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location of lower strength HAZ normal to the loading directions can

result in situations where fatigue cracks can sample more LBZ regions

thus increasing the possibility of brittle fracture. Recognising the

industry concern regarding LBZ, some steel companies have developed

LBZ free steels by alloy modifications to promote the austenite to ferrite
transformation and to prevent the bainite transformation.

5.2.2 Topside Materials

* The corrosivity of the production environments can be broadly

categorised as follows:

* 1/ Non-corrosive production: This includes conditions when corrosion

is not expected to occur. This includes conditions when the C02 partial

pressure is less than 5 psia and conditions when the pH value is higher

than 5.2 even if the C02 partial pressure is 30 psia. The pH value

depends mainly on alkalinity of water, acetate, temperature and C02

partial pressure. This could also include extremely corrosive conditions

where the corrosion is mitigated by the use of corrosion inhibitors.

* 2/ Production containing C02 : This corresponds to conditions where

the in situ pH value is lower than 5.2 or the partial pressure of C02

exceeds 30 psia. Under this environmental category, H2S can be present

as long as its partial pressure does not exceed 0.1 psia.
* 3/ Production containing H2S, or C02 and H2S : This corresponds to

production containing H2S with a partial pressure that exceeds 0.1 psia.

Under this environmental category, unlimited levels of C02 and

chlorides can also be present.

* 4/ Water injection: This is associated with seawater injection. In such a

case, the oxygen and chlorine contents are the important factors

governing the corrosivity. If produced water is reinjected, then the

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