Valves for MEG / Glycol (Monoethylene Glycol — Gas Dehydration) Service
Monoethylene glycol (MEG) is used as a hydrate inhibitor in natural gas pipelines and as a refrigerant in gas processing plants. Triethylene glycol (TEG) is used for gas dehydration (TEG contactors). Both are hygroscopic, viscous, and mildly corrosive. Indian gas transmission companies (GAIL, GSPC, Reliance) use MEG injection extensively in deepwater pipeline service.
Pressure Range
Up to 400 bar for deepwater injection; 10–50 bar for onshore pipeline injection
Temperature
−40°C (sub-sea pipeline) to +190°C (TEG regeneration)
Industries
Offshore gas pipelines (deepwater MEG injection), Onshore gas transmission (hydrate inhibition), LNG regasification terminals
Key Properties — MEG / Glycol (Monoethylene Glycol — Gas Dehydration)
- Concentration: 60–80 wt% MEG/water mixture for hydrate inhibition
- Viscosity: significantly higher than water, especially at low temperatures (−40°C to +20°C)
- Hygroscopic — absorbs water aggressively from process streams
- Mildly corrosive to carbon steel at elevated temperatures without inhibitor
- Boiling point 197°C — no vapour pressure concern at normal operating conditions
Material Compatibility — MEG / Glycol (Monoethylene Glycol — Gas Dehydration)
Ratings are indicative. Actual compatibility depends on concentration, temperature, velocity, and presence of contaminants. Always consult corrosion tables or a materials engineer.
| Material | Rating | Notes |
|---|---|---|
| Carbon Steel (WCB/A105) | Good | Acceptable with corrosion inhibitor dosing. Monitor oxygen ingress — causes accelerated corrosion. |
| SS 316L | Excellent | Preferred for inhibited MEG and TEG service, especially at elevated temperature in regeneration. |
| Duplex SS (2205) | Excellent | Used in offshore MEG service where seawater contamination risk exists. |
| PTFE seats | Excellent | Suitable across full MEG service temperature range. |
| Hastelloy C-276 | Excellent | Used in rich MEG service at elevated temperature in regeneration columns. |
Recommended Valves
Ball Valve (SS 316 body, PTFE seats)
Standard isolation for MEG injection lines and recirculation.
Globe Valve (SS 316, CV-characterised)
Flow control at MEG injection quill or dosing skid.
Check Valve (SS 316, spring-loaded piston)
Pump discharge non-return on MEG injection pumps to prevent backflow.
Needle Valve (SS 316 or 316L)
Flow metering and sample points on MEG injection systems.
Valves to Avoid
Copper alloy valves (glycol attacks copper over time)
Carbon steel at elevated temperature without inhibitor dosing
Valve with low-flow dead zones that allow stagnant glycol to concentrate and corrode
Special Considerations
Applicable Standards
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