Alpha starts to collapse and sink into the sea

  • The 20,000 tonne steel platform of the Piper Alpha melted over the next 80 minutes

  • The standby vessel for Piper Alpha, Silver Pit, was also the standby vessel in the Ekofisk Field when the Alexander Kielland flotel capsized on March 27, 1980. We will likely cover this on an upcoming episode.


  • So we know there were a lot of problems here.

    • Operation issues with respect to work permit communication

    • The rig was not upgraded for gas explosions

    • There was no contingency plan for an emergency with the loss of the control room

    • Most of the personnel that had authority to order an evacuation were killed during the first explosion

    • The fire fighting system was in manual mode

    • Nearby rigs kept pumping flammable liquids to the rig even after there were explosions.

    • Too many men died sheltering in place (as was the procedure) waiting for a rescue.

  • As with all failures of this nature, there was an inquiry which released a full report in November 1990. The report found that the initial liquid natural gas leak was caused by the maintenance work being carried out on pump A and the associated safety valve. The rig operator was found guilty of having inadequate maintenance and safety procedures but no criminal charges were ever filed.

  • The report also made 106 recommendations for changes to North Sea safety procedures

    • 37 were related to operating equipment

    • 32 were related to relaying information to platform personnel

    • 25 were related to design of the platforms

    • And 12 were related to information of emergency services

    • The responsibility to implement these recommendations was on the regulator, operators, industry as a whole and by the stand by ship operators

  • Safety oversight was shifted from the Department of Energy to the Health and Safety Executive as having one group oversee production and safety was a conflict of interest. Shocker.

  • In 1992 the Offshore Safety Act was enacted, which was codified and implemented a lot of the cullen inquiry recommendations

  • Insurance claims of roughly $1.4 billion USD were submitted. The process revealed serious weaknesses about how insurers tracked their potential exposures and their procedures were also reformed.

  • There is a wreck buoy marking the remains of Piper Alpha and a memorial monument with the names of the deceased in Hazlehead park in Aberdeen, scotland.

  • And finally to my fellow engineers, after having studied piper alpha you come away with a feeling that complacency, at a company and individual level, was one of the main reasons the disaster happened. Beware of falling into that trap.

So there you have it, a repurposed offshore drilling platform was only revised for production with little thought on safety and evacuation. On top of that, significant operational and safety procedure issues made the risk of accidents high and the chance of survival low. Lessons were learned from the Piper Alpha disaster, but they didn’t really sink in seeing as we still have offshore rig disasters like Deepwater Horizon that we covered in episode 25.

For photos, sources and an episode summary from this week’s episode head to Failurology.ca. If you’re enjoying what you’re hearing, please rate, review and subscribe to Failurology, so more people can find it. If you want to chat with us, our Twitter handle is @failurology, you can email us thefailurologypodcast@gmail.com, or you can connect with us on Linked In. Check out the show notes for links to all of these. Thanks, everyone for listening. And tune in to the next episode where we will talk about L’Ambiance Plaza. The collapse of a lift slab construction building in Bridgeport, Connecticut during construction.

Bye everyone, talk soon!