Hydraulic Fitting Torque Specifications by Type and Size

General Principles

Always torque fittings to the manufacturer's specification. The values in this guide are typical industry values for steel fittings in steel ports. Reduce torque by approximately 25-30% for aluminum ports to prevent thread stripping.

Lubrication matters. A lubricated thread requires less torque to achieve the same clamping force. If the fitting manufacturer specifies torque for lubricated assembly, do not use that value for dry assembly (you will under-torque).

Use a calibrated torque wrench. Pipe wrenches and channel-locks do not provide consistent torque.

JIC 37-Degree Flare Torque

JIC fittings are torqued finger-tight first, then tightened to specification. The flare-to-cone contact is metal-to-metal, so proper torque is essential.

-4 (1/4" tube): 9-11 ft-lbs -6 (3/8" tube): 17-20 ft-lbs -8 (1/2" tube): 30-35 ft-lbs -10 (5/8" tube): 40-50 ft-lbs -12 (3/4" tube): 55-65 ft-lbs -16 (1" tube): 90-110 ft-lbs -20 (1-1/4" tube): 120-150 ft-lbs

These values are for steel fittings in steel adapters.

SAE ORB Torque

ORB fittings rely on O-ring compression, so torque controls how much the O-ring is squeezed. Too much torque extrudes the O-ring; too little allows bypass leaking.

-4 (7/16-20): 8-10 ft-lbs -6 (9/16-18): 17-20 ft-lbs -8 (3/4-16): 30-35 ft-lbs -10 (7/8-14): 45-50 ft-lbs -12 (1-1/16-12): 55-65 ft-lbs -16 (1-5/16-12): 85-100 ft-lbs

Always install a new O-ring. Lightly lubricate the O-ring with clean hydraulic fluid before assembly.

ORFS Torque

ORFS face-seal fittings have specific torque requirements to compress the O-ring uniformly across the flat face.

-4: 11-14 ft-lbs -6: 22-26 ft-lbs -8: 33-40 ft-lbs -10: 50-58 ft-lbs -12: 70-80 ft-lbs -16: 110-130 ft-lbs

Do not use Teflon tape on ORFS threads. The seal is provided by the O-ring, not the threads. Tape on ORFS threads prevents proper metal-to-metal contact on the retaining nut.

NPT Torque

NPT is the most problematic standard for torque specification because the seal is formed by thread deformation, which varies with thread quality, sealant type, and material. There is no single correct torque value.

General guidelines for steel NPT: 1/8" NPT: 12-15 ft-lbs 1/4" NPT: 18-22 ft-lbs 3/8" NPT: 25-30 ft-lbs 1/2" NPT: 30-40 ft-lbs 3/4" NPT: 40-55 ft-lbs 1" NPT: 50-70 ft-lbs

Always use appropriate thread sealant (Teflon tape or pipe dope). Do not over-tighten NPT. The tapered thread design means excessive torque cracks the female port.