Scraper and Sphere Signalling - Hi-T Pigalert™

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The Hi-T Pigalert™ is made in three pressure classifications – up to ANSI Class 600, and for ANSI Class 900 and 1500. Standard models are designed for use at temperatures from -20ºC to +200ºC, dependent upon the line products and pressure.

Where to Buy
Scraper and Sphere Signalling - Hi-T Pigalert™
Closures   >   Signallers


Operating Capabilities

The Hi-T Pigalert™ is made in three pressure classifications up to ANSI Class 600, and for ANSI Class 900 and 1500. Standard models are designed for use at temperatures from -20ºC to +200ºC, dependent upon the line products and pressure. Alternative elastomer seals can be provided for operating temperatures outside this range.


Simple to install and operate, the Hi-T Pigalert™ is an economically priced unit providing adjustable onsite penetration and giving the operator simple visual indication with a single action reset.

The proven pivotless tumbler mechanism and laminated trigger blade provide the necessary depth of penetration into the pipeline to give a reliable and visible signal with negligible effect on the flow.

The trigger has also been extensively tested with online inspection pigs and the Hi-T Pigalert™ carries full Transco (British Gas) approval.


Standard models are supplied ready for mounting on a base to be welded to the line pipe or vessel. Flange mounted models up to ANSI Class 1500 are also available. All standard units require a 38mm diameter access through both the mountings and the line pipe. Special adaptors and smaller diameter triggers are available for other makes of retro-fit applications. Full instructions covering installation, re-setting, adjustment to suit varying pipe-wall thicknesses and removal under pressure using a jacking bracket are supplied with all models of the Hi-T Pigalert™ at the time of despatch.


Range of Models

All models are bi-directional and available with either mechanically operated signal flags, electrical auto resetting switches or mechanical and electrical signals into combination. Installation on a vertical pipe is possible but must be specified.

Model options and codes are:

M = Mechanical Flag
E = Electrical Switch
F = Flange Mounting
R = Retro-fit t (specify type/make of mounting)
W = Welded Base
V = Valve Model
X = Extension Model (state length)

Standard Models


Under Pressure Removal Models

All the above models can be supplied suitable for removal under line pressure. The code reference is prefixed with V to denote the valve e.g.: V-M-W V-E-W V-ME-W

A range of high pressure Hi-T Pigalert™ models above Class 1500 rating are available.


Adjustable Penetration

The length of trigger extension into the pipeline is preset at the factory to suit the clients specified stand out dimensions. All models can also be set to suit varying thicknesses of pipeline of any diameter on site without being limited to pre-set lengths of mounting bases. The unique trigger carrier mechanism is extended or retracted into the main body by simply releasing a locking screw and rotating the carrier to achieve the correct length to suit the mounting boss and pipe thickness. The maximum adjustment is 25mm (1").

Buried Pipelines

Extended length valved Hi-T Pigalert™ model with the signalling devices mounted on top of a supporting mast can be installed on below ground pipelines. Extensions are specified as the distance from the top of the pipe to the top of the mechanical flag. Maximum extension is 2m for standard models. This can be increased for special applications.

Removal Under Pressure

The Hi-T Pigalert™ is classified in two types: models which are not designed for removal while the line is under pressure, and models which are fitted with an integral valve and suitable for controlled removal when the pipeline cannot be depressurized. A simple jacking bracket tool is available for this purpose, consisting of a safety screw mechanism and bridging clamps to allow rapid removal and reinstallation of the Hi-T Pigalert™ from the line under pressure.


The internal moving parts of all models together with the associated pressure housings are made from stainless steel or the equivalent cast material in accordance with NACE Standard MR-01-75 / ISO 15156 materials are available.

The ball valve fitted to the Hi-T Pigalert™ for the controlled removal of the signallers under pressure, comprises a carbon steel body, stainless steel ball and stem, renewable body seat rings and high-pressure body seals.

For use at low temperatures, full stainless steel valves are also available.

Hydrostatic Testing

The Hi-T Pigalert™ is hydrostatically tested to full code pressure requirement prior to despatch.

Where to Buy

Interested in GD Engineering? Contact the team and arrange a consultation today.

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