Steam Turbine CA-TIG™
Dresser-Rand has more than a decade of experience as an industry leader in steam turbine weld repair processes. The service and reliability of steam turbine rotor repairs are key concerns of Dresser-Rand. From the initial engineering review — to the final inspection prior to returning the unit to service — D-R applies its advanced technology and its many years of product and service experience to steam turbine repairs.
D-R engineers apply the company's Probabilistic Failure Analysis™ fracture mechanics to the proposed weld repairs to evaluate the weld under normal and abnormal operating conditions. This analysis, coupled with empirically measured, non-destructive inspection detection limits provides an assessment to determine the fitness for services of rotor weld repairs.
The steam turbine weld is applied using state-of-the-art Computer Assisted Tungsten Inert Gas Welding equipment(CA-TIG) to provide a consistent, fine-grained tempered weld. The computer-based control of the weld process minimizes operator usage in the weld process and records weld parameter data. The weld filler materials are manufactured to meet stringent D-R specifications to ensure consistent weld deposit properties.
A florescent magnetic particle and ultrasonic non-destructive testing (NDT) inspection of the weld is performed at predetermined hold points during the repair process, referencing specified defect limits. This provides quality assurance of the soundness of the repair.
Rerates / Revamps
Dresser-Rand's CA-TIG welding technology also can be used to upgrade couplings, thrust discs, and airfoil blade attachments by welding the existing rotor. Keyed couplings can be converted to hydraulic or diaphragm couplings to increase horsepower and keyed thrust disc locations can be engineered and replaced by hydraulic conversions. Airfoil blade attachments can be redesigned and upgraded by removing and rebuilding the existing disc rim via welding to allow for the installation of new blades. Entire discs can also be replaced or repositioned.
D-R's advanced weld repair technology provides a cost effective alternative to rotor replacement.