Internal Coating Failures in Deaerator Towers

[Angsi]

Location: Offshore Platform
Fluid: Seawater
Capacity: 46,000 bpd
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The water Injection System consist of a Deaerator Tower, Coarse and Fine Filters. In the past we have been using glass flake lining and Monel/Super Duplex Stainless Steel internals. However, we are experiencing repeated failure of glass flake lining and epoxy coating in this service (3rd time now).

We have heard different versions from Vendors, some saying that the internal coatings have been successfully used in other project and that it is strange failures should only be with us.

Can someone please share their experience?

Will SDSS cladded vessels be the best solution?

Thanks.

 

[kenvlach]

You haven't described the failure or conditions well enough for diagnosis.

My experience is with chopped glass fiber-reinforced resins requiring greater chemical resistance, so can only share some general observations:

Epoxy resins vary greatly in resistance to water permeation. Glass flake increases the resistance, so maybe someone thought that a less expensive resin would work. A more expensive vinyl ester resin will have greater chemical, moisture & temperature resistance than a polyester. Is steam used in the deaeration?
Consider one of these based upon your conditions:

http://www.derakane.com/derakaneCon...ductFamilyPage.ash.nes.tierMenuNavID.products

Also, it is important to have a sufficiently thick topcoating separating the liquid from the glass. Any sand abrasion?

 

[SJones]

What sort of quality assurance is applied to the process from selection of the paint system to handover of the vessel? Has the selected coating system been subjected to a specific qualification testing regime appropriate to the pressures (including depressurisation)? If it has been tested, has the formulation been changed? How was the application inspection?

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/