high pressure water jet usage underwater

High Pressure Water Jet Usage Underwater

OBJECTIVE

To ensure health and safety methods for the operation of high-pressure water jetting

equipment used for cleaning or cutting underwater; and its associated surface support

equipment.

1. Primary Task

STEP Responsibility CHECK

1.1 It is the overall responsibility of the Diving Supervisor to ensure that this

work procedure is made available to all personnel involved in the

operation.

1.2 The Diving Supervisor is responsible for:

• Safety of all diving operations.

• Obtaining permission from Client to carry out diving operations.

1.3 The Water Jet Operator is responsible for:

• The operation of the HP Water jetting machine and its associated hoses/

fittings and the gun

1.4 The DSV Captain is responsible for:

• Mooring of the diving vessel at the work site as per instructions from the

diving supervisor.

• Monitoring sea/ weather conditions, moorings and other boat activity in

the area.

2. Method

Task STEP CHECK

2.1 Care and Maintenance of Equipment

1) As a minimum, a daily check on the pump and associated fittings for any

damage or leaks is carried out. High pressure hoses, guns and lances are

examined for any sign of damage. In the event of leaks or damage being

found, they are reported to the Diving Supervisor, who may decide to

withdraw the equipment from service, pending repair.

2) The fittings on inter-connecting hoses are internally checked at regular

intervals. This is done by disconnecting the fitting and visually inspecting

the metal surfaces.

3) A through flush with fresh water is always carried out on demobilization

prior to periods of extended storage.


2.2 The following precautions are observed

1) Diving Equipment

Debris generated and raised up by the H.P. jet, can and does, interfere

with such equipment as reducer valves, suit inflation valves, etc. Great care

is taken in checking and cleaning this equipment after every dive.

2) Ear Protection

Bearing in mind the high noise levels at present emitted by water jetting

equipment, the effect of noise on the diver is minimized, in particular,

diving helmets as opposed to masks are worn.

_ Wear ear protectors where required.

_ Ensure radio communications are not compromised.

3. Primary Task

STEP Operational Procedures CHECK

3.1 Operating Procedure.

• The OIS Operator in conjunction with the Lead Diver is responsible for

the safe setting up, maintenance and running of the HP Water jetting

Equipment. The dive team will assist where required, by the Lead Diver.

• Once the hoses, water jetting gun and machine are lined up for

operation, a test will be carried out on deck before being lowered to the

underwater work site.

• All hose connections to be secured and no leaking be observed.

• Once the test is completed and all is running in a safe operating manner,

the machine is switched off.

• The diver enters the water and sets himself up at the work site – rigs

clogger and ropes, for comfortable work operations.

• Area to be cleaned using HP Water jetting gear, is inspected and

confirmed for cleaning operations.

• Once the diver is in position and ready for working the HP Water blaster

Gun is lowered to the diver via the downline.

• The diver will then inform the Dive Supervisor who then informs the

Water jetting machine operator – to start the machine.

• Supervisor relays the message back to the diver, once machine is up and

running – diver confirms that he has water pressure on the gun, and

proceeds with the cleaning operations.

• Diver #2 to keep clear of the work area - when Diver #1 is working.

• Diver #1 to keep hands, limbs and umbilical away from HP jet.


3.2 Working Practice

Refer also to IMCA DO 49 Page 13 Sections 6.1

• The equipment is tested before being sent down to the diving job

• The trigger mechanism – cam lever operated -- on the gun, is in good

working order and that the water pressure is shut off/Diverted to the

dump when the trigger is released.

• A retro jet system in place when using this equipment - with protection

shroud in place and secure

• Full diving dress to be worn by the diver during these operations –

u/water communications to be operational

• All divers using water jetting equipment must be familiar with the use of

the equipment relating to the nature of work, which they may be required

to do. Work procedures, IMCA Guidance Note 049 and risk assessments to

be read/ understood and signed off by dive team personnel.

Working Practice

Refer also to IMCA DO 49 Page 13 Sections 6.1

• The equipment is tested before being sent down to the diving job

• The trigger mechanism – cam lever operated -- on the gun, is in good

working order and that the water pressure is shut off/Diverted to the

dump when the trigger is released.

• A retro jet system in place when using this equipment - with protection

shroud in place and secure.

• Full diving dress to be worn by the diver during these operations –

u/water communications to be operational.

• All divers using water jetting equipment must be familiar with the use of

the equipment relating to the nature of work, which they may be required

to do. Work procedures, IMCA Guidance Note 049 and risk assessments to

be read/ understood and signed off by dive team personnel.

The Diving Supervisor must have a sound knowledge of the equipment and

the techniques employed.

• The HP Water jet is a tool and thus a source of danger. Its careless or

improper use may cause danger to life and limb.

• Never work with the equipment when you are tired or not feeling well,

or when you are under heavy medication.

• The user of this equipment must never direct the HP jet at himself or

other persons.

• The user must never fix or tie-off the trigger mechanism.

•The machine is not started until instructions from the Dive Supervisor, via

the Diver.


_ Before the diver asks the surface to start the unit – he must be

comfortable and in a good working position.

_ No other divers are involved in coincident operations, the safety of which

could in any way be jeopardized by the close proximity of jetting

operations. However, if a remotely operated vehicle is available on a

particular work site, consideration is given to using it

for diver monitoring during jetting operations. This is in accordance with

AODC Guidance Note 032, with the provision that no added hazard is

introduced by doing so. This is of assistance to the Supervisor in view of

the difficulties with audio communication between the diver and the

surface, during jetting operations.

_ When operating near the surface, or at the air/water interface, care is

taken to ensure that no other personnel are in such close proximity to

jetting operations that their safety could in any way be jeopardized. Care is

also taken to ensure that the area is kept clear of work boats, zodiacs, etc.,

until the work is completed and the pump shut down.

_ High Pressure water is only supplied on demand from the diver. The

signal to start the pump is given only by the diver when he has reached his

working position and is ready to start jetting. He is warned that he is about

to receive pressure from the surface.

3.3 Testing of Equipment before use:

All systems incorporate at least one safety fluid shut off or dump device.

After setting up the equipment on the surface, the shut off or dump device

is checked to ensure that it is fully operative.

3.4 Warning Notices

In the vicinity of the pump on the surface, adequate warning notices are

clearly displayed, stating that water jetting is in operation and that the

pump is running.

3.5 Handling of Hoses

Great care is taken in the handling of high-pressure hoses the deck of the

vessel, in order to avoid chafing, denting or abrasion against sharp corners.

Hoses are supplied in long lengths with as few couplings as possible.


3.6 Communications

Since audio communications are greatly impaired during underwater

jetting, it is the responsibility of the Diving Supervisor to monitor the

diver’s work and breathing pattern, and to act quickly if any change in

breathing rhythm or any sudden change in performance is observed.

The Diving Supervisor is able to initiate shut down of the pump unit in case

of emergency. This requires him to be in direct and immediate contact at

all times with the person responsible for operation of the pump during

jetting operations.

3.7 Training

A diver using water-jetting equipment is familiar with use of the

equipment relating to the nature of the work which he may be required to

do. The Diving Supervisor satisfies himself that the diver is aware of any

necessary safety procedures, that he fully appreciates the inherent hazards

and risks associated with the equipment and it competent in its use. The

Division Supervisor himself has a sound knowledge of the equipment and

the techniques employed.

3.8 Injuries

Diving personnel are fully aware of the severity of injury which can result

from injection of water at high pressure. Extensive tissue damage can be

caused and there is a danger of severe infection developing. This situation

may exist even if the skin is only slightly broken – or not at all.

3.9 Additional Considerations

In addition to this consider the following job specific points:-

• Weather conditions to be monitored.

• DSV securely moored – engines shut down.

• Ensure that the personnel are familiar with the work procedures –

document toolbox talk.

• Maintain radio contact with ship’s bridge / dive control.

• Divers umbilical snagging on obstructions – fishing nets.

• Divers to be aware of the effects of surge, current and swell.

• Other boats to stay clear from DSV work area.


4. Primary Task

STEP DIVING MEDICAL ADVISORY COMMITTEE RECOMMENDATION CHECK

4.1 The Diving Medical Advisory Committee, London, states that with

increased underwater activity relating to repair and inspection, it is

becoming clear that accidents with high pressure water jets will occur. It

makes the following comments about the management of such accidents:

a) The wound caused may appear insignificant and give little indication of

the extent of the injury beneath and the damage to deeper tissue.

b) Initial mild damage to the wall of an organ may result in subsequent

rapture, particularly if infection has been introduced.

c) The development of subsequent infection is particularly important in

abdominal and joint injuries.

d) The outcome depends upon the extent of initial injury and the presence

or absence of infection and even though the injury seems trivial in the

surface and the patient has not complaints, it is of great importance to

arrange for surgical examination as quickly as possible.

e) Where the surgical examination is not immediately possible in a remote

situation, first aid measures are confined to dressing the wound and

observing the patient closely for the development of further complaints

over four to five days. The development of fever and a rising pulse rate

suggest that the injury is serious, together with persistence of occurrence

of pain.

f) Where surgical advice is unobtainable, consideration should be given to

providing the patient with a course of antibiotic therapy.

g) Every injury caused by high pressure water jetting must be reported and

treated immediately and specialist medical advice sought.

h) To assist with treatment in the event of injury to a diver from a high-

pressure water jet, a plastic card is available which highlights the nature of

the incident. This card should be given to the attending medic or doctor.

high pressure water jet usage underwater

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