IAPMO Uniform Codes Spotlight – October 13, 2022

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From the 2021 UPC Illustrated Training Manual, Chapter 7, SANITARY DRAINAGE

701.2 Drainage Piping. Materials for drainage piping shall be in accordance with one of the referenced standards in Table 701.2 except that:

Requirements for drainage and sewer piping will also apply to vent pipe materials. Table 701.2 is a good reference for determining which material is allowed for building drainage or sewer piping. The drainage waste and vent columns refer to pipe for use within the building either above ground or underground. Building sewer applications are for use outside of the foundation of the building only.

(1) No galvanized wrought-iron or galvanized steel pipe shall be used underground and shall be kept not less than 6 inches (152 mm) aboveground.

Due to the possibility of wrought iron or steel piping rusting, whether galvanized or not, it is not for use underground. The use of galvanized pipe in the drainage system is increasingly rare except for pipe nipple applications. This is because of the increased cost of the material and labor versus other available materials.

(2) ABS and PVC DWV piping installations shall be installed in accordance with applicable standards referenced in Table 701.2 and Chapter 14 “Firestop Protection.” Except for individual single-family dwelling units, materials exposed within ducts or plenums shall have a flame-spread index of not more than 25 and a smoke-developed index of not more than 50, where tested in accordance with ASTM E84 or UL 723. Plastic piping installed in plenums shall be tested in accordance with all requirements of ASTM E84 or UL 723. Mounting methods, supports and sample sizes of materials for testing that are not specified in ASTM E84 or UL 723 shall be prohibited.

The use of plastic materials for drainage and vent piping within the building has been limited in past years because of the high flammability and smoke-creating potential of the material. It would either be prohibited or limited to three or four stories in residential buildings. Plastic pipe ABS and PVC for drain waste and vent (DWV) applications are prohibited within ducts or plenums unless they meet the above specifications for flame spread and smoke-developed indexes according to the requirements of Chapter 14. There are still some areas of the country that prohibit plastics within the building, but most building codes will allow its use when the requirements for fire protection and wall penetration protection are adhered to. Plastic DWV fittings are illustrated in Figure 701.2(2).

If ASTM E84 or UL 723 standard test methods are modified and used as a basis to determine flame and smoke ratings, then the tests don’t comply with the standard and the materials may not comply with the required flame and smoke ratings. An inspector or installer seeing ASTM E84 on a pipe would likely assume that it meets the requirement of the code. Simply adding the ASTM E 84 or UL 723 marking to the wall of the pipe does not necessarily mean that the product was tested in full compliance with the standard in the manner that the code intends. Especially for PVC and CPVC pipe, the inspector or installer should examine the material listing and see if the testing agency has modified the testing method and rendered the pipe material non-compliant.

(3) No vitrified clay pipe or fittings shall be used aboveground or where pressurized by a pump or ejector. They shall be kept not less than 12 inches (305 mm) belowground.

(4) Copper or copper alloy tube for drainage and vent piping shall have a weight of not less than that of copper or copper alloy drainage tube type DWV.

(5) Stainless steel 304 pipe and fittings shall not be installed underground and shall be kept not less than 6 inches (152 mm) aboveground.

Stainless steel has properties that far exceed many materials on the market today, and selecting the correct grade ensures that the product will have a maintenance- free and cost-effective installation. Type 304 stainless steel is an austenitic (non-magnetic) steel that can be severely drawn, spun, rolled, machined, or worked in the cold state. Type 304L is the low carbon version of Type 304. It is used in heavy gauge components for improved welding ability. This type of stainless steel has an excellent corrosion resistance in a wide variety of environments including chlorides.

Type 316L stainless steel contains low carbon and high nickel content and an addition of molybdenum that gives it improved corrosion resistance. The molybdenum tends to help minimize pitting or pin-hole corrosion under certain conditions.

ASME A112.3.1 contains installation procedures for stainless steel drainage systems for sanitary, storm and chemical applications, above and below ground. This standard covers requirements for socket-type, seam-welded stainless steel pipe, fittings, joints and drains for use in sanitary and storm, DWV and chemical waste systems [see Figure 701.2(5)].

(6) Cast-iron soil pipe and fittings and the stainless steel couplings used to join these products shall be listed and tested in accordance with standards referenced in Table 701.2. Such pipe and fittings shall be marked with the country of origin, manufacturer’s name or registered trademark as defined in the product standards, the third party certifier’s mark, and the class of the pipe or fitting.

The 2021 Uniform Plumbing Code Illustrated Training Manual is available for purchase here.

(This email is not to be considered the official position of IAPMO or PHCC of California, nor is it an official interpretation of the Codes.)

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