Tuesday, August 16, 2022

REPAIRING SEA-ERODED DRAINAGE PIPELINES

OnSite, a South Staffordshire Plc business, was recently tasked with repairing the drainage system on an unmanned offshore gas rig in the Southern North Sea some 80 km east of Easington, which lies on the coast some 30 km southeast of Kingston-upon-Hull, UK.

The drainage system on the rig comprises sections of carbon steel piping that required repair after suffering internal corrosion due to being in service for 12 years. The pipes had been initially installed with a non-corrosion resistant alloy with an original design life being only 2 years.

Internal corrosion and large loose scale deposits had caused frequent snagging and blockages. A full clean and removal along the length of carbon piping with replacement was required. Due to the location and nature of the system, the Picote Brush Coating™ system was deemed to be the ideal solution for both appropriate repair and to future proof the drainage system as it required less equipment and no lateral cutting of the pipework.

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GETTING ON BOARD!
Whatever the job requirements, OnSite always ensures its teams are trained
in all safety aspects to the highest standards. Before even stepping foot on the
gas rig, the rehabilitation crew undertook the appropriate safety training.

The 5 days of survival training included:
• BOSIET, which involved the team being in a helicopter shell lowered into a swimming
pool and exiting while fully submerged.
• DONUT, training in quick exit from the gas rig into a survival raft.
• MIST, survival at sea training.
Once the crew was fully trained in the survival aspects of the work, the rehabilitation
equipment was packed and sent via boat to the rig, followed by the team a week later
via helicopter from Norwich airport.

RESOLUTION
The project commenced with the crew cleaning the pipes to be rehabilitated using
high-speed cleaning with a Picote Miller, rotary chain and brush tools, taking care to
disconnect the pipework to a macerator on the line prior to descaling to prevent any
possible damage of the waste handling system.

Outside connections comprised uPVC piping which required further care to clean as
they were hard to reach transition and mastic joints, which had to remain intact.
The Picote Brush Coating™ system offered minimal disruption to the rig’s operation,
which also avoided costly full replacement of the pipes in question.

The equipment required by the OnSite crew comprised a Picote Mini Miller, a Picote
Super Midi Miller, a Picote Maxi Coating Pump and DC1000E Picote epoxy resin. The
coating of pipes had to be completed without the need to reopen lateral connections,
over multiple lengths of DN100 pipe with multiple incoming connections, which were
up to 10 m in length.

OnSite is a leading certified Picote Brush Coating™ business in the UK and on land or
sea offers an expertise in the remedial use of this system.

The coating, once cured, provides a damp proof, corrosion resistant, wear resistant
and non-corrosive lining, which is what made it the perfect solution for the sea water
eroded pipelines on the rig.

OnSite’s team worked solidly for 8 days aboard the rig to complete the job. The feedback from the client on completion of the work was excellent.

PICOTE BRUSH COATING™ SYSTEM
Picote Brush Coating™ System, for this project provided by UKbased Picote reseller S1E, utilises a Picote Milling machine, of a size suitable for the pipe under rehabilitation, and a Picote-designed resin injection unit to coat the inside of the deteriorated pipe with a dual-colour 100% solids epoxy two-part resin (DC1000E). Theresin is supplied in pre-batched  cartridges for ease of use. Brushes attached to the end of the Milling Machine cable spread the resin coating evenly and effectively over the inner pipe surface once it is injected into the host pipe. It is then allowed to cure under ambient conditions. Depending on the state of the host pipe and the degree of repair required, two or more layers of the resin coating can be applied to complete a full rehabilitation.

In terms of the rig rehabilitation work, the initial process for the operation used the Picote Mini Miller to completely clean the internal surface of the pipes requiring rehabilitation. The Picote Super Midi Miller, the Picote Maxi Coating Pump and the DC1000E Picote epoxy resin were then set up to mix and pump in the resin into the sections of pipe being repaired. The Brush system at the ‘business end’ of the Miller cable then picks up the resin in the pipe, spreads it around the inner surface of the pipe. The thickness of the coating applied is controlled by the amount of resin pumped in and the speed of the brush rotation and the rate at which the brush is drawn through the pipe.

The operation is monitored by the operator using CCTV so that the coating can be applied evenly around the pipe circumference. If the coating is too thin, the machine can be reversed over the site, more resin pumped in and smoothed into place. If the coat is too thick the resin pump can be stopped and the resin that is already in place brushed over to achieve the correct thickness. In this instance, The average cure time for the Gas rig operation was approximately 3 hours, a time which was assisted and reduced by the use of a ‘Smart Heater’.

Commenting on the project for OnSite Neale Sims, project lead said: “We at OnSite are very proud of our team and immensely grateful to our client to have been given the opportunity to deliver our specialist lining services in a very demanding but highly interesting environment. We continue to develop and offer new innovations and smarter methods of delivering drainage maintenance services for our customers and see their problems as our challenge.”

Terry Ingleby of S1E went on to say: “It was a pleasure to have the opportunity to be able support OnSite on another unique Brush Coating project, which was away from the day-to-day land drainage sector. Over the years, OnSite has taken on some fascinating projects for the Picote Coating System, investment in all the required equipment and having its team fully trained and certified in the process of this system really supports the company in taking on these projects.”

For Picote, Dawn Greig said: “OnSite has once again demonstrated the versatility of the Picote Brush Coating™ System. Our Technical Team was delighted to work with them to plan for these ground-breaking works, and we are delighted by the outcome. Preparation is key to all rehabilitation projects, Picote high-speed cleaning was essential for success, as well as a fully-trained and knowledgeable team. We look forward to working with OnSite and S1E Ltd on future challenges.”

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