High Pressure High Temperature (HPHT) Design

High pressure high temperature (HPHT) pipelines have specific metallurgy, coating, and design issues. Metallurgy selection needs to consider high strength materials to limit wall thickness whilst taking into account material de-rating and suitable high temperature coatings. Design issues include:

• Control and engineering assessment of localized effects that may contribute to ultimate failure (local buckling, fatigue and fracture) at a global buckle location;
• Material de-rating;
• Girth weld overmatching;
• Miter and angular misalignment;
• Requirement for detailed fatigue and fracture assessment;
• Corrosion;
• Pressure containment;
• Local buckling;
• Load and displacement control;
• Axial load;
• Ratcheting;
• Fatigue and fracture assessment;
• Accounting for the effect of Hydrogen on the material properties, in terms of fatigue response and ultimate strength;
• Pipeline walking.