SPT HAMMER CALIBRATION

Provide your clients with accurate blow count data for use in geotechnical design. By having a current SPT hammer calibration (performed on an annual basis) your firm can be better positioned to provide geotechnical investigation drilling on federally funded bridge, levee or other projects.

SPT hammer calibration is performed using a specially instrumented drill rod connected to accelerometers and a data processor (typically the same unit that is used for PDA data collection). FTC is able to perform SPT hammer calibration during normal production drilling and sampling without delaying your drill crews and avoiding the need to “drill just to calibrate”.

We can quickly mobilize to your job site(s) to perform this calibration. Alternatively, you may arrange to have multiple rigs calibrated by us in a single day by drilling at the same site. Our services are provided in accordance with applicable ASTM standards and you will receive full energy transfer ratio (efficiency) statistical analysis and plots as part of our report for SPT hammer energy calibration performed.

Per ASTM D4633 SPT hammer calibrations should be performed annually or more frequently based upon quality assurance requirements, rig and hammer maintenance intervals and prior to the start of major or critical projects. Most companies utilized drill rigs equipped with SPT auto hammers. Such hammers are typically far more efficient than 60 percent when properly functioning so that the project engineer could design with corrected (typically higher) blow count data by knowing the measured hammer efficiency. SPT hammer calibrations can also reveal potential problems with the hammer system if abnormally low hammer efficiencies are recorded that could then be addressed through hammer repair and maintenance.