AmmoniaCompatibility

Package: neqsim.process.corrosion

Standards: CGA G-2 / G-2.1, ASME B31.3, IGC Code, 49 CFR 173.315, API 660

Evaluates material suitability for anhydrous ammonia, aqueous ammonia, and ammonia-as-hydrogen-carrier service. Key concern is stress corrosion cracking (SCC) of carbon steel in anhydrous NH3 when the oxygen inhibitor level is insufficient.

Key Failure Mechanisms

Mechanism Material Conditions
NH3 SCC Carbon steel Anhydrous NH3 without adequate O2 inhibitor (< 0.1 wt%)
Dissolution/SCC Copper alloys Any ammonia concentration — copper alloys are incompatible
Nitridation Carbon steel, low-alloy Temperature > 300°C
Caustic embrittlement Carbon steel Concentrated aqueous NH3 at high temperature

O2 Inhibitor Requirement

For carbon steel in anhydrous ammonia service, a small amount of dissolved oxygen (0.1–0.2 wt%) inhibits SCC. The class checks whether the applied inhibitor level meets the minimum requirement:

Condition Required O2 (wt%)
Anhydrous NH3, carbon steel ≥ 0.1
Anhydrous NH3, high stress (> 0.8 yield) ≥ 0.2
Aqueous NH3 or stainless steel Not required

Quick Start

Java

import neqsim.process.corrosion.AmmoniaCompatibility;

AmmoniaCompatibility nh3 = new AmmoniaCompatibility();
nh3.setTemperatureC(25.0);
nh3.setPressureBara(10.0);
nh3.setNh3ConcentrationWtPct(99.5);
nh3.setAnhydrous(true);
nh3.setMaterialType("Carbon steel");
nh3.setO2InhibitorWtPct(0.15);
nh3.setStressRatio(0.7);
nh3.setHardnessHRC(20.0);
nh3.setPwhtApplied(true);
nh3.evaluate();

System.out.println("Compatible: " + nh3.isCompatible());
System.out.println("Risk Level: " + nh3.getRiskLevel());
System.out.println("Mechanism: " + nh3.getPrimaryMechanism());
System.out.println("O2 Adequate: " + nh3.isO2InhibitorAdequate());
System.out.println("Max Temp: " + nh3.getMaxAllowableTempC() + " °C");
System.out.println("Recommended Material: " + nh3.getRecommendedMaterial());

Python

from neqsim import jneqsim

AmmoniaCompat = jneqsim.process.corrosion.AmmoniaCompatibility

nh3 = AmmoniaCompat()
nh3.setTemperatureC(25.0)
nh3.setPressureBara(10.0)
nh3.setNh3ConcentrationWtPct(99.5)
nh3.setAnhydrous(True)
nh3.setMaterialType("Carbon steel")
nh3.setO2InhibitorWtPct(0.15)
nh3.evaluate()

print(f"Compatible: {nh3.isCompatible()}")
print(f"Risk: {nh3.getRiskLevel()}")
print(f"Mechanism: {nh3.getPrimaryMechanism()}")

Input Parameters

Method Type Default Description
setTemperatureC(double) double 25.0 Temperature (°C)
setPressureBara(double) double 10.0 Pressure (bara)
setNh3ConcentrationWtPct(double) double 99.5 NH3 concentration (wt%)
setAnhydrous(boolean) boolean true Anhydrous (true) or aqueous (false)
setWaterContentWtPct(double) double 0.0 Water content (wt%)
setO2InhibitorWtPct(double) double 0.0 Dissolved O2 inhibitor level (wt%)
setMaterialType(String) String “Carbon steel” Material: “Carbon steel”, “316L”, “Copper alloy”, etc.
setStressRatio(double) double 0.8 Applied stress / yield stress (0–1)
setPwhtApplied(boolean) boolean false Post-weld heat treatment applied
setHardnessHRC(double) double 22.0 Maximum hardness (HRC)

Output Methods

Method Return Type Description
isCompatible() boolean Whether the material is compatible
getRiskLevel() String “Low”, “Medium”, “High”, “Very High”
getPrimaryMechanism() String Dominant failure mechanism (e.g., “NH3 SCC”, “Copper dissolution”)
isO2InhibitorAdequate() boolean Whether O2 inhibitor meets minimum
getRequiredO2InhibitorWtPct() double Required O2 level for carbon steel (wt%)
getMaxAllowableTempC() double Maximum allowable temperature (°C)
getMaxAllowableHRC() double Maximum allowable hardness (HRC)
getRecommendedMaterial() String Recommended material for the conditions
getNotes() List<String> Assessment notes
toMap() Map All results as a LinkedHashMap
toJson() String Complete JSON report

Ammonia as Hydrogen Carrier

For ammonia cracking / hydrogen production applications, consider: