Case Study: Gas Technology Institute achieves validated reductions in gas-pipeline squeeze-off distances with COMSOL Multiphysics

Improving Gas Pipeline Squeeze-off Standards with Numerical Simulation

Gas Technology Institute (GTI) investigated whether the ASTM minimum squeeze-off distance for polyethylene gas pipelines could be reduced for small-diameter pipes to cut digging, traffic disruption, time, and cost. To address this, GTI used Comsol Multiphysics (Structural Mechanics and Nonlinear Structural Materials modules) to build simulation-driven, finite-element models of the squeeze-off process and assess strain and stress near fused fittings.

Using Comsol, GTI and collaborators implemented a parametric, time-dependent model with a custom viscoelastic‑plastic constitutive law (with Veryst Engineering support) to simulate pressurization, squeeze-off, hold, release, and relaxation. The simulations — validated by accelerated lifetime testing — showed that for pipes under 3.5" the three‑diameter squeeze-off distance did not exceed accepted strain limits and predicted an 80‑year service life at 20°C, supporting a potential revision of the ASTM 12‑inch rule and enabling less invasive, lower‑cost pipeline maintenance.

Gas Technology Institute

Oren Lever

Principal Engineer, Energy Delivery & Utilization