Shot blasting machine for coiled tubes on the Tenaris coating line in Houston

The tube reaches the line wound on a reel. It is unwound, straightened and passes continuously through the shot blasting machine, the induction heater, the paint booth and the extrusion head that applies the coating. At the end it is wound back onto a reel. The surface must come out with the anchor profile the coating needs and free of dust, because anything left on it is trapped underneath.

The previous machine had been causing problems, and Tenaris had a large gas pipeline project ahead, with a qualification date. Three more conditions applied:

• A line that does not stop. Tubes from 1" to 5" in diameter that pass without stopping, at the speed of the whole line.
• A space already taken. The new machine had to fit into the same line, at the height of the equipment downstream.
• Room to grow. In the future, the machine could work in line with the tube mill, at a higher speed.

A BAR 4 continuous shot blasting machine with four blast wheels instead of the three on the previous machine, to cover the whole circumference of the tube with better impact angles.

No pit. The pass line was lowered to 1,400 mm so the machine could fit into the existing line without digging a pit. Tenaris raised the rest of the equipment by 100 mm (4 in).

Ready to go faster. Abrasive recirculation was sized to move to 40 HP blast wheels and about 40 ft/min (12 m/min) if the machine is placed in line with the tube mill. The change is in the blast wheels and drives, not in the machine.

Integrated into the line. The logic runs from the Tenaris line PLC, and the shot valves close automatically if the tube stops.

The machine was shipped to Houston in containers. A CYM technician supervised installation and start-up for three weeks, together with the Tenaris team.

The machine started blasting in mid-August 2023. After only five or six hours of operation, Tenaris reported:

• A dust-free surface at the machine exit.
• A 60 to 75 µm profile, with a 50/50 mix of S330 steel shot and G25 steel grit.
• 20 ft/min (6 m/min) normal line speed. They tested 30 ft/min and the surface came out the same.

If you blast tubes, bars or wire continuously before coating, see the bar and wire shot blasting machine, the pipe shot blasting machine and the article Surface preparation before coating. For a proposal for your line, contact us.