Technology / product information

Lilama 10 Commissions a Large-Scale Heat Treatment Furnace – Enabling the Fabrication of Pressure Pipes Longer Than 7 Meters

Mastering Large-Scale PWHT Technology

Why is post-weld heat treatment necessary?

In steel structures and pressure equipment, welded joints are always the areas subjected to the highest stress concentration. After welding, the adjacent metal zones often retain residual stresses and altered crystal structures. If left untreated, these conditions can lead to cracking, deformation, or reduced fatigue strength over time.

To address this, welded components must undergo Post Weld Heat Treatment (PWHT) to relieve residual stresses, restore mechanical properties, and ensure long-term structural stability and durability.

Large-Scale PWHT Furnace System at Lilama 10

To meet increasingly stringent requirements in steel structure fabrication and energy equipment manufacturing, Lilama 10 has put into operation a large-scale PWHT furnace system, currently among the most advanced heat treatment furnaces in Vietnam.

Key specifications and features include:

Ultra-large furnace dimensions: 9,800 mm (L) × 7,600 mm (W) × 7,600 mm (H), capable of heat-treating large assemblies and pressure pipes longer than 7 meters.

Core equipment imported from the UK and South Korea, ensuring high thermal stability and uniform temperature distribution throughout the furnace chamber.

Automated central control system, monitoring the entire thermal cycle in real time.

Each heat treatment cycle lasts approximately 14 hours, consisting of three main stages:
1️⃣ Heating-up: Gradual temperature increase to avoid thermal shock.
2️⃣ Soaking: Maintaining a stable temperature to allow metal microstructure reconditioning.
3️⃣ Cooling-down: Controlled cooling to prevent deformation and stabilize mechanical properties.

Thanks to synchronized control systems and automated monitoring data, Lilama 10 ensures consistent quality and high reliability in every PWHT cycle, fully meeting the technical requirements of large-scale domestic and international energy projects.

Practical Application: Pressure Penstocks for Pumped Storage Hydropower Exported to Australia

The PWHT furnace system has been directly applied to the fabrication of pressure penstocks for a pumped storage hydropower project exported to Australia—one of the most technically demanding projects worldwide.

After welding, all penstocks were subjected to PWHT to eliminate residual stresses, enabling the products to achieve:

Absolute tightness,

Stable mechanical properties, and

Service life exceeding European standard requirements.

Mastering large-scale heat treatment technology represents a significant milestone for Lilama 10 in heavy structural fabrication, while reaffirming its capability to comply with international EN and ISO standards for export-oriented projects.

Lilama 10 – International-Standard Manufacturing Capability

Fabrication of thick plates up to 110 mm, with rolling width up to 3 meters, suitable for pipes, pressure vessels, and heavy steel structures.

Modern production lines, including MG 3-roll plate bending machines (Italy), 600-ton CNC hydraulic press brakes, shot blasting systems, bevel grinding machines, and 40 mm laser cutting machines.

Automated PWHT furnace system with dimensions 9,800 × 7,600 × 7,600 mm, centrally controlled.

Engineering and welding teams certified to ISO 3834 and EN 1090 (EXC3).

Strict compliance with EN 15626:2018 (Level 1), ISO 11666:2018, and ISO 23279:2017 for non-destructive weld testing (TOFD).

With synchronized technology, equipment, and human resources, Lilama 10 continues to strengthen its position as a pioneering Vietnamese enterprise in European-standard steel structure and energy equipment fabrication.

Contact us today for consultation on pressure pipe and hydraulic pipeline fabrication solutions.