过程装备与控制工程专业英语翻译

装控131 杨哲 1304310125

CORROSION AND ANTICORROSION TECHNOLOGY

IN OFFSHORE PLATFORMS

(Shanghai Shipbuilding Technology Research Institute, CSSC 200032, China)

Abstract: This paper summarizes the corrosion environment and rules of the different

zones in offshore platforms, also briefly introduces the requirements and systems of the

anticorrosion coating .According to the long-term anticorrosion requirements in offshore

platforms, the paper introduces several long-term anticorrosion technology, including thermal

spraying, adding zinc protection and anticorrosion technology with platform legs wrapped

etc,which will provide some references to the research of the long-term anticorrosion technology

in offshore platforms.

Key words:offshore platform;anticorrosion; thermal spraying; adding zinc technology;

anticorrosion wrap

Offshore platform is a kind of large offshore engineering structure. The steel structure in the

long-term salt fog, moisture and water environment, the erosion of seawater and sea creatures,

and produce severe electrochemical corrosion. Corrosion seriously affects the mechanical

properties of the structure of the offshore platform, which affects the safety of the marine

platform. And because the offshore platform off the coast, not as a regular maintenance

like a ship docking, so builders and users of offshore platforms very seriously corrosion of

marine platform. How long-term preservation of offshore platform structure, as well as

research and development of offshore platform structure of the new materials, new

technologies and new processes are of long-term preservation is very important.

1. Corrosion Rules 1 offshore platform

1.1 Corrosion regional boundaries of the marine environment

Offshore platforms extremely harsh environment, sun exposure, salt spray, shock

waves, complex water system, environmental temperature and humidity changes and

marine life make offshore platforms erosion corrosion rate faster. Offshore platforms in

different marine environments, corrosion behavior and corrosion characteristics will be

relatively large differences. Therefore, to offshore platform structure in a marine

environment corrosion corroded areas were analyzed and defined, in order to put

forward effective protection measures. According to the marine environment,

corrosion characteristics and different average corrosion rate, offshore platform in the

marine environment in marine atmosphere can be divided into three major regions

splash zone and immersion zone. In order to better analyze the corrosion of steel

offshore platforms, many researchers turn splash zone into the splash zone and tidal

zone, immersion zone into seawater immersion zone and seabed soil area that is

divided into five areas of corrosion.

1.2

Marine steel corrosion

Ocean-atmosphere: Ocean sea-salt particles cause atmospheric zone accelerate

corrosion, dry surface and wet film alternates salt form of physical, chemical and

electrochemical action affecting metal corrosion.

Splash Zone: The most serious corrosion in the marine environment, the site is

above average tide splash zone. As often as the wet surface, surface oxygen supply is

sufficient, no sea biofouling. Long and short drying surface wetting the surface of the

alternation and spray erosion, mainly caused by physical and electrochemical corrosion

damage and maximum damage.

Tidal zone: steel corrosion tidal area is the lowest, even less than the corrosion rate

of seawater immersion and seabed soil. The average low tide level the following corrosion

nearby area emergence of a peak, it is because steel piles in the marine environment,

with tidal fluctuations, the total amount of oxygen in the steel surface above the waterline

humid than dip below the waterline at sea the steel surface to be much more fully, and to

each other to form a loop, thereby becoming an oxygen concentration difference between

the macro corrosion cell. Corrosion cell-enriched zone is the cathode, namely tidal area;

relatively anoxic zone anode, namely the regional average low tide level below the

waterline. The overall effect is that at every point throughout the tidal zone are subject to

varying degrees of cathodic protection. While the average low tide level less often as the

anode and the emergence of corrosion peak.

Seawater immersion zone: the corrosive seawater immersion zone, the shallow

water may corrode more quickly than the ocean air, the oxygen content of the deep-sea

areas is often much lower than the surface, the water temperature close to 0 oc, corrosion

lighter.

Seabed soil zone: the presence of sulphate reducing bacteria and bacterial sources

and characteristics of seafloor sediments mixed. Less influence by the sea, and the

temperature is low, a small degree of corrosion, but there is some corrosion at the junction

of ocean currents action.

2 offshore platform steel structure anti-corrosion coating technology

Long-term offshore platforms in harsh corrosive environments, maintenance difficulties

during use, so only use anti-corrosion technology provision of high-performance

heavy-duty coatings. Several offshore platform using heavy-duty coatings, each with the

following characteristics:

(1) zinc-rich primer: Requires a high proportion of zinc-containing paint, Kuang

requirements and substrate adhesion. One role is to take zinc-rich primer cathodic

protection, In addition, when the coating damage or when there is not continuous, zinc

Yao can play the role of sacrificial anode to protect the substrate. A zinc-rich primer Tong

inorganic zinc-rich primer, epoxy zinc-rich primer and the like.

(2) intermediate paint: intermediate paint requires comprehensive anti-corrosion ability,

among cattle is characterized by anti-rust paint or impervious material containing material

efficient, female l granular or scaly zinc powder, glass flake, stainless steel flake, satisfied

Mu class Chin shielded and powder-based coatings and cathodic protection type were

kind of new corrosion-type paints and so on.

(3) Finish: finish the role is to provide a protective layer of primer and intermediate coat,

slowed down and limited water vapor, oxygen, and chemical activity of ion penetration.

Also requires impact resistance, anti-aging and anti-insoluble and so on. Finish commonly

used chlorinated rubber, vinyl, polyurethane or acrylic resin coatings.

In addition, heavy-duty anti-corrosion coating to get a good effect, but also need to

pay attention to a number of factors, including the surface treatment of the substrate,

high-quality paint, reasonable coating system, outside construction conditions,

construction coating quality control. Currently heavy-duty coatings mainly used for

offshore platforms atmospheric zone.

l long-term preservation technology offshore platform

structure

For each area of corrosion offshore platforms, in addition to the current anti-corrosion

coating and cathodic protection or impressed current cathodic protection system support,

but also. on the offshore platform have long-term preservation of the use of other

technologies, including long-term platform for thermal spraying anti-corrosion technology,

Zinga protection technology, the platform leg tied corrosion package technology.

3.1 offshore platforms thermal spraying anti-corrosion technology

Thermal spraying technology in offshore platform steel member has a long history.

Thermal spraying of zinc, aluminum and its alloys coating on foreign offshore platform

steel member has successfully applied examples, examples show: thermal spray coating

of zinc-aluminum and its alloys corrosion has become a mature technology, after

appropriate heat sealed spray zinc-aluminum coating at room temperature and high

temperature on steel in the splash zone exhibited excellent corrosion resistance.

Aluminum thermal spray coatings in marine engineering is the biggest application

platform in 1984 to build the H otton tension leg platform. The platform design life of 50

years. 8 years after its use in the splash zone corrosion is found, and brown leakage

effects. Thickness measurement showed that the thickness of the coating does not reduce

platform installation, it illustrates the effect of anti-corrosion marine platform lame spraying

zinc aluminum metal coating layer is obvious, even if the surface of the organic coating off

will ensure expansion of the substrate against corrosion. At the same time after tests

showed that 2001} hot Tut m thick zinc-aluminum coating for steel in the splash zone

protection can ensure life for more than 30 years.

For high-strength steel parts used for offshore platforms, spraying aluminum and

aluminum alloy coating not only provides an aluminum shield, and once the coating is

damaged, it can appear as a sacrificial anode protection drain coating area. The coating

may be applied in a closed paint, aluminum and aluminum alloy coating to seal the pores,

thereby improving coating performance and extend the life of its total. Our thermal

spraying anti-corrosion technology started late, currently used in offshore platform

preservative it is still in the experimental stage, pending further development and

application.

3.2 Zinga offshore platform protection technology

Zinga protection is a quality and convenient method for steel corrosion protection, zinc

add protection to the substrate material has cathodic protection and shielding dual role.

Zinga protection technology has excellent corrosion resistance that Zinga zinc galvanized

coating dry film amounted to 9600, the product purity over 99.995% zinc. Zinga protection

also has a unique blend of heavy, new and existing coating Zinga Zinga coating can be

fully integrated, easy maintenance painted up.

Zinga protection compared with conventional organic coatings, cathodic protection

has a strong effect and may be used as a good bottom, its resistance to corrosion than

conventional zinc-rich primer 5-6 times, corrosion protection up to 25 years to 30 years.

The extent of corrosion of offshore platforms immersion zone serious than the

atmospheric region, but lighter than the splash zone. Full immersion zone generally use

cathodic protection or protective coatings and cathodic protection joint, but seldom alone

paint protection, since there is currently antirust, anti-fouling paint life is difficult to achieve

permanent protection of offshore platforms. Zinga protection technology in the dual role of

long-lasting protective coating and cathodic protection, corrosion protection with a long

service life which make up the general corrosion protection coatings in the life of

deficiencies.

Domestic and offshore platforms by the project proved plus zinc corrosion protection

properties of the coating technology is excellent. 2000 Zinga protection technology is

applied at the local service domestic and offshore drilling platforms, Shekou, Shenzhen

Pinghu oilfield offshore drilling platforms, repair of Zinga coating used has not found a

good rust and corrosion performance.

3.3 Offshore Platform Legs tied corrosion Package Technology

Currently, marine splash zone corrosion of the worst parts of the corrosion problem

has been unprecedented attention, and ongoing in-depth discussion among. Now

recognized as the most mature technology is corrosion Kit tied method. In the United

States, Britain, Japan and other developed countries, a growing number of offshore

platforms to splash zone corrosion leg using a preservative Kit tied technology.

Corrosion sets is a long-acting anti-corrosion technology, used in the splash zone of

marine environmental conditions can make corrosion life of more than 30 years. Corrosion

sets from high-strength multilayer fabric covered with special polyester outer layer, inner

cladding corrosion Thixotrope 3 parts. This three-layer structure closely aggregated

together to form a monolithic whole structure. This unique structure can be set by

increasing or decreasing the thickness of the body and alter the fabric structure to adjust

the physical properties of corrosion sets in order to adapt to different corrosion

requirements. Its multi-layer fabric itself elastic sleeve to make corrosion-designed

package tightly tied ocean tension leg platform, and watertight or airtight sealing

requirements, in order to achieve long-term preservation.

Offshore platform jacket leg corrosion can effectively solve the adverse effects of the

sea organism attachment. Anticorrosive coating the outer sleeve and the inner product of

antifouling component corrosion thixotropes and other unique design, can effectively

prevent the adhesion and growth of marine organisms, so that the corrosion sets

preservative life is greatly extended, and ultimately effective in achieving long-term

corrosion protection The purpose of. Its elasticity effect itself high strength fabric sleeve in

corrosion and piling surface tension of a tight collar, which will not only cover tightly pack

anticorrosive pile legs tied, and will not be due to temperature changes caused by steel

Pipe leg physical changes brought about by thermal expansion and contraction of any

effect. Currently, anti-corrosion sets of leg technique has been applied in more than one

marine projects around the world.

4 Conclusion

Offshore platform steel corrosion, according to the characteristics of the different

regions of maritime corrosion, corrosion rate choose the appropriate corrosion protection

measures. Anti-corrosion coatings emerging new varieties, should be fully aware of their

own performance matching paint and coating between strict coating process. Thermal

spray coatings and zinc plus protection technology is supporting each other coating and

cathodic protection, so as to achieve long-term preservation of the marine platform.

Offshore platforms leg in the splash zone area and the water level changes frequently

withstand collisions tapping and production operations and foreign matter waves is the

corrosion of the worst parts leg, requiring special corrosion protection. Package tied

corrosion technology has unique high strength jacket design, the marine platform leg may

get good corrosion protection effect of changes in the splash zone and district level. To

avoid the possible loss of corrosion, extend the life of offshore platforms, offshore

platforms anti-corrosion technology development is of great significance

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