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Internal Oil Firing Post Weld Heat Treatment (PWHT) is a highly effective method used for stress relieving thick-walled pressure components such as boilers, heat exchangers, and large diameter piping. By heating the component internally using an oil-fired burner system, this technique ensures uniform temperature distribution and deep heat penetration—ideal for heavy industrial equipment that cannot be heated externally with conventional systems.
Internal Oil Firing PWHT carried out by our team complies with leading global standards and customer-specific specifications, including:
ASME Section VIII – Stress relieving requirements for pressure vessels and high-pressure components
API 530 / API 934 – PWHT guidelines for heavy-wall reactors, reformers, and furnace tubes
API 650 / API 653 – Heat-treatment requirements for welded storage tanks and repairs
ASME B31.1 / B31.3 – PWHT requirements for power piping and process piping systems
ISO 17663 – Heat-treatment quality requirements for welded joints
Client-specific PWHT procedures & metallurgical specifications
At Hexigon Engineering, we enable industries to achieve unmatched reliability, superior weld integrity, and long-term operational durability.
Selecting Hexigon Engineering for Internal Oil Firing PWHT ensures your critical equipment receives precise, controlled, and uniform heat treatment—delivered by experts with deep industrial experience.
High-efficiency internal burners designed to deliver uniform combustion heat inside large vessels and pipelines.
Automated controllers to regulate firing rate, soak temperatures, and controlled cooling throughout the heat cycle.
Welded inside the vessel to precisely measure and control internal metal temperature during heating and soaking.
High-grade ceramic wool or rock wool placed around exposed areas to retain heat and maintain temperature uniformity.
Heavy-duty thermocouple and controller cables, splitters, and connectors for safe and reliable system operation.
