3. Integridade Química: Carbono Equivalente e Serviço Azedo

For subsea pipelines, soldabilidade é fundamental. Para garantir a zona afetada pelo calor (Haz) não fica quebradiço, a Carbono Equivalente (CE) is strictly limited.

We typically use the IIW Formula:

For X65QO, $CE_{IIW}$ is usually kept below 0.39, ensuring that offshore welding can be performed with minimal preheating, speeding up the pipe-lay process.

Adicionalmente, because many offshore reservoirs contain $H_2S$, these pipes are often tested for HIC (Hydrogen Induced Cracking) e SSCC (Sulfide Stress Corrosion Cracking). This requires extremely low sulfur levels ($\leq 0.002\%$) and calcium treatment for inclusion shape control (converting elongated sulfides into spherical shapes).