Methanol Drying Calculator
Calculate methanol requirements to reduce water content in gas pipelines after hydrostatic testing. Based on GPSA water content charts with hydrate formation analysis.
Calculation Type:
Pipeline Parameters
inches
miles
Operating Conditions
psig
°F
°F
%
Slug Parameters
inches
feet
%
📚 Learn the Theory
Pipeline drying methods: air, nitrogen, and vacuum drying with dewpoint specifications
Wresidual = Residual free water after pigging (lb)
0.7 = Absorption capacity (lb H₂O/lb MeOH)
P = Methanol purity (fraction)
Water content from GPSA Figure 20-3. Residual water assumes 1.5% pipe volume after pigging. Hydrate temp is a conservative approximation for 0.6 SG gas.
Standards & References
GPSA Section 20 - Water Content of Gas
API RP 1110 Pressure Testing of Steel Pipelines
ASME B31.8 Gas Transmission and Distribution
Engineering Notes
Typical dewpoints: Gathering 40-60°F, transmission -20°F to -40°F
Methanol density: 6.63 lb/gal at 60°F (SG = 0.792)
Absorption limit: 0.7 lb water per lb pure methanol
Slug sizing: Typically 20-40% of pipeline volume
Safety: Methanol is toxic and flammable - full PPE required