Robotic welding and advanced manufacturing

What it means for you

Better welds, better vessels

• Every weld made the same way

  A programmed robot follows the same path, at the same speed and torch angle, with the same welding settings, every time. The weld doesn’t depend on who is on shift, how far into the shift they are, or which day of the week it is.^1,2

• Sound welds on a vessel that lives under pressure

  A cylinder or calorifier sits in an airing cupboard or plant room under pressure, heating up and cooling down, for years. Its welds are where it has to be right. Consistent penetration and a consistent weld shape mean fewer places where a weakness could start.^5,6,7

• The hundredth vessel like the first

  On a bulk or repeat order, the welds on the last vessel off the line are made to the same programme as the first. That matters when a contractor fits dozens of the same cylinder across a development, or a client orders a batch of identical calorifiers.¹

• Capacity you can plan around

  A programmed weld cycle takes the same time each time it runs, which makes production easier to plan. Investing in automation is part of how we keep capacity up and lead times dependable.¹

1. 1.What makes a good weld

   A weld joins two pieces of steel by melting them together. To be sound, it has to melt far enough into both pieces and all the way through the joint where the design calls for it, with the right shape on the surface. Too little heat, or moving too fast, and the metal doesn’t fuse properly.

   Technical note: Incomplete root penetration and lack of sidewall fusion are typically caused by too low an arc energy, too high a travel speed, an unsuitable torch angle or poor fit-up (root gap, root face, bevel angle).^5,6

2. 2.Why a hand weld can vary

   In manual welding, a skilled welder controls the speed, the angle and the distance of the torch by hand and eye. Good welders are very good at it, but no one moves at exactly the same speed and angle on every seam, all day, every day.

   Technical note: Arc energy is proportional to current × voltage ÷ travel speed, so a change in travel speed changes the heat put into the joint, and with it penetration and bead profile. Torch angle governs how well the arc reaches the joint sidewalls.^4,6

3. 3.What the robot changes

   A robotic welder is programmed with the path, speed, angle and settings for a weld. Once the programme is proven, it repeats them the same way on every part, so the heat going into the joint, and the weld it makes, stays consistent.

   Technical note: Automatic welding is defined as welding in which all the welding parameters are controlled, with no manual adjustment during welding; robotic welding is automatic welding by a robot that can be programmed for different paths and geometries. TWI notes the benefit as highly repeatable, high quality welds.^1,2

4. 4.Why the weld’s shape matters

   Where the weld meets the plate, its shape affects how stress builds up there. A smooth, consistent profile along the whole seam avoids sudden changes that could become a weak point when the vessel is repeatedly heated, cooled and pressurised.

   Technical note: The stress concentration factor at the weld toe depends on the weld geometry, including the toe radius and toe angle, and fatigue life assessments of welded joints are highly sensitive to it.⁷

5. 5.What it doesn’t replace

   A robot repeats what it is set up to do, so the quality still comes from the people: good joint preparation and fit-up before welding, a proven weld programme, and inspection and testing afterwards. Our vessels are still designed, welded and tested in our own factory, under our quality system.

   Technical note: Robotic welding depends on getting the required joint shape and fit-up upstream, and on a defined way of verifying the finished joint.³