Belt Pipe Scanner

OVERVIEW

The Belt Pipe Scanner is a girth weld scanner, suitable for use on a wide range of pipe diameters. As the scanner is held onto the pipe using an industry standard toothed drive belt it can be used on non magnetic pipes. It is capable of scanning the full 360° of a circumferential weld and it is available in either a manual or semi-automatic version.

There are three variations of the scanner:-

Type 1 has a manual circumferential drive. When the unit is to be moved in a circumferential direction, a form of indent will restrict the movement to a pre-set value. This will provide a standard square raster pattern with scanning in both directions of movement of the axial bar.

Type 2 uses the movement of the axial bar through a gearbox to provide the circumferential movement of the scanner. When the axial bar is moving in one direction a clutch disengages and no circumferential movement takes place. It is common for the scan to happen in this direction. As the rod is moved in the opposite direction, the clutch engages and the whole scanner moves in the circumferential direction. The length of the stroke determines the circumferential movement, so a 400mm axial stroke will produce twice the movement of a 200mm stroke. This produces a saw tooth scan and the flaw detector can be set to ignore the scan in one direction.

Type 2A is a more complex version in which the circumferential movement can be pre-set to give a different circumferential movement for a given axial movement.

Type 3 uses an electric motor to provide the circumferencial movement. The movement is instigated by the axial bar triggering a limit switch. The movement is controlled by reading the encoder, so moving through a pre set distance. This provides a standard square raster pattern with scanning in both directions of movement of the axial bar.

METHOD OF OPERATION

The scanner can be operated on one of two modes.

The first mode is used for raster scanning where the primary axis is the axial movement. This mode is for the pulse-echo inspection of a weld or for corrosion mapping. The probe is moved axially along the pipe, by the operator, over the required scan length and then the whole unit is moved circumferentially, manually, through a gearbox or by an electric motor.

The second mode of operation is used for TOFD scans. In this mode the axial bar is locked in position with the probes set the correct distance apart and relative to the weld to be inspected. The carriage or gearbox is then pushed, or driven around the pipe to obtain the necessary scan. It is possible to lock the circumferential movement at any position during the scan to allow the operator to move their position before continuing the scan.

Both axis are encoded by an optical, quadrature encoder with a lines per revolution count such as to provide at least 5 lines per mm of movement. A higher count can be provided if required.

DESCRIPTION OF THE SCANNER

Toothed Drive Belt

The purpose of the toothed drive belt, an industry standard item, is to hold the scanner onto the surface of the pipe. The belt has to be measured and cut for each of the different pipe diameters and then the two ends joined together. This same belt is suitable for all pipes of the same diameter as the joining method allows the belt to be joined and re-joined at will. Once the belt has been placed in position and joined, it is tensioned by moving one of the guide pulleys.

The belt also acts as a guide for the scanner to help keep it a constant distance from the weld.

The Axial Bar

The axial bar serves two purposes, one is to carry the probe holder and the other is to operate the encoder. Where the gearbox is used it also drives the circumferential movement.

Gearbox and Carriages

These items contain the method of producing the circumferential movement and also act as a junction box for the electrical, ultrasonic and umbilical connections. The standard length of the umbilical is 5m.

EXTENT OF SUPPLY

Common Items:
industry standard toothed drive belt
belt joining clasp
encoder on each axis
axial arm – stroke 200 mm
1 off constant force tool post
composite tyres on the wheels

Type 1 Scanner
carriage for manual indexing with a lock on the circumferential axis,

Type 2 Scanner
gearbox for automatic indexing with a lock on the circumferential axis,

Type 2A
variable distance gearbox for automatic indexing with a lock on the circumferential axis,

Type 3 Scanner
electric motor drive of the circumferential movement

Optional Extras:-

1. Magnetic wheels
2. Adaptor Bar for TOFD scanning
3. Ability to skew the probe
4. Transit case
5. Long umbilical
6. Constant force toolpost