BS/EN 14596-2018 pdf download.Tanks for transport of dangerous goods – Service equipment for tanks – Emergency pressure relief valve.
The emergency pressure relief valve shall be vapour and liquid tight up to its relieving pressure.
The relieving pressure of the emergency pressure relief valve shall be specified by the manufacturer and shall exceed the pressure arising from 110 % of the sum of:
— the maximum static head of liquid which would be applied by the densest substance in the tank compartment to which the emergency pressure relief valve shall be fitted, and
— the specified relieving pressure of the breather device fitted to the same compartment.
5.2 Weather protection
The emergency pressure relief valve shall be designed, or provision made, to eliminate the accumulation of water. which could freeze and impair the operation of the valve.
If a cover is used to provide the weather protection, then the cover shall not affect the operation or performance of the valve.
5.3 Drop test
Each type of emergency pressure relief valve shall be structurally capable of withstanding, without leakage or permanent deformation that would affect its structural integrity, a drop test as described in 6.3,4.
5.4 Vapour venting performance
The minimum vapour venting capacity of the valve shall be reached at a pressure less than the test pressure of the tank compartment to which it is attached.
5.5 Temperature range
Unless otherwise specified, the design temperature range shall be —20 °C to +50 °C. Where the emergency pressure relief valve is subjected to more severe conditions, the design temperature range shall be extended to —40 °C or +70 °C as applicable.
5.6 Materials of construction
The manufacturer shall provide, with the equipment, a full material specification for those parts which may come into contact with the substances described in Clause 1.
5.7 DimensIonal characteristics
The height of any part of the emergency pressure relief valve shall not exceed 150 mm, above its mounting face, when in the fully open position.
The test medium shall be air or other suitable gas. The choice of the test medium is the responsibility of the manufacturer. The test shall be performed on the complete valve.
— The valve shall be positioned in its normal operating orientation.
— With the valve in the closed position, a steadily increasing pressure shall be applied to the upstream side of the valve. The pressure acting on the downstream side of the valve shall be equal to atmospheric pressure.
— Once the relieving pressure has been noted, the upstream pressure shall be steadily reduced to confirm the reseat pressure.
— The valve shall be considered as starting to open when visually detectable leakage commences. Reseating of the valve shall occur when such leakage stops.
6.2.3.2 Acceptance criteria
The recorded relieving pressure shall be not less than the valve’s specified relieving pressure and the valve shall reseat at a pressure not less than 0,8 times the specified relieving pressure.
6.3 Type tests
6.3.1 General
A minimum of 2 production samples of each model type shall be type tested to demonstrate the performance and mechanical strength of the design.
NOTE Valves having one design. size and set pressure are considered to be of one model type. Unless otherwise noted, all type tests shall be performed at maximum and minimum design temperatures.
Type tests shall comprise the following:
— seat tightness test (EN 12266-1:2012, section A4); and
— relieving pressure test; and
— drop test, and
— Vapour venting performance test.
6.3.2 Seat tightness test
6.3.4.2 Test apparatus
The drop test apparatus comprises a vessel having on one side a mounting flange to which the device under test can be mounted. It shall have all the following characteristics:
a. the dimensions, tolerances and characteristics of the drop test apparatus shall be in accordance with Annex A;
b. the stops shall be of steel and shall not incorporate a material or design feature that would tend to cushion the impact;
c. the impact zone for the stops shall be as specified in Annex A (see detail of sand box);
d. the lifting and release equipment shall permit hoisting to, and dropping from, the test height;
e. the guides and the hoisting equipment shall not restrain free fall;
1. the design of the lifting apparatus and the operating procedures shall be In accordance with local safety regulations and shall be such as to prevent accidental dropping of the test apparatus;
g. the test vessel shall be able to be pressurized to meet the requirements of 6.3.4.3.6
6.3.4.3 Test procedure
The test procedure shall be carried out in the following sequence:
6.3.4.3.1. mount the complete device under test to the mounting flange of the drop test apparatus. The centre-line of the device shall be positioned on the centre-line of the securing flange;
6.3.4.3.2. fill the vessel with water to a level of 1,3 m above the centre-line of the securing flange.
Plug the level indication hole;
6.3.4.3.3. hoIst the apparatus to the release poInt, 1,2 m above rest position;
6.3.4.3.4. stir and smooth to an even consistency the sand of the sand boxes and replace the rubber pad;
6.3.4.3.5. release the apparatus and allow to drop through a vertical distance of 1,2 m;
6.3.4.3.6. within one minute of dropping, pressurize the vessel so that the pressure in the vessel at the horizontal centre-line of the device under test Is 0.8 times the device’s relieving pressure, wipe off the device under test and securing flange assembly and observe for leaks.BS/EN 14596-2018 pdf download.