Hermetically Sealed Load Cell

Designed for offshore applications such as tanker moorings or for underwater use, the hermetically sealed load cell is available for immersion depths down to at least 200 metres. The load cell measures tension, compression or shear loads and is available as a replacement for standard chain shackle pins, or to replace pivot pins in existing mooring bridles or linkages.

Pivot pin for a mooring bridle

SPECIFICATION

Safe Working Loads in the Range 50 - 600 tonnes
Proof Load 1.5 x SWL
Excitation 5 - 10 Volts DC
Bridge Resistance 350/700 ohms
Supply Current (Full Load Output) 22mA

 

OUTPUT

Amplifier Output 0.2 - 1 mA or 4 - 20 mA
Non-Linearity (Best Straight Line through Zero) (BSL) +/- 2% F.R.O.
Hysteresis 2% F.R.O.
N.L. & H Combined error (BSL) +/- 2% F.R.O.
Repeatability +0.25% F.R.O.

 

ENVIRONMENTAL

Operating Temperature Range -20@ to +50@
Maximum Operating Depth 200 metres
Error due hydrostatic pressure Nil

 

Available in calibrated ranges from 50 to 600 tonnes, the load cell has been developed primarily for use with SPM (Single Point Mooring) monitoring systems supplied by .

150 Tonne shackle and pin

Other applications include uses where long term survival in extreme environments is important, such as:
Mooring Load Measurement
Seabed Anchor Load Measurement
Tension Leg Platform Load Monitoring
Process Equipment in Arduous Environments
Mining and Dredging

For underwater applications, signal conditioning electronics are sealed into the pin providing an output capable of transmission over 250 metres of cable or suitable for input to radio or acoustic telemetry system.

The pin is sealed using a removable cap end with compression 'O' rings. The signal cable emerges via an underwater connector which may be connected and disconnected at depths in excess of 200 metres.

Manufactured in corrosion resistant alloy steel, each load cell is supplied with a Lloyd Register of Shipping certificate of calibration and proof load.

A feature of the design is the absence of machined discontinuities on the outer surface, thus eliminating stress concentration factors, which usually reduces the strength of conventional shear pin load cells, permitting higher safe working loads to be used for a given shear pin size.

Developed with assistance from the U.K. Department of Energy, the pin development included preliminary finite element computer analysis performed at City University, London. Although available individually, the load cells can be supplied complete with underwater cable, or as a self contained underwater package with acoustic telemetry to a surface display unit.

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