LPG storage in fixed storage installations are subject to the regular inspections and the preventive maintenance established in the "Technical regulations covering the distribution and use of gas fuels, and in the complementary technical Instructions in JCG 01 to 11 (Royal Decree 919/2006).

The correct maintenance of the installations is a basic condition for guaranteeing its correct functioning and the fulfilment of all the safety measures and, therefore, recommendations for ensuring the correct maintenance of your bulk LPG installation are given below.

Tanks and equipment must be subjected to the tests indicated by their manufactures and by current legislation. For each installation, a Maintenance Book or Document File must contain at least the following:

  • Plan of installation, in which the initial layout of pipes must be precisely indicated with exact dimensions, as well as the final layout after any modifications have been made;
  • Dates and types of inspections that have been carried out, defects observed and repairs performed and, if appropriate, readings of the protection potential (underground steel tanks and pipes).

MAINTENANCE OPERATIONS IN BULK LPG INSTALLATIONS

Preventive maintenance operations must ensure that the installation has the correct gas tightness and is fit for purpose. If the regulations do not mention the minimum number of maintenance inspections/operations per year, the recommended minimum is two. Standard UNE 60250 indicates that the operations to be carried out during said maintenance should include at least the following:

  • Verification that all the elements of the installation are in good condition where they are visible. Special attention should be paid to:
    • The condition of the paint on the elements of the installation, checking that there is no discontinuity or indications of corrosion.
    • Functioning of control and metering instruments (pressure gauges, levels, etc.)
    • Existence of signs forbidding smoking and displaying the emergency telephone number.
    • Checking the existence of drainage, anchoring and foundations.
    • Verifying the correct condition of the enclosure (continuous, and permitting the correct ventilation of the station), access door and locks.
  • Checking the gas tightness of the elements of the installation up to the gas tap at the entrance to the building (tanks, pipes for both the liquid phase and gas phase, vaporiser etc.). This inspection should be carried out with air, inert gas or the gas supply, and with at least the service pressure corresponding to each section or piece of equipment.
  • The gas tightness test can be carried out using a pressure gauge of the appropriate scale or using a gas detector when the entire installation or section is accessible. Any leaks should be located using soapy water, gas detectors or other appropriate method. Open flames should not be used to detect gas leaks. If the average flow rate at service pressure is less than 1 l/h, it is considered that there is no leak in the gaseous phase. If a leak is detected, the tap must be sealed and the installation must not be used, with the leak being repaired as soon as possible.
  • Checking the manoeuvrability of the taps and verifying that they are gas tight at service pressure, using soapy water or a leak detector.
  • Verifying that there are no flammable materials, flash points, unprotected electrical equipment or other foreign elements in the LPG station.
  • For underground tanks, verifying the absence of corrosion in the tank by way of a potential reading according to the requirements of Section 7.7.1.2 (Standard UNE 60250) in the case of tanks with cathodic protection and replacement with new anodes, supplied by DISA, when required and according to the manufacturer's specifications in the case of tanks with additional protection.
  • Verifying the existence of firefighting materials, and that it is in good apparent condition, accessible and ready for use, as well as the working order of the sprinklers and the fire hydrant, if appropriate.
  • Verifying the current status of the regulation inspections of firefighting materials.
  • Verifying the general fulfilment of the requirements of the standard with respect to visible parts, and especially with regard to the safety distances required.
  • Verifying that the earth return is in good condition by measuring the earth resistance, which should be less than 20 ohms. In rooftop tanks, the earth resistance measurement can be taken directly on the tank.
  • Reading of the existing gas in the tank.
  • Checking to see if changes have been made to the exterior of the installation when compared to the original project and to the relevant legal authorisation.
  • Carrying out any necessary repairs for the smooth running of the installation, following acceptance by DISA.
  • Cleaning the surface area of the LPG station, removing weeds and keeping the ground well compacted so that it can be driven over. Withdrawing all flammable material stored in the area of the tank and/or in the parking area of the tanker truck. In general, removing anything that "shouldn't be there."
  • In general, monitoring all conditions that could affect the safety or smooth running of the LPG installation.

All operations carried out should be reflected in the corresponding Maintenance Book or File Document of the installation.


REGULAR INSPECTIONS

LPG storage installations in fixed tanks should be inspected by the maintenance company with whom the owner of the installation has signed the mandatory maintenance contract. These inspections should include the whole installation as described below and the timescale should coincide with the maintenance inspection of the reception installation (every 5 years), with both inspections being carried out at the same time.

For the carrying out of the regular inspection, the correct gas tightness and usage should be verified. To achieve this, the following points will be taken into account:

  1. Checking the last certificate or inspection report issued by the authorised body.
  2. Visual inspection of the installation, with verification of the safety distances indicated in Standard UNE 60250.
  3. Correct condition of firefighting equipment.
  4. Checking, on visible parts, the condition of the outer lining of the tank (must maintain a continuous layer with no indication of corrosion), pipes, drains, anchors, and foundations.
  5. Functioning of taps, control and metering instruments (pressure gauges, levels, etc.), regulators, transfer system, vaporisers and remaining equipment.
  6. The condition of the enclosure, access door and locks. Check that no elements foreign to a storage facility are present inside the enclosure.
  7. Existence and condition of the mandatory signage.
  8. Checking the correct working condition of the systems protecting against corrosion or the tests indicated by the manufacturer of tanks with additional protection.
  9. Measurement of the resistance in the tank's earth return.
  10. Testing the gas tightness of the pipes in the gaseous phase at operational pressure.
  11. Testing the gas tightness of the open charging point and transfer hoses at 3 bar for 10 minutes.
  12. Checking gas tightness by way of a 3 bar test or gas detector in the underground pipes for the liquid phase of charge, except at the charging point.
  13. Checking for gas tightness at operating pressure by means of soapy water or a gas detector in the rest of the elements (such as tanks, valves, gauges, purges, accessories or equipment)
  14. Prepare a CERTIFICATE OF REGULAR INSPECTION.

For installations in existence before the entry into force of current regulations, the technical criteria for the carrying out of Points 1 to 8 in the above list will be those established according to the prevailing regulations (in Spanish) at the time of installation.


PRESSURE TEST

The pressure/hydraulic test is the name given to the test to which the apparatus covered by the Regulation of Pressure Equipment must be subjected.

The tank must be subjected to a pressure test every fifteen years. The owner of the installation must arrange for a Monitoring Authority to carry out the regular pressure tests which, helped by the company contracted to carry out maintenance work, will carry out the test and issue a TEST REPORT once said operation has been carried out satisfactorily. Pressure tests will be carried out according to Standard UNE 60250 regarding tests and trials, as stated below:

  • Pressure test of tank(s), according to that established in the Pressure Equipment Regulation. This consists of hydrostatic pressure testing to 1.43 times the design pressure for 10 minutes as of the moment the pressure is stabilised.
  • Pressure test in liquid phase pipes at 29 bar for 10 minutes as of the moment the pressure is stabilised.
  • Testing of the gas tightness of the tank at a pressure of 3 bar, with air, inert gas or LPG in a gaseous phase.
  • Testing of gas tightness of the pipes of liquid phase at a pressure of 3 bar with air, inert gas or LPG in a gaseous phase for 1 hour, which could be reduced once the pressure is stabilised to 30 minutes in test sections that are less than 20 metres.
  • Testing of gas tightness of the pipes of gaseous phase according to the tests established in either Standard UNE 60310 or UNE 60311, whichever is appropriate, depending on service pressure.

During the pressure test the Maintenance Contractor will install, if necessary, a bank of cylinders that will be provided by DISA, to ensure supply.

The operations included in the pressure test, are listed below:

  1. The tank being tested will be drained, either by using up the remaining content or by transferring it (draining) to a tanker truck.
  2. The residual gas will be flared in appropriate incinerators. Residual gas is understood to be gas remaining in the tank and that, due to its pressure, is not available for consumption by the user(s).
  3. Flaring of the residual gas in its entirety will take place before breaking the top slab of the tank in the case of underground tanks.
  4. Once atmospheric pressure has been reached inside the tank, it should be filled with water at the same time as the displaced gas is flared.
  5. The gas flaring operation is complete when water flows out of the burner.
  6. To avoid the possible entry of gas or water contained in the tank into the water supply line, a non-return valve must be used.
  7. In particular in this operation, the placing of too much pressure on the tank using the available pressure in the mains supply of water is forbidden.
  8. The valves are removed, replacing the magnetic fault indicator with an appropriate blind flange during pressure testing.
  9. The tank will be subjected to hydrostatic pressure testing to 1.43 times the design pressure for 10 minutes as of the moment the pressure is stabilised.
  10. The liquid phase pipes will be subjected to a pressure test at 29 bar for 10 minutes as of the moment the pressure is stabilised.
  11. The safety valves and other equipment will be subjected to the tests specified for them in the applicable legislation.
  12. Completely drain all the water, leaving the tank perfectly dry as well as, where appropriate, the vaporiser and pipes.
  13. Collect the water used for the testing in tanks that are suitable for this purpose, supplied by the company responsible for managing the test.
  14. Thoroughly scrape and brush the sheet metal of the tank until all rust is removed.
  15. Paint the metal with a priming coat of bituminous paint applied by brush to a thickness of 75 to 100 microns.
  16. Remount the tank valves using tested or new accessories.
  17. Purge with nitrogen in the proportion of 54% of the volume of the tank, and blowpipes and elements to expel any residue.
  18. Carry out the same operation in the vaporiser and liquid phase tubes.
  19. Ensure the correct painting of pipes that are buried in trenches. Scrape and paint overhead sections and accessories.
  20. Purge with nitrogen and attend the first fill.
  21. Mount/Dismount the gas cylinder bank.