This article is about Water Distribution System Design Guidelines and Layout specially Upstream of Isolation Valve in commercial buildings, plants and refinery projecs related to Plumbing Engineering System as per international codes and standards.
Water Distribution System Design Guidelines and Layout (Upstream of Isolation Valve)
- Following are the acceptable materials for water transmission and distribution piping networks in Plant hydrocarbon handling areas.
a) 12LC0U or 12LE0U, Steel pipe, ASTM A53 or API 5L, Grade B, cement lined or fusion bonded epoxy lined.
Note: Pipe shall be externally coated if installed below ground and cathodically protected as applicable
b) Ductile iron pipe, AWWA C151, cement lined and shall be externally coated if installed below ground. Joints shall be either ANSI B16.1 flanges or rubber compression rings per AWWA C111.
c) Ductile iron pipe, ISO 2531, cement lined and shall be externally coated if installed below ground. Joints shall be either ANSI B16.1 flanges or rubber compression rings per ISO 4633.
d) 12FE0U, RTR (Fiberglass) pipe per 01-SAMSS-034 for underground application only.
Note: This pipe class through 300 mm ø may be used for off-shore structures dedicated potable water services only.
e) Non-metallic pipe and fittings such as cPVC schedule 80 (12PU0U), HDPE, RTRP (FG Pipe, 12FE0U) may be used for above ground dedicated potable water services and shall have no connections with either fire water; fire/raw water or plant process water services.” - Following materials are the acceptable materials for water transmission and distribution piping network in all areas other than hydrocarbon handling areas.
a) Material listed in item No. A1 of this SAIC
b) 12PV0U, PVC per SASO SSA/14/15, Class 5 pipe and fittings shall be used for below ground applications only.
c) High Density Polyethylene (HDPE) pipe, as specified in ASTM D3350, ASTM F1248 and ASTM F714. Below ground applications only.
d) PVC ASTM D1785, Sch 80, 2″” ø to 6″”ø shall be use for below ground only and for repair or replacement of existing piping of the same type only. (See Item A4 for exemption) - Following are the acceptable materials for irrigation piping network.
a) 12PV0U, PVC, SASO SSA/14/15, class 5.
b) PVC, ASTM D1785, sch. 80 for lines 2″”ø through 6″”ø and shall be use for the replacement or repair of existing piping of the same type only.
C) High Density Polyethylene (HDPE) pipe per ASTM D3350, ASTM F1248 and ASTM F714. - Nonmetallic pipe and fittings, such as cPVC schedule 80 (12PU0U), HDPE, and RTRP (fiberglass pipe, 01-SAMSS-034, 12FE0U), may be used for above ground applications and the piping thereafter shall have no connections with either firewater, fire/raw combined water or plant process water services.
- Above ground installed non-metallic piping exposed to sunlight shall contain ultra-violet inhibitor or shall be protected from ultra-violet damage.
- Plastic pipes, pipe liners and fittings such as PVC, CPVC, HDPE and RTRP (fiberglass pipe); and O-rings, gaskets, lubricants and adhesives, used for potable water systems, shall be tested and certified as suitable for potable water use in accordance with National Sanitation Foundation (NSF) or equivalent standards approved by the chairman of Plumbing and Utility Standard Committee.
Note: Test certification shall be submitted to Saudi Aramco” - The seal or mark of the certifying organization shall be indicated on the pipe.
- Any branch of a water distribution piping network shall not be less than 63 mm nominal diameter
- The mains on water distribution piping network shall be laid out in closed loops with dual supply.
Exception: - The level of water supply reliability within a plant area is up to the proponent of the facility. The water distribution loop and / or dual supply may be omitted within plant area if it is not economically justified. However, a concurrence from the proponent of the facility is required.”
- Sleeves shall be provided to protect all piping through concrete and masonry wall (UPC 313.10.1)
- Unavoidable dead legs shall not exceed 91 m in length. A hydrant or flushing valve shall be provided on the end of raw water dead legs, and a flushing valve shall be installed on the end of drinking water dead legs.
- Minimum clear distance between raw and drinking water lines, if installed in the same trench, shall be 300 mm.
- Valves shall be provided for the following lines:
a. On water transmission lines—not more than 500 meters apart.
b. On major lines feeding to water distribution systems – not more than 1 km apart.
c. In a water distribution piping network – not more than 500 meters of main shall be isolated during single failure.
d. On all those branches of a water distribution piping network supplying water to buildings, facilities, fire fighting equipment, firewater systems, or any user’s points.”
Provide drain valves as required to facilitate maintenance and repairs at the lowest point of the piping system or as designated by responsible authority. - Provide Cross-connection controls to protect potable water systems in accordance with GI-0151.006, Saudi Aramco Sanitary Code and SAES-S-060.
- Back Flow Preventer (BFP) assembly, shall be installed at the following locations:
a) Between a water distribution system and an irrigation piping network. A BFP assembly shall be installed on every sprinkler circuit of irrigation piping network downstream from the remote-control valve.
b) Between a Saudi Aramco-owned water line and a municipal or ministry owned water line. A BFP assembly shall be installed on upstream of the isolation valve on Saudi Aramco owned water distribution system.
c) Between Saudi Aramco owned water systems that can be operated independently.” - All backflow Preventer (BFP) shall conform to AWWA C510, AWWA C511 or Saudi Aramco recognized industry standards.
Note: These assemblies shall be certified or listed by the agencies approved by the Chairman of Plumbing & Utilities Standard Committee.” - All backflow preventer (BFP) shall be tested after installation prior to commissioning of the system.
- Dielectric union, flanges or coupling shall be provided at each piping connection having dissimilar materials.
- Flat-faced flanges shall be mated with flat-faced flanges only and shall use full face gaskets. When the raised-face of a raised-faced flange is machined off, it can be used as a flat-faced flange.
- A sewer crossing a water line e.g. raw water, potable water, combined raw/fire water, dedicated fire water and irrigation water shall be orientated such that the sewer crosses under the potable water line with a minimum vertical surface clearance of 300mm.
- Thrust blocks shall be placed at every change in direction for non-metallic e.g. PVC; cPVC, HDPE, RTR; FRP, etc. piping system.
Exemption:
a) Thrust Blocks may not be necessary for piping in gravity flow systems.
b) Not required for 75 mm ø and smaller nominal pipe size with restrained joints.” - Thrust Blocks shall not cover the pipe joints of thermoplastic and RTR piping system.
- Plastic pipes such as PVC, uPVC, cPVC, RTRP, HDPE, PP, etc. shall be protected from direct contact with concrete by tape wrapping.
- Minimum Horizontal separation distance between sewer lines and water system e.g. raw water, potable water, combined raw/fire water, dedicated fire water and irrigation water shall be as shown in the Table-1 below: (SASC-Para 2.1)
*In the event that these separation distances can not be met, see item No. A23 in this SAIC- Any one of the following requirements must apply to sewer piping that, due to existing conditions must cross over a water piping e.g. raw water, potable water, combined raw/fire water, dedicated fire water and irrigation water regardless of vertical separation; and must have less than 300 mm clear separation even though running beneath the potable water line.
a) The sewer piping crossing a water line e.g. raw water, potable water, combined raw/fire water, dedicated fire water and irrigation water shall be one continuous joint of pipe and both ends of that sewer pipe shall be at least 3 meters beyond the point of crossing.
b) The sewer piping shall be encased in a concrete sheath for a minimum distance 3 meters in both directions beyond the crossing point. The concrete shall be at least 150mm thick. (see item A24)
c) The sewer line shall be encased in a sealed casing of either steel sleeve, PVC or RTR pipe for a minimum distance of 3 meters, in both directions beyond the point of crossing. - Plastic pipes such as RTR piping and fittings enters or leaves a thrust block or concrete encasement, it shall be wrapped with Neoprene wrapping must protrude slightly from the block or at the edges of concrete encasement.
- The thickness and the width of wrap shall comply with Table 5 of SAES-S-070 (Shown below), unless manufacturer requires more than one piece of wrapping.
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Table 5-Neoprene Wrapping Requirements Thickness And Width of Tape Wrap for Various Operational Pressure (mm) Nominal Pipe Size (mm) Atmospheric To 1600 kpa (230 psig) Over 1600 kpa (230 psig) 400 and smaller 12 x 150 mm 12 x 150 mm 24 x 250 mm 500-700 12 x 150 mm 24 x 150 mm 36 x 300 mm 800 and larger 12 x 300 mm 36 x 300 mm 36 x 300 mm - Identification: Color coding of Utility Piping
- All underground Utility Piping e.g. Potable Water System; Raw/Fire Combined Water System; Dedicated Fire Water System; Irrigation Water System, shall be identified through the valve boxes. Color coding shall be in accordance with Table 3 of SAES-A-104, SAES-B-067 and Saudi Aramco Sanitary Code, GI-0151.006 and the direction of normal flow shall be clearly shown at the upstream & downstream of the control valves. Minimum length of color field and size of letter shall be in accordance with the table shown below:
- All above ground Utility Piping e.g. Potable Water System; Raw/Fire Combined Water System; Dedicated Fire Water System; Irrigation Water System, shall be identified through the valve boxes. Color coding shall be in accordance with Table 3 of SAES-A-104, SAES-B-067 and Saudi Aramco Sanitary Code, GI-0151.006 and the direction of normal flow shall be clearly shown at every 20 ft (6096 mm) intervals. Minimum length of color field and size of letter shall be in accordance with the table shown below:
International Codes and Standard References for Water Distribution System
1-SAES-S-010 – Sanitary Sewers.
2-SAES-S-040 – Saudi Aramco Water Systems.
3-Uniform Plumbing Code (UPC), 2000.
4. Sanitary Sewer Pipe LayOut and Design Guidelines.