Engineering calculator reviewed for preliminary design use · Last updated: March 2026
Calculate maximum allowable pipe support spacing per MSS SP-69 and ASME B31.3. Input pipe diameter, wall thickness, material, fluid density, and allowable deflection. Apply to pipe support design and stress analysis as baseline data.
Pipe Support Span Calculator (MSS SP-69)
Pipe support spacing must be designed so that bending stress remains within allowable limits. MSS SP-69 and ASME B31.3 provide guidance for support intervals based on pipe content weight and material properties.
Simplified Bending Stress Formula
L = √(0.33 × σ_allow × Z / w)
σ_allow: Allowable stress [MPa]
Z: Section modulus [mm³] (from OD and thickness)
w: Load per unit length (pipe + contents + insulation) [N/m]
Maximum span is governed by allowable deflection (typically 12-25 mm) and bending stress limits. Deflection is usually the controlling criterion for horizontal pipe runs. Larger pipes and lighter fluids allow longer spans.
Does this account for concentrated loads?
This calculator assumes uniformly distributed weight. Concentrated loads from heavy valves, flanges, or branch connections require shorter local spans or dedicated supports at those points.
These results are preliminary estimates for screening-level design use. They do not replace detailed engineering, code compliance verification, or vendor-certified calculations.