German laser welding company, O.R. Lasertechnologie GmbH (LASER) has developed an additive manufacturing method that enables reliable protection of sensor elements for the oil and gas industry.
Manufactured with a hard alloy, the Direct Metal Deposition (DMD) method makes it possible to significantly extend the lifetime of sensors, which are commonly used to precisely and reliably monitor temperatures, flow rates, and pressure over long periods of time in oil and gas pipelines.
LASER has developed an innovative powder nozzle in collaboration with the Fraunhofer Institute, which allows DMD to be used to prolong the life expectancy of these sensors. The first of its kind nozzle is compatible with the compact EVO Mobile laser welding system which is excellently suited for applying wear-resistant coatings and carrying out repairs or modifications. The system uses relatively low laser output levels starting at 200 watts, but its high deposition rate of up to 5000 mm³/h makes it ideal for a vast range of applications.
For extra protection, sensors are coated with Stellite, a cobalt-chromium-based alloy which is notoriously difficult to machine. The conventional approach is to apply composite clad layers with a total thickness of several millimetres. However, the intense heat applied during the process results in considerable mixing of the sensor’s material with the Stellite cladding.
New powder nozzle prolongs life expectancy of sensors.
With this new method the laser only minimally melts the surface of the sensor, and only at scattered points. Metallic powder, with grain sizes between 45 and 90 µm, is fed coaxially to the laser beam and permanently fuses with the object’s surface. The method allows precise deposition of the material, low heat penetration, and an undistorted, crack-free coating.
The coaxial arrangement also permits deposition of material independently of the direction of cladding, so that the workpiece can be freely rotated in all directions.
In order to prevent oxidation and the formation of tiny bubbles, the work is done in a shielding atmosphere of argon, a noble gas. The minimally evasive technique results in surface quality is free of pores and cracks, very close to the required final contours, and neat.
“We’re proud of having found a way to increase the durability of these sensors with our additive laser technique and thus improve the reliability of gas and oil pipelines,” says Markus Wolf, head of the R&D department at OR LASER.