TWI Industrial Member Report Summary 864/2007
By J C Perrett and P D Sketchley
TWI is at the forefront of developing the friction taper plug welding (FTPW) process, derived from rotary friction welding. Applications include plugging holes placed incorrectly during manufacture or holes that have formed as a result of repairing in-service damage.
The friction taper plug welding process involves drilling a tapered through or blind hole into a plate at the location of interest and then forcing a rotating tapered plug into the hole. The frictional heat generated between the contacting surfaces causes material to soften and flow around the area, welding the two parts together. Friction taper plug welding has been demonstrated in many materials and can now be considered as a practical solid-phase repair method by many industries, particularly in offshore structures. Due to a lack of information in the public domain and little current industrial uptake, there is a need to understand better the FTPW method and the fundamentals of the process.
The objectives for this programme of work were as follows:
- To demonstrate FTPW, both in air and underwater, to fill blind holes in carbon manganese steel.
- To determine FTPW parameters that result in a good quality, flawless-free weld.
- To compare hardness levels for stainless steel and carbon manganese steel plugs.