STU Imperial Range

Hi-Force STU series sub-sea bolt tensioners are designed and manufactured to suit the demanding requirements of divers operating in harsh sub-sea environments. With an easy to operate two piece design comprising of a quick fit/release threaded puller and a hydraulic load cell with integral bridge and an extra long 30 mm piston stroke to reduce re-setting operations, Hi-Force STU series sub-sea bolt tensioners offer a consistent, reliable and cost effective method of tensioning sub-sea bolted joints. All hydraulic load cells are suitable for different thread sizes and interchangeable quick fit/release pullers can be ordered separately, as required, resulting in even greater flexibility and cost savings.

  • Capacities from 256 to 2482 kN
  • Bolt sizes 1" to 3½” diameter
  • Working pressure 1500 bar
  • Single acting design with manual piston retraction
  • High grade alloy steel construction
  • Simple two piece design for easy operation by divers subsea
  • Visible maximum piston stroke indicator
  • Dual quick connect couplings for easy connection
  • Designed to fit most sizes of ANSI and API flanges and some Compact flanges
  • Interchangeable quick fit pullers to cover secondary bolt sizes for each STU model

Sub-Sea Bolt Tensioners Imperial Range
Model Number Quick fit puller Bolt Thread Size Capacity Effective area cm2 Stroke mm Weight kg Tommy Bar
kN tonnes
STU1-100 QFP1-100 1" - 8UN 256 26.1 17.1 20 3.4 TTB06
STU1-112 QFP1-112 1 1/8"- 8UN 256 26.1 17.1 20 3.4 TTB06
STU2-125 QFP2-125 1 1/4"- 8UN 430 43.9 28.7 30 6.0 TTB08
STU2-137 QFP2-137 1 3/8"- 8UN 430 43.9 28.7 30 6.0 TTB08
STU3-150 QFP3-150 1 1/2"- 8UN 553 56.4 36.9 30 7.5 TTB10
STU3-162 QFP3-162 1 5/8"- 8UN 553 56.4 36.9 30 7.5 TTB10
STU4-175 QFP4-175 1 3/4"- 8UN 756 77.1 50.4 30 9.8 TTB10
STU4-187 QFP4-187 1 7/8"- 8UN 756 77.1 50.4 30 9.8 TTB10
STU5-200 QFP5-200 2" - 8UN 1168 119.1 77.9 30 14.5 TTB12
STU5-225 QFP5-225 2 1/4" - 8UN 1168 119.1 77.9 30 14.5 TTB12
STU6-250 QFP6-250 2 1/2" - 8UN 1649 168.1 109.9 30 22.8 TTB14
STU6-275 QFP6-275 2 3/4" - 8UN 1649 168.1 109.9 30 22.8 TTB14
STU7-300 QFP7-300 3" - 8UN 2483 253.2 165.6 30 35.6 TTB16
STU7-325 QFP7-325 3 1/4" - 8UN 2483 253.2 165.6 30 35.6 TTB16
STU7-350 QFP7-350 3 1/2" - 8UN 2483 253.2 165.6 30 35.6 TTB16

Note: Tommy bars are not included. Hi-Force recommends one tommy bar for every four tensioners. Please note that the tommy bar listed will fit related quickfit puller; a different size may be required for the hexagon nut.


Model Number Dimensions in mm
A B C D E F
STU1-100 82 22 119 119 140 61
STU1-112 82 22 119 119 140 64
STU2-125 102 30 140 140 164 73
STU2-137 102 30 140 140 164 75
STU3-150 114 35 142 142 169 82
STU3-162 114 35 142 142 169 85
STU4-175 128 41 151 151 181 94
STU4-187 128 41 151 151 181 98
STU5-200 150 48 164 164 202 112
STU5-225 150 48 164 164 202 116
STU6-250 176 60 183 183 231 136
STU6-275 176 60 183 183 231 141
STU7-300 215 89 215 215 260 162
STU7-325 215 89 215 215 260 173
STU7-350 215 89 215 215 260 175