Sensor networks have gained tremendous appreciation in recent years and have been successfully tested in various application scenarios such as disaster management, pipeline monitoring, and environmental monitoring, as well as different military and security-based applications. In order to protect pipelines from leakage and corrosion, various conventional methods and techniques are used for monitoring. Functioning only in a specific environment, these conventional techniques require special infrastructure and higher maintenance. These challenges could, however, be overcome efficiently by using wireless sensors and robots. Most previous surveys mainly focused on the hardware design of the sensors, basic sensing techniques, and transmission media, but overlooked conducting an exclusive survey of pipeline monitoring schemes using linearly deployed wireless sensor networks or robots. This study attempts to carry out an extensive survey on the factors affecting pipeline monitoring techniques and provides novel classification in terms of classifying them into different strategies, sensor types, sensing coverage, communication methods, and monitoring types. In addition, a survey of comparative analysis of existing pipeline monitoring techniques is also presented, and general pipeline monitoring methods are also compared and summarized. Moreover, the need to explore pipeline monitoring schemes that incorporate wireless sensor networks (WSNs) is highlighted because WSNs are easy to deploy and flexible enough to be installed in any environment. This study discovers that most existing pipeline monitoring schemes that do not deploy sensors in a linear direction, which ultimately increases the cost and reduces overall network performance. Finally, several unresolved issues occurring in the development of pipeline monitoring techniques are highlighted, and future directions are provided accordingly.