Steps to a More Effective UHP Waterjetting Operation

Presented by: Rick Dupuy

UHP Projects, Inc

Learning Outcomes – Describe the purpose of surface

preparation and what it includes– Using SSPC VIS 4/NACE VIS 7, determine

the initial condition of a surface and assess the level of cleanliness

– Using SSPC SP-WJ/NACE WJ standards to demonstrate ability to achieve the level of waterjet cleanliness required for a given job

– Identify the components of the waterjetting system

• 3 Viewpoints required for successful coatings application

1. Owner / Inspector2. Contractor3. Coatings Manufacturer

• 3 Performance Criteria needed for successful coatings

1. Visual – SSPC standards2. Profile – based on coatings manufacturer

requirements for the coatings specified3. Non-visible contaminants

UHP Waterjetting Surface Preparation Processes• Pre-Cleaning• Cleaning• Post-Cleaning – before coating

application

Pre-Cleaning

• Pre-cleaning may involve:– Removal of grease/oil,

gross contaminants– May require the use of

degreasers or other solvents and low pressure water cleaning

– Repair of defects in steel

Pre-cleaning - SSPC SP 1 Solvent Cleaning

• Always performed first if necessary, regardless of which surface preparation method is selected

• Requires removal of all visible oil, grease, drawing compounds, and other contaminants from steel prior to surface preparation

Surface Imperfections May Need to be Corrected Prior to Surface Preparation• Sharp edges• Weld spatter• Burrs• Pits• Crevices• Laminations• Porosity

SSPC PA Guide 11• This guide discusses the technique

called “stripe coating” or “striping” as a way of providing extra corrosion protection measures on edges, outside corners, crevices, bolt heads, welds, and other irregular steel surfaces, including optional surface preparation techniques for sharp edges to improve coating performance

Surface Preparation• Actual surface preparation involves:

– Preparing the surface to accept the coatings specified

– Ensure that the surface is cleaned to the standard specified and for the coatings specified

– Removing existing coatings, rust and other unwanted materials from the surface

– Waterjetting surface to a stated visual cleanliness level

Common Surface Preparation Methods and SSPC Standards

– Degreasing (SP 1)– SP WJ-1 Clean to Bare

Substrate– SP WJ-2 Very Thorough

Cleaning– SP WJ-3 Thorough Cleaning– SP WJ-4 Light Cleaning

Visual Guides for Cleaned Steel• SSPC VIS 1 (Dry Abrasive Blast Cleaning)• SSPC VIS 3 (Hand and Power Tool

Cleaning)• SSPC VIS 4 (Waterjetting)• SSPC VIS 5 (Wet Abrasive Blast Cleaning)• NSRP Flash Rust Guide

Post-Cleaning• Post-cleaning prior to coating

application involves verifying that the surface is:– Dry– Still free of contaminants, including

dust and dirt that could have accumulated since surface preparation

– Still at the required cleanliness level– Ensure that the surface is an acceptable

level of flashrust for the coatings specified

Advantages of UHP Waterjetting• Used where profile is already established• Does a good job of reducing/eliminating surface

contaminants• Used where solid particles will cause harm - controls

unwanted emissions• Can reduce disposal costs particularly on hazardous

coatings• Can minimize containment requirements• Can be used to remove coatings layer by layer • Less interference with other trades and activities• Removes elastomeric coatings effectively

Pressures for Cleaning with Water

• Low-pressure water cleaning (LP WC): less than 5,000 psi (34 MPa)

• High-pressure water cleaning (HP WC): 5,000 to 10,000 psi (34 to 70 MPa)

• High-pressure waterjetting (HP WJ): 10,000 to 30,000 psi (70 to 210 MPa)

• Ultra High Pressure waterjetting (UHP WJ): above 30,000 psi (210 MPa)

Top Coats

Primer

Substrate

Types of UHP Tools

• Manual Guns• Manually operated vacuum attached

– Floor, Deck, Wall (“Lawnmower”)• Automated / Robotic

How do You Decide Which Equipment to Use?• Size of project and project requirements• Project time constraints or productivity

requirements• Knowledge level of personnel doing the work• Jobsite requirement for water collection• Full removal or partial removal of coatings• Hazardous coating removal and

personnel/environmental protection

Typical Equipment Setup for Manual Gun Operation

Remote shutoff

rotating nozzle

Hand activated on/off – double

trigger

Correct Stance and Hose Placement

Recommended PPEStandard PPE – Safety glasses,

hard hats, Hearing protection, FRC

Cut resistant glovesMetatarsal BootsFull Face ShieldsHeavy rain suitsTask specific PPE – Safety

harnesses, respirators, H2S monitors, etc.

Cut Resistant Clothing is

Becoming More Operator Friendly

Automated / Robotic Equipment

• Vacuum Recovery removes both coatings and effluent water from the nozzle (Keeps water from pooling on the surface)

• Closed Loop (Water filtered and recirculated)

• Open Loop (Water used once)

Automated UHP Equipment

Vacuum System

Remote-Control System

Horizontal Large Surface Robot

Manually Operated Vacuum Attached Equipment

Primary Components of the Waterjetting System• Pump – Positive Displacement or Intensifier

• Pressure and volume are considerations• Type of power source

• Gun – Dry shut off or Dump• Rotating or non-rotating

• Hose• Vacuum system if required• Nozzle• Accessories

Skid-Mounted UHP Pump

Skid mounted UHP Pump

Typical Single User Pump

Pump with Vacuum Recovery

Vacuum Systems

• Sized to the flow and the application. – Venturi nozzle to drum– Skid mounted vacuum systems– Large vacuum truck

• How is the effluent from the vacuum going to be handled

• Multiple tools from same system• NEVER put your hand in front of

the vacuum hose.

Vacuum System

•Vacuum equipment is often integrated into a skid package. This unit can be mounted on the back of a pickup truck with a 220 gallon tank

40-55,000 psi Hose

Hoses and Connections• Burst rating should be a minimum of 2.5

times working pressure of the hose• Test high-pressure hoses at 1.5 times

working pressure• Fittings should be rated for the working

pressure• Inspect hoses for shroud abrasion, leaks,

and flow restrictions (such as squashed fittings) before each use

Hose Accessories: Bend Restrictors, Containment Grips (Whip Check)

Proper UHP Hose Care

• Never run hoses over sharp edges – use softeners and suspend hoses

• On long vertical runs don’t let the hose connectors bear the full weight of the hoses

• Don’t let vehicle traffic run over hoses• Store hoses in a protected location

with ends connected• Always clean and lubricate ends

before connecting

Handheld UHP tools• Attached to the UHP pump

by hose• Incorporates a control valve,

guard, lance (barrel), usually a rotation device and nozzle

• Comes in various lengths, normally with dual triggers. May also have a support handle and a shoulder stock

• The control valve used to relieve the pressure further defines the gun type

Traditional UHP waterjetting used handheld tools

remote shutoff

rotating nozzle

hand activated on/off

UHP waterjetting using handheld tools

Handheld UHP toolsDump gun:

– Moves pressure to the atmosphere, i.e. water continues to flow but at low pressure when the valve is released

Dry shut-off gun:– Pressure is retained in the system

with a shutoff control valve, i.e. you see no water at the gun, but it is re-circulated to the system

Dump Gun• Dump gun:

– Designed with a tube for depressurization (dump mode) at the nozzle

– May be used alone or in a multi-gun operation with an adjustable constant pressure valve to ensure that pressure does not change abruptly

– When the dump gun valve is closed, the gun is blasting with free passage of water through the nozzle

– When the valve is released the water is “dumped” at the gun

– The operator can modulate the pressure

Dump Gun

Dry Shut-Off Gun– Designed for use with a pressure regulator (or

tumble box) for single or multi-gun applications

– When the internal valve is open, water flows through the nozzle. When the operator closes the valve, there is no flow through the gun

– The shut-off gun is either “on” or “off.” The operator cannot modulate the pressure at the trigger. This can slightly improve productivity

– Pressure is relieved away from the operator– The tumble box is designed to maintain

constant pressure in the hose and gun.

Dry Shut-Off Gun

Nozzles• Rotating• Non-Rotating• Self-rotating• Fan or zero-degree• Self-propelled or air-propelled• Number of orifices and size• Wear guards available

UHP Nozzle Assemblies Nozzles are usually multi-orifice configurations Use sapphire or diamond orifices for UHP WJ.

UHP Waterjetting is a Proven Technology with Proven Benefits • Write good specifications• Choose an experienced UHP

contractor • Use the correct equipment for the

project• Follow good quality practices

Questions?