Assembly of Thermoplastic (PVC, UPVC, CPVC and HDPE) Piping

This article is about Assembly of Thermoplastic (PVC, UPVC, CPVC and HDPE) Piping in commercial buildings, plants and refinery projects related to Plumbing Engineering System as per international codes and standards.

Assembly of Thermoplastic (PVC, UPVC, CPVC and HDPE) Piping

General

1. Before assembly each piece of thermoplastic pipe and fitting shall be examined for cuts, scratches, gouges, kinks, buckles, and ultra-violet (sun) damage. Damaged lengths of pipe shall be cut out and discarded. Damaged fittings shall be discarded. Thermoplastic pipe and fittings that show ultra-violet damage and weathering effects shall not be used.
2. Primer and solvent cement shall not be used past the manufacturer’s expiry date on the label or one year past the date of manufacturer, if no expiry date is specified.
   Solvent cement shall conform to ASTM D2564 for joining PVC to PVC and ASTM F493 for joining CPVC to CPVC or PVC
3. Field fabricated, mitered fittings shall not be used
4. Thermoplastic flanges when used, shall be of flat face. Matting flanges of different approved material shall also be of flat face and shall be assembled with full-face elastomeric gaskets, 3mm thk and 50 to 60 shore A durometer hardness.
5. Flat washers shall be used under nuts and bolt heads on nonmetallic flanges.
6. Flanged joints shall have the following requirements:
   a) Flanged joints on nonmetallic piping system shall be made with flat face flanges and full-faced elastomeric gaskets.
   b) Flanges shall have pressure rating equal to or greater than the nonmetallic piping pressure rating.
   c) Bolt tightening procedures and maximum torque for bolting on nonmetallic flanges shall be in accordance with ASTM D4024.
   d) Washers shall be used for bolting nonmetallic flanges.”
7. In pressurized systems, connections to metal valves, larger than 50 mm nominal pipe sizes, shall be by means of flanges
8. Nonburied metal valves including metal valves in buried valve boxes, shall be supported independently of nonmetallic piping. In buried condition, metal valves 4 inch in size and larger shall be supported independently of nonmetalic piping.
9. Nonmetallic pipe shall be carried through a metallic sleeve in a valve box wall. Nonmetalic sleeve is acceptable provided the sleeve shall have mechanical characteristics and properties at least similar to that of the pipe passing through the sleeve. The space between the pipe and sleeve shall be sealed with approved (acceptable to the Aythority Having Jurisdiction) flexible waterproof mastic sealant.
10. The distance between the valve box wall and the back of the nonmetallic flange, inside the valve box, shall be not less than 150 mm to permit work access.
11. Threaded flanges shall not be used on nonmetallic piping systems
12. Plastic pipes, fittings, and plastic valves that do not have built-in protection from Ultraviolet (UV) light (exposed to sunlight) shall be shielded by painting with an exterior-grade, water-based emulsion, or tapewrap with UV resistant pressure sensitive tape utilizing adhesive that will not affect the plastic material.
13. Prior approval from the Chairman of Plumbing and Utilities Standards Committee is required for installation of nonmetallic piping under slabs or similar concrete structures

Assembly of HDPE

1. HDPE piping shall be installed as per the manufacturer’s instructions.
2. Underground HDPE sewer piping shall be installed in accordance with ASTM D2321.
3. Sliplining of existing sewer pipe with HDPE pipe shall be in accordance with ASTM F585.
4. Flange adapters with metal back-up flanges may be used for mechanical joining HDPE pipe to other piping materials, valves, tanks, pumps and other equipment. Such flange adapters shall be heat fused to the pipe
5. Extrusion gun welding, pipe threading, and solvent or epoxy cementing are not permitted for joining of HDPE pipe.

Assembly of CPVC Piping

1. Cut the pipe square, using a tubing cutter or a fine-toothed hand saw and miter box. (ASTM F 493 Para X1.1)
2. All ridges caused by tube cutter and burrs with sandpaper or knife shall be removed. (ASTM F 493 Para. X1.2)
3. Check dry fit of pipe in the fittings to ensure that there is an interference fit. The dry pipe or tubing should enter the fitting socket from one third to two thirds of the full socket depth when assembled by hand. (ASTM F 493 Para. X1.3)
4. Pipe end fitting socket shall be cleaned. Wipe away dust, moisture, and foreign material with dry cloth or use a cleaner, or primer or sand with fine abrasive paper. Cleaner or primer shall be that recommended by the cement manufacturer for use with CPVC plastic pipe. (ASTM F 493 X1.4 )
5. Heavy thick coat of CPVC cement to the pipe end and a light thin coat to the inside of the fitting socket shall be applied. If cement dries on either surface before joining, apply another coat. (ASTM F 493 Para X1.5)
6. Immediately insert the pipe into the fitting worth a slight twisting motion until it bottoms in the socket. Quickly align fitting direction. Hold the joint together momentarily until cement has set. Remove excess cement from the joint. (ASTM F 493 Para X1.6)
7. After the joint has been made, the piping shall not be moved until the drying time listed in table shown at the end of this Check list, has elapsed

Assembly of PVC Piping

1. Cut pipe square with the axis, using a fine tooth hand saw and a mixer box, or a fine tooth power saw with a suitable guide. Rotary cutter may be used if the cutting blades are specifically designed for cutting plastic pipe in such a way as not to raise a burr or ridge at the cut end of the pipe. Standard rotary metal pipe cutter may be used provided that all the ridge raised at the pipe end by the wedging action of the cutting wheels would be removed. (ASTM D 2855 Para 7.1)
2. Chamfer or deburr pipe (ASTM D 2855 Para 7.2).
3. Insert the pipe into the fitting and check that the interference occurs about 1/3 to 2/3 of the socket depth. (ASTM D 2855 Para 7.3)
4. Note: When the pipe and fittings are at their tolerance extremes or when schedule 80 pipe is used, it may be possible fully insert the dry pipe into the socket until it bottoms. If this occurs, the fit between the fitting should be snug.”
5. Surfaces to be joined shall be cleaned and be free of dirt, moisture, oil and other foreign material (ASTM D 2855 Para 7.4)
6. Apply the cement with the natural bristle, nylon brush or suitable applicator. Using a 1/2-in brush or dauber for nominal pipe size 1/2 in and less, a 1-in brush or dauber for pipe up through 2-in nominal pipe size and a brush width at least 1/23 of nominal pipe size for above 2 in, except that for pipe sizes 6 in. and larger a 2-1/2 in brush is adequate. (ASTM D 2855 Para 7.5.2)
7. Apply primer to inside socket surface. Applicator or brush sizes shall be as specified in Item 20 of this check list. (ASTM D 2855 Para 7.5.3.1)
8. Soften surface of male end pipe, to be inserted into socket, to depth of fitting socket by uniform ally applying a liberal coat of primer. Be sure entire surface is well softened. (ASTM D 2855 Para 7.5.3.2)
9. Brush inside socket surface with primer, then without delay, apply cement to pipe while the surfaces are still wet with primer
10. Apply cement lightly but uniformly to inside socket (ASTM 2855 Para 7.5.3.4)
11. Immediately after applying the last coat of cement to the pipe, and while both the inside socket surface and the outside surface of male end of the pipe are SOFT and WET with solvent cement, forcefully bottom the male end of the pipe in the socket. Turn the pipe or fitting 1/4 during assembly (but not after the pipe is bottomed) to distribute the cement evenly
12. Assembly shall be completed within 20 seconds after the last application of cement. (ASTM D 2855 Para 7.7.1)
13. After assembly, wipe access cement from the pipe at the end of the fitting socket. (ASTM D 2855 Para 7.7.2)
14. After the joint has been made, the piping shall not be moved until the drying time listed in table shown below, has elapsed.

Joint Drying Time Before Movement

Note : These Temperatures are pipe surface temperatures and are not air temperature limitations.

International Codes and Standard References for Assembly of Thermoplastic (PVC, UPVC, CPVC and HDPE) Piping

RTR and Thermoplastic Piping Material Receiving Inspection (Pressure and Sewer Pipe)

RTR and Thermoplastic Piping Handling, Storage and Preservation Checklist

1- SAES-S-070 – Installation of Utility Piping System.
2-SAES-L-610 – Nonmetallic Piping.
3-ASTM F 493 – Standard Specification for Solvent Cements for Chlorinated Poly(Vinyl Chloride) (CPVC) Plastic and Fittings.
4-ASTM D 2855 – Standard Practice of Making Solvent-Cemented Joints with Pol(Vinyl Chloride) (PVC) Pipe and Fittings.