AB The International Marine Contractors Association

Code of Practice for the Use of High Pressure Jetting Equipment by Divers

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AODC 049 August 1988

AB

The International Marine Contractors Association (IMCA) is the international trade association representing offshore, marine and underwater engineering companies. IMCA promotes improvements in quality, health, safety, environmental and technical standards through the publication of information notes, codes of practice and by other appropriate means. Members are self-regulating through the adoption of IMCA guidelines as appropriate. They commit to act as responsible members by following relevant guidelines and being willing to be audited against compliance with them by their clients. There are two core activities that relate to all members: Safety, Environment & Legislation Training, Certification & Personnel Competence The Association is organised through four distinct divisions, each covering a specific area of members interests: Diving, Marine, Offshore Survey, Remote Systems & ROV. There are also four regional sections which facilitate work on issues affecting members in their local geographic area Americas Deepwater, Asia-Pacific, Europe & Africa and Middle East & India.

AODC 049

This Code was produced by the AODC Safety & Technical Committee and supersedes AODC 007 published in 1982.

The code should be read in conjunction with the comprehensive code of practice on all aspects of water jetting operations, which contains a section on underwater jetting based on this Code, published in 1982 by the Association of High Pressure Water Jetting Contractors, revision of which is planned to commence during 1988.

Thanks are due to all companies and organisations who co-operated in the production of this new guidance note.

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The information contained herein is given for guidance only and endeavours to reflect best industry practice. For the avoidance of doubt no legal liability shall

attach to any guidance and/or recommendation and/or statement herein contained.

Code of Practice for the Use of High Pressure Jetting Equipment by Divers

AODC 049 August 1988

1 Scope....................................................................................................................... 1

2 Definitions .............................................................................................................. 1

3 Equipment .............................................................................................................. 1 3.1 High Pressure Pump Unit................................................................................................................................. 1 3.2 Dump Safety Gun............................................................................................................................................... 1 3.3 Dry Shut Off Gun .............................................................................................................................................. 1 3.4 Trigger Mechanism ............................................................................................................................................ 1 3.5 End Connections................................................................................................................................................ 1 3.6 Lance..................................................................................................................................................................... 2 3.7 Nozzles ................................................................................................................................................................ 2 3.8 Retro Jets............................................................................................................................................................. 2 3.9 High Pressure Hoses......................................................................................................................................... 2

4 Care and Maintenance of Equipment.................................................................. 2

5 Protection of Personnel ........................................................................................ 2 5.1 Life Support Equipment .................................................................................................................................... 3 5.2 Ear Protection .................................................................................................................................................... 3

6 Operational Procedures ....................................................................................... 3 6.1 Working Practice............................................................................................................................................... 3 6.2 Testing of Equipment Before Use .................................................................................................................. 3 6.3 Warning Notices................................................................................................................................................ 3 6.4 Handling of Hoses.............................................................................................................................................. 4 6.5 Frost Precautions............................................................................................................................................... 4 6.6 DP Interference.................................................................................................................................................. 4 6.7 Communications ................................................................................................................................................ 4

7 Training................................................................................................................... 4

8 Injuries .................................................................................................................... 4

1 Scope

This code of practice covers health and safety procedures for the operation of high pressure water jetting equipment used for cleaning or cutting underwater, and its associated surface support equipment.

2 Definitions

High pressure water jetting, as covered by this code, relates to all water jetting, including the use of abrasives. It is intended to apply equally to operations on or near the surface where there can be a risk to the operator or to others working in the vicinity, either in the water, on a platform, or on an adjacent diving system.

3 Equipment

3.1 High Pressure Pump Unit

This unit should be capable of long and continuous operation using filtered sea water and should be suitable for use in the marine environment (see para 6.7.2).

3.2 Dump Safety Gun

This type of gun has a fail-safe valve which, when the trigger is released, diverts water from the nozzle to ambient water. The attention of operators is drawn to the severe jolt which can be experienced when the pressure is dumped by releasing the trigger. A choke can be fitted in the dump line to reduce this effect.

3.3 Dry Shut Off Gun

When the trigger is released on this type of gun, the pressure is retained in the supply line. It is used in conjunction with a regulating or unloading valve on the surface.

3.4 Trigger Mechanism

3.4.1 The trigger is a cam lever operated mechanism designed to return to the safe position on release. The effort required to maintain it in the open position over extended periods of time produces significant levels of fatigue. This is increased in underwater operations due to environmental effects such as loss of stability due to water movement, weightlessness causing loss of momentum etc. Locking of the trigger in the open position by wire, tape or other artificial means which cannot instantly be released if necessary, is extremely dangerous practice and should not be employed.

3.4.2 A new design of trigger has been identified which would greatly reduce the amount of pressure required to maintain the trigger in the open position, but is also capable of instant release. This would preclude the unsafe practice by some divers of locking the trigger. Incorporation of this new design is being pursued and is expected to be available in the near future.

3.4.3 A safety catch is provided on existing equipment as required by the Association of HP Water Jetting Contractors Code of Practice. Divers should use it.

3.5 End Connections

End connections for high pressure hoses are subject to a high level of erosion and corrosion and should be of high quality material suitable for the required pressure. They should be checked at regular intervals.

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3.6 Lance

The length of the lance should be such as is practical for the type of operation being undertaken. However, it must be emphasised that the inherent potential for accidental self injury during use of high pressure jetting guns increases as the length of lance decreases.

3.7 Nozzles

There are many different types giving various spray patterns and reaction forces.

3.8 Retro Jets

3.8.1 All HP water guns to be handled by divers underwater must be fitted with a retro jet. The type of nozzle fitted to the retro jet must be such as to provide a reaction equal to that of the lance in order to balance the gun.

3.8.2 All retro jets must be guarded with a venturi type diffuser tube which is either positively locked onto the gun, or if removed, releases the retro nozzle from the gun to avoid self injury to the diver.

3.9 High Pressure Hoses

3.9.1 The high pressure hose connecting the various items of equipment must not be used above its safe working pressure (SWP). Hoses clearly marked with their brand and SWP should be preferred.

3.9.2 Connecting couplings should be clearly marked, kept to a minimum as practical be of non-corroding material, and of pressure rating at least equal to, but preferably more than the hose itself.

4 Care and Maintenance of Equipment

4.1 As a minimum, a daily check on the pump and associated fittings for any damage or leaks should be carried out by a competent person. High pressure hoses, guns and lances should be examined for any sign of damage. In the event of leaks or damage being found, they should be reported to the diving supervisor who may decide to withdraw the equipment from service pending repair.

4.2 The fittings on interconnecting hoses should be internally checked at regular intervals. This should be done by disconnecting the fitting and visually inspecting the metal surfaces.

4.3 A through flush with fresh water should always be carried out on demobilisation or prior to periods of extended storage.

4.4 Testing of pump unit and associated equipment in regular use should be carried out by a competent person every six months and a certificate of fitness provided. Where the water jetting system has been hired from an equipment supplier either as an integral unit or in component parts, a certificate of fitness valid for no more than six months from the date of test and examination should be provided by the Hirer to the effect that the equipment has been satisfactorily tested prior to commencement of hire.

Subsequent six-monthly testing should be carried out either by the hirer or the contractor on all, or part of the system as applicable, for the duration of the hire period.

4.5 Due to the highly complex nature of some of the HP units currently on the market, full operating and maintenance instructions should be available with each pump and strictly adhered to.

5 Protection of Personnel

The following precautions should be observed.

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5.1 Life Support Equipment

Grit supplied by the gun or raised by the HP jet can and does interfere with such equipment as reducer valves, suit inflation valves, etc. Great care must be taken in checking and cleaning this equipment after every dive.

5.2 Ear Protection

Bearing in mind the high noise levels at present emitted by water jetting equipment, the effect of noise on the diver should be minimised; in particular, diving helmets as opposed to masks should be worn. (Certain obligations are placed on designers, manufacturers, importers, suppliers and users of plant and equipment to control and limit noise emission from them. In the UK, for example, Section 6 of the Health & Safety at Work etc. Act has been amended to take account of the Consumer Protection Act which became effective on 1 March 1988 and regulations are also proposed in line with the EEC Directive "Prevention of Damage to Hearing by Noise Emission from Plant and Equipment" the provisions of which must become effective by 1 January 1990).

6 Operational Procedures

6.1 Working Practice

6.1.1 No jetting should be carried out except on instructions from the Diving Supervisor.

6.1.2 No other divers should be involved in coincident - operations the safety of which could in any way be jeopardised by the close proximity of jetting operations. This applies equally to operations using atmospheric diving suits and underwater vehicles of all types. However, if a remotely operated vehicle is available on a particular work site, consideration could be given to using it for diver monitoring during jetting operations, in accordance with AODC guidance note 032 and provided no added hazard would be introduced by doing so. This may be of assistance to the supervisor in view of the difficulties with audio communication between the diver and the surface during jetting operations.

6.1.3 When operating near the surface, or at the air/water interface, care should be taken to ensure that no other personnel are in such close proximity to jetting operations that their safety could in any way be jeopardised and that the area is kept clear of workboats, zodiacs, etc., until the work is known to have been completed and the pump shut down.

6.1.4 Wherever possible, the working area should be kept free from tripping hazards or other debris and, depending on conditions, adequate lighting should be provided.

6.1.5 High pressure water should only be supplied on demand from the diver. The signal to start the pump should only be given by the diver when he has reached his working position and is ready to start jetting, and he must be warned that he is about to receive pressure from the surface.

6.2 Testing of Equipment Before Use

All systems should 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 should checked to ensure that it is fully operative.

6.3 Warning Notices

In the vicinity of the pump on the surface, adequate warning notices should be clearly displayed, stating that water jetting is in operation and that the pump is running. (Printed warning notices are available from the Association of HP Water Jetting Contractors).

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6.4 Handling of Hoses

Great care should be taken in the handling of high pressure hoses on the quay or on the deck of a surface vessel in order to avoid chafing, denting or abrasion against sharp corners. Hoses should be supplied in long lengths with as few couplings as possible.

6.5 Frost Precautions

When icing conditions are anticipated, adequate frost precautions should be taken by either draining the equipment or using anti-freeze. Under no circumstances should the pump be started if icing of the equipment is suspected.

6.6 DP Interference

Noise from HP jetting operations may interfere with the acoustic reference system of a dynamically positioned ship. DP operators should be consulted prior to the commencement of HP water jetting operations.

6.7 Communications

6.7.1 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.

6.7.2 The diving supervisor must be able to initiate shut down of the pump unit in case of emergency. This will require him either to be in direct and immediate contact at all times with the person responsible for operation of the pump during jetting operations, or to have an emergency cut out switch close to hand.

7 Training

A diver using water jetting equipment must be familiar with use of the equipment relating to the nature of the work which he may be required to do. The diving supervisor should satisfy himself that the diver is aware of any necessary safety procedures, fully appreciates the inherent hazards and risks associated with the equipment and is competent in its use. The diving supervisor himself must have a sound knowledge of the equipment and the techniques employed.

8 Injuries

8.1 Diving personnel should be 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.

8.2 Every injury caused by high pressure water jetting must be reported and treated immediately and specialist medical advice sought. In this regard a specific recommendation from the Diving Medical Advisory Committee is attached at Appendix I.

8.3 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. (See Appendix II).

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Appendix I

The Diving Medical Advisory Committee Recommendation

With increased underwater activity relating to repair and inspection, it is becoming clear that accidents with high pressure water jets will occur. The following comments about the management of such accidents have been made by the Diving Medical Advisory Committee: 1. The wound caused may appear insignificant and give little indication of the extent of the

injury beneath and the damage to deeper tissue. 2. Initial mild damage to the wall of an organ may result in subsequent rupture,

particularly if infection has been introduced. 3. The development of subsequent infection is particularly important in abdominal and

joint injuries. 4. The outcome depends upon the extent of initial injury and the presence or absence of

infection, and even though the injury seems trivial on the surface and the patient has no complaints, it is of great importance to arrange for surgical examination as quickly as possible.

5. Where 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 suggests that the injury is serious, together with persistence or occurrence of pain.

6. Where surgical advice is unobtainable, consideration should be given to providing the

patient with a course of antibiotic therapy.

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Appendix II Advice to Attending Medic or Doctor 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 can be given to the attending medic or doctor. The card reads:

"This man has been involved with high pressure water jetting at pressures up to 14,500 lb/in (100 MPa, 1000 Bar, 1019 kg/cm ) with a jet velocity of 900 miles (1440 km) per hour.

Please take this into account when making your diagnosis.

Unusual infections with micro-aerophilic organisms occurring at lower temperatures have been reported. These may be gram negative pathogens such as are found in sewage. Bacterial swabs and blood cultures may therefore by helpful."

The card is available from:

Association of High Pressure Water Jetting Contractors 28 Eccleston Street, London, SW1W 9PY Telephone +44 (0) 1 730 7605

ScopeDefinitionsEquipmentHigh Pressure Pump UnitDump Safety GunDry Shut Off GunTrigger MechanismEnd ConnectionsLanceNozzlesRetro JetsHigh Pressure Hoses

Care and Maintenance of EquipmentProtection of PersonnelLife Support EquipmentEar Protection

Operational ProceduresWorking PracticeTesting of Equipment Before UseWarning NoticesHandling of HosesFrost PrecautionsDP InterferenceCommunications

TrainingInjuries