Download - Steps to a More Effective UHP Waterjetting Operation Presented by: Rick Dupuy UHP Projects, Inc
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?