Lonestar is equipped with state-of-art Fracture Toughness (CTOD) testing and sample preparation facility along with numerous years of experienced engineers on staff to carry out these tests.

More and more industries are choosing to be proactive in failure prevention by testing material properties beyond the normal testing requirements. One such test that goes beyond traditional material property analysis is the CTOD test, which is now an essential parameter to verify material performance in the oil and gas industry. Crack Tip Opening Displacement (CTOD) is one of a family of fracture mechanics tests that measures the resistance of a material to crack growth.

Resistance to fracture of a material is known as its fracture toughness. Fracture toughness generally depends on temperature, environment, loading rate, composition of the material and microstructure, together with its geometric effects. These factors are of particular significance for welded joints, where metallurgical and geometric effects are complex.

Testing Methods

• BS 7448: Parts 1-4 Fracture Mechanics Toughness Tests
• ASTM 1820 Standard Test Method for Measurement of Fracture Toughness
• ASTM/BS/BSEN/ISO/Client specified Test Method for Fracture Toughness

Testing Suitability

CTOD is particularly suited to pipeline, offshore structures and drilling equipment (pipes, plates, flanges, valves, tubes, beams, structural steel). CTOD test is used to determine the fracture mechanics properties of ductile materials and can be thought of as the simulated opening of a pre-existing fatigue crack prior to fracture. The data obtained can be used for critical defect assessment, in which the critical defect size can be determined.

Testing Process

Machining of the test specimen (Sample Preparation);
Fatiguing of the specimen within specified limits (Pre-Cracking);
Breaking of the specimen under controlled conditions (Fracture);
Post analysis of specimen and data to obtain CTOD Value (Data Analysis)