1.1 Drainage System
The petroleum production facilities shall be equipped with the following drainage systems :
a) Oil drain
b) Oily Contaminated Water
c) Clean Water A (subject to accidental Oil contamination)
d) Clean Water B (not subjected to accidental Oil contamination)
e) Sanitary Water
f) Chemical water
The petroleum production facilities shall be equipped with the following drainage systems :
a) Oil drain
b) Oily Contaminated Water
c) Clean Water A (subject to accidental Oil contamination)
d) Clean Water B (not subjected to accidental Oil contamination)
e) Sanitary Water
f) Chemical water
1.2 Types of Drainage System
The following sections provide guidance on types of drainage system and the basic design features to be incorporated within the drainage system.
1.2.1 Ditch Gravity Drain System
The effluent flows in open channels or drains normally lined and laid to falls or level.
1.2.2 Closed drain Gravity System
The system is configured as a conventional gravity system with sealed access manholes. The materials and construction techniques used are of a higher integrity than open system.
The oil contaminated water line in process area will be flood system except inside dike sewer line and main trunk line. Seal height will be kept 50 mm from inside top of pipe.
Connections to the drainage system are by airtight connections at tanks, bunds, process unit, etc. At changes of gradient and direction, bends are used instead of manholes. Connections from laterals to the main sewer line are by flat tees or branches.
1.2.3 Oil Traps and Debris Collection
At the discharge side of the drainage system, traps for oil, silt and debris shall be provided.
The following sections provide guidance on types of drainage system and the basic design features to be incorporated within the drainage system.
1.2.1 Ditch Gravity Drain System
The effluent flows in open channels or drains normally lined and laid to falls or level.
1.2.2 Closed drain Gravity System
The system is configured as a conventional gravity system with sealed access manholes. The materials and construction techniques used are of a higher integrity than open system.
The oil contaminated water line in process area will be flood system except inside dike sewer line and main trunk line. Seal height will be kept 50 mm from inside top of pipe.
Connections to the drainage system are by airtight connections at tanks, bunds, process unit, etc. At changes of gradient and direction, bends are used instead of manholes. Connections from laterals to the main sewer line are by flat tees or branches.
1.2.3 Oil Traps and Debris Collection
At the discharge side of the drainage system, traps for oil, silt and debris shall be provided.
1.3 Design Criteria
The following design criteria shall be used to design drainage system:
1.3.1 Rainfall Intensity
The estimate of design rainfall intensity is 200 mm/ hour
1.3.2 Runoff coefficients
Runoff coefficients shall be as follows:
The following design criteria shall be used to design drainage system:
1.3.1 Rainfall Intensity
The estimate of design rainfall intensity is 200 mm/ hour
1.3.2 Runoff coefficients
Runoff coefficients shall be as follows:
1.3.3 Minimum earth covering
Minimum earth covering for buried pipes shall be as follows :
Minimum earth covering for buried pipes shall be as follows :
1.3.4 Minimum Pipe Size
The minimum pipe size shall be as follows :
1. Branch = 4-inch diameter
2. Lateral = 6-inch diameter
3. Main line = 8-inch diameter
The minimum pipe size shall be as follows :
1. Branch = 4-inch diameter
2. Lateral = 6-inch diameter
3. Main line = 8-inch diameter
1.3.5 Freeboard
The minimum freeboard for an open ditch shall be 100 mm.
1.3.6 Drainage area
The maximum catchments area of drainage flow to a catch basin shall be 400m² in paved areas, and 900m² in unpaved areas.
1.3.7 Vent Pipe
In process area where furnaces are present, adjacent manholes shall be vented to a safe location.
Water sealed manhole shall have a vent pipe and shall be minimum 3-inch diameter pipe size.
The vent pipe shall oriented to avoid hazards to personnel.
The terminating point for vent pipe shall be located as follows :
At least 3-meter above any adjacent service platform
A minimum of 3-meter above grade
At least 15-meter measured horizontally from any fired heater or other source of ignition
A minimum of 1-meter above roof building
A minimum of 1-meter above highest level of pipe rack.
1.3.8 Discharge (Q) formula Calculation of discharge will be used by “Rational Formula”.
Q = 0.277 C I F m³/ sec. (SI unit)
where:
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