CoP - HP Waterjetting

CODE OF PRACTICE

FOR THE USE OF HIGH PDSSURE

AND ULTRA HIGH PRESSURE

WATER JETTING EQUIPMENT

ISBN- I 874278 02 4

Published by And 0 Copyright of the Water Jetting Association I 7 St Judiths Lane, Sawtry, Huntingdonshire, Cambs. PE28 5XE

ISBN 1 874278 02 4

First published 1982 - A5 (Red Cover) Revised 1992 - A5 (Green Cover) Amended 1993 - A5 (Blue Cover) Amended 1995 do. Amended 1999 do. Revised and Expanded 2002 - A4 - (Blue Cover)

0 The Water Jetting Association All rights reserved. No part of this publication may be reproduced, scanned, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, computerised or otherwise, without prior arrangement with and the written permission of the publishers.

, This copyright notice is printed in red ink. If you are in possession of a copy where these two paragraphs, in italic script, are not printed in red, you are probably in possession of an illegal copy.

Possession of a copy of this Code does not imply membership of the Water Jetting Association.

Members of the Water Jetting Association are bound by their membership conditions and Professional Charter to work according to the requirements of this Code.

A list of member companies may be consulted on the Associations website. www.waterjetting.org.uk

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W J A . Code of Practice High and Ultra High Pressure Water Jetting

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2.0

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6.0

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INDEX Introduction

Scope

Training

3.1 Inductions 3.2 Training Course Requirements.

Experience

Accidents and Diseases associated with High Pressure Water Jetting

5. I 5.2 Falls 5.3 Risks from ejected material 5.4 Inhalation/Contamination risks from aerosols 5.5 Noise risks 5.6 General Health considerations 5.7 Leptospirosis (Weils Disease)

Direct water jet injuries

Personal Protective Equipment

6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9

Body Protection Eye / Face Protection Foot Protection Hand Protection Head Protection Hearing Protection Respiratory Protection Working at Height PPE (Personal Protective Equipment) Records

High Pressure Jetting Team: Organisation and Duties

7. I 7.2 7.3 7.4 7.5 7.6 7.7 7.8 7.9

Supervisor Team Leader Lead Operator Machine Operator Foot Control Valve Operator Safety Standby Additional Operators One Man or Single Person Operation Team Composition

Prohibited Areas

W J.A. Code of Practice High and Ultra High Pressure Water Jetting

9.0

10.0

11.0

12.0

13.0

14.0

15.0

Frost Protection

Waste Disposal

High Pressure Water Jetting Units (see also Section 18 - Ultra High Pressure Jetting)

11.1 Drive 1 I .2 I 1.2.2 1 1.3 The Jetting Unit

Pump and Controls Maximum Working Pressure and Pressure Safety Relief Devices

High Pressure Hose Assemblies

12.1 General Requirements 12.2 12.3 Marking and Inspection 12.4

Maximum Working Pressure and Pressure Testing

Rigid, Semi Rigid and Flexible Lances (Flexilances)

Control Valves

13.1 Adjustable Pressure Control Valve 13.2 13.3 Diverter/Selector Valve 13.4 Electro-Pneumatic Jetting Guns etc.

Automatic Pressure Regulator (Unloader Valve)

Accessories

14.1 14.2 14.3 14.4 14.5 14.6 14.7 14.8 14.9

Jetting Guns (dump types) Dry Shut-Off Jetting Guns Foot Control Valves (Dump types) Foot Control Valves (Dry Shut type) Nozzles (for use with Jetting Guns) Nozzles (for use with lances and hoses) Nozzles (fixed installation) Surface Preparation Tools Rotating Hose Pipe Cleaning Rigs

The Safe Use of Water Jetting Equipment

15.1 15.2 15.3 15.4 15.5 15.6 15.7 15.8

General Jetting Guns. Foot Control Valves. Lances (Rigid or Semi-Rigid) - Manual Control Lances (Flexible) - Manual Control Nozzles High Pressure Hose Guidelines for High Pressure Hose

Cnpynglit of The Warer Je//rrig Assocrotio of o copy wliere tliese two setiterices a

11 red iiik. If ynii ore rri Ixssessrori I Imsessioti of ail illegcrl copy.

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16.0 Care and Maintenance of Equipment

16.1 General 16.2 Water Filtration 16.3 Responsibility 16.4 Competent Persons 16.5 Records

17.0 Abrasive Jet Cutting Systems

17. I 17.2 17.3 Remote Handling Systems 17.4 Types of Abrasive 17.5 PPE 17.6 Site Clearance

Additional Hazards and Precautions Types of Abrasive Feed Systems

18.0 Ultra High Pressure Jetting

18.1 18.2 18.3 18.4 18.5 18.6 18.7 18.8 18.9

Scope and definition Additional Training Differences between UHP and conventional jetting Jet Velocity Energy Comparisons Risk Assessment PPE Water Quality Additional Mechanical Considerations

APPENDICES:

DAILY SAFETY CHECKLIST

MEDICAL NOTES. (HIGH PRESSURE WATER JET INJURIES)

ILLUSTRATIONS OF HIGH PRESSURE HOSE END FI7TINGS.

HOSE RE-ENDING REQUIREMENTS.

CONFINED SPACES (GUIDELINES).

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I red ink. If you nre in possession possession of nn illegnl copy.

Copyriglit of The Wnter Jetting Associnti of n copy where these IWO sentences

I red ink. If you nre in possession possession of nn illegnl copy.


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INTRODUCTION and Definitions

The Water Jetting Association produces and regularly amends this Code of Practice (COP) by pooling the knowledge and experience of its members, gained over many years working with all types of Water Jetting Equipment used for an ever increasing range of applications.

Throughout this COP the use of the word shall indicates a mandatory requirement which must be met in order to be able to state that a company will comply with the requirements of the Water Jetting Association Code of Practice. The word mandatory is not meant to imply any statutory obligations.

The use of the word should indicates recommended practices to be adopted.

Throughout this Code, the use of the words man, men, or manning includes and applies to both male and female operatives. This traditional use of the words is never intended to be gender-specific or exclusive.

The Association wishes to record its appreciation and thanks for the considerable help given and information provided by the Health and Safety Executive.

SCOPE

In this Code of Practice (COP) the term High Pressure Water Jetting (HP) will be taken to include all pressures up to 1700 barg.

Equipment operating above this pressure is referred to as Ultrcr High Pressure (UHP) A separate section is included to cover some of the additional operational requirements associated with UHP Jetting. (Section 18)

The term High Pressure Whter Jertirig covers all water jetting processes including those using additives or abrasives where there is ;in energy input to increase the pressure applied to water. A separate section is included to cover some of the additional operational requirements associated with abrasive Jetting work. (Section 17)

This COP applies to all High Pressure m d Ultra High Pressure Water Jetting ;IS defined above, where there is a risk of injury.

This COP is applicable to all High Pressure Water Jetting applications in which hot or cold water is mechanically/hydraulically propelled at pressures up to 1700 barg.

In the event of an injury involving the injection of water into the body, prompt hospital treatment must be given, even if the injury appears superficial. The Water Jetting Association Medical Card or the Operators Photocard provides further details. (See also Appendix 2)

TRAINING

Manual High Pressure Water Jetting, if not handled competently, is a potentially hazardous process due to the power of the jet and the proximity of the operator to the jetting equipment.

After provision of suitable equipment, the most important risk-reduction measure is Training.

All personnel required to use this technique must have received the appropriate training and work in teams where the ratio of experienced to inexperienced operatives never falls below 50 % (see section 4)

All personnel who wish to undertake High Pressure Water Jetting shall be trained to an appropriate standard such as provided by a WJA approved training organisation.

1 W J A . Code of Practice High and Ultra High Pressure Water Jetting I

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3.1.1

3.1.2

3.2

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4. I

4.1.1

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4.2

4.3

4.4

Inductions

On large sites, site-specific inductions may be required prior to any work being undertaken.

I t is recommended that all personnel working with high pressure jetting equipment on industriaVpetrochemica1 sites should hold the CCNSG (ClientKontractor National Safety Group) Safety Passport, and the CSCS (Construction Skills Certification Scheme) card or endorsement on construction sites.

Training of Operators

The Water Jetting Association has established minimum basic or mandatory Safety Awareness Training requirements for operators. Further Training manuals cover additional aspects and applications of High Pressure Water Jetting.

The Association also administers Systems for the approval of Training Providers and Instructors who may present Training Courses, leading to Certification and Registration of operators, based on these manuals.

The Manuals and Courses are subject to regular revision.

Any person involved in the use of High Pressure Water Jetting should have received training to a standard which as a minimum complies with that provided by the above courses, and is appropriate to the type of jetting operations undertaken.

The Training provided by these basic courses does not extend into matters of competence, but ensures a sound level of knowledge and ability to carry out safe working practices as required by this Code of Practice. Section 4.0 deals with matters of experience and competence.

Training records for all persons who have attended courses and reached a satisfactory standard in the test must be kept by their employing company and be available for inspection. In order to comply with this Code and hold a current WJA Training Certificate or Photocard there is a requirement for Refresher Training at intervals of 36 months.

EXPERIENCE

An experienced person (where the term is used within this COP) means an operative who has been actively involved in the regular use of High Pressure Water Jetting Equipment for at least I2 months.

Evidence of competence of trained personnel must be held by their employer and be available for auditkite review where required.

Personnel must have received formal recognised training (such as approved by the WJA), and be able to demonstrate 12 months relevant experience.

In any team at least half of the operatives must be experienced. In the case of an odd numbered team the number of experienced operatives should be rounded up e.g. in a three man team, two must be experienced.

The Supervisor must be able to demonstrate knowledge of High Pressure Water Jetting and be capable of selecting the correct equipment relevant to the task and operating conditions.

A Team Leader must have at least 12 months active jetting experience and should be trained in emergency first aid.

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ACCIDENTS AND DISEASES ASSOCIATED WITH HIGH PRESSURE WATER JETTING

Direct water jet injuries

The most serious potential accident relates to the direct impact of a water jet on the body. The pressure required to penetrate the skin is in the order of 7 barg.

With working pressures in excess of 2,500 barg currently available the potential for serious injury is clear.

Injuries caused by the impact of a water jet may appear insignificant and give little indication of the extent of the injury beneath the skin.

A small entrance wound and lack of an exit wound does not indicate the extensive disruption of deeper tissues, which can result from dispersion of kinetic energy after penetration of the skin by water.

Any person injured by the impacUpenetration of a High Pressure Water Jet should seek expert medical advice immediately.

All persons undertaking High Pressure Water Jetting must carry at all times either a waterproof Medical Card, or the WJA Photocard, which carry the same information.

These are available from the Water Jetting Association and are approved by the Employment Medical Advisory Service (EMAS).

The Medical card gives basic details of the medical treatment for water jet injuries and precautions to be taken to combat the possible effects of the injection of contaminated water into the body.

More comprehensive advice on dealing with Water Jetting Injuries is given in Appendix 2. This information is also available from the WJA website (www.waterjetting.org.uk)

First Aid

First Aid administered on site should include the control of bleeding by the application of pressure over the area of bleeding, and elevation of the injured limb where possible.

Arrangements should then be made for the immediate transfer of the patient to a hospital medical facility.

Falls

Nozzle reaction forces acting either directly on the operative or the structure from which work is being carried out are a potential cause of accidents.

The reaction force can push the operative backwards causing him to loose his footing and fall. For this reason no water jetting work shall ever be carried out from a ladder.

Scaffolding must be adequately secured to prevent i t being pushed over.

This is particularly important when using a gimbal mounted gun.


5.2.1.5 If a MEWP (Mobile Elevated Work Platform) is being used the operator should be anchored to the platform by a short lanyard connected to a full body harness with associated energy absorber.

If scaffolding or a MEWP is not reasonably practicable then Fall Arrest Equipment can be used providing it includes a full body harness and energy absorber.

The maximum recommended nozzle reaction force for hand-held High Pressure Water Jetting is 250 Newtons.

Operatives should take regular breaks to recover from fatigue.

The working environment, including any extremes of temperature, will also increase operator fatigue.

5.2.1.6

5.2.2

5.2.3

5.2.4

5.3 Risks from ejected material

5.3. I The exit velocity of water from a nozzle at a pressure of 1000 barg is circa 1600 kms per hour and i t follows therefore that a substantial danger from flying debris must be allowed for.

The operative is to be protected by waterproof clothing, gloves, and face protection. Other persons may need to be protected by appropriate tenting. (see Section. 6).

Other persons must be kept away from the working area by appropriate signage and if necessary by the posting of sentries.

5.3.2

5.3.4

5.4 Inhalatiotdcontamination risks from aerosols

5.4.1 When High Pressure Jetting Equipment is used to remove coatings or to clean surfaces that are contaminated with a hazardous substance or bacterial infection i t is possible these may be entrained in the resulting aerosol.

The nature of the contaminant must be identified by the owner of the plant, who shall provide the required information on the hazardous substances (e.g. Data Sheet). A COSHH assessment may be required and if appropriate suitable PPE shall be used.

The operator must be provided with and wear adequate clothing in accordance with the Risk Assessment for the task.

5.4.2

5.4.3

5.4.4 Special consideration may have to be given to personal hygiene e.g. clothing may need to be treated as contaminated waste, and operators may need to shower.

5.5 Noise risks Noise levels will exceed 85dbA in almost all applications and appropriate hearing protection must be used. In addition to the Jetting Gun operator this consideration will apply to the second man at the pump who may be exposed to even higher noise levels, depending on the location of the pump.

5.6 General Health Considerations

5.6. I Working with High Pressure Water, even in Drains and Sewers, is not considered to present a serious health risk, especially if good hygiene practices are followed.

Many of the rarer infections with which people could come into contact usually begin with flu-like symptoms. In reality, operatives are more likely to catch flu than a work related disease.

5.6.2

Copyrighi of The Warer Jetiiiig Associotiori of a copy where t1ie.w iivo setiietice.v are

I WJ.A. Code of Practice High and Ultra High Pressure Water Jetting I

5.6.3

5.6.4

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6.3.2

However with flu-like symptoms the GP should be informed that you have been involved in working in sewers. This is especially important if there is no outbreak of flu in the general population.

High Pressure Water Jetting, - especially in Drains and Sewers, - is often physically demanding. Consideration should be given to having a regular health check-up, especially later in life.

Leptospirosis (Weils Disease)

The bacteria that cause this disease may be present in various aninials but is widespread in the rat population. It is spread by rats urine and found in damp/stagnant places which are not regularly flushed by water.

I t gains entry to the human body mainly via cuts, but infection can also occur via the mouth, (to the lungs) and eyes.

The disease is now less prevalent in the water industry due to good hygiene standards.

As the disease is unusual in the general population your GP may diagnose i t as flu. I t is therefore important that operatives show their niedical card to the GP so that he/she is aware that i t could be a more serious condition.

PERSONAL PROTECTIVE EQUIPMENT ( or PPE.) (SEE ALSO A DDITIONA L NOTES IN SECTIONS 17 A N I ) 18 - Abrcisive Cutting, arid UHP Water Jetting)

Adequate personal protective equipment shall be provided in accordance with the Risk Assessment.

I t must be stressed that normal PPE will not give full protection against high velocity water jets and the direct impact of a je t of water with energy levels currently in use is likely to cause serious injury or death. Various types of PPE are available which will give protection for a short time against a jet, thereby giving the operator an opportunity to direct the jet away from himself or to dump the pressure. Consideration of the use of such PPE must be included in the Risk Assessment.

Body Protection

All team members must wear waterproof clothing or suitable alternatives relevant to the work being undertaken. Consideration should bc given to the use of clothing with enhanced resistance to penetration andor sectional rigid body protection.

Eymace Protection

Subject to the Specific Task risk Assessment Full Face visors with chin-guard may be required to be worn by all team members. (See also section 6.5 - Head protection.)

This is likely to require the supply and use of visors made to at least Grade B impact resistance.

Foot Protection

Following a Site-Specific Risk Assessment foot protection may be required e.g. Steel toe- capped Wellington boots (with steel insteps).

Special boots with metatarsal protection are available and should be worn when undertaking work that requires directing the water jets towards the floor.

WJA. Code of Practice High and Ultra High Pressure Water Jetting

6.4

6.4.1

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Hand Protection

Heavy duty waterproof gloves should be used. Special attention should be given to maintaining gloves in good condition to ensure proper grip and personal hygiene.

Care should be taken to ensure gloves are the correct size. (Wearing gloves that are too large can jam the trigger mechanism of the gun in the open position).

When carrying out hand controlled Rigid Lancing, waterproof gloves with extra grip may be specified.

Head Protection.

Safety helmets (suitable for use with full face visors and chin-guards, if required) must be worn. (Refer to section 6.2 for Eye/Face protection.)

Hearing Protection.

Most water jetting produces noise levels in excess of 85 dbA and hearing protection will be required. In some cases noise levels can be sufficiently high to require the use of ear defenders, for example when operating in a confined space.

Respiratory Protection.

The Risk Assessment must consider the possibility that the High Pressure Jetting operation may generate a water mistherosol that contains harmful material.

A COSHH assessment may be necessary and, if appropriate, respiratory protective equipment provided.

Use of harness when working at height. (See also section 5.2)

If a suitable working platform (scaffold, MEWP) cannot be provided due to the nature of the work then other precautions against injury from falling shall be used e.g. a fall arrest device together with ful l body harness and energy absorber.

Operatives shall be trained in the correct use of such equipment.

Working from ladders is prohibited.

PPE Records

An effective system of maintenance of PPE is essential to make sure that the equipment continues to provide the degree of protection for which it was designed. As part of this procedure records of examinations should also be kept. This examination can range from a general equipment examination covering, for example, the correct provision of gloves to a more formal six-monthly visual inspection of a full body harness.

High Pressure Jetting Team: Organisation and Duties

Supervisor

The operation must be under the direct supervision of a competent and qualified Supervisor responsible for assessing the particular hazards at the site leading to a safe system of work and which could include e.g. Method Statements and Task Risk Assessments.

The Supervisor is also responsible for ensuring that any Statutory requirements are identified on the permit and for verifying compliance with the control measures. (see 3, 3.2 and 4.0)

I W J A . Code of Practice High and Ultra High Pressure Water Jetting I

7.2 Team Leader

7.2.0 The Team Leader must have successfully completed the training requirements (see 3.2) and obtained the practical experience required (see 4.0).

Responsibilities include:

7.2.0.1 Safety Checklist (see APPENDIX 1 )

Selecting suitable equipment and completing all the checks detailed in the Daily

7.2.0.2 specific documentation.

Ensuring compliance with any requirements of the Job Permit or other site

7.2.0.3 Conducting a team talk prior to starting the task.

7.2.0.4 communication and any signals to be used.

Ensuring that all team members clearly understand the means of

7.2.0.5 in gaining experience.

Ensuring that operatives are rotated in their duties to minimise fatigue and assist

7.2.1 The Team Leader must be able to fi l l any of the positions described below.

7.3 Lead Operator

7.3.1 The Lead Operator is usually the person immediately in control of the Jetting Gun, Lance plus Foot Control Valve, or Drain Cleaning Hose.

7.3.2 It is the responsibility of the Lead Operator to signal to the Machine Operator when it is safe to bring the system up to full power.

7.3.3 However, if the operation requires a senorate Foot Control Valve Operator, because the Lead Operator is unable to operate both the Foot Control Valve a& control the lance, the Lead Operator must signal to the Foot Control Operator when it is safe to bring the system up to full power.

7.4 Machine Operator

7.4.1 The Machine Operator is responsible for operating the High Pressure Jetting Unit.

7.4.2 In a two-man team the Machine Operator will also be responsible for the Safety Standby duties.

7.4.3 Special Equipment is available for One Man or Single Person Operation. This must be used strictly in accordance with the manufacturers instructions. (See section 7.8)

7.5 Foot Control Valve Operator.

7.5.1 The Foot Control Valve Operator is responsible for operating the Foot Control Valve on instructions from The Lead Operator.

7.5.2 The Foot Control Valve Operator must have uninterrupted sight and/or communication with the Lead Operator at all times.

Copyright of 77ie Water Jetting Associiitio of a copy where these two sentences a

in red ink. Ifyou lire in ~msse.wioii 11 p\ses.si i~i~ of an illegiil copy.

Copyright of 77ie Water Jetting Associiitio of a copy where these two sentences a

in red ink. Ifyou lire in ~msse.wioii 11 p\ses.si i~i~ of an illegiil copy.

I W J.A. Code of Practice High and Ultra High Pressure Water Jetting I

7.6

7.6.4

7.6.5

7.7

7.7. I

7.7.2

7.7.3

7.8

7.8. I

7.8.2

7.8.3

7.8.4

7.8.5

Safety Standby.

7.6.1 unauthorised entry into the Prohibited Area (see Section 8) the pressure must be shut off safely and immediately.

7.6.2 Warning the team of the development of any unsafe situation.

7.6.3 Ensuring equipment is shutdown in an emergency or in the event of unauthorised entry into the work area.

If a two man team is working, the Machine Operator will undertake the duties of the Safety Standby.

If the team consists of duties.

Additional Operators

The duties of the Safety Standby include:

Controlling the entry of people into the prohibited area. In the event of an

than two men the Safety Standby must notbe assigned any other

Additional operators may be required when Lance work is under way to support the lance and assist in controlling reaction forces.

They may also be required to assist with handling long hose lengths and in situations where communication between team members is difficult, e.g. acting as a look out in order to keep members of the public away from the Jetting area.

Wherever practicable remote shut off devices should be used in preference to multiple line of sight operations.

Single Person Operation (One Man Operation)

This is any jetting operation utilising only one person to control both the jetting and the Pump Unit.

Single Person Operation is permissible in circumstances where, having undertaken a full assessment of all the risks i t can be clearly demonstrated that there is no increase of risk to the operator and third parties.

Adequate barriers should be provided to prevent persons from entering the work area.

The operator shall be fully familiar with the equipment to be used.

An adequate remote control system with fail-safe provision shall be used to control both the pump unit and the jetting operation during all Single Person Operation.

\

C o ~ g l i t of The Water Jetting Associati of a copy wliere these MO sentence.s

in red ink. Ifyou are in po.~se.~.sirin I I possession of an illegal copy.

I WJ.A. Code of Practice High and Ultra High Pressitre Water Jetting I

7.9 TEAM COMPOSITION

A COMPLETE TEAM SHOULD BE PROVIDED IN EACH OF THE FOLLOWING SITUATIONS

EQUIPMENT IN USE TEAM NUMBERS/DUTIES

Safety Gun with conventional or rotary nozzle. Drain/Pipe cleaning.

Machine Operator/Safety Standby ( I ) Safety Gun/Droin Jetting (Lead) Operator ( I )

As above but with Safety Gun Operator (Lead Operator) out of sight of Machine Operator.

Machine Operator ( I ) Safety Standby ( I ) Safety Gun (Lead) Operator ( I )

Manually Controlled Flexible Lance.

As above with Lead Operator out of sight of the Machine Operator.

Manually Controlled Rigid Stainless Steel Lance.

As above with Rigid Lance Operator out of sight of Machine Operator

Machine Operator/Safety Standby ( I ) Flexible Lance (Lead) Operator ( I )

Machine Operator ( I ) Safety Standby Flexible Lnnce (Lead) Operator ( I )

Machine Operator/Safety Standby ( I ) Rigid Lance Operator (Lead) ( I ) Additional Operators (as required)

Machine Operator ( I ) Safety Standby ( I ) Rigid Lance Operator (Lead) ( I ) Additional Operators (as required)

7.9.1 In some circumstances (See 7.3) an additional Foot Control Valve Operator may be required.

7.9.2 The decision shall rest with the Supervisor and be noted in the Method Statement and Risk Assessment.

8.0 PROHIBITED AREAS

8.0. I Barriers should be erected at ;I distance of ;it least 10 metres all around the jctting operation to prevent entry by unauthorised persons.

8.0.2 People must be protected.

8.0.3 Hoses must be protected if outside the taped off area.

8.0.4 Alternatively a suitable protective screen at least 2 nietres high and able to rcsist a high velocity jet or flying debris, is acceptable at a closer distance if this is assessed ;IS safe by the Supervisor.

Copynglrl of Tlre Water Jertitig of a copy wlrere these h V 0

it1 red i r k If)otr are in possession possessiotr of an illegal copy.

W J A . code of Practice High and Ultra High Pressure Water Jetting

8.1 NO ENTRY signs in accordance with the following wording must be prominently displayed. Suitable PVC signs are available from the Water Jetting Association

8.2

9.0

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10.1

10.2

NO UNAUTHORISED ENTRY

HIGH PRESSURE WATER JETTING IN PROGRESS

Persons wishing to enter the area must wait outside the barrier until the jetting has stopped and permission to enter is obtained from the Safety Standby. If unauthorised entry is detected the pressure should be shut off safely and immediately. Under no circumstances must the jetting operators be distracted.

FROST PRECAUTIONS

WARNING: DO NOT START ENGINE OR PRIME MOVER

If the equipment has been inadvertently allowed to become chilled and any residual water in the pump or hoses has been frozen, i t is essential that the whole system is first thoroughly thawed, then cautiously flushed without any nozzle or other restriction attached to the high pressure hose.

Ice may have been retained in the system. No attempt must be made to force the ice out by starting the engine or prime mover. Ice can be ejected from the hose at high speed as the pump is started. These ice bullets can travel for a distance of 20 - 30 metres with possible lethal consequences.

During periods when there is a risk of freezing, drain the entire system andor take the precautions advised by the manufacturer. Alternatively the following procedure may be followed.

Remove gun or nozzle from HP Hose.

Pump water from water break tank until level of water is just above the water filter.

Add recommended quantity of neat anti-freeze into water tank. Check concentration after subsequent fills.

Place High Pressure Hose end into water break tank and secure.

With unit in recycle mode run the pump until the anti-freeze mix works through the system.

Shut off engine or prime mover.

If no break tank is fitted, follow the manufacturers recommendations.

WASTE DISPOSAL

Collection and disposal of wastehesidues from the High Pressure Water Jetting process must be arranged in accordance with the latest environmental protection legislation and other specific site procedures.

A Site-Specific COSHH assessment may be required.

Copyriglit of The Water Jetting Associatio of (I C C J ~ Y ivliere tliese two sentences a

in red ink. If yoii are in possessiori n possession of an illegal copy


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11.1

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HIGH PRESSURE JETTING UNITS (Also see Appendix 5 for UHP Equipment)

Drive.

The drive may be diesel, petrol, gas or electric.

Equipment intended for use in hazardous areas must be fitted with approved safety and shutdown devices appropriate to individual site requirements.

Electric powered equipment and controls must be enclosedinsulated as necessary to meet any specific individual site safety requirements.

Care should also be taken to ensure that the electrical system is protected frotn the ingress of water.

All electrically operated High Pressure Water Jetting Units shall be checked daily for external damage with special emphasis on connections, junction boxes, switches and supply cables.

Correct direction of rotation of the electrical motor should be checked on initial installation and after every reconnection.

Pump and Controls.

The Pump will typically be a positive displacement piston, plunger, or oil operated diaphragm design or alternatively a hydraulic intensifier arranged to deliver High Pressure Water to the outlet connector.

I t must be equipped with adequate Inlet Filtration, a Pressure Relief Safety Device and an Operating Pressure Indicator (Fluid Damped Pressure Gauge or Digital Readout).

Over pressure relief shall be set at a minitnumlO% above the Maximum Working Pressure of the lowest rated item in the operating system.

Maximum Working Pressure All systems and assemblies shall have a safety device which prevents the permissible pressure from being exceeded by more than 15%.

The permissible pressure is defined as the maximum working pressure of the lowest rated item or component in the operating system or assembly.

In this context, the following three types of Pressure Relief Safety Devices are acceptable:

(1) Bursting or RuDture Disc

The bursting pressure will be indicated by the marking or colour which must conform to a published and well understood explanation.

The disc must be fitted according to the manufacturers recommendations.

Replacement of discs which have failed due to over pressure should not be carried out until the cause of the over pressure has been identified and eliminated.

I IK J.A. Code of Practice High and Ultra High Pressure Water Jetting 1

11.2.4

11.2.4.1

1 1.2.4.2

1 I .2.4.3

11.2.5

1 1.2.5.1

11.2.5.2

11.2.5.3

11.3

11.3.1

11.3.2

12.0

12.1

12.1.1

12.1.2

12.1.3

12.1.4

12.2

(2) Spring Loaded Pressure Relief Valve

This type of valve may be designed for manual or automatic resetting.

The setting of the relief pressure must be tamper proof and the lift pressure and Maximum Working Pressure recorded on a sealed tag attached to the valve body.

The relief setting shall be checked and reset at predetermined intervals, a new tag fixed to the valve and a record kept for future reference.

(3) Air Operated Safety Relief Valve

This valve functions in a similar way to spring loaded Valves but with a preset air pressure holding the valve closed against the high pressure water.

The mechanism will be a diaphragm or piston.

The same requirements for the use of Tags applies as in Section 1 1.2.3.3 above.

ALL SAFETY RELIEF DEVICES MUST BE CAPABLE OF PASSING THE FULL FLOW OF THE PUMP TO WHICH THEY ARE FITTED WITHOUT SIGNIFICANT PRESSURE RISE.

The Jetting Unit

This may be trailer mounted, vehicle or skid mounted and enclosed by an acoustic canopy as appropriate.

The Drive and Pump may be mounted within the Jetting Unit and it may incorporate all controls, instruments and gauges plus hose and accessory storage as required to meet the intended duty.

HIGH PRESSURE HOSE ASSEMBLIES

General Requirements

High Pressure Hose and fitting manufacturers must be accredited in accordance with IS0 9000.

Compatibility between hose and end fitting is essential.

All assemblies must only be manufactured by the hose manufacturer or their authorised distributors.

(See also Appendix 4 - Hose Re-ending)

MAXIMUM WORKING PRESSURE AND TEST PRESSURE

THE MAXIMUM WORKING PRESSURES OF HIGH PRESSURE HOSE ASSEMBLIES SHALL ALLOW A SAFETY FACTOR OF 2.5 to 1 IN RELATION TO THE MINIMUM BURST PRESSURE.

TEST PRESSURE FOR HIGH PRESSURE HOSE ASSEMBLIES SHALL BE 1.5 TIMES MAXIMUM WORKING PRESSURE.

I W J.A. Code of Practice High and Ultra High Pressure Water Jetting I

12.3 Marking and Inspection

12.3.1 ALL HIGH PRESSURE HOSE SHALL HAVE THE FOLLOWING: A unique reference number stamped or engraved onto the fitting from which the following information can be obtained for each assembly:

0 The maximum working pressure. 0 Date of manufacture. 0 Name of manufacturer. 0 Traceability.

12.3.2 A certificate of conformity shall be provided for audit when required for each assembly showing the:

Manufacturers/assemblers name. 0 Test date. 0 Test Pressure.

Unique reference number.

Note: Frequency of inspection of hoses and hose assemblies must be at least on a daily basis.

12.4

12.4.1

12.4.2

12.4.3

12.4.4

12.4.5

12.4.5. I

12.4.5.2

12.4.6

3.0

3.1

3.1.1

3.1.2

RIGID, SEMI-RIGID AND FLEXIBLE LANCES

Rigid or Semi-Rigid Lances may have nozzles fitted to them with any combination of forward, backward, angled, fixed or rotary jets.

There is no industry standard for Flexilances and in general they must comply with the requirements set out in 12.1 to 12.3 above.

They are provided for use manually or in conjunction with a Powered Lance handling device (such as the FreelanceTM)

Nozzles for use with Flexilances may be conventional or of the rotary type and must have more rearward than forward facing nozzles.

Lances (powered - rigid and flexible)

These are mechanical devices which control the movement of rigid or flexible lances and which offer increased operator safety. Typical examples are PowerlanceTM (rigid) or FreelanceTM (flexible)

This equipment must be used in accordance with the manufacturers instructions.

Rigid and flexible lanceshozzles designed for use in a powered system shall never be operated manually.

CONTROL VALVES

Adjustable Pressure Control Valve

This valve is designed to dump to atmosphere or recycle excess water from a high pressure pump that would otherwise cause overpressure with a given nozzle and or engine speed.

Spring loaded versions are manually controlled. Pneumatic control is also available which allows for applications that require remote control.

N.B. THIS VALVE DOES NOT UNLOAD THE SYSTEM.

in red ink. Ijym are LI pmessioi l 11 Immsion o j an illegul copy.

Copyrighl of The WoIer Jmitig AssociaIio of a copy wlierr rliese WO seiilences a

WJ.A. Code of Practice High and Ultra High Pressure Water Jetting

13.2

13.2.1

13.2.2

13.2.3

13.2.4

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13.2.6

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13.3. I

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13.4.3

13.4.4

14.0

14.0.1

14.0.2

14.0.3

14.0.4

14.0.5

Automatic Unloader Valve

This device limits the pressure at which the pump operates by releasing a preset proportion of the generated flow back to the pump suction chamber or to waste.

It should be used to regulate the water pressure from the pump and can be individually set for each operation. N.B. This device may be integral with the pump assembly.

This type of device maintains residual high pressure water between the unloading valve and the jetting gun. The jetting gun must be activated immediately after the high pressure jetting uni t is switched off to release the residual pressure.

All High Pressure Water Jetting Units and Pressure Washers used with a Dry Shut Jetting Gun must be fitted with an Unloader Valve.

When this valve is used in systems with a maximum working pressure exceeding 210 barg a Safety Relief Device must also be fitted. In these cases the unloader valve set working pressure must not exceed 90% of the Safety Relief Device setting.

This type of valve is widely fitted to Pressure Washers in which application it also fulfils the function of the Safety Relief Device.

Diverter/Selector Valve

This is a three port valve mounted on the High Pressure Jetting Unit which will, by manual or remote control, divert the flow from the high pressure outlet to recycle via the header tank and allow system pressure to drop to zero.

Electro Pneumatic Jetting Gun Controls

This system enables the Gun Operator to control the power supplied to his Jetting Gun by means of a low voltage cable or pneumatic line to the jetting unit.

On depressing the trigger the pump uni t is brought on load and the engine speed controlled by a pre set electro pneumatic/mechanical control or computer controlled throttle.

There must be no significant delay between release of the trigger and system pressure dropping to zero.

I t is recommended that armoured cable should be used in these operations.

ACCESSORIES - GENERAL CONSIDERATIONS There is a very wide range of accessories available and reference should be made to manufacturers literature to select the appropriate equipment for the application.

Care must be taken if the accessory selected has a lower working pressure than the Jetting Unit with which it is to be used.

In this case the Pressure Relief Safety Device must be reset to the maximum working pressure of the accessory by a competent person.

If this is not possible an alternative Safety Relief Device with the correct operating range must be fitted.

NB. It is recommended that a traceability procedure similar to that for High Pressure Hoses be used for all accessories. (See section 12.1)

Copyright of The Wuter Jetting Assmiuti of a copy where these two sentences

i red itik. Ifyoii UIE in possession possession of un illegal copy.


14.1

14.1.1

14.1.2

14.1.3

14.1.4

14.1.5

14.2

14.2.1

14.2.2

14.2.4

14.2.5

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14.3.6

14.4

14.4.1

14.4.2

14.5

14.5.0.1

14.5.0.2

DUMP TYPE JETTING GUNS

These have a three-port valve assembly with one inlet and twooutlet ports.

One of the outlet ports will be fitted with a high-pressure barrel the other will be a low- pressure dump outlet, which may be fitted with a diffuser.

The Jetting Gun will be controlled by a trigger, which must require minimum effort to operate.

A trigger guard shall be provided and a lock-off device fitted to avoid accidental operation.

An adjustable shoulder stock and side handle may be fitted to assist the control of nozzle reaction forces.

DRY SHUT-OFF JETTING GUNS

These have a two-port valve assembly with one inlet and one outlet port.

The outlet port will be fitted with a high-pressure barrel. Other features are as for the Dump Gun.

When the pump is switched off, care must be taken to release system pressure between pump and Safety Gun by depressing the trigger.

N.B. Some Guns incorporate an electric or electro pneumatic switch which operates an unloader/diverter valve on the pump uni t to provide zero flow through the gun on release of the trigger.

DUMP TYPE FOOT CONTROL VALVES

These are a three-port valve assembly with one inlet port and two outlet ports.

One of the outlet ports will be arranged to supply high-pressure water to the required accessory, the other will be a low-pressure dump outlet.

Control will be by a foot pedal, this should require minimum effort to depress and must be shielded against accidental operation by an adequate shield.

The assembly must be mounted in a frame capable of providing stability during operation.

When a hose is fitted to the dump port this must be secured to prevent hose whip when the foot pedal is released.

DRY SHUT TYPE FOOT CONTROL VALVES

These are a two port valve assembly with one inlet and one outlet port

Other features are as for the Dump type of Foot Control valve.

NOZZLES FOR USE WITH JETTING GUNS

The nozzle is fitted to the Guns high pressure barrel.

The function of a water jetting nozzle is to convert the latent energy (i.e. high pressure) into kinetic energy (i.e. high velocity). There are two types or groups of nozzle.

Criwriglit of The Water Jettiiig Associuri of o copy where these two seiitences

in red ink. If you ure in pmsessioii it p.ses.sion of on illqul cow.

I WIJ.A. Code of Practice High and Ultra High Pressure Water Jetting 1

14.5.1

14.5.2

14.5.3

14.5.3

14.5.4

14.5.5

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14.6.3

14.7

14.7. I

14.7.2

14.8

14.8.1

14.8.2

14.8.3

The conventional or fixed orifice nozzle (forward facing) provides a wide range of jet configurations from virtually 0' pencil jets to wide-angle fan jets.

Rotarv/orbiting nozzles range in type from the single orbiting jet to multi orifice rotary assemblies.

Nozzle size must be selected with regard to the maximum operating pressure of the system and the nozzle reaction force likely to be generated.

Note: Rotary nozzles may be self rotating or powered by air or by a hydraulic motor.

Nozzle material will be as supplied by various manufacturers and shall be certified for the pressure to be used.

Where ceramic or sapphire inserts are used they must be fitted according to the manufacturers instructions.

SPECIAL SAFETY NOTE Rotary Nozzles are known to suffer stoppages of the rotary function due to a build up of debris.

NO ATTEMPT MUST BE MADE TO CLEAN THESE OR ANY OTHER NOZZLE UNTIL THE JETTING UNIT IS SWITCHED OFF AND THE PRESSURE STORED IN THE SYSTEM RELEASED.

NOZZLES FOR USE WITH LANCES AND HOSE

These are primarily intended for tube, pipe and drain cleaning/descaling these are available as fixed or rotating versions.

The Jet configuration must be carefully selected in relation to the duty required and operating safety.

When using nozzles with forward facing jets care must be taken to ensure there is always a greater power exerted by the rear facing jets.

Nozzles (fixed installations)

Generally used for internal cleaning/descaling of process containers and storage and transportation tanks.

As there is the potential for this equipment to be operating for long periods with minimum staff levels, special care must be exercised in routing of hoses, the erection of barriers and danger signs.

Surface Preparation Tools

These may be conventional rotary nozzles as fitted to the Gun or alternatively special purpose devices for coating removal prior to recoating or undertaking NDT.

They may be hand operated or powered, mounted on a hydraulic arm or remotely controlled.

Consideration should be given to using these tools in conjunction with a vacuum recovery system.

Copyri& of llre Water Jetting Associati ora copy where these two seiitence.7

iii red ink. Ifyoir are in IMssessessioit n possession of ail illegal copy.

~ ~~


14.9

14.9. I

14.9.2

15.0

15.1.1

15.1.2

15.1.2.1

15. I .2.2

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15.2.1

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15.2.4

Rotating Hose Assemblies, Pipe Cleaning Rigs

These are specially designed assemblies or equipment (used i n the cleaning / clescaling of pipes) in which the entire hose assembly is rotated and powered into the pipe which requires cleaning.

This equipment is designed for use with high power pumps and must only be used by specially trained personnel.

THE SAFE USE OF HIGH PRESSURE WATER JETTING EQUIPMENT

Training All staff involved in using the equipment must be trained and have achieved a level of experience appropriate to their allocated duties.

Water quality

Water to be used for High Pressure Water Jetting should be of potable quality and free of suspended solids.

If this is not available those responsible for the water supply must provide data relating to the water quality and a COSHH assessment if this is indicated.

COUPLINGS AND CONNECTORS

THREADED COUPLINGS, CONNECTORS AND ADAPTORS SHALL HAVE COMMON THREADS AND MUST BE SUITABLE FOR THE WORKING PRESSURES TO BE USED.

THIS MUST BE TAKEN INro ACCOUNT WHEN SETTING THE MAXIMUM WORKING PRESSURE FOR THE ENTIRE ASSEMBLY.

Safety Check, Team Talk, Risk Assessment

Prior to the commencement of work, the Team Leader must complete a Daily Safety Check.

The team leader must also review the Task Risk Assessment at the job site with all members of the team (Conduct a Team Talk) (See also Appendix I)

Signals If the operation requires hand signals to be used these must be agreed and understood by all team members before work starts.

JETTING GUNS

The high pressure barrel of the Jetting Gun should be a minimum of I metre long for standard applications.

In cases where short barrels need to be used, this may require additionid training and must be covered in the Method Statement /Task Risk Assessment.

The maximum recommended nozzle reaction force for hand held Jetting Guns is 250 Newtons. If the power in use means this figure will be exceeded additional support should be provided.

This may be in the form of a gimbal or some other structure or carriage but must not in itself create a hazard.


15.2.5

15.2.6

15.2.7

15.3

15.3.1

15.3.2

15.4

15.4. I

15.4.2

15.4.3

15.4.4

15.5

15.5.1

15.5.2

15.5.3

15.5.4

15.5.5

The trigger mechanism is vulnerable to ingress of diddebris and must be cleaned at frequent intervals.

If a shoulder stock or side handle is fitted this must be adjusted to give the most comfortable position for the operator.

THE TRIGGER MECHANISM MUST NEVER BE LOCKED OR WEDGED IN THE ON POSITION.

USE OF FOOT CONTROL VALVES

When a Foot Control Valve Operator is required he will normally take instruction from the Lead Operator.

See also section 14.3 and 14.4

LANCES (RIGID /SEMI RIGID) MANUAL CONTROL

The use of manual controlled Rigid Lances is most common in descaling Tube Bundles in which some or all the tubes are blocked.

The length of a Rigid / Semi-Rigid or combination of Lances shall be such that the operator/s can maintain control at all times.

When any lance is in use the nozzle must be safely positioned within the work piece, and the operator suitably protected from the high-pressure water jets, prior to pressurisation of the system.

Due to the foreseeable possibility of a lance being ejected/thrust from a tube at high speed (by the hydraulic reaction of the lance within the tube) provision must be made to alert the operator to, and protect the operator against, this event. ready to react and immediately release pressure.

The Foot Control Valve Operator must be

LANCES (FLEXIBLE) MANUAL CONTROL

Flexible Lances are used for tube cleaning applications in which restricted access prevents the use of Rigid lances or the type of cleaning is more suited to this equipment.

Due to its characteristics i t is not possible to push the Flexilance against nozzle reaction forces and nozzle selection must reflect this, nozzles always having more backward than forward facing jets.

Where operating space allows it is recommended that a suitable length of rigid stainless steel leader (Lance Stinger) should be used between the Flexilance and the nozzle to assist handling.

In the event that the nozzle becomes detached from a Flexilance, the Flexilance will be thrust from the tube at high speed and the Foot Control Valve Operator must be ready to react and immediately release pressure.

There is a Whiplash danger under these circumstances and a Lance Guard must be used where practicable.

Copyright of The Water Jetting of a copy where these two

W J A . Code of Practice High and Ullra High Pressure Waler Jetting

15.6

15.6.1

15.6. I . 1

15.6.1.2

15.6.2

15.6.3

15.6.4

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15.7

15.8

15.8.1.

15.8. I . I

15.8. I .2

15.8.1.3

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15.8. I .5

15.8.2

NOZZLES

Correct Nozzle selection is critical in achieving a good performance from High and UHP Jetting Equipment.

They must always be fitted correctly without any leaks using the correct spanner.

Wrenches or spanners with serrated teeth, e.g. 'Stillson' type wrenches, must never be used.

Apart from establishing damage, visual inspection of nozzles themselves is less valuable in monitoring wear than noting the Jet pattern and working pressure.

A deteriorating jet pattern and /or a fall in the working pressure are the main indications of nozzle wear, in the case of conventional nozzles.

(This is not a safety hazard but it is recommended that replacements are made when pressure loss exceeds 10% of original or the jet pattern is no longer producing the required results.)

Rotary Nozzles, especially the free spinning versions in which the rotor containing the nozzle inserus spins on a fixed shaft, should be inspected for wear daily. If any Shaft wear is apparent the assembly must be replaced.

(The manufacturer's guidelines for measuring wear must be followed)

NB. A drop in operating pressure may indicate shaft wear, in this case work must cease and the cause of the fall in pressure must be ascertained and rectified before work restarts.

HIGH PRESSURE HOSE

Supervisors and Team Leaders must understand the implications of pressure losses in hose and be aware of the precautions to be taken when using additional lengths of small diameter hose.

Guidelines for the use of High Pressure Hose

Great care must be exercised in the selection, use and routine inspection of High Pressure Hoses.

They should be inspected at each shift change or daily as a minimum.

High Pressure Hoses must be removed from service if any wire braid is broken or heavily corroded, end fittings damaged, worn or heavily corroded, or kinked sufficiently to damage inner lining or braid.

Special attention must be given to the condition of the hose immediately adjacent to end fittings. If the hose is kinked or damaged at this point i t must be removcd from scrvice.

Hoses should not be laid across roadways. If this is unavoidable, suitable hose ramps must be used, permission obtained from the appropriate authorities and warning notices displayed.

If a length of hose is accidentally crushed, for example by a forklift truck wheel, that length of hose must be taken out of service immediately.

Any damage that results in a hose being withdrawn from service must be reported to the Supervisor who should arrange examination by a competent person who may report on the course of action advised.


15.8.3

15.8.4

15.8.5

15.8.6

15.8.7

15.8.8

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15.8.14

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16.0

16.1

16.1.1

16.1.2

16.1.3

16.2

16.2. I

16.2.2

16.2.3

Records should be kept of the work done and the hose should be retested before being returned to service.

Hoses should be routed away from pedestrian walkways. Where this is not possible some form of shield may be considered.

Hoses must be secured at intervals along their length when accessing high buildings or structures.

Hose covershheaths may be used as added protection in certain situations.

Hose restraining devices of the correct rating should be used as protection against coupling failure.

Hose Feed Guides should be used to reduce the risk of damage to hoses when cleaning pipes or drains.

If a leak develops in a hose coupling work shall cease until the problem is rectified.

Hose connectors must never be tightened whilst the equipment is pressurised or the power unit running

Hose couplings must never be over tightened.

Tools with serrated gripping jaws can cause damage and must not be used.

Care must be taken never to bend a hose beyond the minimum specified bend radius and protection must be provided when any hose is laid across sharp edges etc.

A hose reduces in length when pressurised. Due allowance must be made for this in all applications.

This shortening of the effective length of the hose may damage the couplings, connectors and hose.

CARE AND MAINTENANCE OF EQUIPMENT

General

Regular care and maintenance is essential for the Jetting Unit and Ancillary Equipment.

This must be carried out in accordance with the manufacturers instructions.

Work done should be recorded / certificated.

Water Filtration

Water filtration is a very important factor in the safe and reliable operation of all High Pressure Water Jetting Equipment.

This increases in criticality when Ultra High Pressures are used. (See Section IS)

Failure to maintain filtration systems correctly is likely to create cavitation within the system and the possibility of serious damage.

THE EQUIPMENT MANUFACTURERS INSTRUCTIONS MUST BE FOLLOWED REGARDING WATER SUPPLY AND FILTRATION.


Servicing of all components making up the High Pressure Jetting Unit.

Pressure Relief Valve inspection, maintenance and resetting.

16.3

This must be carried out iiccording to the Manufacturer's recommendations.

6 Monthly or at Pre-Delivery Inspections

16.3.1

Pressure ControlKJnloader Valves servicing.

Safety Guns and Foot Operated Control Valves.

Rotary Nozzle Assemblies (All types)

Inspectionheplacement of all fluid retaining components including connectors and couplings.

16.3.2

16.3.3

16.4





Responsibility

The Maintenance of High Pressure Water Jetting Equipment can be divided into three categories:

(1) Routine maintenance

Trained Jetting Operators may be authorised to carry out these tasks in accordance with the manufacturers instructions.

(2) Servicing and Repair of equipment. This work must only be carried out by suitably qualified personnel.

Inspection and Testing of Pressure Jetting Equipment and associated Safety Relief Valves. This work must only be carried out by suitably qualified personnel.

(3)

Competent Persons

Records must be kept of persons competent to carry out work on High Pressure Water Jetting Equipment.

These must include: details of courses attended and qualifications obtained.

Only such persons must carry OUL the following work:

DESCRIPTION FREQUENCY

16.5 Records must be kept of all maintenance and repair work carried out, these must show:

0

0 Date work done.

0

Items inspected. Condition of items inspected. Next service due date.

The name of the person who carried out the work.

Details of work done or repairs carried out. Components replaced and the reasons.

Copyright of Tire Water /e of o copy where these

I red ink. If'yori ore in psses.sion p.wes.sion of on illego1 cqn:


17.0

17.1

17.1.1

17.1.2

17.1.3

17. I .4

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17.2.1.

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17.2.1.4

17.2. I .s

ADDITIONAL CONSIDERATIONS HIGH PRESSURE ABRASIVE JET CUTTING (COLD CUTTING)

Additional Hazards and Precautions to be taken.

Abrasive Jet Cutting techniques may be used for cutting most materials and composites and are suitable for use in areas where conventional cutting equipment would be unacceptable due to the risk of sparks.

Consideration must be given to the following requirementshazards not found in conventional water jetting.

Operators must be specially trained in the use of the equipment.

Protection must be provided for components or structures within range of the cutting jet and ricochet of abrasive particles.

Changes in the structural integrity of the itendstructure being cut must be assessed and suitable supports provided where necessary. This must include the safe retentionhandling of cut items as the process continues.

Equipment must be positioned to allow for the safe manual or mechanical handling of abrasive.

Account must be taken of the increased loads likely to be imposed on the structure being cut, by the retained waterhbrasive mix.

Remote control nozzle handling systems should be used where practical. (see section 17.3)

The equipment must be earthed to meet site requirements.

COSHH assessments on the abrasive used and the resulting debris may be required

Types of Abrasive Feed Systems

Venturi injection Direct injection

Venturi Injection

This comprises a mixing head and nozzle assembly, abrasive supply hose and an abrasive container usually known as a hopper.

The abrasive may be dry or in slurry form.

High-pressure water passes through a nozzle mounted in the mixing head behind the cutting nozzle.

This draws abrasive into the mixing head and accelerates this through the cutting nozzle to produce a high velocity stream of water and abrasive.

Operating pressure in the UHP range may be utilised with this type of system providing suitably rated components are used.

Co~yriglit of The Water Jettirig Associati of a copy where these hvo sentences

n red ink. If you are in posses.~ic~~ I ~msse.ssion of an illegal copy.

WJ.A. Code of Practice High and Ultra High Pressure Water Jetting

17.2.2

17.2.2.1

17.2.2.2

17.2.2.3

17.2.2.4

17.2.2.5

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17.3. I

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17.4.1

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17.6

17.6.1

17.6.2

Direct Injection

The Direct Injection method provides for the water and abrasive to be carried to the cutting head in a single hose under pressure.

Abrasive is introduced to the system through a hopper. This must be fitted with a fine screen to prevent foreign material entering the process.

A diaphragm pump transports abrasive from the hopper into the pressure vessel through a system of interlinked valves.

Water and abrasive is mixed together in a pressure vessel, pressure being supplied by a high pressure pump. The water and abrasive mix is transported at low velocity via control valves to the nozzle that generates a high velocity stream of waterhbrasive.

Cutting systems normally incorporate two pressure vessels, one working while the other is recharging with abrasive.

Remote Handling Systems

These systems normally consists of hydraulic powered rotary and linear drives and incorporate a nozzle carrier mounted on a track or rotating device.

These must be held securely in position by magnets, ratchet straps, clamps or other approved device.

The nozzle carrier is adjustable for angle of cut and stand off distance.

'Qpes of Abrasive Material

Many grades of abrasive are suitable for Abrasive Jet Cutting depending on the application and the type of process in use but attention must be given to the following factors.

Uniform particle size and freedom from foreign material must be achieved in order to minimise or prevent system blockages.

When using Venturi Systems at High and Ultra High Pressure care must be taken in selection of sufficiently fine grades of material to avoid blockages and excessive wear.

Materials containing free silica must not be used.

PERSONAL PROTECTIVE EQUIPMENT

Standard PPE as used for High Pressure Water Jetting may be used but special care is required in the cleaning and maintenance of equipment due to the presence of abrasive in the operating area.

SITE CLEARANCE

Abrasive and other residues may contain toxic or noxious substances resulting from the cutting process.

Due care must be exercised in the disposal of these residues in accordance with the local environmental requirements.


18.0

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18.1.2

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18.6

18.6.1

ADDITIONAL CONSIDERATIONS ULTRA HIGH PRESSURE WATER JETTING (UHP)

The term Ultra High Pressure Jetting, or U.H.P.

Throughout this Code the term UHP applies to all Jetting carried out at pressures above 1700 barg. (See Section 2 of this Code)

The growing availability and use of UHP Water Jetting Equipment, especially for surface preparation, means that many more operators will be required to work with pressures in excess of I700 barg than has previously been the case.

Additional training and experience.

I t is therefore very important to stress the need for adequate additional training.

Inexperienced Operators should also always be deployed with fully experienced Team Leaders in order to avoid the risk of injury.

Differences between UHP and conventional High Pressure Jetting.

There are a number of differences between conventional High Pressure and Ultra High Pressure Water Jetting. The most important of these are listed below.

Water flow in UHP systems is generally lower than in conventional HP systems and the nozzle reaction force is not as high, even though the energy released is much greater.

Jetting Guns can therefore feel easier to control but this should not be allowed to generate complacency regarding the perceived decrease in risk.

The Jet Velocity of a 2500 barg UHP system is in excess of 2,400 Kilometres per hour.

ENERGY COMPARISONS

The energy available from a conventional 100 horsepower (or 76 kilowatt) unit working at 350 barg is approximately

6 kilowatts per square millimetre.

The energy available from a similar power unit working at 2500 barg is approximately

117 kilowatts per square millimetre.

THE UHP UNIT THEREFORE HAS AN OUTPUT OF ENERGY APPROXIMATELY

18 TIMES GREATER

THAN THE CONVENTIONAL UNIT.

Risk Assessments must take this factor into account.

The Risk Assessment should also consider whether the entire task, or parts of it, can be automated or whether robotic processes can be utilised

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I WJ.A. Code of Practice High and Ultra High Pressure Water Jetting 18.7 Personal Protective Equipment

Special PPE is available including boots with improved metatarsal protection. Clothing with enhanced penetration resistance andor sectional rigid body protection should also be considered.

18.7.1

18.8

18.9

18.9.1

18.9.2

18.9.3

It is important to note that whilst these items offer some improved protection, especially when using multi orifice rotary nozzles, they offer less protection against water jets from single orifice nozzles.

Water Quality

The filtration of water is critical for the reliable operation of UHP systems and the manufacturers instructions must be carefully followed.

Additional Mechanical Considerations

The pressures involved in UHP systems require the use of gland fittings (autoclaves) or equivalent fittings for fluid connectors and hose couplings.

Special care must be taken to protect these and to ensure that no dirt enters the system during coupling/uncoupling operations.

Hose restraints should be used to reduce the risk of whiplash injury. When in use they must be fitted according to the manufacturers instructions.

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WJA. Code of Practice High and Ultra High Pressure Water Jetting

APPENDIX 1 (PI of 1) TYPICAL DAILY SAFETY CHECK LIST

PERSONNEL 1 . Are all Team Members trained and correctly certificated? 2. Are new or additional operators deployed safely? 3. Are all the required Permits and Authorisations FOR THIS JOB signed? 4. Do all Team Members understand the Task Risk Assessment? 5. Are the Team wearing the correct PPE? 6. Is there a direct sight line between the Lead Operator and the Foot Control Valve Operator? JETTING UNIT/ SERVICES I . Have all routine equipment checks on the Jetting Unit been carried out. 2. Is the Safety Relief Valve set correctly relevant to the equipment to be used? 3. Is the water filter clean and fitted correctly? 4. Are the Stop/Shutdown Controls working correctly? 5. If shut down valves (Chalwyn Valves) and Spark Arrestors are required, are they fitted

and in good condition? 6. Is the Earth Wire connected and continuity confirmed? 7. Is the unit roadworthy (where trailer mounted)? Tyres- Coupling/Hitch - Controls - Lights - Brakes - Battery - Chassis- 8. Is water supply from an approved source? 9. Are water supply hoses without leaks and correctly protected from damage? ACCESSORIES / HOSES / FLEXILANCES /RIGID LANCES I . Are HP hoses suitable for the application and certificated? 2. Have they been inspected for damage and approved fit for use? 3. If special safety devices are to be used, are all team members competent in their use? 4. Have Flexilances and/or Rigid Lances been inspected and approved fit for use? 5. Safety Gun checked and suitable for application? 6. Safety Foot Control Valve checked and suitable for application? NOZZLES 1 . Is the nozzle in use as specified in the Procedure / Method Statement? 2. Is the nozzle undamaged clean and all orifices free from obstruction? 3. If using Rotary Nozzles, have they been inspected for wear as per manufacturers instructions? WORK SITE I . Is sufficient protection erected to prevent injury / damage to passers by and other equipment? 2. Are barriers and signs erected as uer the COP? 3. Is the work area / platform a safe place for the operation to be undertaken? 4. Are arrangements for the control and disposal of waste fluids satisfactorv.?

I I

5. Are arrangements for good housekeeping in place and enforced? 6. Are arrangements in place to check the system is free from air locks? 7. Are arrangements in place to check the pressure system is leak and defect free? 8. Are arrangements in place to clear equipment from site at completion of iob?

IMPORTANT ALL QUESTIONS MUST BE ANSWERED YES OR N/A BEFORE WORK MAY START

Operation.. ........................................ Location.. ............................... Signature of Team Leader.. .................. Print Name ........................... Company .......................................... Date ....................................

~~~~ ~


APPENDIX 2 WATER JET INJURIES (P1 of 3)

MEDICAL NOTES - HIGH PRESSURE WATER JET INJURIES INTRODUCTION Pressure injection injuries, especially to the hand and upper extremities, with water, grease, paint, gasoline or

paint thinner are well described. High Pressure injection injuries are serious injuries with life and limb

threatening potential. The pressure required to penetrate the surface of the skin is i n the order of 7 x 10 N/

m2 or 100 psi. However, pressures currently used for High Pressure Water Jetting can exceed 2500 bar

(35500 Ibs/in2). The combination of irritant material and high pressure results in an extremely intensive

inflammatory reaction which develops within hours of the injury occurring. The irritant material may travel

proximally along visceral planes, nerves or tendon sheaths resulting in vascular compression and local

necrosis.

NATURE OF INJURY The theoretical velocity of the jet can be derived from the formula: 8.34 (p=lbs/in*). With water pressure up to 2500 bar (355001 bs/in2) velocities in the order of 1550 m.p.h. (2500 KM/HR) can be encountered.

The kinetic energy dissipated on impact can, of course, be derived from KE = 1/2MV where M is the mass of water ejected and V the velocity of impact. Even with parts of the body that have a capacity to absorb only small quantities of water, say 0.035 oz ( 1 gramme) as in the case of the finger, the energy expended may be of the order of 1500 ft Ibs (63.21 Joules). With other parts of the body with greater capacity the energy levels will be that much higher.

When a High Pressure injection injury occurs the kinetic energy absorbed by the tissues is substantial and the toxic material is often driven from the fingertip to the palm. Injuries in which an irritant material is injected have a particularly poor prognosis even with prompt exploration and debridement. Amputation of the finger is often required in these cases.

Water injection injuries do not result in the sane degree of secondary tissue damage and toxicity although the greater pressures and nozzle velocities can result in very extensive tissue injury. The pattern of tissue damage can be similar to that of high velocity missile gunshot wounds. All High Pressure Water Jet injuries should be considered surgical emergencies. The small entrance wound and lack of an exit wound is not indicative of the extensive disruption of deeper tissues which can result from dispersion of kinetic energy after penetration of the skin by water.

High Pressure Water Jet injuries may result in the infiltration of water and air into the tissue planes. The resulting subcutaneous emphysema can be an indication of the extensive internal damage. A classic radio- graphic appearance of diffuse subcutaneous air may be found.

High Pressure Water Jet injuries present with several unique features. The external manifestations in the injury are unreliable in predicting the extent of internal damage. Bacterial or chemical inoculation can cause significant morbidity. High Pressure Water Jet wounds may involve vascular or neurological injuries. Wounds of the abdominal wall may involve intraperitoneal injuries.

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W J.A. Code of Practice High and Ultra High Pressure Water Jetting I

APPENDIX 2 WATER JET INJURIES (P2 OF 3)

INITIAL ASSESSMENT 1. At scene.

The importance of the injury and the potential severity must be recognised immediately.

First aid measures should include controlling any bleeding by the application of pressure over the site of the bleeding and elevation of the injured limb where possible. Arrangements should then be made for the immediate transfer of the patient to a hospital medical facility.

It is recommended that the hospital Accident and Emergency Department be contacted by telephone whilst the patient is in transit with the following details:

1. Time of the injury ii. iii.

The nature of the material in the jet To reiterate to hospital Accident and Emergency staff that although the initial injury may appear to be minor, the potential for serious complications arising exists and these patients require referral to the duty Orthopaedic team for assessment.

2. In hospital. I . Assess the patient for any life-threatening injury and ensure that the airway, breathing and

circulation are controlled and stable.

ii. Control any external haemorrhage by the application of pressure.

iii. Obtain the following details in the history: a. Time of the incident b. Details of the contaminant C. Past medical history d. Any antibiotic allergies e. Date of last Tetanus injection

3. Examination. I . General examination. ii. iii. Check for local swelling. iv. V. 1.

Examination of the injury site - note the size and site of the entry wound.

Assess the range of movement. Assess nerve and tendon function. Obtain x-rays of the injured area to check for the presence of subcutaneous air.

NB Normal examination at this stage does not exclude serious and potentially limb threatening complications developing.

4. Refer the patient for assessment by a senior Accident and Emergency doctor or the Orthopaedic team.

5. The patient should be taken to theatre for exploration of the injured limb.

6. Prophylactic broad spectrum antibiotics will be required at the earliest possible stage.

7. Ensure that Tetanus prophylaxis is up-to-date.

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~~~~ I W J A . Code of Practice High and Ultra High Pressure W a t e r r I

CONCLUSION

High Pressure Water Jet injuries should be considered surgical emergencies. A high index of suspicion of associated internal injuries and aggressive surgical intervention are required.

Although water injection is not as toxic to tissues as petroleum based agents, High Pressure Water Jet injuries pose a serious risk of bacterial infection (20%). Bacterial contaminants include grain positive and gram negative bacteria, fungi and uncommon pathogens including aeromonas hydrophia. The water used in high pressure jet devices may be contaminated with sewagc or oil lubricants. For these reasons, broad spectrum antibiotics should be started and continued for several days post operatively.

Unfortunately, the initial apparently minor nature of the iiijury associated with the delay in the progression to severe inflammation frequently results in a delay i n referral. The management of such injuries consists of immediate exploration extended as widely as necessary with surgical debridement of all toxic material, areas of obvious necrosis should be excised and the wound left open. Serial surgical debridement may be necessary. Open wound management has been shown to offer the best results for injuries. One series reported an 84% digit salvage rate and return to normal hand function in 64% of patients. Amputntion may still be necessary in some cases.

Refs.

Burke E and Brady 0. . Veterinary and industrial High Pressure injection injuries. British Medical Journal 1996, 3 12, 1436.

OSullivan S., ODonohue J. and OConnor T. .. Occupational High Pressure iiijection iiijury of the hand. Dermatology 1997, 194, 3 I I .

Harvey R., et al - Major vascular injury from High Pressure Water Jet. Journal of Trauma, 1996,40, 165- 1 67.

The Water Jetting Association acknowledges with thanks the help given in the revision of these notes by:

Mr John Heyworth MB ChB FRCS FFAEM.

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APPENDIX 3 (P1 OF 2)

ILLUSTRATIONS OF TYPICAL HIGH PRESSURE HOSE AND END FITTINGSKOUPLINGS

Fig.1. Hoses intended for use at pressures up to 420 barg. This hose is usually of a single / double wire braid construction with a crimped swivel nut /cone nipple connector. BSP parallel threads are most common.

12 mm Bore - Rubber Covered Wire Braid Hose.

Hose End

-

Up to 420 bar

Fig, 2. 12 mm Bore - Rubber Covered Multi Spiral Hose. Hoses for use at pressures up to 1400 barg. The hose is usually of multi spiral construction and must have a solid or thrust wire swivel nut. Cone nipple metal/metal connectors with parallel threads or fittings with integral 0 rings may be used. Metric and Imperial threads are available.

Multi Spiral

Hose

Jose

. --.

! End

3 Up to 1400 bar


APPENDIX 3 (P2OF2)

Fig. 3. Plastic Covered Multi Spiral Hose. Hoses of this type are used for Flexilance applications and at pressures to 1500 barg. Use solid swivel nuts.

Pressures up to 1500 bar Multi Spiral Hose End

Up to 1500 bar

Fig.4. Hoses of this type, fitted with gland type (Autoclave) fittings (or equivalent) are used at operating pressures up to 3000 barg. These use a metal-to-metal seal and two swivel nuts, one of which is adjustable on the nipple shaft. They must be kept clean, protected from darnage and only used i n accordance with the manufacturers instructions.

Plastic Covered Multi Spiral Hose for UHP.

UHP Multi Spiral Hose

Pressures up to 3000 bar UHP Hose End

Up to 3000 bar

(The illustrations above are reproduced by kind permission of various sources.)


APPENDIX 4 (Pl OF 1)

HOSE RE-ENDING

High Pressure hose assemblies and fittings must always be supplied by manufacturers who comply with the requirements of I S 0 9000.

Nothing in this section over-rides those basic requirements. (See also Section 1 1 of this Code for general specifications)

Fluid Power Assemblies However in the course of normal operating conditions High Pressure Water Jetting is not considered to be a Fluid Power Assembly and the procedures and regulations applying to Fluid Power Assemblies do not apply to High Pressure Jetting which has quite specific and different requirements.

The procedure of hose re-ending whilst unacceptable in many hydraulic applications is a necessary nortnal crnd essenticrl procedure for Jetting hoses. In most jetting applications the re-ending of hoses after locally- generated damage such as kinking or other mechanical shock to the hose is repairable.

In such circumstances re-ending is considered an essential part of the lifetime care and maintenance of the hose assembly.

Re-ending as a repair or treatment for wear, abrasion, and long term damage is not permitted.

In the absence of any other, mandatory requirements the procedure for the re-ending of hoses is to be subject to the same stringent requirements as for the original supply of hoses and fittings. (See also Section 1 I )

This is particularly true with regard to the need to maintain adequate records and to ensure proper traceability of the history of the hoses, fittings, and resultant assemblies.

Manufacturers requirements

All reputable manufacturers recognise the unique position occupied by High Pressure Water Jetting hoses and assemblies and will arrange for andor approve hose re-ending subject to particular constraints and safeguards.

The following specialist routines may be encountered.

Reputable manufacturers will either carry out the work themselves or nominate an agent (or a series of agents) who can provide national coverage and are approved to carry out the re-ending work.

This may involve a complete examination before re-ending takes place.

Both hose ends may need to be re-ended at the same time.

Some manufacturers insist that only their own fittings are used.

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I WJ.A. Code of Practice High and Ultra High Pressure Water Jetting I

APPENDIX 5 (P1 OF 3)

CONFINED SPACES

WHEREVER POSSIBLE THE NEED FOR ENTRY INTO A CONFINED SPACE SHOULD BE AVOIDED.

Prior to entry a risk assessment must be carried out, and this should include appropriate methods of rescue. This may be a generic assessment leading to a standard safe system of work.

However, on reaching the site a local assessment must be carried out to confirni that conditions are as expected.

For example, if, on arriving to clear a domestic sewer, there is a strong smell of solvent the generic assessment may not be suitable as additional precautions may be necessary.

If in doubt stop and get advice.

The following should be taken into account.

0

0

Oxygen deficient atmosphere (02).

Environment e.g. weatherhides 0 Access and egress.

Toxic gases e.g. hydrogen sulphide (H,S) carbon monoxide (CO). Asphyxiants (gases which displace air) e.g. carbon dioxide (CO2). Flammable materials e.g. methane (CH,), petrol vapour.

Oxygen rich atmosphere - leads to accelerated combustion.

Entry shall not be made or permitted into a confined space unless the atmosphere has been tested for gases that may be present.

A safe result must be obtained before entry is attempted and arrangements made thereafter for the continuous monitoring whilst persons are in the confined space.

Suitable Breathing Apparatus (BA) must be provided and used where necessary.

This may involve an escape set for self rescue.

For more complicated or involved work it may be necessary to use self contained or line fed breathing apparatus.

Detection equipment must be serviced regularly /tested or replaced. Sampling should be done at

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