U19 AMIGO instrument

40mm 8 channel flat array probe 5KHz

Standard weld probe 5KHz)

Right angle pencil probe 5KHz

Straight mini pencil probe 5KHz

TSC were contracted to carry out ACFM inspection on numerous louvre support column assemblies, louvre roof support columns and base supports at Chiswick Park, London.

The purpose of the inspection was to locate any surface breaking defects in the weld caps and weld toes, through the existing paint coating. All butt welds were ground flat and painted to finished standard. An ACFM array probe with width coverage of 40mm was used, one pass either side of the weld centre line to provide total width coverage of approximately 80mm through the full circumference of the weld. Single coil weld probes were used on the base plate fillet welds on the louvre roof support columns and on the circumferential welds on the base stub columns.

Use of the array probe provided simultaneous data for both X and Y directions (i.e. longitudinal and transverse to the line of the weld).

U19 AMIGO instrument

40mm 8 channel flat array probe 5KHz

Hyde Lane underbridge was constructed in 1969 and carries the two lines of the Bristol and Gloucester line over Hyde Lane one mile south west of the A435 in Cheltenham. It is an early form of the ‘Western Region Box Girder' bridge, constructed from three main box girders, cross girders, deck plate and ballasted track. The superstructure is supported on reinforced concrete cill beams on masonry stone abutments and wing walls.

ACFM was carried out using a flat 40mm array probe to investigate the integrity of corners on cross girder webs. Inspection of the up line side was completed in one night shift, with the benefit of only having a partial road closure for 12 hours. The down line side was again completed in a second 12 hour shift.

U19 AMIGO instrument

40mm 8 channel flat array probe 5KHz

Micro pencil probe 5khz

Another challenging project TSC has been involved in is the inspection of welds on an historic bridge, constructed in 1867, spanning the river Thames.

Longitudinal beam web repairs had been carried out on the bridge, involving joining the original cast iron material with steel insert plates. Time and weather over many years had caused corrosion and degradation of some of the side panels.

Tests carried out in TSC's workshop on material samples prior to the inspection resulted in a high degree of confidence in the system for use on what is an unusual combination of welded materials, and the fact that there was a relatively thick primer and paint coating.

ACFM inspection was carried out using a hand held array probe with positioning encoder. The advantage of using the array system over single coil probes is that a much larger area can be inspected in one pass of the probe. This situation was ideal as the welds had been ground flat. In practice, an area of approximately 35mm wide was covered, thus inspection of the entire weld face and heat affected zone was accomplished in a single pass with the paint coating completely untouched.

Rail underbridge

U19 AMIGO instrument

Standard weld probe 5KHz

Straight pencil probe 5 KHz

Several major UK based civil engineering contractors were working in partnership on the repair and maintenance of a pair of steel underbridges, just to the north of Oxford Station. The bridges each carry two tracks over a waterway in a single span. The bridge has recently had a new abutment built under the southern end to give it proper support.

The six main girders have between them span cross girders which in turn support rail bearers and the deck plate. A limited amount of ACFM testing was carried out to assess if any fatigue cracking was present. 

Roadside lamp post weld inspection

U19 AMIGO instrument

Standard weld probe 5KHz

ACFM inspection was conducted on 114 QEII bridge lamp post welds. No cleaning or paint removal was required. Inspection was carried out by rope access technicians and a remote ACFM operator, removing the need for plant, cherry pickers or scaffold.