WJA Guidance Note – 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 WJA’s 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.
1) 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 350bar 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 This standard states “hose lines whose outer layer has been damaged down to the outer wire layer shall be withdrawn from service“.
2) 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 waterjetting hoses the user should refer back to the original manufacturer 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 new 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.
Provision and Use of Work Equipment Regulations (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, inefficient working order and in good repair’.
PUWER Regulation 12 covers protection against specific hazards. It states:
‘Every employer shall take measures to ensure that the exposure of a person using work equipment to any risk to his/her 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 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 and Safety Regulations that hose re-ending be prohibited.
ENDS Ref: 001/14