Thermal Stress Mitigation Through Three-Dimensional Expansion Loop Design On Piping Line PL-1018-A

Abstract

Thermal expansion due to fluctuating operating temperatures presents a major challenge in
industrial piping systems, particularly at critical connections such as nozzles and flanges. This study analyzes
line pipe PL-1018-A in the test tank facility of Gathering Station A, South Sumatra, which transports crude
oil at 200°F and is classified as a critical line. To mitigate excessive thermal stress, a three-dimensional
expansion loop was designed to absorb multi-axial displacement within limited space. The stress evaluation
followed ASME B31.3 standards and included span analysis, loop dimensioning, displacement, and stresses
from sustained, thermal, and occasional loads, as well as nozzle load and flange leakage assessments. Results
indicate a maximum support span of 28.04 ft and an expansion loop dimension of 24 in × 56.49 in. Recorded
stress values for sustained (11,616.1 psi), thermal (4,071.6 psi), and occasional loads (22,876.5 psi) remained
below allowable limits. Thermal displacement did not exceed 100 mm, and all nozzle and flange stress
components were within allowable ranges specified by the manufacturer and ASME Section VIII Div. 1. Thus,
the proposed design is technically feasible and ensures safe operation under analyzed conditions.