High Pressure Water Jetting

Purpose
This document provides information, guidelines, international placement services and requirements for performing high pressure water jetting activities. The potential hazards associated with high pressure water jetting and precautions necessary to perform the work in a safe manner are highlighted. Scope
Applicable to all high pressure water jetting activities.

References
Code of practice (1995), by Association of High Pressure Water Jetting Contractors. Manufacturer's Safety Requirements HPWJ-pumps and Equipment, by The Technical Committee. HPWJ Manufacturer's. 1982.

Objectives
To specify the requirements for the safe and efficient execution of high pressure water jetting activities.

Definitions
Remark : No effort is made to provide an exhaustive list, further information can be found in the referenced documents.
Pressure : 1 bar - 100 kPa (kiloPascal) and 1 barisapprox. 14.5 psi (pound per square inch)
Force : 1 Newton = 0.1 kgf

High Pressure Water jetting is the use of water in excess of 100 bar to clean fouled surfaces. Lance, rigid metal pipe used to carry the nozzle and connected to the high pressure transport hose. Flexible Lance, length(s) of flexible hose to carry the nozzle and connected to the high pressure transport hose. Nozzle, special tool at the end of the lance to provide the desired spray pattern.

Water Jet, stream of water produced from the nozzle. Straight Jet, pin jet, pencil jet or glass rod, round shaped pattern of the water stream from the nozzle. Typical for cutting application. Fan Jet, spread water stream in one wide plane. Typical for surface cleaning. Foot control valve, (foot pedal or dead man's valve) the operator's safety control valve. PTW, Permit To Work. PPE, Personal Protective Equipment.

Responsibilities
The Project Manager is responsible for the proper execution and verification of all work, related to the high pressure water jetting activities. Proper execution means that all contract documentation is in order, procedures and instructions are adhered to, and communicated in a proper manner, the results are documented.

Certification and permits
It is essential that for HPWJ operations a valid PTW is available. ^Client's requirements may include a separate PTW, with specific safety requirements. Prior to the start of the work on each shift a detailed inspection of the equipment shall be carried out. Inclusive the verification of the record of Plant Services inspection and hose certification. The qualification of the operator shall be verified. Proof of the qualification shall be available. The Project Manager shall carry out a Risk Assessment prior to the start of the work.

Specific Safety requirements
The rapid cutting action of the high velocity water is the principal hazard. Preventions shall be taken to avoid danger to other staff. All personnel involved with HPWJ activities shall wear the required PPE at all times. Hard hat with goggle and face visor, PVC-suit, safety rubber boots with non skid soles, and impervious gloves shall be worn at all times as a minimum standard for the operator. Barriers shall be installed to avoid interference with other activities in the HPWJ area.

On all access roads signs shall be erected to inform staff that HPWJ-work is being done. Adequate foot-protection shall be worn, metal protection for top of foot and ankles. The mandatory foot-control valve, when released will drop the system pressure to a safe level within one second. The actuating device shall be protected to prevent inadvertent operation.

Specific Operating requirements
No loose objects or material in or on the equipment being cleaned are permitted to avoid that these objects are turned into projectiles by the high pressure water jet. Nozzle reaction force under high pressure conditions and large orifice diameters shall not exceed 25 kgf (250 N) in confined space the reaction force shall not exceed 15 kgf (150 N). Forces in excess of 25 kgf (250 N) can cause loss of control of hand held lances.

Only qualified and trained personnel is allowed to operate the equipment.

A minimum of 4 men shall work as a unit. Two men to operate the lances, one man to monitor the engine, pump and ancillary equipment and one man to act as a standby man, maintaining "constant surveillance of the job area. No HPWJ shall be done on equipment that is handheld, nor on equipment that is not secured properly. Adequate measures shall betaken to avoid that the operator can point the HPWJ lance or nozzle to himself, by installing a rigid section of sufficient length (minimum 1.5 times the internal diameter of the pipe or section) when cleaning pipe internally. When working in open area the minimum length of the lance shall be 1650 mm from nozzle to handle.

When moleing or rodding, the lance shall be clearly marked with paint or tape, at a distance minimum 600 mm from the nozzle. When manually rodding, the nozzle shall be inserted in the tube prior to pressurizing the system and removed from the tube after depressurizing. The lance should be directed through a shield which should be designed to protect the operator from water-spray and to prevent the lance from being inadvertently withdrawn from the tube while still under pressure. HP-system hoses shall be handled to prevent kinking and excessive wear. High pressure hose connections shall have safety chains bridging each joint.

Training
Each person assigned to HPWJ-activities shall be adequately trained in the practical and safe operation of the equipment. ^Training schedule shall include as a minimum; PPE, inspection of the equipment and hoses, purpose of the various parts and identification of malfunctioning, practical work showing the cutting action of the water jet, system operation, safety devices, safety precautions, waste water disposal, emergency procedures.

Effluent disposal
Consideration shall be given to the toxicity and disposal of material removed during cleaning operations. Special facilities may be required to collect debris wash water. Such requirements shall be part of the Permit to Work.

Attachments
GEN.001.899 High Pressure Water Jetting record

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