Working as a Saturation Diver

By Kevin Duck

Saturation DivingSaturation 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 Down

The 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.

1 hour Notice to Dive

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 SurfaceAfter 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.

Diver’s Lockout

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.

Decompressing

DECO – 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