FP-96 English Version - Eastern Federal Lands Highway Division

Section 551(2) Open-end diesel hammers. Equip open-end (single acting) dieselhammers with a device, such as rings on the ram or a scale (jump stick)extending above the ram cylinder, to permit visual determination of hammerstroke. Submit a chart from the hammer manufacturer equatingstroke and blows per minute for the hammer to be used. A speed versusstroke calibration may be used if approved.(3) Closed-end diesel hammers. Submit a chart, calibrated to actualhammer performance within 90 days of use, equating bounce chamberpressure to either equivalent energy or stroke for the hammer to be used.Equip hammers with a dial gauge for measuring pressure in the bouncechamber. Make the gauge readable from ground level. Calibrate the dialgauge to allow for losses in the gauge hose. Verify the accuracy of thecalibrated dial gauge during driving operations by ensuring that cylinderlift occurs when bounce chamber pressure is consistent with the maximumenergy given in the hammer specifications. Do not use closed-enddiesel hammers that do not attain cylinder lift at the maximum energybouncechamber pressure relationship given in the hammer specification.(4) Air or steam hammers. Furnish plant and equipment for steam andair hammers with sufficient capacity to maintain the volume and pressurespecified by the hammer manufacturer. Equip the hammer with accuratepressure gauges that are easily accessible. Use a hammer with the massof the striking parts equal to or greater than one third the combined massof the driving head and pile. The combined mass shall be at least 2,750pounds.Measure inlet pressures for double-acting and differential-acting air orstream hammers with a needle gauge at the head of the hammer whendriving test piles. If required, also measure inlet pressures when drivingproduction piles. A pressure versus speed calibration may be developedfor specific driving conditions at the project as an alternative to periodicmeasurements with a needle gauge.(5) Nonimpact hammers. Do not use nonimpact hammers, such asvibratory hammers, unless permitted in writing or when specified in thecontract. If permitted, use such equipment for installing production pilesonly after the pile tip elevation or embedment length for safe support ofthe pile load is established by static or dynamic load testing. Control theinstallation of production piles when using vibratory355