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Explore our core range of thermit welding components designed to ensure precision, reliability, and performance in every rail joint.
Thermit welding, also known as aluminothermic welding, is a fusion welding process that uses an exothermic chemical reaction between aluminum powder and iron oxide to produce molten steel. This molten steel is then poured into a mold surrounding the rail gap, creating a strong, continuous joint. The "portions" in thermit welding refer to the carefully measured and pre-packaged sets of consumables required to complete a single weld — including thermite powder, crucibles, sand moulds, luting sand, mould clamps, and ignition materials.
Each thermit welding portion is engineered to match a specific rail profile, rail grade, and welding standard. This precision is critical because even minor variations in chemical composition or portion weight can affect the metallurgical properties of the weld, ultimately impacting the safety and longevity of the rail joint. Modern thermit welding portions are manufactured under strict quality control protocols, ensuring consistent results across thousands of welds performed in the field.
The global rail industry is experiencing unprecedented growth. According to industry forecasts, the worldwide railway infrastructure market is projected to exceed USD 400 billion by 2030, driven by urbanization, sustainability goals, and the expansion of high-speed rail networks across Asia, Europe, Africa, and the Americas. Within this vast market, thermit welding remains the dominant method for joining rails in the field, accounting for an estimated 70–80% of all field rail welds globally.
The commercial demand for thermit welding portions is tightly linked to new railway construction, track renewal programs, and ongoing maintenance activities. Countries such as China, India, Indonesia, Saudi Arabia, Egypt, and nations across sub-Saharan Africa are investing heavily in new rail corridors. Meanwhile, established networks in Europe, North America, and Japan require continuous maintenance welding to keep aging infrastructure safe and operational.
From a supply chain perspective, the thermit welding portions market is characterized by a relatively small number of specialized manufacturers who possess the metallurgical expertise, quality certifications, and field experience to serve railway authorities worldwide. RMTS, based in Tianjin, China, has emerged as a competitive force in this market, offering a full range of thermit welding consumables backed by rigorous R&D and on-site technical support.
Thermit welding accounts for approximately 70–80% of all field rail welds performed globally, making it the most widely adopted rail joining technology in both new construction and maintenance operations. The demand for high-quality thermit welding portions continues to grow as rail networks expand across developing economies.
While mainline railways represent the largest application segment, thermit welding portions serve a diverse range of industrial and transportation sectors. Understanding these applications reveals the versatility and commercial breadth of this technology:
The thermit welding industry is not static — it continues to evolve in response to changing railway standards, environmental regulations, and technological advancements. Several key trends are shaping the future of thermit welding portions:
Modern rail steels are becoming increasingly sophisticated, with higher carbon content and alloying elements designed to resist wear and rolling contact fatigue. Thermit welding portions must evolve in parallel, with R&D teams developing new powder formulations that match the mechanical properties of these advanced rail steels. RMTS invests significantly in metallurgical research to ensure its portions produce welds with optimal hardness, tensile strength, and impact resistance.
The integration of digital technologies into the welding process is a growing trend. Automated preheating systems, digital temperature monitoring, and AI-powered weld inspection are being adopted to reduce human error and improve consistency. Future thermit welding portions may include embedded sensors or QR-coded packaging that links to digital quality certificates and recommended welding parameters.
Railway authorities worldwide are setting ambitious carbon reduction targets. Thermit welding portion manufacturers are responding by optimizing packaging to reduce waste, developing lower-emission formulations, and implementing cleaner manufacturing processes. The inherent advantage of thermit welding — requiring no external power source — already gives it a lower carbon footprint compared to electric welding methods in remote locations.
As rail networks become more interconnected across borders, the demand for internationally certified thermit welding portions is increasing. Standards such as EN 14730 (European), TB/T 1632 (Chinese), and AREMA (American) set rigorous requirements for weld quality. Manufacturers like RMTS are pursuing multiple international certifications to serve diverse markets and facilitate cross-border railway projects.
Railway operators increasingly require rapid-response welding solutions for emergency track repairs. Compact, pre-assembled thermit welding portion kits that include all necessary consumables in a single package are gaining popularity. These kits reduce preparation time and enable maintenance crews to restore track service within hours rather than days.
RMTS is a manufacturer specializing in railroad thermit welding materials, based in Tianjin, China. With a factory spanning 5,500+㎡ and 30+ professionals dedicated, we are committed to delivering reliable and efficient thermit welding solutions to clients across the globe. Our products are designed to meet the highest industry standards, ensuring durability and performance in various applications.
We understand that successful welding projects require not only high quality products but also expertise and knowledge. That's why we offer comprehensive on-site training programs to help our clients master the thermit welding process, enabling them to achieve optimal results and build a strong reputation in their respective fields. Additionally, our experienced team provides project welding instruction services, offering hands-on guidance and support to ensure seamless execution, no matter where the project is located.
Driven by a customer-centric approach, RMTS is dedicated to fostering long-term partnerships by delivering exceptional products and services tailored to the unique needs of our clients. Whether you are looking for reliable thermit welding materials, expert training, or project support, RMTS is your trusted partner in achieving welding excellence.
The thermit welding process for rail joining follows a carefully controlled sequence of steps, each of which relies on specific components within the welding portion kit. Understanding this process helps railway engineers and procurement teams appreciate why portion quality is so critical:
The rail ends are cut, cleaned, and aligned with a precise gap (typically 23–25mm). Proper alignment ensures that the molten steel fills the joint evenly and that the finished weld meets geometric tolerances. The mould clamps from the thermit welding portion kit are used to secure the sand moulds around the rail gap.
Pre-formed sand moulds are placed around the rail ends and sealed with luting sand to prevent molten steel from leaking. The quality of the sand mould directly affects the weld profile and surface finish. RMTS sand moulds are engineered for dimensional accuracy and thermal stability, ensuring consistent results across different rail profiles.
The rail ends are preheated using an oxy-fuel burner to a specific temperature (typically 600–900°C depending on the welding standard). Preheating ensures proper fusion between the thermit steel and the parent rail material. Inadequate preheating is one of the most common causes of weld defects.
The thermite welding powder is placed in a crucible and ignited. The exothermic reaction reaches temperatures of approximately 2,500°C, producing molten steel and aluminum oxide slag. The molten steel flows through the crucible tap hole into the mould cavity, filling the rail gap. The entire reaction takes only 20–30 seconds.
After the molten steel solidifies, the moulds are removed and the excess weld metal (riser) is trimmed. The weld is then ground to match the rail head profile. Quality inspections, including visual examination and ultrasonic testing, verify the integrity of the completed joint.
Every component in a thermit welding portion — from the powder chemistry to the sand mould dimensions — must meet exacting specifications. A single defective portion can result in a weld failure that compromises track safety. This is why railway authorities worldwide insist on sourcing portions from certified manufacturers with proven track records like RMTS.
RMTS have a highly skilled R&D team that works tirelessly to ensure that we produce thermit welding materials that meet the specific needs of each type of rail.
In addition to its strong R&D capabilities, RMTS actively participates in railway projects across China and abroad. The company collaborates with railway authorities, construction companies, and maintenance organizations to provide its expertise and materials for various projects.
By participating in railway projects, RMTS contributes to the development and maintenance of China's extensive railway network. Whether in high-speed rail, urban transit systems, or conventional rail lines, RMTS offers its thermit welding materials and services to ensure the integrity and safety of the rail infrastructure.
Furthermore, RMTS maintains partnerships with research institutions, universities, and industry experts in China. These collaborations enable RMTS strengthens its R&D capabilities in thermit welding technologies.
Next-generation thermit welding portions will feature tailored alloy compositions to match increasingly sophisticated rail steels, including head-hardened and bainitic grades used in high-speed and heavy-haul applications.
Artificial intelligence and machine learning are being integrated into weld inspection processes, enabling real-time defect detection and predictive maintenance scheduling based on weld quality data.
Eco-friendly production methods, reduced packaging waste, and lower-emission thermite formulations are becoming priorities as the rail industry aligns with global sustainability commitments.
RMTS's strong R&D abilities, coupled with its involvement in railway projects, demonstrate the company's commitment to providing advanced thermit welding solutions that meet the specific demands of the railway industry.
From new high-speed rail corridors to critical maintenance on legacy networks, RMTS delivers thermit welding portions that railway professionals trust for safety, durability, and performance — every weld, every time.
As part of the Phase 2 expansion of Jakarta's Mass Rapid Transit (MRT) system, RMTS was contracted to provide aluminothermic welding solutions for the new underground and elevated tracks. The project involved welding 600 rail joints across a 12-kilometer stretch, connecting key areas of the city to reduce traffic congestion.
Our team worked closely with PT MRT Jakarta to ensure the welds met international safety standards. The project was completed on time, and the new line has been operating smoothly since its launch. Jakarta MRT officials highlighted the durability of the welds, which have withstood the high frequency of train movements and tropical weather conditions.
Challenge: The client faced the challenge of welding materials of T62 and P65 rails. The welding process needed to meet the rigorous standards set by the railway authorities, ensuring optimal track performance, longevity, and safety.
Solution: Our team collaborated closely with the client, thoroughly understanding their specific requirements. We provided them with our high-quality thermit welding materials, including welding kits, tailored to suit the T62 and P65 steel rail specifications.
Customer Satisfaction: The client expressed utmost satisfaction with our thermit welding materials. They acknowledged the superior quality, reliability, and technical support provided by our team. Our materials played a crucial role in enabling them to deliver high-quality rail construction projects and meet the demands of the railway industry.
KTMB Railways are aimed to improve connectivity across the city's suburbs. RMTS the most trusted supplier with 1000 aluminothermic welding materials for the new tracks, which included both underground and elevated sections. The project required precise welding to ensure smooth and safe operations, which serves millions of passengers annually.
RMTS's welding materials were chosen for their ability to create strong, seamless joints that could withstand the humid climate and heavy usage. The project was completed ahead of schedule, and the new line has significantly reduced travel times for commuters.
Browse our full catalog of thermit welding consumables, each engineered for precision, durability, and compatibility with global rail standards.
