Safe removal on live pressurised pipeline
Minimal asbestos exposure for workers and environment
The PTT Pipeline Life Extension Project is one of the largest onshore pipeline recoating projects undertaken using RPR heat induction technology. The pipeline system, located in the surroundings of Bangkok and the Chonburi province of Thailand, was originally commissioned in 1981 and is owned and operated by PTT (Petroleum Authority of Thailand), one of Thailand’s largest public listed energy companies.
The pipeline system comprises 24″ and 28″ pressurised API 5L steel pipes ranging from 8 to 12mm in wall thickness, operating at temperatures between 32 and 50 degrees Celsius. The exterior coating consisted of 8 to 12mm thick Coal Tar Enamel (CTE) applied over an asbestos mesh, a coating system that presents significant challenges from both a removal and a hazardous materials management perspective.
In 2005, PTT detected disbonding issues across portions of the protective pipeline coating. Further investigations in 2010 confirmed the disbonding had spread considerably, prompting a decision to recoat major sections of the pipeline. An extensive evaluation was carried out to identify a removal method that was safe, environmentally responsible, and capable of delivering the throughput required to complete a project of this scale within a practical timeframe.
Following that evaluation, the RPR Induction System was selected as the preferred removal method and formally specified in the project bid documents. The method was approved by Technip, which issued operating procedures mandating use of the RPR system in its patented automatic mode. Two main contractors, ITD and TRC, were selected through the bidding process and collectively acquired 10 RPR units for daily use on the project. Work commenced in June 2015 with a total project duration of 3 years, covering the recoating of 116 kilometres of pipeline across two sections of 92km and 24km respectively.
Recoating 116 kilometres of live, pressurised gas pipeline without shutting down operations presented an extraordinary set of technical, environmental, and logistical challenges. The pipelines remained active throughout the entire project, meaning that any removal method had to be capable of operating safely on pressurised gas infrastructure without creating any risk of ignition, pipeline damage, or process interruption.
The existing Coal Tar Enamel coating, applied over an asbestos mesh, added a further layer of complexity. Asbestos-containing materials require strict exposure controls to protect both workers and the surrounding environment, making any removal method that generates airborne particles, dust, or aggressive waste streams entirely unsuitable. Traditional abrasive blasting and ultra-high pressure water jetting were ruled out on these grounds, as both would have created unacceptable asbestos contamination risks in open-air trench conditions.
The sheer scale of the project also introduced significant on-the-ground challenges. Working across approximately 4,000 individual trenches of 28 to 30 metres in length, teams faced reduced excavation rates in densely inhabited areas and at road crossings, difficult trench wall stability in wetland conditions, and heavy rain and flooding during the Thai monsoon season. Each trench had a strict open-time window of just 4 days from excavation to backfill, placing considerable pressure on the removal rate and operational efficiency of the chosen method.
The RPR Induction System was deployed across the PTT pipeline project using a fleet of 10 RPR units operated by contractors ITD and TRC. Each unit was configured in a self-contained RPR 10-foot container plug-and-play setup, allowing rapid mobilisation and relocation between trench sites across the 116-kilometre pipeline corridor.
Operating 10 hours per day, 6 days per week across 10 months of the year, the RPR units worked continuously through each trench section, thermally debonding the CTE coating from the pipe surface without abrasion, chemicals, or any process that could compromise the integrity of the live, pressurised pipeline beneath. The induction process generates heat selectively within the coating layer, causing it to separate cleanly from the steel substrate as solid flakes rather than airborne particles, which was critical for managing the asbestos content of the removed material safely.
On coating thicknesses of up to 10mm, RPR units achieved removal rates of 12 to 14m² per hour, equating to 5 to 6 metres of 28″ pipe per hour per unit. This level of throughput was sustained consistently throughout the active work period across both pipeline sections. Following coating removal, the exposed pipe surface was prepared to SA 2.5 via sweep blast before the application of a 2K Liquid Epoxy recoating system.
By the 30-month mark, approximately 65 kilometres of pipeline had been successfully refurbished using the RPR Induction System, with zero reported safety incidents, minimum equipment wear and tear, and no warranty or malfunction claims recorded across the entire fleet of 10 units.
