Choke Design

Corrosion sour and sweet

Deep-water offshore, remote arctic locations and some difficult-to-manage reservoirs contain carbon dioxide and hydrogen sulfide at low depth. There are two types of corrosion that occur in steel material when H2S and CO2 are present in hydrocarbon fluid. H2S creates sour corrosion while CO2 creates sweet corrosion. However, we came out with a combination of H2S and CO2 effects on corrosion. Sour corrosion occurs when hydrocarbon fluid contains CO2 and H2S above a partial pressure of 0.05 psi.

JVS supplies a range of exotic nickel-based alloys such as Alloy 718, Alloy 825, Alloy 628, super duplex and duplex stainless steels for corrosion protection. These materials are available for trim as well as body and bonnets. We regularly supply NACE MR0175 compliant chokes.

An effective internal cladding can provide an effective barrier against corrosion attack. We providenickel alloy, duplex stainless steel, and stainless steel cladding. Currently, nickel alloy 625 cladding is the best corrosion-resistant solution. To keep cost down, instead of using solid nickel alloy 625, 3 mm finished cladding is engineered solution. This corrosion-resistant overlay is carried out on low alloy steel body and bonnet. The process helps to keep the overall cost down and extend life of chokes. Performance against corrosion is as good as solid nickel alloy 625.