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

6

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

7

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)

8

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

9

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

11

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

12

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?