Thermite Weld Inspection
TKS provides comprehensive testing services for assuring quality of welds of all types of rails manufactured to current AREMA specifications. These testing services cover both the initial process qualification and as well as routine QA requirements. Tests are preformed at our facilities in State College, PA by experienced and qualified personnel. Test results are provided at normal and quick turnaround times. The different thermite weld testing services provided by TKS are:
Chemical Analysis: TKS provides chemical analysis of rails to identify the presence and the amounts (by weight percent) of the following elements: Carbon, Manganese, Phosphorous, Sulfur, Silicon, Nickel, Chromium, Molybdenum, Vanadium and Aluminum. Optical Emission Spectroscopy (OES) analysis is performed to determine the chemical composition of the rails and evaluated with respect to the standards specified in AREMA Manual for Railway Engineering Chapter 4. OES is the reference technique for elemental analysis of solid metallic samples and is capable of performing rapid simultaneous analysis of up to 60 elements.
Slow Bend Test & Bond Integrity
The rail is supported on a 72″ span with the weld joint centered between the supports, and central static load is applied. For vertical loading, dial gages used to record vertical deflection, are located 3″ on either side of the central loading point and on the center of the rail base. For lateral loading, the load is applied at the center of the span through the rail’s neutral axis, and the deflections at rail head and at edge of rail base are recorded by dial gages located 3″ on either side of the loading point. Bond integrity is determined from the fracture faces of the slow bend test samples. AREMA manual stipulates that the bond between two joining rail ends shall not contain no more than one inch diameter discontinuity.
Weld Hardness Testing
Brinell Hardness Test (prescribed by ASTM E 10) to carry out precise measurement of the diameter of an indentation made with hardened balls of various diameters under various loads is performed. We provide the optics and analysis software (Digital Optical Comparator System) for the required diameter measurement and subsequent calculation of the Brinell hardness in accordance with the ASTM standards.
TKS utilizes several techniques for preparing material samples for analysis including metallographic preparation for either micro-structural or macro-structural analysis. Macro-etching involves taking a cross-section of the large component, grinding and polishing the surface and etching the piece and then, visually analyze the degree of micro-structural segregation. TKS also provides micro-structural analysis using scanning electron microscope (SEM) and other microscopic techniques.
Magnetic Particle Testing
TKS uses standard magnetic particle equipment for testing of thermite welds. The inspection procedure follows the recommendations outlined in ASTM E709 – 08 i Standard Guide for Magnetic Particle Testing. The procedure may vary depending on the rail type, profile, surface condition, etc. AC electromagnetic yokes are used.
Deterioration mechanisms include:
Static and dynamic mechanical stresses, and
These mechanisms result in the loss of metallic cross-sectional area (LMA) and local faults (LF), such as broken individual wires and strands.
Our NDT technology provides real engineering data that can be used to assess the structural integrity, allowable load rating, and remaining life of wire rope.