Grade overview

P91 uses a controlled Cr-Mo-V-Nb alloy system and heat treatment to develop a tempered martensitic microstructure.

Typical applications

High-temperature steam piping, headers and power-generation components.

Equivalent / related designations

Properties are highly sensitive to heat treatment, welding heat input and PWHT. Improper fabrication can seriously degrade creep performance.

Common manufacturers and supply

Supplied by specialized power-industry seamless pipe producers with strict heat-treatment and QA controls.

Fabrication and selection notes

Confirm the exact product standard, edition, dimensions, delivery condition, mechanical properties, impact requirements, heat treatment, welding procedure, corrosion environment and certification. A grade name alone is not sufficient for procurement or design approval.

QA/QC documentation

For critical service, verify heat number traceability, mill test certificate, chemical analysis, tensile/impact results where required, NDT, heat-treatment record and project-specific third-party inspection requirements.

Element Folio engineering reference. Requirements vary by standard edition, product form and manufacturer; verify the latest governing specification.