ANSI AWWA C904-16 pdf download.Crosslinked Polyethylene (PEX) Pressure Tubing
The selection of materials is critical for water service and distibution tubing in locations where the tubing will be exposed to signifcant concentrations of pollut- ants comprised of low-molecular-weight petroleum products or organic solvents or their vapors. Research has documented that tubing materials, such as polyethylene, polybutylene, polyvinyl chloride, PEX, and asbestos cement, and elastomers used in joining gaskets and packing glands are subject to permeation by low-molecular- weight organic solvents or petroleum products. If potable water tubing must pass through such a contaminated area or an area subject to contamination, consult with the manufacturer regarding permeation of tubing walls, jointing materials, and so forth before selecting materials for use in that area.
Additional resources about permeation of elastomeric joint gaskets and plastic tubing are provided in appendix B.
4.2.1.1 Tubing covered by this standard shall conform, as a minimum, with the requirements of PEX 1306 as classified in ASTM F876. PEX classified with a material designation code of PEX 3306 and PEX 5306 also meets this requirement.
4.2.1.2 The material shall be crosslinked by peroxides or silane compounds in extrusion or by electron beam after extrusion so the tubing meets or exceeds the performance requirements in this standard. The minimum percent of crosslinking shall be 70 percent for peroxides, 65 percent for silane compounds, and 65 per- cent for electron beam when tested in accordance with ASTM D2765, Method B, as defined in ASTM F876. Tubing may incorporate an optional polymeric outer layer. Tubing with outer layers must meet technical requirements as per established policies defined within ASTM F876 and PPI TR-3.
4.2.1.3 PEX tubing shall have a long term HDS (hydrostatic design stress) equal to or better than given in Table 1, when the HDB (hydrostatic design basis) is determined in accordance with ASTM D2837. HDS and HDB ratings shall be listed in accordance with procedures no less restrictive than those of PPI TR-3.
4.2.2 Reworked material. The use of reclaimed, recycled, or reworked materials is not permitted.
4.2.3 Certification. PEX tubing covered by ANSI/AWWA C904 shall be tested and certified for use with potable water by an accredited testing agency. Product testing shall be no less stringent than required by NSFIANSI 61 or the health effects portion of NSFIANSI 14. This applies to applications for potable water, wastewater, and reclaimed water systems as described in Sec. 4.2.1.ANSI AWWA C904-16 pdf download.