Friction Welding Developments SUT Gadgets & Widgets 19 ...flow plastically under pressure (without...
Transcript of Friction Welding Developments SUT Gadgets & Widgets 19 ...flow plastically under pressure (without...
Capability Presentation
Friction Welding Developments
SUT – Gadgets & Widgets
19th September 2018
Stephen Booth
The Friction Welding
Process
The Friction Welding Process
What is Friction Welding?
Friction welding is a form of solid phase welding e.g.
when a blacksmith puts two pieces of metal into a
furnace, heats them up until they are glowing hot then
places them together onto an anvil before striking them
with a hammer
1. Rotate the stud at high speed
2. Apply pressure forcing the stud onto the substrate
3. Friction between the stud tip and the substrate causes
the metal surfaces to heat and a thin layer of metal to
flow plastically under pressure (without melting) to the
periphery of the weld, removing impurities from the
interface
4. The rotation is stopped and the pressure maintained for
a few seconds to produce a solid phase forged weld
with a fine grain structure
Friction Welding Process Characteristics
A Macro section through a S355 stud
friction welded to S355 plate
• Controlled welding parameters make it highly
repeatable (topside and subsea)
• No mixing of stud and base material so dissimilar
metals can be joined readily
• Residual stresses at the weld are compressive
giving good fatigue strength
• No need to remove coatings
• Hydrogen is not evolved or absorbed (solid
phase process with no liquid weld pool)
• Low resistance connection (>0.01ohm)
• Large surface area welded connection means
high currents can be carried
Friction Welding
Tooling
Every weld is automatically logged providing a comprehensive
record
Can be used topside or subsea
For subsea use it can be handled by either a diver or a ROV
Depth proven to 1,500m. Additional hyperbaric testing is required
to prove theoretical maximum working depth of 4,000m
Limited to 24mm studs. Larger is possible with engineering input
Fully integrated solution for ROV delivery of anode attachment
Hydraulic Friction Welding System
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A customised control system provides a fully automated weld process, with real-time data
being used to monitor and control the welding process
Vehicle had to be recovered after every weld
Reloading of studs was performed by technician on deck
Long durations of time spent on launch & recovery
Hydraulic Friction Welding System
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Historically the weldhead was mounted on a frame which was supported by the ROV, this had
many disadvantages.
Version 1 - 2014
Similar to standard subsea torque tool
Felt familiar to ROV pilots
Enabled subsea stud changing
Remote Welding Jacket (RWJ)
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A customised remote welding jacket was designed and built to allow the ROV to handle the
weldhead in a similar manner to a standard torque tool.
Version 2 - 2018
Revised handles due to feedback from ROV pilots
Revised rear cage to suit larger motor on weldhead
Ball lock mechanism for nose cone to eliminate need to
twist during engagement
Chuck designed to be operated through control system software
Designed to be integrated into the Remote Welding Jacket
Engineered to allow a tensile load to be pulled on the stud once
welded
Proserv have a Patent on the methodology behind the use of the
RWJ and actuated chuck
Subsea Stud Changing
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As part of the upgrades to the equipment we decided that we needed to have a method of
reloading the weldhead subsea.
Parameter Optimisation
Dry welding
Range of burn off values were tested
Tests indicated there was an optimum
burn off
New stud tip design improved
penetration
Parameter Optimisation
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As part of the continued product development we engaged with TWI to perform a study of the
parameters used during the friction welding process.
A series of variables were determined for testing, these included rotational speed, welding
force, stud diameter and stud tip design.
Wet welding
Performed welds without any form of shrouding
medium
Tests indicated a slightly higher force than dry
welds was beneficial
No reduction in weld quality when compared to dry
welding
Evaluate if similar welds are achievable with
current tooling
Compare weld quality of portable equipment to
fixed equipment
Identify if there are any upgrades required
Create a new database of weld parameters
Parameter Optimisation – Next Steps
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To quantify the results of the TWI report, we are currently replicating the welds using our
standard portable friction welding equipment.
Case Studies
Sheringham Shoal Wind Farm (Cathodic Protection)
Project Background
The client required a solution for attaching retrofit cathodic protection to 88 windfarm monopiles using
remote intervention. Four connection points per monopile were required allowing the anode mattresses to
be positioned on the seabed around each pile.
Solution
Proserv provided their HMS 3000 friction welding technology and worked together with a third party tooling
supplier to provide a solution that enabled the welding of M16 carbon steel studs directly to the monopiles.
These studs allowed the cables from the anode mattresses to be placed on the seabed which were
directly connected to the monopile providing the required cathodic protection. Proserv’s solution allowed
the welding tool control panel to be integrated with the ROV and the hydraulic feed taken directly from the
ROV’s HPU.
Scope
Proserv carried out an initial weld qualification process which was approved by DNV, laying the
foundations for the offshore scope to be undertaken at a later date. During offshore operations Proserv
provided a HMS 3000 friction welding system consisting of a subsea weld head and subsea control
system which was integrated into the ROV and subsea stud changer. All welds were completed to the
client’s satisfaction with real-time data issued to the client demonstrating the project was carried out in-line
with DNV approved procedures.
Conclusion
The provision of the HMS 3000 system and stud changer allowed for the project to be completed without
the need for diver intervention. The DNV qualified weld procedure gave the client confidence that welding
operations would provide the requisite cathodic protection without compromising the structural integrity of
the monopiles during the welding operation. The provision of the cathodic protection has extended the
working life of each monopile.
Anode Attachment - Friction WeldingClient: Statoil
Location: North Sea, UK sector
Equipment: Friction Welding
Benefits
• No need for diver intervention
• Cost savings through preventative
maintenance
• High quality, high integrity approved
cathodic protection solution
Gullfaks Bundles (Supplementary Anode Retrofit)
Overview
Statoil had a requirement for an anode retrofit to the Gullfaks bundles due to the original galvanic anodes
suffering from trawler damage. Proserv was chosen to supply a solution that would make terminations to
the bundles and provide preventative maintenance cost savings.
Solution
Proserv’s friction welding technology was selected as the ideal solution for the anode retrofit to the
Gullfaks bundles. A bespoke clamping arrangement was also designed, built and tested by Proserv for
deploying the friction welding technology onto 38.5” and 49.5” Ø bundles. This method was chosen over
traditional anode clamps which are significantly more vulnerable to future trawler damage. The tooling was
deployed and operated by an ROV in water depths up to 200 metres with 42 anode sleds being installed,
with two cable terminations from each.
Conclusion
The Proserv termination solution, including a bespoke clamping arrangement, provided a significantly
lower snag risk to alternative anode clamps. The solution provided was more robust and less likely to
cause damage to the bundle if it became snagged.
Remote Anode ReplacementClient: Statoil
Location: North Sea
Equipment: Friction Welding
Benefits
• The terminations were made close to the
seabed to avoid future trawler damage
• No interruption to production
• Cost savings through preventative
maintenance
Thistle Field - Cathodic Protection
Project Background
A North Sea Operator embarked on a major program of work to extend the life of the one of their
installations in the North Sea. Along with a third party, Proserv was engaged to supply a solution for the
reinstatement of the Cathodic Protection (CP) system on the platform.
Solution
Proserv’s friction welding technology was selected as the ideal solution to connect anode sled cables to
the jacket structure. This method was chosen over an impressed current cathodic protection (ICCP)
system because of its reliability, ease of deployment and significant cost savings due to the ability to
operate the technology using an ROV. As the friction welding anode retrofit was the preferred solution
over ICCP, a bespoke interface solution was developed by Proserv to retrofit the anode sleds, the discrete
anodes, monitors and measures the performance of the system over its life.
Conclusion
This retrofit solution provided by Proserv is the first of its kind, offering substantial cost savings over the
ICCP system. The client, like many others, had concerns over retrofitting ICCP systems to platforms that
originally had galvanic systems due to reliability and risk of stray currents which can accelerate corrosion,
rather than prevent it. Offering a cost-effective galvanic retrofit solution which can be installed using ROVs
provides substantial benefits to the client and is a unique offering in the market at present.
Bespoke Cathodic Protection Engineering SolutionClient: North Sea Operator
Location: UKCS
Equipment: Friction Welding
Benefits
• ICCP was the only option for a major
anode retrofit solution - now there is an
alternative
• Significant cost-savings (around 50%)
• ROV-installed
• Improved reliability
• Low-risk as no concern over stray
currents like there is with ICCP
Questions?