Hydraulic Nut

Hydraulic Nut

Our hydraulic nut eliminates conventional bolt load torquing inaccuracies occurring from stud twisting and friction losses at the nut face and thread interfaces. The compact standard sizes of our hydraulic nut are ideal for confined spaces or where envelope restrictions prevail.

Whether you tension one bolt or several bolts at a time, our hydraulic nut produces uniform compression of casings, flanges, bearing housings or connection rods. The improved tensioning return of the nut will eliminate excessive and erratic bolt loads. The multi-bolt tensioning serves to shorten assembly and/or maintenance time. Additionally, our hydraulic nut allows for a minimal number of operators. Altogether, this provides for quick and easy installation which, in turn, translates to cost savings.

Hydraulic Nut Overview

  • Unique Metal-to-Metal Seal Design
  • Tolerant to harsh environments
    • Applications up to 500°F
    • Water charged for special application
  • Multi-bolt Tensioning
    • Simultaneous “Daisy Chaining” provides uniform clamp loads and shorter assembly time.
  • Accommodates confined spaces and envelope restrictions.
  • Inherent Safety
  • Forces act along bolt axis and not thought torque reaction arms.
  • Compact Standard Sizes and Custom Designs


Standard Hydraulic Nuts

Riverhawk has a standard hydraulic nut line capable of producing preloads up to 45,000 psi thread stress for nominal thread diameters from 1.50” (38 mm) up to 7.00” (178 mm).

Riverhawk Hydraulic Nut Data Sheet
Hydraulic NutHydraulic Nut

Thread Diameter “A” (in) Hydraulic Ram Area (in2) Maximum Hydraulic Load (lbs) Nut Height “B” (in) Nut Diameter “C” (in) Maximum Stroke (in)
1.500 2.651 79,530 2.250 3.000 0.225
1.625 3.111 93,330 2.438 3.250 0.244
1.750 3.608 108,240 2.625 3.500 0.263
1.875 4.142 124,260 2.813 3.750 0.281
2.000 4.712 141,360 3.000 4.000 0.300
2.250 5.964 178,920 3.375 4.500 0.338
2.500 7.363 220,890 3.750 5.000 0.375
2.750 8.909 267,270 4.125 5.500 0.413
3.000 10.603 318,090 4.500 6.000 0.450
3.250 12.444 373,320 4.875 6.500 0.488
3.500 14.432 432,960 5.250 7.000 0.525
3.750 16.567 497,010 5.625 7.500 0.563
4.000 18.850 565,500 6.000 8.000 0.600
4.500 23.856 715,680 6.750 9.000 0.675
5.000 29.452 883,560 7.500 10.000 0.750
5.500 35.637 1,069,110 8.250 11.00 0.825
6.000 42.412 1,272,360 9.000 12.000 0.900
6.500 49.775 1,493,250 9.750 13.000 0.975
7.000 57.727 1,731,810 10.500 14.000 1.050

Hydraulic Nut

  1. Maximum hydraulic load is produced when the hydraulic nut is pressurized to 30,000 psi.
  2. Retained bolt loads up to 45,000 psi preload stress in the thread tensile area.
  3. The alloy steel used in standard applications maintains its properties up to approximately 500°F.
  4. Detailed instruction manual provided with each hydraulic nut.
  5. All hydraulic nuts are tested at maximum rated pressure prior to shipment.
  6. Multiple tools can be linked together for simultaneous tensioning.
  7. Custom designs and materials available if above designs do not fit your application.


Custom Hydraulic Nuts

Riverhawk specializes in custom hydraulic nuts that are specifically designed to meet demanding customer requirements. Hydraulic nut material, thread forms, load capacity, stroke capacity, and corrosion protection coatings are a few of the custom options available. Riverhawk engineers work directly with our customers to determine the best solution for their most challenging applications. Download a custom hydraulic nut application sheet here.

Hydraulic Nut Installation and Operation

Installation and operation of hydraulic nuts is simple. In most cases the hydraulic nut will fit within the same space as your existing hardware and does not require any additional thread length. The hydraulic nut is screwed onto the stud and connected to a hydraulic pump (manual or air operated) using flexible high pressure hoses. When hydraulic oil is pumped into the nut it generates a large axial force. The force generated is proportional to the amount of pressure applied, the greater the hydraulic pressure the higher the force generated. This force compresses the flanges and stretches the stud creating a gap between retainer and the hydraulic nut cylinder. The operator turns down the retainer against the hydraulic nut cylinder and releases the hydraulic pressure. The retainer prevents the stud from returning to its original length. Since the stud is stretched within its elastic region it has a natural tendency to return to its original length. This in-turn creates the clamping force that holds the joint together. The whole tensioning process can be completed in less than 2 minutes.

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To learn more about our hydraulic nuts contact a member of our team. We will be more than happy to assist you with your project needs.

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