Views: 200 Author: EHI Technical Team Publish Time: 2026-10-21 Origin: Site
In the petrochemical industry, forgings are widely used in core equipment for reaction, heat exchange, separation, storage, drilling and production, thanks to their outstanding properties such as dense microstructure, high strength, high pressure resistance and corrosion resistance.
Reactors represent the field with the most extensive use and the most stringent requirements for petrochemical forgings. Taking hydrocracking reactors as an example, their critical pressure-bearing components including shells, shell sections and heads are all manufactured from heavy forgings. Such equipment operates year-round under high temperatures of 350℃–480℃ and ultra-high pressures of 15–20 MPa, together with severe hydrogen attack and hydrogen sulfide corrosion. Ordinary carbon steel is highly susceptible to hydrogen embrittlement and hydrogen-induced cracking. Therefore, hydrogen-resistant steels and high-strength alloy steels must be adopted, such as SA-387 Gr22 (2.25Cr-1Mo), 15CrMoR, 12Cr1MoV, and P91/P92 heat-resistant steels. By incorporating alloying elements like chromium and molybdenum, these grades can effectively stabilize carbides and resist high-temperature creep and hydrogen atom permeation. In addition, since the medium in fluid catalytic cracking (FCC) units contains catalyst particles, heat-resistant alloy steels such as P91 and P92 are commonly selected for cyclone separators and reactor shells to balance high-temperature strength and wear resistance.
Tube sheets are fundamental core components of heat exchangers, subjected to temperature differences and pressure differentials between the tube side and shell side. For high-pressure heat exchangers in hydrogenation, cracking and other units, tube sheet forgings and various high-pressure flanges need to operate reliably for long durations under high temperature, high pressure and corrosive media. Materials including 15CrMoR, 316L stainless steel and 2205 duplex stainless steel are frequently specified for these service conditions. In particular, 2205 duplex stainless steel combines high strength with excellent resistance to pitting and crevice corrosion, making it the preferred material for heat exchange equipment under high chloride ion corrosion conditions.
Static equipment such as towers and storage tanks extensively uses ring forgings as load-bearing parts including skirt rings and support rings. For openings on spherical tanks such as manholes and flanges, forgings are also adopted. For conventional oil product storage tanks, carbon steels such as Q355B and Grade 20 steel are commonly used. For highly corrosive chemical solvents or strong acid media, 316L stainless steel or 2205 duplex stainless steel is required. In piping and valve systems, forged flanges are critical to maintain high-pressure sealing and prevent leakage. Components for oil and gas drilling and production such as drill pipe joints and Christmas trees are mostly made of high-strength alloy steels including 42CrMo and 35CrMo, which achieve superior strength and toughness after quenching and tempering treatment. For seawater corrosion in offshore drilling and production environments, 2507 super duplex stainless steel (F53 / UNS S32750) is widely used. Its yield strength is more than twice that of 316L, enabling it to withstand deep-sea high pressure and chloride ion attack.
For sour oil and gas fields with high hydrogen sulfide (H₂S) content, nickel-base alloy forgings such as Alloy 725 feature exceptional resistance to sulfide stress cracking (SSC), serving as core materials for downhole tools, valve bodies and subsea Christmas trees. In chlor-alkali processes, PTA plants and strong acid environments (e.g., concentrated sulfuric acid, acetic acid), titanium and titanium alloy forgings (such as TA2 and TC4) possess irreplaceable advantages. Forgings like titanium rings deliver an annual corrosion rate below 0.001 mm in wet chlorine and organic acids, with tensile strength ranging from 895 MPa to 1100 MPa. Their weight is only 57% of that of steel, greatly reducing equipment dead weight and maintenance costs.
Forgings are also widely applied to transmission parts in petrochemical installations, including compressor crankshafts, connecting rods, as well as various shafts and gears. The tensile strength, impact toughness and fatigue life of forgings guarantee the long-period safe operation of equipment.
Why must forgings be used for petrochemical equipment instead of castings?
The core reason lies in the huge gap in service condition adaptability and performance. Castings tend to contain internal defects such as blowholes, shrinkage porosity and slag inclusions, with loose microstructure and inferior strength, toughness, fatigue resistance and stress cracking resistance. They cannot withstand the high-temperature, high-pressure, strongly corrosive and alternating-load working conditions in the petrochemical industry. By contrast, forgings undergo plastic deformation during forging, featuring dense internal structure, refined grains and freedom from porosity defects. They combine high strength, high toughness, creep resistance, hydrogen embrittlement resistance and corrosion resistance, with superior sealing performance and pressure-bearing stability. Forgings can meet the stringent requirements of petrochemical units for long-term continuous operation, zero leakage and low failure rate. Hence, forgings are mandatory for core pressure-bearing, load-carrying and sealing components.
How to select between duplex stainless steel 2205 and 316L stainless steel??
Why is 2507 super duplex stainless steel preferred over 2205 for forgings used in deep-sea drilling and production?
Why do 42CrMo and 35CrMo, commonly used for forgings of petrochemical transmission components, require quenching and tempering treatment??
