Thyssengas GmbH is an independent gas pipeline operator and one of the leading German LNG transport companies. Based in Dortmund, Germany, the company was established in 1921 and operated the first German gas pipeline, built in 1910 between Duisburg and Hamborn and Wuppertal and Barmen. Every year, Thyssengas transmits up to 10 billion cubic metres of gas through a 4,200 km long underground transmission network.
Pipeline integrity management system
In order to ensure that gas transport lines operate with as little damage and environmental impact as possible while still being economical, Thyssengas GmbH operates a pipeline integrity management (PIM) system. The task of the PIM is to determine the overall process for the integrity assessment of lines and thus to control the operative implementation of inspections, maintenance and repairs of the line network.
The status (integrity) of a pipeline is obtained by consolidating and evaluating various sources of information. These are gathered from operational organisation, data documentation and technical operational management. It thus forms the connection between management, organisation, information and technology.
The input data for integrity evaluation comes mainly from the employed geographic information system (GIS) system, the KKS management system, and from performed inspection measures. The data is entered into the Smallworld GIS® and georeferenced by adjusting for the equipment. Corresponding functionalities consolidate equipment data and inspection results for the line segment to be evaluated. Later, the summarised data is exported as input data for integrity evaluation. The KKS management system supplies further input data relevant for evaluation. This consists of information about KKS protective systems, soil values, and KKS effectiveness. Trascue PIMS® prepares different input data and forms dynamic segments. Missing input data is supplemented by estimates.
Use of drones
Despite gas supply, the main responsibility of the company is to ensure that the gas is transported safely, and that its supply to customers is uninterrupted. Pipeline failure or possible consequences of gas leak or explosion not only cause material damage for the company and society but also lead to substantial environmental costs. Therefore, the company has to guarantee proper functioning of its systems in every aspect.
Thyssengas has been carrying out aerial pipeline surveys for many years using helicopters, as a land-based survey across the entire length of the system is far too labour intensive. All the pipelines are regularly inspected and analysed for safety by a helicopter. The main purpose of these inspections is to assess if new construction projects in the proximity of a pipeline are a threat to its safety. When problems are detected, measures are taken in order to neutralise the risk. Each aerial pipeline inspection leads to the generation of 200-400 notifications (depending on the season). About half of these contain new, previously unknown information. All notifications are transmitted to the company’s servers at the end of each survey day through an automated workflow. From here, automatic messages are created in the GIS (geo information system in Smallworld) and in the enterprise resource planning (ERP) system, with no need for manual rework. These messages are available to master areas for processing. After on-site inspection, the data is prioritised and fed back using the same reporting chain to the helicopter, so that external supervisors inside the helicopter have the latest information.
To bring further efficiency in aerial surveys, Thyssengas initiated a project in 2012 to monitor high pressure gas pipelines with low-weight, autonomous flying drones. These drones, which operate more or less independently, are known as Quadrokopters. They come equipped with optical devices which enable the rapid detection of any interference in the gas pipeline. The first objective of this project is the analysis and pattern recognition of possible threats to the gas pipe (such as heavy construction equipment). Furthermore, the system can be used to survey and map newly built or modified pipes. Compared to conventional monitoring by helicopters, drones have the advantage of high environmental compatibility and low noise, as they emit no carbon dioxide and are extremely quiet when flying. They also provide the necessary security in a cost-effective way.
Microdrones are used wherever inspection by human supervisors is impossible or too dangerous. With its rugged, weather-resistant carbon fibre body, the md4-1000 achieves a flight time of up to 70 minutes. The video and telemetry down link allows the transmission of live video images as well as all the relevant telemetry data. All the data is graphically displayed using the ground station software which is included in the scope of supply, so the pilot is provided at all times with flight-relevant optical and acoustic information, for example, battery level, position, altitude, distance, wind speed and other operating conditions. In addition, all the measurement and position data is captured by the flight recorder and can be used for later evaluation and documentation. The software allows detailed flight planning to get under way prior to the start of the flight.
The optional GPS waypoint system allows pre-defined flight routes to be flown over automatically. For automated flights using waypoint navigation, the ground station software incorporates a flight planning module. This can be used to change even the complete flight plan on site at short notice, and completely new routes can be entered with just a few clicks of the mouse. During the planning of a waypoint route, the system automatically tries to avoid operating errors. For instance, critical flight situations such as insufficient programmed altitude above the ground or routes that are too long to manage with just one battery are automatically flagged. The system provides feedback about the estimated flight time and the expected image date coverage of the surveyed area. The precise adjustment of the camera and lenses is particularly important for measuring purposes so that any potential picture overlap can be considered upfront.
In sum
One serious risk to pipeline safety is uncontrolled gas leaks. In such a case, preventive steps include specialist checks for leakage and emergency shut-off systems. To this end, ultramodern methods such as intelligent pigging are used to react instantly to the detected leakage and to initiate maintenance and repair works. What poses an additional problem is the very nature of the material of which pipelines are made. Metal, being a basic component of pipes, is subject to corrosion. In general, the safety of the network is monitored from a central control desk in Dortmund that focuses mainly on the pipeline pressure and quality. The round-the-clock service immediately responds to emergency situations and starts repair works. Furthermore, it is worth mentioning the measures for direct protection of the natural environment. Thyssengas incorporated the need for environmental protection in all its operational plans. New building works needed to expand transmission grids are designed along with protective measures. When a new pipeline is laid, its natural environment is restored.