DIN17175 St45.8 is a high-carbon steel boiler pipe grade compliant with German DIN standards, designed for medium-to-high pressure boiler systems that require enhanced strength and thermal stability. A defining characteristic of St45.8 is its higher carbon content (0.28-0.35%) and optimized alloying, which deliver superior mechanical performance: it has a minimum yield strength of 295 MPa and tensile strength of 490-630 MPa, significantly higher than St35.8. This strength allows it to withstand pressures up to 9.8 MPa and temperatures as high as 480°C, making it suitable for more demanding heat transfer applications. It also undergoes rigorous quality control, including ultrasonic testing and hydrostatic pressure testing, to ensure zero defects and leak-proof performance—critical for high-pressure boiler safety.
The main function of St45.8 is to serve as a reliable conduit for high-pressure steam or hot water in boiler systems where structural integrity under extreme thermal and pressure loads is non-negotiable. Its advantages are centered on high-strength and thermal resilience: unlike St35.8, it resists deformation and fatigue even when exposed to frequent pressure spikes and temperature cycles, reducing the risk of pipe failure. It also has good creep resistance, meaning it maintains its shape and strength over long periods of continuous high-temperature operation—essential for industrial boilers with extended service lives. While it requires slightly more precise welding (with controlled pre-heat to avoid cracking), its overall durability offsets the additional fabrication effort.
St45.8 is extensively used in large-scale industrial boilers, such as those in power plants (for generating electricity), refineries (for oil and gas processing), and heavy manufacturing facilities (e.g., steel mills, cement plants), where medium-to-high pressure steam drives turbines and industrial machinery. It is also a key material in utility boilers that supply steam to urban heating networks, as it can handle the higher pressure needed to distribute heat over long distances. Additionally, St45.8 is used in marine main boilers of large cargo ships and naval vessels, where it supports the high-pressure steam systems that power the ship’s propulsion. It also finds application in waste-to-energy plants, where it conveys high-temperature steam produced from waste incineration, withstanding the harsh operating conditions of such facilities.
