NORSOK-approved HNBR compounds like PPE EnDura® H3592B dominate 150–165°C service. Retaining >75% elongation after 10 weeks in 25% H₂S at 150°C, they outperform standard HNBR by 400% in sour environments, making them standard in subsea control modules and riser seals. https://globalsealstech.com/medical/