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 1.18 inch 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 28.8 to 279 tons
  • Bolt sizes 1" to 3½” diameter
  • Working pressure 21750 psi
  • 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
  • Customized and special design tensioners are available on request

Sub-Sea Bolt Tensioners Imperial Range
Model Number Quick fit pullers Bolt Thread Size Capacity Effective area inch2 Stroke inch Weight lbs Tommy Bar
kN Tons
STU1-100 QFP1-100 1" - 8UN 256 28.8 2.65 0.79 7.5 TTB06
STU1-112 QFP1-112 1 1/8"- 8UN 256 28.8 2.65 0.79 7.5 TTB06
STU2-125 QFP2-125 1 1/4"- 8UN 430 48.4 4.45 1.18 13.2 TTB08
STU2-137 QFP2-137 1 3/8"- 8UN 430 48.4 4.45 1.18 13.2 TTB08
STU3-150 QFP3-150 1 1/2"- 8UN 553 62.2 5.72 1.18 16.5 TTB10
STU3-162 QFP3-162 1 5/8"- 8UN 553 62.2 5.72 1.18 16.5 TTB10
STU4-175 QFP4-175 1 3/4"- 8UN 756 85 7.82 1.18 21.6 TTB10
STU4-187 QFP4-187 1 7/8"- 8UN 756 85 7.82 1.18 21.6 TTB10
STU5-200 QFP5-200 2" - 8UN 1168 131.3 12.07 1.18 32.0 TTB12
STU5-225 QFP5-225 2 1/4" - 8UN 1168 131.3 12.07 1.18 32.0 TTB12
STU6-250 QFP6-250 2 1/2" - 8UN 1649 185.3 17.04 1.18 50.3 TTB14
STU6-275 QFP6-275 2 3/4" - 8UN 1649 185.3 17.04 1.18 50.3 TTB14
STU7-300 QFP7-300 3" - 8UN 2483 279 25.66 1.18 78.5 TTB16
STU7-325 QFP7-325 3 1/4" - 8UN 2483 279 25.66 1.18 78.5 TTB16
STU7-350 QFP7-350 3 1/2" - 8UN 2483 279 25.66 1.18 78.5 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 quick fit puller; a different size may be required for the drilled hexagon nut.


Model Number Dimensions in inch
A B C D E F
STU1-100 3.23 0.87 4.69 4.69 5.52 2.4
STU1-112 3.23 0.87 4.69 4.69 5.52 2.52
STU2-125 4.02 1.18 5.52 5.52 6.46 2.88
STU2-137 4.02 1.18 5.52 5.52 6.46 2.96
STU3-150 4.49 1.38 5.59 5.59 6.66 3.23
STU3-162 4.49 1.38 5.59 5.59 6.66 3.35
STU4-175 5.04 1.62 5.95 5.95 7.13 3.7
STU4-187 5.04 1.62 5.95 5.95 7.13 3.86
STU5-200 5.91 1.89 6.46 6.46 7.96 4.41
STU5-225 5.91 1.89 6.46 6.46 7.96 4.57
STU6-250 6.93 2.36 7.21 7.21 9.1 5.36
STU6-275 6.93 2.36 7.21 7.21 9.1 5.56
STU7-300 8.47 3.51 8.47 8.47 10.24 6.38
STU7-325 8.47 3.51 8.47 8.47 10.24 6.82
STU7-350 8.47 3.51 8.47 8.47 10.24 6.9