How Triazine Reacts With H2S in Crude
Triazine-based H2S scavengers are typically manufactured by reacting formaldehyde with an amine, most commonly monoethanolamine or a methylamine, to build the triazine ring structure. When triazine reacts with H2S in a crude oil or condensate stream, it does not simply neutralize the H2S and disappear. The reaction releases a dithiazine byproduct and frees the original amine backbone used to build the triazine molecule, and both of those reaction products travel downstream with the treated crude.
The Byproduct Problem Refineries Actually See
Dithiazine can polymerize and foul contact towers, scrubbers, and pipeline internals if it accumulates over time, but the amine byproduct causes a separate and often more consequential problem once the crude reaches a refinery crude unit. Any unreacted triazine remaining in the oil phase will also thermally decompose back into its parent amine when it passes through the crude furnace, adding to the total amine load carried into the atmospheric tower.
How Amine Byproducts Turn Into Salt Deposits
Once that amine reaches the atmospheric tower overhead system, it can combine with chlorides present in the crude to form amine chloride salts. These salts are often only sparingly soluble under overhead operating conditions, which means they can deposit on tower trays and in overhead exchangers and piping rather than staying in solution and washing through the system. Deposited salt layers create classic under-deposit corrosion conditions and can also restrict flow and reduce heat transfer efficiency in the affected equipment.
Desalter Performance and Overhead Corrosion Risk
Refinery studies have found that triazine concentrations above roughly 1,000 ppm in crude can measurably degrade desalter performance, which compounds the problem, since a poorly performing desalter passes more chlorides and other salt precursors into the crude unit in the first place. The result is a feedback loop in which elevated triazine drives desalter upset, and desalter upset increases the chloride load available to react with triazine’s own amine byproducts, worsening the salt deposition and corrosion risk that triazine use contributed to in the first place.
Why This Matters Beyond the Refinery Gate
Because these effects show up downstream of the point where triazine was actually injected, the operator who applied the chemistry rarely sees the consequences directly. Refiners have responded by monitoring amine content in incoming crude and, in many cases, requiring producers, gatherers, and marketers to use vetted non-triazine chemistries before crude will be accepted, since a shipment with high triazine or amine carryover can create real operational costs at the refinery that have nothing to do with the wellhead H2S problem triazine was originally used to solve.
Non-Triazine Alternatives Built for Liquid Hydrocarbon Systems
Non-triazine, non-amine H2S scavenger chemistries are formulated specifically to avoid generating the amine and chloride salt precursors responsible for these downstream issues, reacting with H2S through a different pathway that does not carry the same refinery liability.. For crude oil and condensate applications in particular, where treated fluid is headed toward a refinery rather than staying within a gas plant, choosing a scavenger chemistry built for liquid hydrocarbon service rather than defaulting to a gas-phase triazine product can avoid pushing a treatment cost onto a refinery further down the supply chain.
