Helical Pile Acceptance Torque for a Target Capacity

torque = (allowable x factor_of_safety) / Kt = ultimate / Kt. A 22,500 lb allowable at FS 2 on a 1.5 in solid shaft (Kt 10) needs 4,500 ft-lb; a lower-Kt 3.5 in pipe (Kt 5) needs 9,000 ft-lb for the same capacity. This is the field-acceptance torque the crew watches on the drive-head gauge. An installation check, not a load test; the engineer of record governs.

Installation torque = ultimate / Kt = (allowable × factor_of_safety) / Kt (lb-ft). Kt by shaft type: 1.5 in solid 10, 1.75 in solid 9, 2.875 in pipe 7, 3.5 in pipe 5.

ICC-ES Acceptance Criteria AC358 (helical foundation systems) by name; manufacturer technical bulletins (CHANCE, Magnum, Ram Jack, AB Chance) by name.

ICC-ES AC358 free at icc-es.org. Manufacturer Kt values free in each manufacturer's published evaluation report.

Estimate. Engineer of record governs the design and acceptance. Verify against the project structural drawings and the manufacturer's published capacity / chart.

Field names used by the API: shaft, target_capacity_lb, capacity_basis, factor_of_safety, torque_ft_lb

• Kt table data/construction/helical-pile-kt.json keyed to shaft typemanufacturer technical bulletins
• Acceptance check only the torque correlation is an installation acceptance check, not a substitute for a load testICC-ES AC358
• Default factor of safety 2.0 unless user supplies (engineering-practice default for axial helical piers)ICC-ES AC358 typical