Reliability and longevity are of vital for valves , and testing allows for making adjustments and repairs where necessary . Therefore , until the product reaches the customer , it must be thoroughly inspected and tested to ensure it complies with international standards . π www . valve-world . net Valve World February 2024
Chemical industry
Valve manufacturing process
Based on the relevant requirements , industrial valve manufacturers consider the advantages and disadvantages of casting and forging methods . Choosing which method to employ depends on factors such as desired strength , design complexity , production volume , and budget constraints . By understanding the pros and cons of each method , manufacturers can optimise their valve manufacturing process for various applications . At first glance , valves may seem to consist of a few parts , but sealing is complex , particularly when demanding zero leakage during fluid / gas-tight testing . This complicates the manufacturing process . Due to the wide variety of valve specifications and the presence of the valves in all types of environments , the material requirements for stainless steel are very strict . However , valve manufacturers perform a bubble seal test before the valve leaves the factory . Here , the seat is tested for significant leakage . Other key parameters include flow speed , valve function ( on / off or modulating ), whether fire safety is required , and other additional functional requirements .
Casting process
The correct and effective control of casting solidification is the first important condition for obtaining quality products . This process programme includes the pouring system , riser , and complementary process amount . Due to their uneven wall thickness , valve parts cast in steel should undergo sequential cooling and sequential solidification to reduce the internal stress of the casting , shrinkage , and other defects . Attention should be paid to design , the pouring system , correct pouring positioning , riser design , volume shrinkage calculations , and shrinkage control . In the machinery industry , thin shell casting is more complex and difficult . However , valve casting is an important part of the manufacturing process , as good casting determines the success of a valve .
Forging process
Forging a valve involves correctly shaping stainless steel , heating , and pressing the block with industrial tools at forging temperature . Industrial forged valves are generally used on small , high-grade pipelines with high processing costs . Forged valves have increased performance in severe service and high-temperature applications . The forging process eliminates surface porosity , removes internal voids , decreases
Stainless steel valves have various applications due to their excellent performance in terms of temperature limits , corrosion resistance , and high-pressure tolerance .
wall thickness , and allows for a smaller temperature gradient and less thermal fatigue . Forged valves can withstand the stresses of high-temperature applications and high pressures without compromising their integrity while boasting better corrosion / heat resistance , tensile strength , higher strength , ductility , durability , and a significantly increased lifecycle than cast valves . The wall thickness doesn ’ t affect the functionality of the valve . The benefits of forged valves include minimising wasted material ( due to the fact they are shaped in one solid piece ), and the valves ’ ability to handle high temperatures and high pressure well with minimal shrinkage , porosity , and cracks . They are ideal for applications in the nuclear , oil and gas and power generation segments . Thermal fatigue reduction is a major benefit of forged valves as they have a thinner wall , which means if they are heated or cooled quickly , it won ’ t be detrimental to the valve ’ s functionality .
Valve inspection and testing
Reliability and longevity are of vital for valves , and testing allows for making adjustments and repairs where necessary . Therefore , until the product reaches the customer , it must be thoroughly inspected and tested to ensure it complies with international standards . π www . valve-world . net Valve World February 2024
43