1、NEMA Standards PublicationNational Electrical Manufacturers AssociationNEMA PRP 2-2014Guidelines for Solvent-Cementing Joints for PVC Rigid Nonmetallic Conduit, Duct, and FittingsNEMA Publication PRP 2-2014 Guidelines for Solvent-Cementing Joints for PVC Rigid Nonmetallic Conduit, Duct, and Fittings
2、 Published by: National Electrical Manufacturers Association 1300 North 17th Street, Suite 900 Rosslyn, Virginia 22209 www.nema.org 2014 National Electrical Manufacturers Association. All rights, including translation into other languages, reserved under the Universal Copyright Convention, the Berne
3、 Convention for the Protection of Literary and Artistic Works, and the International and Pan American copyright conventions. 2014 National Electrical Manufacturers Association NOTICE AND DISCLAIMER The information in this publication was considered technically sound by a consensus among persons enga
4、ged in its development at the time it was approved. Consensus does not necessarily mean there was unanimous agreement among every person participating in the development process. The National Electrical Manufacturers Association (NEMA) standards and guideline publications, of which the document here
5、in is one, are developed through a voluntary standards development process. This process brings together volunteers and/or seeks out the views of persons who have an interest in the topic covered by this publication. Although NEMA administers the process and establishes rules to promote fairness in
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8、 completeness of any information published herein, and disclaims and makes no warranty that the information in this document will fulfill any particular purpose(s) or need(s). NEMA does not undertake to guarantee the performance of any individual manufacturers or sellers products or services by virt
9、ue of this standard or guide. In publishing and making this document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity, nor is NEMA undertaking to perform any duty owed by any person or entity to someone else. Anyone using this docum
10、ent should rely on his or her own independent judgment or, as appropriate, seek the advice of a competent professional in determining the exercise of reasonable care in any given circumstance. Information and other standards on the topic covered by this publication may be available from other source
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12、ty or health purposes. Any certification or other statement of compliance with any health- or safety-related information in this document shall not be attributable to NEMA and is solely the responsibility of the certifier or maker of the statement. NEMA PRP 2-2014 Page i 2014 National Electrical Man
13、ufacturers Association FOREWORD The purpose of these guidelines is to describe the procedures and recommended practices for solvent-cementing joints in PVC conduit, duct, and fittings. This guideline is in no way intended to assume or replace any responsibilities of engineers, customer representativ
14、es, owners, or other persons in establishing engineering design practices and procedures best suited to individual job conditions. The NEMA Polymer Raceway Products Section through its members works closely with the American Society for Testing and Materials, appropriate government agencies, and oth
15、er organizations in the periodic review and revision of its standards for any changes necessary to keep them up to date with evolving technology. Proposed or recommended revisions should be submitted to: Vice President, Industry Operations National Electrical Manufacturers Association 1300 North 17t
16、h Street, Suite 900 Rosslyn, Virginia 22209 This guideline was developed and approved by the NEMA Polymer Raceway Section. At the time of approval, the Polymer Raceway Section consisted of the following members: Anamet Electrical, Inc.http:/Mattoon, IL AFC Cable Systems, a part of Atkore INew Bedfor
17、d, MA Allied Tube and Conduit, a part of Atkore IHarvey, IL Champion Fiberglass, ISpring, TX FRE Composites 2005 Inc. St. Andre -dArgenteuil, PQ, Canada Hubbell IShelton, CT IPEX Management IMississauga, ON, Canada Legrand North Americawww.legrand.usWest Hartford, CT Panduit CTinley Park, IL Royal B
18、uilding PShelbyTownship, MI Southern Pipe, Inc.www.southern-New London, NC Thomas & Betts, a member of the ABB GMemphis, TN Underground Devices, INorthbrook, IL United Fiberglass of ASpringfield, OH NEMA PRP 2-2014 Page ii 2014 National Electrical Manufacturers Association CONTENTS Foreword . i To P
19、rime or Not to Prime . 1 Selection of Solvent Cement 1 Cutting Conduit or Duct 1 Cleaning . 2 Application Procedure 2 Assembly Precautions 3 Atmospheric Considerations 3 NEMA PRP 2-2014 Page 1 2014 National Electrical Manufacturers Association GUIDELINES FOR SOLVENT-CEMENTING JOINTS FOR PVC RIGID NO
20、NMETALLIC CONDUIT, DUCT, AND FITTINGS Most forms of PVC conduit, duct, and fittings are meant to be assembled or joined by means of solvent-cementing of the integral bells or PVC couplings. Solvent cements contain chemicals that dissolve the surface of the PVC, softening it. As the chemicals evapora
21、te, they leave a PVC resin behind that fuses the mating surfaces. TO PRIME OR NOT TO PRIME Primers are a form of chemical cleaner that can be used to remove surface impurities, soften, and dissolve the joining surfaces in order to better prepare them for solvent-cementing. The National Electrical Co
22、de (NEC) does not require PVC primer to be used in the joining of PVC conduit. However, under certain conditions, primer can aid in ease of assembly and enhance the quality of the joints. Primer should always be considered for use in extreme cold weather and whenever the conduit spigot exterior or b
23、ell interior has foreign material on it that is not easily removed by wiping with a clean, dry cloth. When using PVC primer, wear proper clothing, gloves, and eye protection. Never use PVC primer in the presence of sparks or flames. Avoid breathing of fumes, and provide proper ventilation at all tim
24、es. For more information on PVC primers, refer to ASTM F 656, Standard Specification for Primers for Use in Solvent Cement Joints of Poly(Vinyl Chloride) (PVC) Plastic Pipe and Fittings. SELECTION OF SOLVENT CEMENT Solvent cements intended for use with PVC conduit and duct should meet all the applic
25、able requirements of ASTM D 2564, Solvent Cements for Poly (Vinyl Chloride) (PVC) Plastic Piping Systems. Since solvent cements are available in a wide range of viscosities and wet film thicknesses, consider the nature of the particular project when trying to decide between regular, medium, or heavy
26、-bonded cement. Environmental conditions (temperature and humidity), type of joining fit (interference or clearance fit between the bell and spigot), and conduit Trade Size must be considered when selecting the appropriate type of solvent cement. CUTTING CONDUIT OR DUCT Cut conduit or duct square wi
27、th its longitudinal axis using a saw or other suitable tool as shown in Figure 1. Ensure that all burrs or ridges that resulted from cutting are removed from the conduit or duct end. A knife, file, pipe reamer, or abrasive paper can be used to remove burrs and to apply a slight chamfer to the cut en
28、d. Failure to remove ridges or burrs could result in the cement being scraped from the socket surface, causing the joint to fail. Ridges or burrs could also damage the conductors or cables being installed. NEMA PRP 2-2014 Page 2 2014 National Electrical Manufacturers Association Break sharp edges an
29、d remove burrs Figure 1 Acceptable Method for Cutting Conduit or Duct CLEANING Ensure that surfaces to be joined are free from dirt, moisture, oil and other foreign material. Wipe surfaces with a clean dry cloth. If the surfaces require further cleaning, a chemical or mechanical cleaner must be used
30、. Mechanical cleaners include fine abrasive paper or cloth (180 grit or finer) or clean, oil-free steel wool. Chemical cleaners include a primer meant for use with PVC or those recommended by the conduit, duct, fittings, or cement manufacturer. APPLICATION PROCEDURE 1) Test dry fit of the joint to e
31、nsure that the conduit or duct and fitting can be joined. Interference fits do not bottom out when dry fitted with the coupling (-2/3 insertion is normal for interference fit joints). After solvent cement is applied, the spigot of an interference fit bottoms out in the coupling. 2) If using primer,
32、apply it to the inside socket surface. Use a scrubbing motion to ensure penetration. Then apply primer to the male end to the depth of the fitting socket. Finally, apply primer again to the inside socket surface. Do not allow the primer to “puddle” inside the bell of the conduit or duct. 3) Without
33、delay, apply cement lightly but uniformly to the inside socket surface. Take care to keep excess cement out of the socket or bell-to-pipe transition area. Apply cement to the outer surface of the male end. 4) Immediately after applying the cement to the conduit or duct, while both the joining surfac
34、es are soft and wet with solvent cement, forcefully bottom the male end of the pipe in the socket, turning turn. This distributes the cement evenly. 5) After assembly, wipe excess cement from the conduit or duct at the end of the fitting socket. A properly made joint normally shows a bead around its
35、 entire circumference. 6) Until the cement is set in the joint, the conduit or duct might back out of the fitting socket if not held in place for approximately 1-2 minutes after assembly. Take care during assembly not to disturb or apply any force to joints previously made. NEMA PRP 2-2014 Page 3 20
36、14 National Electrical Manufacturers Association ASSEMBLY PRECAUTIONS PVC solvent cement is fast drying and must be applied as quickly as possible. Assembly should be made within 20 seconds after the last application of cement. If there is any sign of drying of the cemented surfaces, they should be
37、recoated. Hold the assembly in place for approximately one minute to prevent the conduit or duct from backing out of the fitting socket. Take care not to disturb or apply any force to newly assembled joints. Early handling can compromise the integrity of joints. Recommended set time is related to te
38、mperature as follows: 30 minutes minimum at 60-100F 1 hour minimum at 40-60F 2 hours minimum at 20-40F 4 hours minimum at 0-20F ATMOSPHERIC CONSIDERATIONS Under conditions of high humidity, quick application of solvent cement is important to minimize condensation of moisture from the air on the ceme
39、nt surface. Temperatures of the mating surfaces should not exceed 110F at the time of assembly. The temperature can be reduced by swabbing the surface to be cemented with a wet rag, provided the conduit or duct is thoroughly dry before cement is applied. At temperatures below freezing, solvent cemen
40、ts penetrate and soften PVC more slowly than in warmer weather. Because solvent cements and primers are highly flammable, do not use open flame or electric heaters to warm them. Take care to remove moisture, such as ice or snow, from pipe and fitting surfaces before applying cements and primers. In
41、cold weather, use primers to soften joining surfaces before applying cement. Source: ASTM D 2855, Making Solvent-Cemented Joints with Poly(Vinyl Chloride) (PVC) Pipe and Fittings NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION 1300 NORTH 17TH STREET, SUITE 900 ROSSLYN. VA 22209www.NEMA.orgTO ORDER ADDITIONAL NEMA STANDARDS VISITwww.gLObAL.IhS.cOM OR cALL 1-800-854-7179/1-303-397-79565612_0514TB
