Cold Applied Vessel Linings Take The Heat

Offshore process vessels operating at elevated temperatures and pressures represent one of the most arduous service environments and major challenges for asset owners and operators.

These vessels, and in particular those involved in the separation of oil/water and gas as it enters the process stream, are constantly subjected to a wide variety of aggressive conditions which can ultimately lead to severe internal erosion and corrosion. (Read More)

Dating back to the 1970s, organic epoxy linings, pioneered by Belzona, were used for the protection of process vessels. In 1994, linings resistant to explosive decompression and temperatures of up to 120°C were introduced for the protection of well test separators, production separators, knock-out drums and a variety of other types of process equipment.

With the sinking of increasingly deeper wells leading to higher operating temperatures and pressures, vessel operators are now faced with a difficult task to combat the problems associated with this kind of service environment. As a result, materials able to resist more arduous conditions had to be developed.

Novel solution to high temperature immersion

The first step of Belzona’s high temperature lining research project was the introduction of first generation Belzona 1500 series linings in 1998. Over the following 16 years, Belzona’s R&D department analysed data from the field and researched innovative technologies and filler systems that could enhance material characteristics and in-service performance that would allow for the coating to resist elevated temperatures, but at the same time, remain flexible in order to diminish the risk of cracking. This research has culminated in the introduction of next generation HT vessel linings in March 2014, hand applied Belzona 1593 and spray applied Belzona 1523.
According to Belzona’s Chief R&D Chemist, Richard Collett, “Belzona 1523 and Belzona 1593 are the culmination of 20 years of experience in formulating high temperature linings, starting in 1994. These linings are based on a combination of several ‘state of the art’ technologies and I believe they are our best high temperature linings yet.”

Key aspects developed

Increased flexibility and toughness – enhanced performance

The high cross-link density required in coatings to achieve their high temperature immersion resistance leads to rigid coatings being susceptible to cracking during thermal cycling and substrate flexing. Belzona 1523 and Belzona 1593 have been formulated to exhibit toughness and flexibility with rubbery domains that inhibit crack propagation incorporated into the structure. With high tensile strength and elongation, these coatings are designed to withstand temperature and pressure cycles while preserving their integrity and maintaining adhesion, as well as providing corrosion and chemical resistance. Unlike rigid coatings, these next generation linings are less brittle and can tolerate high radial, circumferential and longitudinal stress, reducing material ruptures, breaks and fissures, moving in sympathy with the substrate.

Simplified application methodology and inspection

The next generation linings address an application issue previously experienced when applying a two coat system of HT linings - bypass the need for grit blasting between coats, provided the second coat is applied within a 24-hour overcoat window. In addition, their unique curing mechanism activated at ambient temperatures eliminates the need for separate post curing processes and the lining will cure in service ensuring a faster turnaround.

High viscosity coatings are often over applied in an attempt to make the application easier and to improve the flow out, which can lead to over-thickness and have a big impact on cost but more importantly on performance. Improved rheology in this case allows a more uniform thickness can be achieved.

An important consideration for lining manufacturers is visual inspection during application. Dark coloured linings can make it very challenging due to poor lighting inside the vessel. Next generation linings have been formulated in light contrasting colours enabling quicker and more precise identification of potential problems at the application stage. They are also spark testable and with minimal bloom formation on the surface, false alarms due to surface tracking will be eliminated.

Feedback received so far from the field concerning the use of the next generation HT linings has been positive, citing simplified application techniques and savings achieved as a result of greater coverage rates paired with decreased contractor expenses. Additionally, considering that newly released materials are the next generation versions of their predecessors, Belzona 1591 and Belzona 1521, field experience demonstrating longevity can be further effectively utilised to assist corrosion engineers and asset operators with the vessel corrosion protection material selection.

Edited by Marina Silva, contributors:
Richard Collett and Anna Michael
Belzona Polymerics Limited

Belzona Polymerics Limited
www.belzona.com
Telephone: +44 1423 567641
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