Inspection in the petrochemical industry often involves onshore locations as well as offshore installations. ACFM provides an ideal NDT solution in this environment.

Many components in the petrochemical industry are coated either in paint, lagging or more exotic materials such as zinc or intumesent fire protection materials. In addition the complicated branching and clustering of some of defect types - for example stress corrosion cracking or hydrogen induced cracking - makes accurate sizing difficult.

ACFM has been used in almost every aspect of the petrochemical industry including refineries, distillation towers, pipelines, boilers, furnace tubing and storage tanks. Special probes also allow easy inspection of threads (such as drill-string connections and sucker rods).

Crucially ACFM provides the ability to inspect components without removing the coating. With ACFM, patches of cracking can be located beneath coated surfaces and the severity graded appropriately. This means that a coating only has to be removed for further inspection or repair in known areas of cracking.

This results in a significant time and cost saving where previously areas required coating removal pre-inspection, and re-application post-inspection, regardless of whether an area suffered cracking.

The technique can also be deployed on hot surfaces so that inspection is often possible without shutting down the plant. Standard probes can be used on surfaces up to 200 degrees centigrade for short periods, and special probes are available for use up to 500 degrees centigrade if required.

Although mostly used to detect and size fatigue cracking, ACFM can be used for other types of cracking found in the petrochemical industry such as stress corrosion cracking and hydrogen induced cracking.

In addition to normal ferritic steels, ACFM can be used on all other metals found in the petrochemical industry, such as austenitic stainless steel, inconel or duplex steel.

Refinery reactors

U19 AMIGO instrument

Standard weld probe 5KHz

Right angle pencil probe 5KHz

Right angle transverse pencil probe

ACFM inspection was carried out on five existing Powerformer reactors at a major UK refinery.

Areas investigated were shell to compression pad welds, compression pad to nozzle welds and upper flange welds. TSC were able to provide the client with a fast and effective solution for defect investigation in the welds, prior to a major turnaround program. The reactors were planned to be replaced and lifting the 75 ton reactors could only be carried out using the top nozzle. All reactors were online, with a surface temperature of approximately 150 degrees centigrade, therefore production was not affected.

Standard TSC probes were used for this inspection, however we also manufacture probes that can withstand temperatures of up to 500 degrees centigrade.

U19 AMIGO instrument

40mm 8 channel flat array probe 5KHz

Standard weld probe 5KHz

Right angle pencil probe 5KHz

Straight mini pencil probe 5KHz

The Billings 2006 annual shutdown used a dedicated ACFM team for inspection of distillation towers. Technicians working in teams were able to access internal and external welds, up to 120 metres above ground, carrying all the required equipment up the external access ladders, and with no requirement for external power. Inspection was rapid and highly efficient.

Shutdown inspection also involved numerous heat exchanger shell welds, again results were obtained rapidly, extremely cost effective and allowed the client to restart the plant ahead of target.

LPG storage spheres

U19 AMIGO instrument

Straight mini pencil probe 5KHz with 50m cable

Standard weld probe 5KHz

30m RS232 comms cable

Ten main leg supports on LPG storage spheres were inspected in two days using standard ACFM inspection techniques and rope access. All associated pipe work connecting to the spheres (6 inch to 36 inch nozzles) was also inspected. All components had a zinc based paint coating 100 microns thick which was left intact for the ACFM.

Pressure vessel internal inspection

U19 AMIGO instrument

40mm 8 channel flat array probe

Standard weld probe 5KHz

Right angle pencil probe 5KHz

Straight mini pencil probe 5KHz

ACFM inspection was carried out on selected welds on vessels during a major plant shutdown. General locations for inspection were sulphur recovery units, coker knock out drums, cokers, gas amine absorbers, flash drums, separators and stabilizer condensers.

All weld inspection was on vessel internal welds. Further selected areas of manways, nozzles and drains were competed.

LPG spheres

U19 AMIGO instrument

Standard weld probe 5KHz

Right angle pencil probe 5KHz

Straight mini pencil probe 5KHz

ACFM inspection was undertaken on LPG sphere T-0606 at the Moerdijk Chemical Plant by request of Shell Nederlands Chemie BV.

Two main circumferential welds and six transverse welds were selected by TSC's client for ACFM inspection. All welds had original paint coating intact, though several areas were stripped of flaking paint. Access was good in all areas. The configuration of the welds was ideally suited for the use of a standard ACFM weld probe.

Chemical plant reformer tubes

U9 instrument with ACPD

Standard weld probe 5KHz

Straight pencil probe 5KHz

One of the largest chemical corporations in the United States, in association with a leading US Inspection company, contracted ACFM inspection services for work on 304H stainless steel reformer tubes and inconel to steel furnace outlet pigtails.

Inspection of the reformer tubes was carried out using a single coil probe, achieving excellent results - though time consuming for the amount of inspection area involved. From this experience in 1995, TSC now offer the most technologically advanced, compliant array probes, covering 45mm wide areas in one pass and with the ability to detect defects in any orientation.