When protecting oil and gas facilities from lightning, special attention is paid to places of possible gas leakage, as well as to breathing valves. The ZANDZ technical center was given a task of performing lightning protection of the manifold at an oil tank farm
A manifold is a valve block with many flanged pipe connections and a large number of isolation valves. It is necessary to protect not only the listed places, but also the space within 3 m horizontally and vertically from them in case of gas escape and sparks entering it. Near the manifold there is a drainage tank with a breathing valve, the space above which must also be protected within 5 m horizontally and vertically.
Due to the presence of a lightning rod 35 m high, united with a mast, and a lightning rod on a tank 23 meters high in the tank farm, it was enough to install one free-standing lightning rod with a height of 14 m to protect these objects.
The following news will tell you how to properly perform lightning protection of the manifold and drainage tank.
It is necessary to calculate the lightning protection and grounding of the manifold and the drainage tank using the existing lightning rods.
Calculations of lightning protection are made in accordance with the following documents:
- Electric Installation Code" EIC 7th ed. (hereinafter - EIC).
- Instructions for organization of lightning protection of buildings, structures and industrial communications" IS 153-34.21.122-2003 (hereinafter IS).
- Instructions for lightning protection of buildings and structures" AD 34.21.122-87 (hereinafter - AD).
Lightning arresters are used for protection of structures from lightning strikes. The lightning conductor usually consists of a lightning rod, intercepting the lightning strike, a down conductor and a ground electrode. All these elements allow to safely drain lightning current into the ground without a damage for the protected object.
In accordance with IS, the object is classified as special, representing danger to the immediate environment. According to AD, the manifold (outdoor installation of class B-Iг) belongs to the II category of lightning protection.
Upon the customer's request, the protection zone of lightning rods should include the following space:
- within 5 m horizontally and vertically from the breathing valve of the drainage tank;
- within 3 m horizontally and vertically from isolation valves and flanged joints of pipelines.
Description of manifold and drainage tank external lightning protection system
The set of measures to provide the required lightning protection of the manifold and drainage tank is offered by the following solutions:
- Installation of one ZZ-201-014 free-standing air terminal 14 m high.
- Existing lightning rods with the height of 35 m and 23 m are used.
- Lightning rods create protection zones with the reliability of 0.9 at the marks hx1 = 7.5m and hx4 = 5.37m, indicated in Figure 1.
Figure 1. Plan with the layout of lightning protection elements and grounding device
The set of measures on the provision of the necessary requirements to the grounding device is presented by the following solutions:
- Laying of the horizontal ground electrode for current spreading in two directions with an angle of 90 degrees between them. The ground electrode is made of corrosion-resistant copper-bonded steel tape with the cross-section of 4x30 mm (GL-11075), the depth of laying is 0.5 m.
- 2 vertical electrodes (copper-bonded steel rods with the diameter of 14 mm) 3 meters long are installed with the distance between them of at least 5 m.
- An embedded part of the foundation is used as the third vertical electrode.
- Connection of vertical and horizontal electrodes, as well as horizontal electrodes with a lightning rod is carried out with the help of clamps ZZ-005-064.
Accessories for lightning protection of manifold and drainage tank
Table 1 - List of material needs
|Lightning protection system|
|1.||ZZ-201-014||ZANDZ Vertical lightning rod 8 m high (galvanized steel; with embedded parts under the foundation)||1|
|2.||ZZ-005-064||ZANDZ Clamp for connecting conductors (up to 40 mm)||3|
|3.||GL-11075-10||GALMAR Copper-bonded tape (30 * 4 mm / S 120 mm²; coil of 10 meters)||1|
|4.||ZZ-001-065||ZANDZ Copper-bonded threaded grounding rod (D14; 1.5 m)||4|
|5.||ZZ-002-061||ZANDZ Threaded coupler||3|
|6.||ZZ-003-061||ZANDZ Starting tip||2|
|7.||ZZ-004-060||ZANDZ Driving head for a jackhammer||1|
|8.||ZZ-006-000||ZANDZ Conductive grease||1|
|9.||ZZ-007-030||ZANDZ Waterproof tape||1|
|10.||ZZ-008-000||ZANDZ Header for a jackhammer (SDS max)||1|
Do you have questions about calculation of lightning protection of the manifold and the drainage capacity? Please contact our ZANDZ Technical center!