1、Evaluation of Fire Risk Related to Corrugated Polyethylene Pipe - _ - Brought to you by the CPPA, a non-profit industry trade association dedicated to providing unbiased, non-branded information about the use and installation of underground corrugated po I yet h y I ene drainage pipe. You r Informat
2、ion Resource Preface The material presented in this technical booklet has been prepared in accordance with recognized principles and practices, and is for general information only. The information should not be used without first securing competent advice with respect to its suitability for any gene
3、ral or specific application. While the material is believed to be technically correct, the Corrugated Polyethylene Pipe Association makes no representation or warranty of any kind, and assumes no liability therefore. Inquiries on specific products, their attributes, and the manufacturers warranty sh
4、ould be directed to member companies. An up-to-date directory of the membership of the Corrugated Polyethylene Pipe Association is available on request. Introduction Potential Fire Sources Combusti bi I ity Comparison Historical Incidence of Fire Conclusion is technical booklet examines the issue of
5、 flammability and corrugated polyethylene pipe and includes data about state-by-state usage of high density corrugated polyethylene (HDPE) pipe as reported by several state Departments of Transportation. These studies and years of field installations indicate that the use of properly installed corru
6、gated polyethylene pipe does not represent a fire risk. HDPE is permitted under National Fire Protection Association Standard 820 and is approved for use by the US. Forest Service in the Forest Service Specifications for Construction of Roads and Bridges. Likewise, the Canadian forestry sector has u
7、tilized HDPE for many years. With the threat of forest fires, these approvals are particularly noteworthy. In addition, HDPE meets AASHTO M-294, the materials standard which is accepted by nearly every state in the U.S. for gravity flow applications. Ministries of Transport across Canada also have a
8、pproved HDPE for various gravity flow applications. Roadside Fires Although discouraged, grass fires and burning roadside vegetation represent the most common sources of fire risk to corrugated polyethylene pipe installations. In 1994, the Florida Department of Transportation conducted five field bu
9、rn tests to determine the overall risk of fire and rate of consumption during actual grass fires. During these tests, it was observed that corrugated polyethylene pipe was “unlikely to ignite during a grass fire of expected intensities.” Even when an in-pipe fire did occur, the Florida DOT field tes
10、ts showed the burn rate to be relatively low, progressing at a rate of 1.7 ft/hr (or 0.51 m/hr.). In addition, there are numerous preventive measures which can be considered to help prevent fire damage. These include installing rip-rap or gravel around exposed ends, using nonflammable end sections a
11、nd employing other methods which can be used to keep grass and combustibles away from the pipe ends. Other Fire Risks Another possible - although extremely rare - source of fire risk is associated with spilled fuel and other flammable liquids. (it is generally recognized that a fire under these cond
12、itions would result in intense heat and potential explosions that would destroy virtually any kind of pipe system.) In this situation, corrugated polyethylene pipe would present no greater risk of fire than would any other type of pipe material. Ignition and Melting Temperatures Pipe Material Asphal
13、t or Coal Tar Coatinq When fire is a design consideration for drainage installations, it must be a consideration for all potential pipe materials, or for that matter, all construction materials that might come in contact with the fire. Te rn pera t u re React i on 450F (327C) lanition The autoigniti
14、on temperature (also called burn point) is the temperature at which a material will self ignite. During a fire, high density polyethylene drainage products can withstand temperatures notably higher than the ignition temperature of asphalt and coal tar coatings, which are sometimes used to improve th
15、e durability of metal pipe. Temperature comparisons shown in Table 1 indicate the worst case (either melting or ignition temperature) for HDPE and coatings used on metal pipe. Table 1 Comparison of Ignition and Melting Temperatures I Zinc 1 787F 419“C) 1 Meltina* 1 I High Density Polyethylene I 750F
16、 (399C) I Ignition3 1. Florida Department of Transportation Report No. 94-7A, High Density Polyethylene Pipe Fire Risk Evaluation, July 1994. 2. ASTM A849-85, Post Coated (Bituminous) Corrugated Steel Sewer and Drainage Pipe, Section 6.1.4. 3. Ray E. Bolz and George L Tuve. CRC Handbook of Tables fo
17、r Applied Engineering Science, 2nd Edition. Boca Raton, FL: CRC Press, lnc., 1973, p. 1052. Fire and Product Performance Pipe usually behaves differently toward heat and flame following installation, compared to when it is completely exposed. Table 2 summarizes the expected behavior of different pip
18、e materials when compared under installed conditions. Table 2 Effects of Burning on Installed Pipe Materials Pipe Material Asphalt Coated Metal Coal Tar Coated Metal Zinc Galvanized Steel Reinforced Concrete Polyethylene Re marks Loss of coating due to fire causes structural changes and reduces dura
19、bility. Damaged coatings permit premature corrosion and reduce design life. Can reduce structural integrity of base material. May require lab analysis to determine extent of damage. Heat causes cracking and crumbling. Constituents expand/ contract at different rates. Fire can cause melting of produc
20、t. Pipe will ignite if temperature is significantly high. Pipe Repair and Replacement A severe fire may cause so much damage that all or part of the system may need repair, regardless of material. If fire is a consideration in material selection for the original design, another consideration needs t
21、o be the ease with which the pipe can be restored should damage occur. If laboratory analysis of a metal pipe shows a sufficient loss of strength or durability following a fire, the entire pipe may need to be replaced. Installation of replacement pipe systems will be cumbersome in developed areas. R
22、einforced concrete pipe is even harder to replace. It is a difficult undertaking to cut away the damaged portion of a culvert and replace just those sections. Although heavy equipment is needed in nearly every phase of the replacement process, lack of accessibility to the site can complicate the pro
23、blem. High density polyethylene pipe repairs can be made easily by cutting away the damaged sections with a hand saw, then attaching a short section of similar pipe with a coupling band. The pipe can be transported and installed without heavy equipment, and the light weight of HDPE helps to simplify
24、 the process. torm sewers and culvert pipes are not exposed to fire in the normal course of duty. But even when the pipe is subjected to fire, the material usually will succumb only if the conditions are right. A state-by-state survey conducted as part of a Florida DOT study in 1994 found that at le
25、ast 41 states used polyethylene pipe, predominantly for edge drains, underdrains, culverts and other gravity flow applications. Since Georgia first started using polyethylene pipe in 1968, these 41 states have an accumulated total of 381 years usage. Yet in all that time, only eight fires were repor
26、ted by four states (see Table 3), and all these fires were judged to be minor isolated instances. In its survey of user states, the North Carolina Department of Transportation found only three states that had ever experienced any fire damage to HDPE: Colorado, Georgia and New York. In Colorado, ther
27、e had been melting of pipe end sections, but the pipe was heavily laden with sawdust from a nearby sawmill. Georgias experience had been in a controlled environment to check first-hand the materials susceptibility to fire. And New York recorded an incident where a pipe was packed with paper and wood
28、 and set ablaze. The case was considered arson and the pipe was damaged, although not beyond its usefulness. In his report summary, William A. Swaney of the North Carolina DOT Value Management Section mentions that some states have concerns over HDPE pipes ability to withstand fire. However, they ar
29、e aware of this and feel that their concerns are completely addressed. There are options available such as nonflammable end sections or treatments. Yet, 61 % of the user states do not use special treatments of this type. High density polyethylene compares very well with other familiar construction m
30、aterials in regard to its burning characteristics, and any susceptibility to melting or burning should be considered with respect to the application. The use of corrugated HDPE pipe for stormwater management is accepted in 47 of 50 states in the US. and in most federal, provincial and municipal tran
31、sportation jurisdictions in Canada. Millions of feet of pipe have been successfully installed in applications across the North American continent. “Weve been using HDPE pipe for small culvert replacements for over 10 years now and weve had no in-use fire-related problems that Im aware of,” said John
32、 Hurd, Ohio Department of Transportation assistant hydraulic engineer. Ohio accepts both HDPE and PVC plastic pipe, as well as concrete, steel, coated steel and aluminum as viable materials. In addition, Hurd noted that he does not believe combustibility is a culvert design concern. “We know HDPE pi
33、pe is extremely durable and its an economical pipe to use.” State MT NC Table 3 Year First Used Fires 1994 None 1979 None State-by-State Usage of Polyethylene Pipe and Reported Incidence of Fire NH NJ State I Year First Used I Fires 1989 None 1992 None Unknown CA 1984 NV NY OH OK OR PA CO I 1984 14
34、1984 None 1989 1* 1981 None 1988 None 1992 None 1980 None I I CT 1 1988 I None IL IN FL 1 1989 1 None 1975 None 1977 None GA I 1968 1 None sc SD TN TX UT VT 1989 None 1985 None 1984 None 1981 None 1982 None 1983 None Unknown 2 KY MA I KS I 1990 I None 1978 None 1971 None MO MS I I MD I 1980 I None 1
35、987 None 1989 None MN 1988 None 1 ND 1 Unknown I None I NM I 1990 I None I wv I 1978 I None I I WY 1 1990 1 None Source: Florida Department of Transportation Report No. 94-7A, High Density Polyethylene Pipe Fire Risk Evaluation, July 1994. *Arson suspected. ince the late 1960s, corrugated polyethyle
36、ne pipe has been used in thousands of installations. During this time, the accumulated number of “usage” years adds up to nearly four centuries, while the number of fires totals up to less than 10. Independent studies by the Tennessee and Florida Departments of Transportation have ruled that polyeth
37、ylene pipe is not a significant fire risk. And after conducting a similar study, the Texas Department of Transportation also ruled that “flammability is not an issue.” Although it is possible to ignite polyethylene pipe, experience shows that it is a very rare occurrence indeed. Yo ur Information Resource CPPA 4235 Monroe St. Suite 124 Toledo, OH 43606 fax: 41 9-885-5848 (800) 510-CPPA O 1996 Corrugated Polyethylene Pipe Association Printed in U.S.A. on recycled paper with soybean ink.
