Health And Safety
In this section
The WJA Statement of Policy in relation to the Health and Safety Commissions ‘Revitalising’ initiative.
The Medical/Surgical advice about Water Jetting Injuries (taken from the WJA Codes of Practice – Blue & Red)
Reference to Personal Protective Equipment (PPE) (taken from the WJA Codes of Practice – Blue & Red)
1Health And Safety Awareness Policy Statement
The Water Jetting Association fully supports the HSE programme called ‘Revitalising Health and Safety’. The ultimate objective of making a collective effort to protect people from injury is fully supported by the WJA Council.
There are 3 Key Targets in this programme, these are:
A reduction of 10% in fatal and major injuries.
A 20% reduction in work-related ill health.
A 30% reduction in working days lost.
2High Pressure Water Jetting Injuries
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 in the order of 7×105 N/m2 or 100psi. However, pressures currently used for ultra high pressure water jetting can exceed 2500bar (35,500lbs/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: 8.3vp (p=lbs/in2). With water pressures up to 2500bar (35,500lbs/in2) velocity in the order of 1,550 m.p.h. (2,500 KM/HR) can be encountered.
The kinetic energy dissipated on impact can, of course, be derived from KE = MV 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 expanded may be of the order of 1,500ft lbs (63.21 Joules). With other parts of the body with greater capacity the energy levels will be 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 the prompt exploration and debridement. Amputation of the finger is often required in these cases.
Water injection injuries do not result in the same 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 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 radiographic 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 intraperioneal injuries.
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 bleeding site 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:
- – Time of the injury.
- – 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
Assess the patient for any life-threatening injury and ensure that the airway, breathing and circulation are controlled and stable.
Control any external haemorrhage by the application of pressure.
Obtain the following details in the history:
- – Time of the incident.
- – Details of the contaminant.
- – Past medical history.
- – Any antibiotic allergies.
- – Date of last Tetanus injection.
- – General examination.
- – Examination of the injury site – note the size and site of the entry wound.
- – Check for local swelling.
- – Assess the range of movement.
- – Assess nerve and tendon function.
NB: Normal examination at this stage does not exclude serious and potentially limb threatening complications developing.
4. Obtain X-rays of the injured area to check for presence of subcutaneous air.
5. Refer the patient for assessment by a senior Accident and Emergency doctor or the Orthopaedic team.
6. The patient should be taken to theatre for exploration of the injured limb.
7. Prophylactic broad spectrum antibiotics will be required at the earliest possible stage.
8. Ensure that Tetanus prophylaxis is up to date.
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 petroleum based agents, high pressure water injuries pose a serious risk of bacterial infection (20%). Bacterial contaminants include gram positive and gram negative bacteria, fungi and uncommon pathogens including aeromonas hydrophia. The water used in high pressure jet devices may be contaminated with sewage 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 injury associated with the delay in the progression to severe inflammation frequently results in a delay in 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. Amputation may be necessary in some cases.
Burke F. and Brady O.
Veterinary and industrial high pressure injection injuries. British Medical Journal 1996, 312, 1436.
O’Sullivan S., O’ Donohue J. and O’Connor T.
Occupational high pressure injection injury of the hand. Dermatology 1997, 194, 311.
Harvey R.,et al
Major vascular injury from high pressure water jet. Journal of Trauma 1996, 40.
The Water Jetting Association acknowledge with thanks the help given in the revision of these notes by:
Mr. John Heyworth MB ChB FRCS FFAEM. August 1999.
3Personal Protective Equipment (PPE)
Any person working with a high-pressure water jetting system or working in its vicinity, must wear suitable protective clothing commensurate with the risk involved in the jetting operation.
When selecting the appropriate PPE to be worn, it is essential that a Risk Assessment is carried out in advance of commencing operations and that the correct selection is made relative to the pressure and flow rate being used and the potential hazard.
It is essential that both employers and employees receive appropriate training in order to understand the selection criteria and need for protection.
It is not permissible to commence hand held water jetting operations at 1700 bars and above (ultra high-pressure) without wearing appropriately rated PPE, selected according to the risk involved.
It must be strongly emphasised that Ultra High Pressure PPE does not give complete protection. However, it will provide enhanced resistance to penetration of the water jet thereby giving time to avoid further contact or to stop the operation and hence reduce the potential injury.
Operators must appreciate that this type of PPE whilst lessening the likelihood of a severe injury will not give them complete protection and therefore high standards of training, supervision and operator vigilance will still be required.
Guidance Note 101 – Revised Jan 2015
Re-ending of High Pressure Hoses Used in Water Jetting Applications
It has been common practice in the high pressure water jetting industry to re-end high pressure hoses when a hose has sustained locally generated damage to its outer casing or threaded connections. In the 2008 Edition of The WJA Code of Practice it was stated that re-ending was a “necessary, normal and essential procedure for jetting hoses” and was allowable under certain named circumstances.
However, to comply with the latest British Standards it has become necessary to revise that guidance and this has been done in the latest 2012 Edition of the WJA Code of Practice. This note clarifies that guidance and states the Water Jetting Association (WJA) position on the subject.
There are several British Standards (BS EN’s) which relate to high pressure hose assemblies and the 2012 WJA Code of Practice now refers to two standards that specifically deal with matters of hose damage and/or re-ending.
BS EN 1829-2:2008 – This European Standard applies to hoses, hose lines and connectors intended to be used with high-pressure water jet machines operating at 350 bar and above. It therefore covers most water jetting applications and some drain cleaning applications.
This standard states “hose lines whose outer layer has been damaged down to the outer wire layer shall be withdrawn from service”.
BS EN ISO 4413:2010 – This European Standard specifies general rules and safety requirements for hydraulic fluid power systems and components used on machinery as defined by ISO 12100:2010, 3.1. It deals with all significant hazards associated with hydraulic fluid power systems and specifies the principles to apply in order to avoid those hazards when the systems are put to their intended use. All jetting machines and drain cleaning machines can be defined as “hydraulic” in operation and hence fall within the scope of this standard. In addition the vast majority of high pressure hoses used for jetting drains and sewers up to 225mm in diameter are of rubber construction and are covered by the hydraulic hose standards.
The guidance on hose re-ending in BS EN ISO 4413 is that “hose assemblies shall be constructed from hoses that have not been previously used in operation as part of another hose assembly and that fulfil all performance and marking requirements given in appropriate standards”. Stated simply this means that it is prohibited to cut a section/end from a used hose and re-end it to form a new assembly.
The reason given by the British Fluid Power Association (BFPA) for not re-ending is that it is impossible to know if the original hose has been stretched, crushed, degraded by sunlight or damaged by chemicals and therefore the hose assembly safety cannot be guaranteed if a new end is fitted.
The 2012 WJA Code of Practice now states that “regarding the re-ending of water jetting hoses the user should refer back to the originalmanufacturer for instruction”. However, operators and users should be aware that the re-ending of hoses will contravene BS EN ISO 4413 and could expose them to increased hazards.
Within the relevant British Standards there is currently no route that allows the re-ending of hoses. It is specifically disallowed in BS EN ISO 4413 and avoided all together in BS EN 1829-2.
PUWER Regulation 5 covers equipment maintenance and builds on the general duty in the Health & Safety at Work Act (HASAW), which requires work equipment to be maintained so that it is safe. It states:
“Every employer shall ensure that work equipment is maintained in an efficient state, in efficient working order and in good repair.”
PUWER Regulation 12 covers protection against specified hazards. It states:
“Every employer shall take measures to ensure that the exposure of a person using work equipment to any risk to his health or safety from any hazard specified in paragraph (3) is either prevented, or, where that is not reasonably practicable, adequately controlled.”
It goes on to list in paragraph 3 “the unintended or premature discharge of …… liquid…… produced used or stored in the work equipment” as one of these hazards and gives an example:
“Explosion of the equipment due to pressure build-up, perhaps due to the failure of a pressure-relief valve or the unexpected blockage or sealing off of pipework”
It is therefore the opinion of the WJA that in order to comply with the Published Standards, PUWER and Health & Safety Regulations that hose re-ending be prohibited.
WJA GUIDANCE NOTE 102 – Feb 2015
Further to the WJA Technical Committee Meeting (January 2015) when Auto Shutdown Valve – Variations in Operation / Shutdown Times was discussed and this Guidance Note was produced.
PUWER Regulations Regarding Stop Controls on Work Equipment
Regulation 15: Stop Controls – states that:
Every employer shall ensure that, where appropriate, work equipment is provided with one or more readily accessible controls the operation of which will bring the work equipment to a safe condition in a safe manner.
This acknowledges that it is not always desirable to bring all items of work equipment immediately to a complete stop if this could result in other risks. For example, stopping a press that has just crushed an operators arm may not be helpful if it means that the operator is trapped in the press after it comes to a halt and cannot be removed quickly by medical staff.
This means that we come back to the ‘Risk Assessment’ and we would need to use the results of the RA to determine whether or not the machine should be ‘stopped’ as quickly as possible. In the case of a water jetting machine it is difficult to imagine a scenario where it would not be desirable to stop the jet as quickly as possible and hence machines should be designed to include a rapid shut down device. A valve that takes many seconds to close a high pressure water jet supply cannot be considered appropriate.
Furthermore the Machinery Directive 2006/42/EC section 18.104.22.168 states that a machine ‘must be fitted with an emergency stop device which must stop the hazardous process as quickly as possible, without creating additional risks.’
The directives and regulations clearly require that any process giving rise to a hazard, which can be stopped quickly without causing additional hazards, should be stopped as quickly as possible in order to minimise the risk to operators.