Working as a Saturation Diver

By Kevin Duck

Saturation Diving

Saturation Diving is a safe and economical way to use divers to carry out tasks subsea.

Saturation Divers live in chambers for up to 28 days, that are pressurized to the same working depth.

Sat System

The living chambers are on the surface usually on the deck of a ship or barge.

The normal min chamber configuration is three living chambers, two wet pots (entry locks), diving bell and lifeboat.

Food Supplies

Diver’s receive their meals via

Medical Lock - is a two way pressure vessel that is built into side of chamber that can be vented to surface by Life Support Technicians so LST’s can put meals into divers. This is done by closing door on inside of chamber then informing LST.

LST then vents medical lock to surface opens outer door. LST places meals into medical lock closes outer door, pressurize lock when medical lock is at same pressure as divers in living chamber, diver’s then open inner door of medical lock and removed their meal. This process happens whenever food or equipment is need by diver’s.

Shower And Toilet

Wet Pots (entry locks) is joined to living chambers and is separated by two sealing doors this is where divers have a toilet and shower and is normally where the diving bell locks onto the diving system (chamber).

Trunk – Is a very short man-way that connects to entry locks (wet pots) to diving bell and is used when entering or leaving diving bell, the Trunk can be sealed at both ends when bell is connected to diving system. Trunk is vented to surface when bell is locking off, this enables bell to safely detach from diving system.

The BellDiving Bell – locks onto trunk and the entry lock so Divers are able to enter bell and transit to subsea work site. Inside diving bell are 2 divers helmets connected to separate umbilical's

Blow DownThe Sat commences with a Blow Down. Divers enter living chambers when chamber is on the surface normally at the start of a diving contract. Diver’s enter chamber via open chamber door they take mostly personal belongings like anyone takes when going on a long trip. Once all divers have entered chamber the chamber doors are closed and secured by LST. The chamber is pressurized with mixed gas (helium + oxygen). This is done slowly so temperature in chamber will not become too high also mixed gas circulates and mixes evenly with air already in chambers.

When Diver’s have been pressurized to working depth that is the end of blow down.

Diver’s

Bellman – Is a Diver in control of bell and is responsible for safely connecting Diver’s helmet and equipment to the other two Diver’s that will leave the bell. Bellman also feeds out umbilical to Diver as Diver goes to job.

Diver 1 – Is the first diver to leave bell and is in control of the dive and directs all subsea work via Dive Supervisor’s instructions

Diver 2 – Is next to leave bell and works with Diver one.

Each dive, Diver’s change positions so the next dive Dive 1 – changes to Bellman. Diver 2 changes to Diver 1 and so on.

One Hours Notice – Is when LST has been informed by Diving Supervisor to tell Divers that they are required to be ready to enter diving bell to transit to do sub sea task.

Within that hour Divers normally wake from rest, LST locks in meal (breakfast), Diving Supervisor briefs Divers on task and Divers don their diving suits.And Bellman go’s into bell for bell checks

Bell Locking Off

Lock Off - Is when Diver’s 1 hour’s notice has ended and Diver’s have entered the bell via the entry lock (Wet Pot) and trunk have closed bell internal door and has asked the Diving Supervisor to pressurize the bell or vent trunk so bell can lock off diving system.

Left Surface

After bell has locked off from trunk bell is moved (trollied) to moon pool or outboard of ship and lowered into water and then down to working depth.

On The BottomGot the door - Is when bell has been stopped at working depth and bottom door of bell has equalized with that depth and diver 3 (bellman) is able to open bottom door so Diver’s can leave bell to do tasks.

D iv e r’s L o c k o u t

Lock0ut – Is when Diver 1 leaves the bell and swims to worksite. Diver 2 locks out 10-15 mins later. After Diver 1 is settled on job and has pulled through his umbillical.

Divers are locked out for 6 hours to do their subsea tasks. 10-15mins before 6hrs has lapsed Dive Supervisor request Diver 1 back to the bell. The Bellman then pulls up Diver 1’s umbilical into bell until Diver is in bell. While Diver 1 is returning to bell Diver 2 tidies up work site ready for next dive team to continue the task. Diver 2 then returns to bell.

Back In The Bell

Got a Seal – Once both divers are in bell the Bellman will close bottom door and pressurize the bell about 1m deeper than diving bell depth, this he will check with internal depth gauge and equalization valve.

When Bellman has confirmed he has a seal on the bottom door he will inform Diving Supervisor that he has got a seal.

Left Bottom – After supervisor has confirmed seal on bell, diving bell will leave bottom. Bell will be stopped after 5m of travel and Bellman and Dive Supervisor will check that bell bottom door is still sealed. If seal is confirmed bell continues upward travel.

On SurfaceBell Locked On – When bell has returned to surface and trollied to mate with diving system a hydraulic clamp closes and locks the bell onto trunk.

TUP – (Transfer Under Pressure) – When Dive Supervisor pressurizes trunk to the same pressure as diving bell and wet pot so that Diver’s can open bell door and move from bell to wet pot (transfer under pressure) once all three divers have moved from bell to wet pot, a Bellman from next team of Divers that is waiting in wet pot will transfer into bell to start diving bell checks (similar to what pilots do before a flight) bell + trunk doors will be closed returning Divers remove wet suits and return to their living chamber.

DecompressingDECO – After 28 days or sooner when subsea job is complete Diver’s start decompressing (return to surface) decompression time depends on depth and company diving tables.

When decompressing Diver’s normally read books, watch movies and eat a lot. Decompression can take up to 10 days