welded stainless steel

Welded ferritic stainless steel tubes are the VALTIMET solution to improved high pressure feedwater heater performance. We have mastered the welding of high strength ferritic alloys to provide thinner walled tubing with superior corrosion and erosion resistance, high thermal conductivity, a coefficient of expansion close to that of carbon steel used in plant structures, and excellent mechanical properties. The result is a more economical heater that is lighter weight, simpler to manufacture and more efficient.

To improve the characteristics of welded austenitic stainless steel tubes, VALTIMET has developed and patented a near-seamless technique for LP heaters which is a cold working and heat treatment technique called Roll Sink Annealing®. Immediately after welding, the tube is cold worked, then induction heat treated in-line and rapidly cooled, all under a protective atmosphere. The resultant weld bead exhibits recrystallization and homogeneous mechanical and corrosion-resistant properties.

Extra care guarantees the finest quality.
VALTIMET's weld lines are painstakingly designed to minimize residual stresses. From uncoiling through welding, bending, testing and packaging, automatic conveyance systems reduce handling and risk of damage. Specially shaped rollers are used for guiding, gauging and straightening.

VALTIMET performs non-destructive testing to meet customer specifications. Following welding, all feedwater heater tubes are in-line eddy current tested and defective areas are removed. Optional ultrasonic inspection can also be performed off-line for both austenitic and ferritic grades. Before U-bend, all straight tubes are subjected to air underwater testing. After U-bend, tubes are again pneumatically, or upon request, hydrostatically tested.