Iran, because of its strategic position, has experienced attacks and conquests leading to the building of many towers, forts, castles, and so on that are older than 3000 years. Defense plays an important role in humans' lives, because all humans like security and peace and try to maintain them in their personal and social lives. Providing security and peace in personal and social lives requires the observation of principles to which all individuals should stick to. The type and quality of events and humans' defense styles can lead to both a reduction in threats and an increase in them. Defense is an important factor which helps humans to solidify and preserve their identities and if they do not try to maintain principles that are valuable to them, in fact they lose part of their identity. Now, those countries with more effective and more advanced passive defense, which have allocated big budgets to this type of defense, are more successful in wars and when facing natural disasters. On the one hand, the occurrence of critical situations stemming from natural disasters such as earthquakes, floods, and on the other hand, the complexity of wars and modern technologies used in wars has given a different face to passive defense. Currently, the most important purpose of passive defense is to immunize and reduce the vulnerability of necessary infrastructures. Such measures have been taken in most countries or they are being taken. Passive defense refers to measures that do not require the usage of warfare; and by taking these measures, we can reduce damages to important and sensitive military and non-military equipment in order to reduce fatalities, or at least we can minimize damages and fatalities. In this paper, we examine damages to under-water pipes with a passive defense attitude.