Indonesian Refinery Increases Inspection Productivity

By replacing conventional X-ray inspection of pipework butt welded joints with ultrasonic inspection using the new USM Vision from the Inspection Technologies business of GE Measurement & Control (USA), the Plaju refinery in Sumatra has been able to increase inspection efficiency by 67%. This has provided significant time saving, as the refinery can typically inspect over 600 welds in a short turn round period.

The Plaju refinery at Palembang is the fourth largest refinery in the Pertamina group. Pertamina is the Indonesian state-owned oil & gas company and operates six refineries, some of which, including Plaju, produce Liquefied Petroleum Gas (LPG). Plaju is integrated with petrochemical plant and also produces purified terapthalic acid (PTA) and Paraxylene. The refinery is constantly being enlarged and adapted and this involves much on-site construction. This is fabricated and inspected on-site.

As Mister Rinaldi, the Senior Station Inspector at the refinery explains, “Weld inspection is a vital part of the work we do. Previously this had all been done by X-ray. This was mainly because inspection codes have historically been written covering X-ray. Today, codes are available for ultrasonic inspection and particularly for phased array. As we were already aware of the many benefits of ultrasonics over radiography, in terms of greater convenience, as there is no need for film processing, radiation screening and waste chemicals disposal, we decided that automated ultrasonics could provide a more efficient inspection solution.

Most of the ultrasonic Level II inspectors at the refinery only had experience of manual ultrasonics but USM Vision’s intuitive, 100% guided operation soon allowed teams of two inspectors per shift to carry out code-compliant inspection of 50 welds per day. These inspections were carried out without the need to shut down production or transport welded pipe to screened areas, as would have been the case with radiography. Furthermore, the inspection productivity could have been doubled by using a second USM Vision in the same production area, which, again, is something which is not possible with radiography.

USM Vision can operate in phased array and TOFD mode and is supplied with its operating software and GE’s Rhythm analysis software, as well as the probes and wedges to suit the selected codes and pipe ranges. Set-up is menu-directed allowing the operating software to calculate the ultrasonic parameters for each weld and pipe combination and create an easy-to-follow inspection plan. The operator can then scan the weld, with an encoded scanner, using TOFD or Phased Array in parallel or linear scanning mode. Inspection data is transmitted to a review station in the industry-accepted protocol, allowing advanced analysis tools, such as real time volume-corrected imaging, to allow easier and more reliable image interpretation. By using GE’s Rhythm software platform, inspection data can be reviewed and shared, reports generated and inspection results archived for tracking or further analysis. Recent developments have seen the introduction of USM Vision 1.2, which allows both sides of a weld to be inspected in one scan, effectively doubling productivity. This capability is available in all new USM vision systems and can be retrofitted to existing systems.