Purpose: To define and provide installation rules for vapour and liquid detection for liquid hydrocarbon terminals. Ethanol and FAME (these products are considered as hydrocarbon for this company rule) are also
included in this company rule.
Application : Liquid hydrocarbon terminals in M&S perimeter (Refer also to document GM-GR-DJ-001 for JV Depots) with a capacity exceeding 1000 m³. This Company Rule outlines the minimum requirements for MS perimeter. However, if local regulations are more stringent, then those shall be applicable.
Purpose
Application
1 – Reference documents
2 – Abbreviations
3 – Generalities
3.1.1 – Product properties – with respect to LEL and Flash point
3.1.2 – Objectives – Functions
3.1.3 – Types of Hydrocarbon detector
3.1.4 – Safety of the detection system
4 – Information collection and management
5 – Installation rules
5.1 – Bunds
5.1.1 – Bund with low flash point products
5.1.2 – Bunds with high flash point products
5.1.3 – Bunds with low and high flash point products
5.1.4 – Double wall tanks
5.1.5 – Remote impoundement
5.2 – Pumphouse
5.2.1 – Pumphouse with pumps for high flash point products
5.2.2 – Pumphouse with pumps for low flash point products
5.3 – Other installations
6 – Tests and calibration
6.1.1 – Vapour hydrocarbon detectors
6.1.2 – Liquid hydrocarbon detectors.
Vapour and Liquid Hydrocarbon Detection System
1 – Reference documents
CR-MS-HSEQ-332 : Overfill Prevention Process in conjunction with REG-GR-SEC-029 ;
CR-MS-HSEQ-161 : Opérations critiques et situations dégradées
STD-LOG-001 : Hydrocarbon detection
STD-LOG-040 : Water treatment
CR-MS-EXP-001 : Tanks operation
GS-MS-ELE-001 Electrical design
GS-MS-INS-012 Hydrocarbon and Fire Detection
2 – Abbreviations
LEL – Lower explosive limit
FAME – Fatty acid methyl esters (biodiesel)
PLC – Programmable logic controller
3 – Generalities
3.1.1 – Product properties – with respect to LEL and Flash point
* If kerosene (including Jet A-1) is stored at a temperature higher than its flash point, it should be considered as a low flash point product.
3.1.2 – Objectives – Functions
From the CR-MS-HSEQ-332 : §7.10.2 – Loss of containment detection, a hydrocarbon detection device shall be put in place in liquid hydrocarbon depots, covering the different parts of the facilities as detailled in the following chapter.
The purpose of this device is to detect as quickly as possible any leakage of product and the location of this leakage, so that, urgent action should be taken to avoid an accident or a loss of product.
Depending of the product and of its characteristics, liquid or vapor detector (or both) shall be implemented.
A risk analysis specific to the depot shall define the different parts of the facilities needing such a device, and also, the kind and the location of detector for each of them (see §5), but at least, the facility will be in accordance with the rules defined in chapter 5.
3.1.3 – Types of Hydrocarbon detector
Two types of hydrocarbon detector are used in liquid hydrocarbon depot :
Vapour Hydrocarbon detector VHD
Liquid Hydrocarbon detector LHD
Vapour Hydrocarbon detectors
The following hydrocarbon vapour detectors (non exhaustive) are available :
Catalytic sensor detectors
Spot infrared detectors
Infrared beam barrier
Photo Ionisation Detector (PID)
Liquid Hydrocarbon detectors
The sensor is either a (i) probe that can monitor the thickness of the hydrocarbon phase floating on water in the sump or oil-water settling chamber or a (ii) liquid liquid hydrocarbon detector fitted on a float or fixed and designed to detect a layer of fuel that exceeds a specific thickness.
3.1.4 – Safety of the detection system
This device is an important equipment for safety. Detectors (sensors), controls systems (relays or PLCs) and monitoring systems shall be fail safe i.e. in case of any failure, the default is activated.
The entire detection system shall be provided with backup power supply in case of power shutdown. The time of support shall be at least 1h, as describes in GS MS ELE 001. If it is not the case, an appropriate procedure has to be implemented accordingly to the CR Downgraded situations.
Emergency shut downs (ESD) shall not have any action on the hydrocarbon detection system. This device still remain in use even if any other safety equipment is activated.
The functioning of the detection system shall never be bypassed unless specific approval is obtained for such Downgraded Situation (eg maintenance). In that case, an appropriate procedure has to be implemented accordingly to the CR Downgraded situations. A Schedule of test and maintenance shall be define, in accordance with the chapter 6
4 – Information collection and management
In case of liquid or vapour hydrocarbon detection, a sound or/and light alarm shall be triggered and heard/seen in every appropriate place permitting to the depot staff to take action as quickly as possible.
As a good practice, It is recommended that a monitor screen displaying the layout of the terminal with position of each detector is available. A specific procedure for each terminal shall describe all the actions to be taken in case of an alarm.
Every gas or liquid detection are recorded.
5 – Installation rules
The number of detectors and their location will be determined considering the operational area, its topography (low points), general wind direction, likely location of source of potential leaks and ignition (flanges, connections..) and on the results of a risk analysis.. At least, the following rules shall be respected.
5.1 – Bunds
5.1.1 – Bund with low flash point products
One hydrocarbon vapour detector shall be installed at the lowest point (with due consideration to wind direction) in each bund within the enclosure.
5.1.2 – Bunds with high flash point products
Liquid hydrocarbon detector shall be installed in the collection sump or drain pit at the lowest point of each compartment within the enclosure.
5.1.3 – Bunds with low and high flash point products
One hydrocarbon vapour detector and one liquid detector shall be installed at the lowest point (with due consideration to wind direction) in each bund within the enclosure.
5.1.4 – Double wall tanks
No hydrocarbon detection shall be required outside the outer shell of the tank since there is hydrocarbon detection between the two shells, according to the type of product.
Remark: the double skin tanks do not need any hydrocarbon detection, but a leak dectection, refers to CR MS EXP 001 tank operations.
5.1.5 – Remote impoundement
Hydrocarbon detector shall be installed in this type of bund.
5.2 – Pumphouse
5.2.1 – Pumphouse with pumps for high flash point products
At least one liquid hydrocarbon detector shall be installed at the lowest point of the pump house in the water collection sump or drain pit.
5.2.2 – Pumphouse with pumps for low flash point products
At least one vapour hydrocarbon detector shall be installed in the pump house, near the lowest point with due consideration to wind direction.
Depending on the area of the pump house and number of pumps, it may be necessary to install more than one vapour hydrocarbon detector.
In case of a pump house with pumps delivering the low and high flash point products, the rule defined for mixted products bund is to apply.
5.3 – Other installations
Vapour Recovery Unit (VRU)
A liquid hydrocarbon detector shall be installed at the lowest point of the pump house in the collection sump or drain pit. Depending on the area of the VRU, a vapour hydrocarbon detector shall be located in the best location based on the risk assessment (with due consideration to wind direction).
Water separation unit
Oil water separators shall be fitted with one liquid hydrocarbon detector to detect presence of hydrocarbon before the exit of the separator. The detection will give an audible and visible alarm. A good practice is having an automatic valve.
Note : A densimetric stop-valve with an alarm is considered as a liquid hydrocarbon detector.
Pipeline Receipt manifold (for receipt by pipe, rail, vessel and truck) and Pipe Ways
For the manifold inside the terminal (vessels and pipeline receipt), a hydrocarbon detector will be install, with the same rules as a pump house. For the rest of parts of the facility, the need and the kind of detection system shall be defined by a risk analysis.
6 – Tests and calibration
The different operation of test, maintenance and calibration are recorded for each detector.
6.1.1 – Vapour hydrocarbon detectors
Proof of testing : twice a year in accordance with supplier specifications. The calibration is realised by a specific contractor if needed.
6.1.2 – Liquid hydrocarbon detectors
Proof of testing : twice a year in accordance with supplier specifications