Pres-Vac is ready to deliver the first of a series of ship set high-velocity pressure vacuum valves manufactured entirely in duplex stainless steel grade 2205 for a Medium Range 50k dwt oil/product/Chem carrier.
The vessel is to carry special cargoes and operate in a very harsh environment, which require the cargo tanks and all related equipment to be in duplex stainless steel.
The vessels are built to the latest rules and regulations like:
EU-MED Regulation (EU) 2018/773;
EN ISO 15364:2007; EN ISO 15364:2016; EN 12874:2001; EN ISO 16852:2010;
EN ISO 16852:2016; API 2000; IMO MSC/Circ. 677; lMO MSC/Circ. 1009; IMO
MSC.1/Circ. 1324-1325; USCG; ATEX.
Duplex stainless steels (austenitic-ferritic) are usually selected for their high mechanical properties and high corrosion resistance (particularly to stress corrosion cracking). The process is complexed especially at the end of the fabrication where Duplex stainless steel must be cooled as quickly as possible to room temperature after hot forming to avoid the precipitation of intermetallic phases (Sigma phase in particular) which drastically reduce the impact resistance at room temperature as well as the corrosion resistance.
Duplex grades are especially attractive for this kind of project when mechanical properties are important. It provides overall better corrosion resistance, particularly chloride stress corrosion and chloride pitting corrosion. To ensure the highest quality the valves have been manufactured using robots and the Machining has been done using special tools due to the hard surface of the material.
Since it is high-velocity pressure vacuum valves closing metal to metal and known for its near nil leakage, it has been of utmost importance to machine the seat and disk to perfection.
The result is fantastic, and we are very proud, especially with the whole process, which has been done by dedicated, skilful and well-educated staffs.