Incorporated standard

PPI TR-4

PPI TR-4, PPI HSB Listing of Hydrostatic Design Basis (HDB), Hydrostatic Design Stress (HDS), Strength Design Basis (SDB), Pressure Design Basis (PDB) and Minimum Required Strength (MRS) Ratings For Thermoplastic Piping Materials or Pipe, updated May 1, 2024, (PPI TR-4); IBR approved for § 192.121(b).