Thermite Weld Inspection

TKS provides comprehensive testing services to ensure the 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 performed 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 a 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 the rail head and at the edge of the 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 any more than one-inch diameter discontinuity.

 

Weld Hardness Testing

The Brinell Hardness Test (prescribed by ASTM E 10) is performed to precisely measure the diameter of an indentation made with hardened balls of various diameters under various loads. 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.

 

Metallographic Tests

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, etching the piece, and then visually analyzing 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 to test 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:

• External corrosion,

• Internal corrosion,

• Abrasion,

• Static and dynamic mechanical stresses, and

• Wear

 

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.