In the summer of 2023, the ZANDZ.com Technical Center (ZANDZ TC) made a calculation of lightning protection for a facility related to an oil and gas condensate field complex.
According to the explosive zone classification in the IEC, a room located beyond the explosive zone should be considered non-explosive if there are no other factors exist that may result in explosion in the room. Examples of such factors are Class B-Ia rooms, which are only accessible in the event of an accident and do not normally generate explosive mixes of combustible gas. Lightning protection of such facilities is made according to Category II of RD 34.21.122-87 (RD).
The object, which lightning protection calculation was performed by TC ZANDZ, is a block-modular building of turbo-expanding assembly made of sandwich panels. The expected lightning strike value per year is less than 1. The calculation shall be made for Zone B.
Protection zone of a double lightning arrester, RD, Appendix 3
Lightning protection solution for the facility
Protection of buildings against lightning strikes is provided by using lightning arresters. Lightning arrester is a device that is elevated over the protected facility through which the lightning current goes into the ground bypassing the protected facility. It consists of a lightning rod that accepts the lightning discharge directly, a current collector, and a ground terminal.
A set of arrangements ensuring compliance with the lightning protection requirements is based on the following solutions:
- two of 5 m lightning rods are installed on the wall. It is taken into account that 1 m of the height of lightning rod is necessary for mounting;
- the lightning arresters are interconnected to create two current collectors using galvanized wire D = 8 mm from each lightning arrester;
- current collectors are attached (with mounting step 0.6 to 1 m):
- on the roof and the wall using clamps ZZ-11747;
- current collectors are connected and branched using clamps ZZ-11551.
Solution for protective grounding
A set of measures to ensure the necessary requirements for the earthing device is represented by the following solutions:
- installation of a 3 m grounding arrangement consisting of a horizontal electrode (steel galvanized bar 4 x 30 mm), depth 0.5 m and 3 vertical electrodes (14 mm diameter copper-plated steel rods);
- interconnection of vertical and horizontal electrodes is carried out using clamps ZZ-005-064;
- connection of current collectors with the output of a galvanized bar from the ground is made using clamps ZZ-202-013;
- design of the grounding arrangement corresponds to item 1.7.55 of the EIC. Grounding arrangements for protective grounding and grounding for lightning discharges are common.
The location of the elements of the lightning protection system and the grounding arrangement is shown in a drawing in a separate file. The indicated protection zone corresponds to zone B according to RD.
The list of materials used is provided in Table 1.
Table 1. The list of required materials
Do you have any questions about lightning protection for the cadet school or other facilities? Please, contact the ZANDZ Technical Center!
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