CIPP Liner Thickness, Fully Deteriorated Host (ASTM F1216)
When the host pipe is no longer structural, a CIPP liner has to carry the soil, the traffic.
Example
You enter
- Host pipe inside diameter (in) 12
- Measured host ovality (%) 5
- Soil cover above the pipe H_s (ft) 5
- Groundwater above the pipe H_w (ft, 0 if below it) 2
- Soil unit weight (pcf) 120
- Live load at the pipe (psi; HS-20 about 2 at 5 ft) 2
- Modulus of soil reaction E's (psi, 500 poor to 2,000 fair host) 1000
- Long-term flexural modulus E_L (psi) 150000
- Initial (short-term) flexural modulus E (psi) 300000
- Long-term flexural strength (psi) 2500
- Soil support enhancement factor K 7
- Safety factor N 2
You get
- Total load (psi) 6.5
- Load thickness (in) 0.199
- Stiffness thickness (in) 0.186
- Thickness (in) 0.199
Checked against published worked examples from: Iowa Statewide Urban Design and Specifications (SUDAS).
Details, formula, and sources
ScopeWhen the host pipe is no longer structural, a CIPP liner has to carry the soil, the traffic, and the groundwater as a pipe of its own. ASTM F1216 asks for the thickest of four checks: the soil-and-live-load buckling relation with the water buoyancy factor and the elastic support coefficient, a minimum stiffness on the initial modulus, groundwater buckling, and ovality bending; this reports each and names the one that governs. A 12 in clay sewer under 5 ft of cover, 2 ft of water, and HS-20 traffic at 5% ovality needs 0.20 in, against 0.19 in for stiffness alone. The soil modulus is the judgment call; the liner maker's data governs.
Formula or tableASTM F1216 Appendix X1, fully deteriorated gravity pipe: thickness = the greatest of X1.3 t = [0.375 (N q_t / C) squared D cubed / (E_L R_w B' E's)]^(1/3) with q_t = 0.433 H_w + w H_s R_w / 144 + W_s, R_w = 1 - 0.33 H_w / H_s (not under 0.67), B' = 1 / (1 + 4 e^(-0.065 H_s)); X1.4 t = D (1.116 / E)^(1/3) (E I / D cubed at least 0.093 on the initial modulus); X1.1 groundwater buckling; X1.2 ovality bending against the long-term flexural strength. C = ((1 - q) / (1 + q) squared) cubed.
Source and editionASTM F1216 Appendix X1 design relations by name, worked as in the Iowa SUDAS Design Manual Section 14C-2 (Equations 14C-2.02 to 14C-2.11 and the fully deteriorated design example).
Free accessThe Iowa SUDAS Design Manual Section 14C-2 is free at iowasudas.org; ASTM F1216 itself is licensed and no table from it is reproduced.
What governsEstimate. AHJ and licensed professional govern.
API field nameshost_id_in, ovality_pct, soil_cover_ft, groundwater_head_ft, soil_unit_weight_pcf, live_load_psi, soil_modulus_psi, long_term_modulus_psi, initial_modulus_psi, long_term_flexural_strength_psi, enhancement_factor, safety_factor, total_load_psi, load_thickness_in, stiffness_thickness_in, thickness_in
- Soil modulus E's 500 psi for badly cracked pipe with voids to 2,000 psi for fair pipeIowa SUDAS 14C-2
- Water buoyancy factor floor 0.67ASTM F1216 X1.3
- Poisson's ratio (X1.1) 0.3ASTM F1216