Corrosion of Wet Steel By Hydrogen Sulfide-Air Mixtures

Bond, Danielle; Marsh, G. A.

doi:10.5006/0010-9312-6.1.22

Cited by 15 publications

(8 citation statements)

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“…Fur den Sonderfall x = 3, y = 1 und z = 1 folgt G1. (1). Fur groBere Werte von x und z entstehen Polythionsauren, deren Bildungsreaktionen nach den Angaben im Potential-pH-Diagramm [9] aber offensichtlich gegenuber der Oxidation des S zu HSO;/SO:-nicht begiinstigt sind.…”

Section: (4)unclassified

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Korrosionsreaktiorren von elementarem Schwefel mit unlegiertem Stahl in wäßrigen Medien

Kuster

Schlerkmann

Schmitt

et al. 1984

Materials & Corrosion

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Unlegierter Stahl wird durch elementaren Schwefel in Gegenwart waariger Medien bei Raumtemperatur verhaltnismafiig stark angegnffen. Die Korrosion erfolgt bevorzugt an den Beruhrungsstellen der Feststoffe Fe und S unter Muldenbildung. Gleichzeitig erfolgen eine geringe pH-Absenkung sowie eine geringfugige Bildung von H2S und Sulfat-Ionen. Der Vorgang wird durch Neutralsalze sehr stark stimuliert, durch Phosphate inhibiert und durch alkalische Medien, wie z. B. Na,CO, und Ethylamin rnit pH > 12, vollig unterbunden. Dies kann zum Korrosionsschutz genutzt werden. Mit zunehmender Salzkonzentration (c > 1 mom) nehmen die Abtragungsraten wieder ab. Durch zunehmende Stromungsgeschwindigkeit konnen die Abtragungsraten zunehmen, wobei aber nur gleichformiger Flachenangriff auftritt. Elektrochemische Untersuchungen zeigen, dafi die Reduktion des Schwefels am Korrosionsprodukt FeS stattfindet und fiir die Korrosion geschwindigkeitsbestimmend ist. An Pt-Kathoden wird bei Abwesenheit von FeS keine Schwefelreduktion beobachtet. Als Startreaktion fir die Korrosion im System Fe/S/H20 wird eine geringe Disproportionierung des S zu H2S04 angenommen, wobei FeS entsteht.Plain carbon steels are rather severely attacked by elemental sulphur at room temperature in the presence of aqueous media. The corrosion occurs preferentially at the places where the two solid substances iron and sulphur are in contact with each other and results in shallow pit formation. At the same time the pH is also decreased slightly and small amounts of H,S and sulphate ions are formed. Neutral salts stimulate the corrosion process whereas phosphates inhibit it and the alkaline media such as Na2C03 and ethylamine with pH > 12 prevent it completely. The latter can be made use of for corrosion protection. At high salt concentrations (c > 1 moV1) the corrosion rate, however, decreases with increasing salt concentration. The corrosion rate may increase with increasing flow velocity of the medium, but the corrosion takes place uniformly.The results of electrochemical investigations show that the reduction of sulphur occurs at the corrosion product FeS and is the rate controlling step. No sulphur reduction is observed on platinum electrodes when no FeS is present. It is assumed that the starting reaction to initiate corrosion in the system Fe/S/H,O is a slight disproportionation of S to H,S04 resulting in the formation of FeS.

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Section: (4)unclassified

“…2 einen Ausschnitt fiir Aktivitatsparameter mit einem konstanten Molverhaltnis fiir G1. (1). Demnach muB also die Reaktion nach G1.…”

Section: (4)unclassified

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Korrosionsreaktiorren von elementarem Schwefel mit unlegiertem Stahl in wäßrigen Medien

Kuster

Schlerkmann

Schmitt

et al. 1984

Materials & Corrosion

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“…[7][8][9][10][11][12][13][14][15][16] Sustained average rates of 450 mpy (11.4 mm/y) were measured in neutral, 1 mM H 2 S solutions. Sustained average rates in neutral, 10 mM H 2 S solutions were measured at 300 mpy (7.6 mm/y).…”

Section: Discussionmentioning

confidence: 99%

Corrosion in an Aqueous Hydrogen Sulfide, Ammonia, and Oxygen System

Schutt¹,

Rhodes²

1996

CORROSION

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Rotating cylinder experiments demonstrated that corrosion rates of steel exposed to oxygenated aqueous solutions containing hydrogen sulfide (H 2 S) and ammonia (NH 3 ) were dependent upon pH, the presence of oxygen (O 2 ), H 2 S concentration, and flow. Corrosion was more severe than expected based upon a review of published reports considering systems at relatively low ammonium hydrosulfide (NH 4 HS) concentrations and above pH 6. Dependence of carbon steel (CS) corrosion rates on pH and the impact of O 2 was strong, but only prior to reaction between H 2 S and O 2 . The influence of H 2 S concentration was unexpected in that neutral, 1 mM solutions were more corrosive than neutral, 10 mM solutions in short-term tests and on a sustained basis.

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“…Mild steel corrosion in such environments has been investigated since the 1940s, and was mostly concentrated on uniform corrosion. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Rather few studies available in the open literature have addressed localized corrosion in H 2 S-containing environments. There, most of the effort was on aqueous solutions that contain moderate to high amounts of H 2 S (pH 2 S = 0.01 MPa to 0.5 MPa) with temperatures ranging from 50°C to 150°C.…”

Section: Introductionmentioning

confidence: 99%

Localized Corrosion of Mild Steel in Marginally Sour Environments

et al. 2017

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Localized corrosion has been a challenge for the integrity of mild steel pipelines, specifically at operating conditions where a trace amount of H 2 S is present alongside CO 2 at lower temperatures. The presence of H 2 S will lead to the formation of a protective iron sulfide layer that will decrease the general corrosion rate; however, a trace amount of H 2 S may only form a partially protective mackinawite layer that could result in localized corrosion. In the current study, mild steel specimens (API 5L X65) were exposed to a 1 wt% NaCl solution sparged at 0.096 MPa pCO 2 and 15 ×10 −6 MPa or less pH 2 S ( ≤150 ppm H 2 S/CO 2 ). At pH 5.0 and 30°C the bulk solution was undersaturated with respect to iron sulfide-mackinawite and iron carbonate. At these marginally sour conditions, a H 2 S/CO 2 threshold of approximately 100 ppm was deduced, below which localized corrosion happened. No localized corrosion occurred for the same environmental conditions when H 2 S/CO 2 ratio was above 100 ppm or when there was no H 2 S present.

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Corrosion of Wet Steel By Hydrogen Sulfide-Air Mixtures

Cited by 15 publications

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Korrosionsreaktiorren von elementarem Schwefel mit unlegiertem Stahl in wäßrigen Medien

Korrosionsreaktiorren von elementarem Schwefel mit unlegiertem Stahl in wäßrigen Medien

Corrosion in an Aqueous Hydrogen Sulfide, Ammonia, and Oxygen System

Localized Corrosion of Mild Steel in Marginally Sour Environments

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