18.104.22.168 There is a commentary available for this Clause. The nominal wall thickness shall be not less than the design wall thickness calculated from the formula in Clause 22.214.171.124 plus the allowances specified in Clause 4.3.10. Note: In determining the nominal wall thickness, manufacturing tolerances need not be considered. 126.96.36.199 There is a commentary available for this Clause. The nominal wall thickness for steel carrier pipe shall be not less than the applicable value given in Table 4.5. Note: Although experience has shown that pipe with D/t ratios up to 120 can be successfully installed with normal or special handling and construction procedures, the designer is cautioned that susceptibility to flattening, buckling, and denting increases with increased D/t ratio, decreased wall thickness, decreased yield strength, and combinations thereof.
* Threaded pipe is not allowed for pipe larger than 114.3 mm OD. Notes:
1) For intermediate pipe outside diameters, the least nominal wall thickness shall be as tabulated for the next
larger pipe outside diameter.
2) The least nominal wall thickness of threaded pipe having national pipe threads shall be as given in this Table
for threaded pipe. The least nominal wall thickness for threaded pipe having other than national pipe threads shall be not less than that specified for plain-end pipe, and the thickness under the last engaged thread (based upon nominal dimensions) shall be at least 0.5 times the nominal thickness of the pipe.
3) For crossings, see also Table 4.10.
188.8.131.52 Where external or internal coatings or linings of cement, plastic, or other materials are used on steel pipe, such coatings or linings shall not be considered to add strength.