MANIFOLD LIGHTING PROTECTION AT AN OIL PLANT IN TATARSTAN

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.

Task

It is necessary to calculate the lightning protection and grounding of the manifold and the drainage tank using the existing lightning rods.

Solution

Calculations of lightning protection are made in accordance with the following documents:

1. Electric Installation Code" EIC 7th ed. (hereinafter - EIC).
2. Instructions for organization of lightning protection of buildings, structures and industrial communications" IS 153-34.21.122-2003 (hereinafter IS).
3. 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:

1. Installation of one ZZ-201-014 free-standing air terminal 14 m high.
2. Existing lightning rods with the height of 35 m and 23 m are used.
3. 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.

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