(PPFA User Bulletin 8-82 (7/82))
PLASTIC PIPING: A POSITIVE RESPONSE
The purpose of this report is to acquaint those interested in the capabilities and limitations of thermoplastic piping products used in plumbing systems.
The general term "plastic" is used to cover several organic, polymeric materials with distinctly different chemical compositions. A great advantage of plastic materials is that they are man-made and can be varied to enhance certain properties. The particular polymeric material that provides the best combination of properties and economics can then be utilized. The success of plastic in this industry has been, and will continue to be, dictated by such things as relative cost of raw materials, availability of materials, energy conservation, ease of fabrication, ease of installation,
and durability. Analysis of these factors shows some distinct advantages for plastics over many of the competitive materials. Plastics have proven their viability in many industries other than pipe and fittings. Surveys of the total construction, transportation, packaging, and clothing industry, as well as many others, all show the consistent pattern of success for synthetic materials over many of the previously used alternatives.
The PPFA publication, "The Growing World of Plastics Piping", provides more detail about the several plastic materials that are significant in the piping area and identifies the ASTM product standards which cover the various plastic pipes and fittings. It also identifies the applications for which each product is utilized.
There are two areas in which plastic piping significantly differs from other materials. These areas, which are discussed in more detail below, are:
Solvent Cement Joints
- The use of solvent cement joints, and
As this term indicates, plastic-to-plastic joints usually involve the use of solvent cement. During the application of the solvent cement and the curing of the joint, these solvents evaporate. A question has been raised about the health hazards to workers exposed to the solvent vapors in the atmosphere. There are several factors that can affect the solvent
vapor concentration, e.g., temperature, humidity, rate of cement usage, size and ventilation of room or work space, and even cement formulation. In order to determine the vapor concentrations under a broad range of actual use conditions, CAL/OSHA and the Hazard Evaluation System and Information Service of the California Department of Health Services made an extensive investigation. The conclusion reached was that "adverse worker health effects from the major solvents found in cements and primers are unlikely based on the relatively low toxicity and field measurements of exposures under a range of working conditions." (Reference: J. Stohlton correspondence, dated November 11, 1980.)
Suggested installation precautions, endorsed by PPFA, do exist. ASTM F402-88, recommends the use of gloves and eye protection, as well as adequate ventilation, when working with solvent cement. Solvents are not a new, unknown quantity. Workers are accustomed to safely dealing with them in the form of lacquer paints, glues and adhesives.
Plastics are combustible. Starting with this fact, one can develop a whole series of questions, each of which might result in further questions depending on the piping application, pipe material, use conditions, and a host of other factors. This could be built into an almost endless series of tests and experiments. However, because plastic piping already has an extensive service history, it has been possible to investigate its effects on fire incidents; and the following can be reported:
- Plastic piping conveying water under pressure in a building has never been identified as a fuel source in a building fire or as the cause of fire spread. As a matter of fact, there are several documented cases in which plastic pipe has ruptured, sprayed water on the fire, and put it out.
Plastic piping has gained acceptance for use in residential fire sprinklers in a number of California communities. Those advances led the California State Fire Marshall to develop a "Voluntary Standard for Automatic Fire Sprinkler Systems for One and Two-Family Dwellings." PB and CPVC piping are listed as accepted products in this standard. Both PB and CPVC fire sprinkler systems are UL Listed.
- Plastic piping has been used for DWV and storm water drains within buildings for more than 30 years. In some areas more than 90% of new one and two-family residences are being plumbed with plastic DWV piping. With this broad usage over an extended period of time, any increase in fire risk due to the use of plastic piping should be reflected in the fire reports filed with state fire marshals. At the request of the California legislature, the State Fire Marshall thoroughly investigated the subjects of these reports and concluded that "the use of plastic pipe in non-fire rated construction, whether in residential, commercial or industrial occupancies, does not represent any unusual fire risk." In a supplemental letter (October 23, 1980) California Fire Marshall Phillip Favro indicated that a search of published literature produced no information concerning fires involving plastic pipe.
- The use of plastic piping in fire rated walls or with branch connections that pass through the membranes has been investigated in the United States and Canada. Since the fire ratings of walls are based on the ASTM E-119 tests, this test was also used in these investigations. A series of one-hour and two-hour rated walls with wood studs and gypsum board coverings were plumbed with plastic DWV piping having trap connections through both sides. Some of the walls were tested under load bearing conditions and others
were tested as non-load bearing walls. This test work was done at the Ohio State University Building Research Laboratory and led to the conclusion that plastic DWV piping with fixture connections can be installed in a fire-rated, wood stud and gypsum board wall so that the wall assembly will maintain its original fire rating. In doing these tests it was found to be necessary to seal the openings where the branches pass through the gypsum board. These tests also showed that the piping within the wall is not involved in the early stages of a fire and that the plastic has some tendency to soften and close off openings as the fire progresses. (For more complete details, see the PPI report entitled "Fire Testing Plastics DWV Systems".)
Subsequently, additional E-119 fire tests were performed at the University of California, Berkeley, to investigate different techniques or devices that could be used in place of, or as a supplement to the sealing of the branch connection penetration. These tests also showed that plastic DWV piping can be installed in fire rated walls without reducing the fire
rating. The California tests were also initiated to investigate the effects of a different plumbing arrangement (waste and vent stack in same stud space).
On the basis of all this evidence and the test data, PPFA believes one must conclude that plastic DWV piping can be used in both fire rated and non-fire rated buildings without any significant increase in hazard, even though plastic is a combustible material.
The use of plastic piping in fire walls is not a unique case of putting combustibles in fire walls. Other combustible materials (e.g., wood studs) are regularly used in fire walls.
The "fire-danger" challenges to plastic piping have been adequately refuted by various studies showing plastic piping to be a safe product under proper use. Plastic piping has shown itself to be an economical product, comparative cost studies have shown it to be cheaper to purchase and to install than other piping, as well as having a longer life. People who pay the bills are the ultimate judges of cost effectiveness and have decided that plastic piping is the product of choice. Plastic piping is presently used in almost
all major U.S. cities. A number of companies that previously manufactured only metal piping have recognized plastic piping's significant place in the market and now also manufacture plastic piping.
Over the past 30 years, plastic piping has grown into a major factor in the plumbing market. During the 1970's, the following changes in material usage in piping were recorded:
||Percent Change (Lbs.)
|| + 6%
|| - 6%
| Cast Iron
The success of plastic in the pipe and fitting industry today cannot be denied and the future holds even greater promise.
POSITIVE RESPONSE BULLETIN BIBLIOGRAPHY
Springborn Laboratories, Inc. "% Change in Usage (Pounds)", 1978.
"Fire Tests of ABS Plastic Vent and Drain Pipes in Kitchen and Bath-room Mock-Ups of Wood Framed Dwellings," G. E. Troxell, The University of California, Berkeley, June 1965.
"Fire Tests of Six Inch Wood One-Hour Fire-Rated Walls with Plastic DW Plumbing Systems", The University of California, Berkeley, November 1976.
"Standard ASTM Fire Endurance Test and Fire and Hose Stream Test on Duplicate Non-Load Bearing ABS Plumbing Wall Assemblies", Report No. 5473, The Ohio State University, April 1973
"Standard ASTM Fire Endurance Test and Fire and Hose Stream Test on Load Bearing ABS Plumbing Wall Assemblies", Report No. 5560, The Ohio State University, January 1974.
"Standard ASTM Fire Endurance Test and Fire and Hose Stream Test on Duplicate Load Bearing Poly Vinyl Chloride Plumbing Wall Assemblies", Report No. 5661 The Ohio State University, January 1974.
"Standard ASTM Fire Endurance Test and Fire and Hose Stream Test on Duplicate Non-Load Bearing ABS Plumbing Wall Assemblies", Report No. 5615, The Ohio State University, January 1974.
This PPFA User Bulletin is designed to provide guidance in achieving the efficient, effective and informed use of plastic pipe. The suggestions and advice contained in this Bulletin are offered merely to provide plastic pipe users with a general frame of reference. Because specific situations may, and often do require special treatment, the suggestions and advice are obviously not universally applicable. Therefore, the user should carefully assess the requirements of his specific situation before marsally applicable. Therefore, the user should carefully assess the requirements of his specific situation before making practical application of anything contained in this publication.