The North Sea Diver – working under pressure

This year, Norway celebrates 50 years since the discovery of oil in the North Sea. At the same time, the country’s third-largest oil field ever – Johan Sverdrup – has opened.

The Norwegian state earns some 250bn kroner (€25.3bn) a year from taxes on oil and a 67% state ownership in Equinor. This represents nearly a fifth of the country’s income. None of this would have been possible without the North Sea divers. Books have been written about them, but none have been written by them, points out Hans Claesson.

He is now 69, and gets in touch with the NLJ in connection with Norway’s state broadcaster NRK’s TV series “Lykkeland”, which focusses on the first few years after oil was discovered on the Norwegian continental shelf.  

“Do you want to know how it really was?” he asks.

The "Norwegian oil adventure” as it is known in Norway started when an American head of the Phillips Petroleum oil company holidayed in the Netherlands in 1960. In the middle of tulip field, he saw the same types of oil derricks that he was used to seeing back home in Oklahoma. The Dutch had found one of the world’s largest natural gas fields, Groningen.

Nobody had expected to find oil and gas in that part of Europe. But then it hit him: what if the same geological structures carried on out into the North Sea? Several oil companies had had the same idea, and had already explored the possibility of looking for oil off the UK. But Phillips Petroleum were the first to contact Norwegian authorities. 

Hasse Claesson was there when it started. At 22, he was Sweden’s first US-educated deep-sea diver, and nearly crushed his leg during his first job in the North Sea when a wave hit the operating deck of the diving vessel, dislodging a cargo of gas containers.  

At the same time, young Hans Claesson dreamt about becoming a scuba diver. He had read Twenty Thousand Leagues Under the Sea by Jules Verne and The Silent World by Jaques-Yves Costeau. In the middle of Stockholm, divers were looking for the royal Wasa ship, which had sunk more than 300 years ago. 

He trained to be a sports diver early on, before applying to serve as a clearance diver in the Swedish navy as part of his military service. He was not accepted. After finishing his military service he travelled to California where he could get vocational training as a deep-sea diver. On 6 February 1973, he went to Stavanger for a job interview. He was hired immediately. Eight hours after leaving Stockholm, he was already in a helicopter on his way out over the North Sea. 

When the oil industry began looking for oil and started building production platforms in the North Sea, the only experience came from shallow water exploration in the Mexican gulf. In the North Sea, the first fields were found 70 to 80 metres down. That might not sound much, but one unit of atmospheric pressure at sea level – or one bar – increases by one bar for every ten metres. At 80 metres, the pressure is nine bars.

“Air becomes so compressed and thick that it feels like it is trickling through your fingers when you move your hand inside a diving bell,” says Hans Claesson.

When diving, human tissue absorbs the air you breathe. If you surface too quickly, gas will be released to form small bubbles which could quickly grow big enough to cause pain or prevent blood flow. It is known as divers’ disease and can be fatal. 

This is why it is necessary to ascend gradually, allowing the body to adjust. But the deeper you dive, and the longer you spend down there, the longer it takes for the body to adjust. A half-hour dive to 80 metres means you need over two hours of decompression. A one hour dive means ten hours decompression. 

The solution is to use a pressure chamber at the surface, on a platform or a vessel. The diver is taken there in a diving bell at the end of the job, and can go through a gradual decompression.  

The diving bell is used to transport the divers up and down in the water. The bell is linked to a pressure chamber on deck, where the divers can enter as they maintain the same pressure as they experience when they are working. The divers then gradually decompress inside the bell.    

In order to breathe under such high pressure, the light gas helium is mixed into the air which the divers are breathing in. This gives them a “Donald Duck” voice, just like when you breathe in helium from a party balloon. 

All this has been described many times before, but Hans Claesson now describes in great detail how the jobs were carried out, the wait, the jargon, the dangers and also the boredom and monotony of being locked in a pressure chamber, always a bit cold and eating food which tasted nothing there unless it was very spicy. 

“The aim has been to include as many details as possible, and to describe things just the way they were. I have many notes, logs and my own diving logbook where I wrote down what was happening,” says Hans Claesson.

He also has several hundred letters which he sent home to his fiancé and later wife, Tuulikki from Finland.

Hans Claesson’s picture of a colleague standing on a platform leg at the Gulftide production platform, whose base – high above – would be hit by breaking waves during severe storms. The dimensions were already huge during Claesson’s time as a North Sea diver. 

Claesson describes the period in great detail, and although conversations have been reconstructed they do reflect the way things sounded at the time. One of the jobs was to find a leaking pipe which was used to fill crude oil into an oil tanker vessel.   

“Then suddenly the bottom latch loses its seal. He immediately sinks down into the dark water, and is left standing at the bottom right under the bell. 

“‘Diver left the Bell’ he manages to say, and hears Norman answer ‘Roger, diver left Bell’. Let’s see, he thinks, and tries to orient himself. It is dark as hell. He can see less than one metre in front of him. But wait, the spotlight is over there. Looks more like a candle than a 1000 watt torch.” 

After scarping off the sediment from the pipe in order to read its markings, he follows the pipe and uses his hands to feel his way and make sure he does not miss where the leak is. 

“Then he can hear it, and soon he can see the bubbles rising. Yes, there is a clear breach in the pipe!

“Surface! Breach on the outside of the first flange, by the welding point. I carry on outwards!”

The divers were not only the eyes and ears of the platform builders. They also repaired any damage that occurred. One of the most dangerous jobs was cutting anchor chains when new platforms were getting ready to be towed into the North Sea. Burning the massive chains was a manhood test, he says.  

“To cut it correctly, you needed to burn it off evenly all the way round, or you risked creating pockets of vapour which could explode. You got very nervous sitting there, hollowing out the six inches thick chain. It could take five to ten minutes. The coarse anchor chain was so tense that it would be there one minute and gone the next.”

Hans Claesson quickly climbed the grades and became a divemaster. He also invested in and equipped a diving vessel in Stavanger for the final assembly of the concrete platforms Cormorant A and Brent C. Tuulikki joined him there. His responsibilities as divemaster were considerable. 

“As he watches the divers on the TV monitors, the thought hits him that the divers somehow must have taken the terms patience, tolerance and trust to a new and higher level. Or perhaps a deeper one? They are trapped inside a steel tube together with people someone else have picked, and they are completely dependent on the outside support team getting everything right.”

None of the diving teams Hans Claesson worked on or was responsible for experienced a fatal accident. Ten divers died on the Norwegian sector between 1967 and 1979. 34 people died in helicopter transport accidents in the same period. 25 people died from falling from great heights while working on platform construction or maintenance. 19 people died during loading and unloading, or as a result of explosions. 

The largest accident happened one year later, when the Alexander L Kielland platform, serving as living quarters for oil workers, capsized in a storm killing 123 people. By then, Hans Claesson had already returned to Sweden, after spending five years as a North Sea diver.

So what does he make of the NRK series “Lykkeland" which has been broadcast in several Nordic countries?

“I think it’s a good drama all in all, which has captured that period of time well. But you can always pick on details. The scene where a diving bell is torn loose under water is not so realistic, as it weighs next to nothing submerged. It would have been more realistic if the wire snapped when it was lifted out of the water,” he points out.

Hans Claesson today. The full title of his book is The North Sea Diver. A novel about an occupational journey from dream to reality. Read more about the book here (in Swedish)