A major Australian alumina refinery relies on large-diameter steel pipelines to move red-mud slurry, a highly abrasive by-product of the refining process. On one 762 mm (DN750) line, internal erosion had thinned a section along the bottom of the pipe to as little as 2.69 mm of remaining wall — roughly 79% wall loss on a pipe originally built from 12.7 mm carbon steel. Wall loss at that level risks a slurry release, unplanned downtime and costly section replacement. Cutting out and replacing the spool was not viable within the production schedule, so the operator needed a carbon fibre composite pipeline repair that could return the line to its full design rating without taking it out of service.
Our Solution
HJ3 engineered a Type A CarbonSeal HT1 red mud slurry pipe repair in accordance with ASME PCC-2 Article 401. The design specified 10 layers of CarbonSeal™ HT1 carbon-fibre reinforcement, producing an installed composite thickness of approximately 12.95 mm over a 457.2 mm repair length. The system included CarbonSeal™ HT1 primer, defect filler, saturated carbon reinforcement and a ChemSeal™ protective topcoat. Surface preparation required SSPC-SP11 power-tool cleaning to bare metal, with a 50–76 micron surface profile achieved using suitable equipment such as MBX Bristle Blasting or the Safety Tool Rough Boy.
Results
The completed carbon fibre composite pipeline repair restored the eroded section to its full 34 bar design pressure and extended the service life of the asset. It was installed live, with zero shutdowns, avoiding an unplanned outage and the cost and lead time of replacing the pipe spool. Delivered to a recognised international standard, the repair gave the operator a durable, code-compliant result with no interruption to production.
Frequently Asked Questions
Can HJ3™ composite systems be applied to hot, in-service assets?
Yes. HJ3™ systems suit assets running up to 120 °C operating temperature, and the cured laminate will withstand excursions to 175 °C. The correct system is selected against the asset’s actual operating and peak temperatures, so confirm service conditions with PIPESERV before specifying.
Does the pipeline have to be shut down for a composite repair?
No. On this job the CarbonSeal™ HT1 repair was installed with the line still in service at 24 bar, so production continued throughout and no shutdown was required. Live installation is one of the main reasons operators choose a composite repair over cutting out and replacing a spool.
What standard is an HJ3™ composite repair engineered to?
This repair was designed and installed to ASME PCC-2 Article 401 as a Type A repair. HJ3™ CarbonSeal™ systems also conform to ISO 24817 and CSA Z662, so the repair is a code-compliant engineered solution rather than a temporary patch.
How much wall loss can a carbon fibre composite repair restore?
Considerably more than most operators expect. On this pipeline the wall had eroded to 2.69 mm of remaining steel from an original 12.7 mm — roughly 79% wall loss — and ten layers of CarbonSeal™ HT1 returned the section to its full 34 bar design pressure. Each repair is calculated for the specific defect, remaining wall and design conditions.
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