Safety at gas receiving station
As a connected party and owner of the connection building, you are responsible for safety. The safety regulations in the European Directive on safety in potentially explosive atmospheres (ATEX) apply to the installation in the gas receiving station as well as the space in which the installation is installed.
In the interests of safe working practices, you should always inform Gasunie of works within the zone. You can contact our operational work preparation personnel for that. For the telephone numbers, see “Safety Contact”.
Classification of the building and consequences for electrical equipment
The safety classification for indoor spaces and the associated standards depends on the ventilation factor of these spaces (the number of times per hour that the content of the space is ventilated). Almost all gas receiving stations are ventilated less than five times per hour. Consequently the gas pressure regulation space is classified as zone 1. The space within a one metre radius of the ventilation openings and door openings on the outside of the gas pressure regulation space also comes within zone 1.
Gasunie has produced drawings of the zones at the station, on which gas pressure regulation space and the outside up to one metre away are classified as zone 1. This has consequences for the equipment used in this zone. Gasunie ensures that its installation complies with these regulations. It is your responsibility to ensure that the part of the installation that you own complies with the regulations.
Gasunie has the complete electrical installation at the station tested once every 8 years. Gasunie will inform you of any defects in your installation and will ask you to rectify them.
Your gas installation connection and gas installation must not constitute a hazard that could disrupt the operation of the national gas transmission network. To comply with section 2.9 of the Connection Conditions for Gas - NNO, you must take the following measures in your own gas installation connection. Failure to comply with this condition means that section 2.10 of the Connection Conditions for Gas - NNO apply. Protective measures are taken in the gas receiving station to protect the connected party's gas installation from too high gas pressure.
The design pressure must always be higher than the pressure of the gas supplied to you by Gas Transport Services. This is necessary because the regulated pressure is protected in the gas receiving station by a blow-off safety feature and 1 or 2 cut-out safety features. A margin is necessary to ensure that this is set up to operate safely.
The table below gives the relation between supply and design pressure (MOP; maximum operating pressure and the maximum outlet pressure (MIP; maximum incidental pressure) of the GOS.
Gas receiving station - Gasunie Possible highest setting of safety features in the GOS Outlet pressure (Pu) Normal supply pressure MIP (max. incidental pressure outlet side) bar bar 0,5 t/m2,0 4,4 > 2,0 t/m4,0 6,6 > 4,0 t/m8,0 11,0 > 8,0 t/m13,6 17,6 > 13,6 t/m15,0 22 > 15,0 t/m17,0 22 > 17,0 t/m22,5 27,5 > 22,5 t/m38,0 44 40 (open pijp) 46 (1.15 X MOP) 80 (open pijp) 92 (1.15 X MOP)
The minimum design pressure of your gas system depends on the highest setting (MIP) of the safety features in the gas receiving station and on the chosen design code/standard for your system. Based on these data, a notified body (NoBo) must determine what the design pressure of your gas system should be.
A supply pressure as shown in the first column is agreed with you (see table under; How high should the design pressure of the gas installation connection and the gas installation after the gas receiving station be?.
The table shows the maximum pressure allowed in the pipeline in the event of an incident.
You must ensure that the design pressure of your pipeline system is suitable for this MIP. If appliances are connected to this system which do not normally work if the gas pressure approaches the MIP (see 2nd column), then these appliances must be protected against this. This can be done by means of electric or mechanical safeguards against overpressure.
There is normally one supply gas pressure regulator in the gas receiving station/letdown station, equipped with safety devices to reduce the gas pressure to the set value of the gas outlet pressure and a second reserve gas pressure regulator which is identical. For higher capacities there are three gas pressure regulators (two supplying gas + a reserve). In the event of a fault in the supply gas pressure regulator or when maintenance work is being done, the reserve takes over the gas supply at a lower pressure. To give an indication, the pressure can drop 0,3 bar in a gas receiving station/letdown station equipped with two gas regulators in these circumstances. Where there are three gas regulators, in the worst case scenario the pressure can drop by about 0,6 bar. This can affect the settings of the low pressure monitoring system in your combustion installation. You are therefore recommended to set your low pressure monitoring system to a minimum of 0,4 to 0,7 bar (depending on the number of runs in the gas receiving station) lower than the settings of the gas receiving station, taking account of the loss of pressure over the connecting pipelines.
You must be able to demonstrate that the installation has been designed, manufactured and inspected in accordance with the applicable legislation and regulations. You must be able to demonstrate that the installation has been maintained and inspected in accordance with the applicable legislation and regulations throughout its use.