FAQ
Weld profiling and fatigue strength improvement, explained
What is weld profiling and why do it?
Weld profiling is a post-weld treatment that reshapes an entire weld seam — both the weld cap and the weld toe — into a smooth, continuous transition from seam to base plate. Unlike weld toe grinding, which treats only the toe, profiling addresses the entire weld seam. Weld profiling removes or reduces stress concentration factors (SCFs) associated with weld cap angle, weld toe radius, and weld toe undercuts, thereby increasing the fatigue strength and fatigue life under cyclic loading of a welded construction.
How is weld profiling applied in the manufacturing of monopile foundations and wind turbine towers?
Profiling of inside and outside circumferential/girth weld seams in monopile foundations and tower sections may be performed either manually, using belt or disc grinders, or using the Maxars TM401 weld profiling robot system.
Both aim to meet DNV-RP-C203’s target geometry: a large-radius transition from weld toe to base plate with complete undercut removal within the depth limits specified by DNV-RP-C203.
Where manual grinding relies on operator skill to meet these geometry improvement recommendations, CNC-robotic weld profiling achieves it through programmed and laser-guided machining operation with a dust-free and repeatable-quality (uniform-profile) outcome.
Do ‘weld fatigue improvement’, ‘weld profiling’, ‘geometric improvement’, ‘weld grinding’ and ‘weld shaving’ all mean the same thing?
No. The different terms belong at different levels.
‘Weld fatigue improvement’, the improvement of the fatigue strength of the weld, is the overall aim. ‘Geometric improvement’ is one of two methods for achieving that aim, and residual stress improvement is the other.
Geometric improvement is achieved using ‘weld profiling’, whereby stress concentration factors (SCFs) are removed. SCFs include weld seam flank angle, weld toe radius and weld toe defects.
Residual stress improvement using ultrasonic peening (UIT) or other mechanical impact methods alters the residual stress state in the weld toe from tensile to compressive, thereby delaying crack initiation.
Weld grinding and weld shaving describe two distinct mechanics for doing weld profiling: grinding removes material abrasively, producing dust. Machining cuts material away, producing collectible and reusable metal shavings.
How does CNC-robotic weld profiling compare to manual weld profiling?
CNC-robotic weld profiling using the Maxars TM401 weld profiling robot system is 15-20 times faster than manual weld grinding, directly lowering machine and labour-time cost per metre.
It also produces documented, repeatable geometry (±0.2 mm accuracy) independent of operator skill, unlike the variable results of manual grinding, and eliminates grinding dust entirely while cutting noise to about 80 dB.
What joint geometries is your TM401 robot system designed for, and how about plate offset?
The TM401 is programmed for four circumferential weld joint geometries: same-thickness joints, thickness-transition joints with a welded taper, thickness-transition joints with a 1:4 plate taper, and inside conical top joints. Across same-thickness and thickness-transition joints, it also automatically adjusts for localised plate offset (misalignment) of up to ±3 mm, using laser-guided sensing to detect and compensate for the offset during profiling.
Contact us
To inquire about our weld profiling robot technology and to book a demonstration in your monopile or tower production facility, please contact:
Project and Market Manager,
Morten Flatau
Telephone: +45 21 25 75 00
Mail: mf@maxars.com
CEO,
Claus Valsted
Telephone: +45 21 25 75 15
Mail: cv@maxars.com
Office hours are 8:00 AM to 4:00 PM (CET)