This article is about RTR Piping Installation, Specification, Laying and Assembly in commercial buildings, plants and refinery projects related to Plumbing Engineering System as per international codes and standards.
RTR Piping Installation, Specification, Laying and Assembly
Laying RTR Piping in the Trench
All RTR pipes and fitting shall be visually inspected for scratches, damage end, cracks, delamination, crushing, weathering, and cracked O-rings and gaskets.
Visual acceptance limits on allowable defect on RTR pipe and fitting shall be in accordance with table 1 of 01-SAMSS-029 and Table 3 of 01-SAMSS-034. Damage pipe and fittings shall not be installed.
RTR Sewer Pipes & Fittings for Gravity Flow 01-SAMSS-029
RTR Pressure Pipe & Fittings – 01-SAMSS-034
- Pipe and fittings shall be cleaned and dried before installation.
- Any primer, solvent cement or adhesive that is beyond the stamped expiration date shall be discarded, Solvent cement that has gelled or thickened shall be discarded. Leaking or open containers shall also be discarded.
- Unrestrained gasketed joint piping must be joined together in the trench.
- Adhesive bonded and restrained gasketed joint piping of 250 mm nominal pipe size and less may be assembled next to, or in the trench. Piping larger than 250 mm nominal pipe size shall be assembled in the trench.
- For trenches 2 m deep or less, pipe assembled next to the trench shall not be moved within three pipe lengths of an uncured joint. The pipeline shall be lowered into the trench progressively to avoid excessive joint angular deflection
- For trenches deeper than 2 m, pipe shall be assembled in the trench.
- Geotextile shall be used depending upon the soil condition to prevent soil wash away around the buried pipe.
- In trenches containing firewater lines and piping with internal pressure in excess of 200 psi, a non-woven geotextile with a unit weight of at least 130 g/m² should enclose the clean sand bedding layer and backfill materials.
Note: For other services or piping with internal pressure below 200 psi usage of the geotextile depends on the soil conditions. Refer to construction drawings or specifications to verify whether geotextile has been specified / required or not.” - 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.” - In pressurized systems, connections to metal valves, larger than 50 mm nominal pipe sizes, shall be by means of flanges.
- 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.
- 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 Authority Having Jurisdiction) flexible waterproof mastic sealant.
- 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.
- Threaded flanges shall not be used on nonmetallic piping systems.
- 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 tape wrap with UV resistant pressure sensitive tape utilizing adhesive that will not affect the plastic material.
- 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 RTR Piping
- Joints shall be of restrained type (adhesive-bonded, butt-and wrap lamination joints, or mechanical type joints), or unrestrained type (gasketed bell-and-spigot type joints).
- Joints shall be assembled in accordance with the manufacturer’s procedures for a specific application. Heating blankets shall be used to cure adhesive bonded joints.
- RTR flanges when used shall be of flat face. Mating flanges of different approved material shall also be of flat face. RTR flanges with factory manufactured confined O-ring gasket groove is also acceptable.
- They shall be assembled with full-face elastomeric gaskets, 3 mm thick, and 50 to 60 Shore A Durometer hardness.
- Flange pressure rating requirements and bolt tightening procedures and maximum torque requirements shall be in accordance with SAES-L-610.
- Gasket material including elastomeric seals shall be suitable for the type of fluid used, and the environment to which it will be exposed.
- Flat washers shall be used under nuts and bolt heads on nonmetallic flanges.
- The following guidelines shall be used for assembly of threaded connections up to 75 mm nominal pipe size:
a) RTR piping shall not be threaded in the field.
b) Chipped or cracked RTR threads, flattened metallic threads, and metallic threads with burrs shall not be used.
c) Threads shall be cleaned with a suitable solvent to remove oil and grease.
d) Temporary connections shall use a Teflon-based pipe-thread sealant without lumps or metallic additives.
e) Permanent connections shall use an epoxy-resin pipe-joint adhesive.” - Field-fabricated mitered fittings shall not be used.
1-½ inch and smaller connections for instrumentation, vents and drains may employ the pipe manufacturer’s recommended saddle type connection.
International Codes and Standard References for RTR Piping Installation
1- SAES-S-070 – Installation of Utility Piping Systems,.
2- SAES-L-610 – Nonmetallic Piping.
3- 01-SAMSS-029 – RTR Sewer Pipes & Fittings for Gravity Flow.
4- 01-SAMSS-034 – RTR Pressure Pipes & Fittings.
RTR and Thermoplastic Piping Material Receiving Inspection (Pressure and Sewer Pipe)
RTR and Thermoplastic Piping Handling, Storage and Preservation Checklist