Visual inspection of a raised manhole requires attention to detail.
The INEOS chemical plant in Cologne, Germany, was shut down for two months for maintenance activities in a turnaround project with an investment volume of 100 million euros and involving 6,000 people. TÜV SÜD Chemie Service accompanied the large-scale project — a feature on the testing and inspection practice on-site.
The day is cloudy. A spot of bright color catches the eye against the dully monochrome industrial architecture. A red crawler crane, 188 m high, stands out from the futurist labyrinth of scaffolding which encases the chemical plant. Higher than the Cologne Cathedral and with a mass of 927 tonnes, the crane is the largest item of mobile material handling equipment that has ever been used in a turnaround at the Cologne INEOS site. Over the next two months, the crane and other equipment will be used to find the answer to one question: Can the safe and reliable operation of the highly complex chemical plant be guaranteed for the next five years?
Top performance for maximum safety
Around 2,000 employees work at the INEOS location in Cologne, at the interface between the mineral oil and the chemical industries. In the chemical plant, naphtha, a crude-oil distillate, is “cracked” to produce the two basic chemicals of propylene and ethylene. These substances are used as basic building blocks in areas such as the production of plastics, washing detergents and solvents, fertilizers and synthetic fibers by the chemical industry. In the cracking process used to manufacture the chemicals, long-chain hydrocarbons are split into smaller molecules under high pressure and high temperatures. The cracker plant is regularly subjected to high physical loads and must satisfy high legal and corporate safety requirements. For this reason, the plant is shut down every five years for testing, inspection, and maintenance.
How firmly the safety principles of the planned shutdown are anchored in the plant's safety concept and in the awareness of all stakeholders immediately becomes clear upon entering the INEOS grounds. The turnaround — the largest in the company's history — involves 6,000 people, more than 10,000 work orders, and an action list comprising over 7,600 inspections, service tasks, and tests to be carried out over the next eight weeks. Work is performed around the clock.
Everybody working on the 15-hectare chemical site must attend safety instruction sessions and don personal protection equipment (PPE): safety goggles, safety helmets, safety footwear, and fire-resistant gear. Electronic ID cards must be carried at all times. In addition, all visitors must register at a computer terminal before they are allowed to enter the plant. This ensures that the turnaround managers know the number of people on site in the plant at all times. The safety precautions are effective. In fact, there are zero reportable industrial accidents at the end of the two-month turnaround.
A temporary “container village” is erected in front of the cracker plant. Container offices accommodate the partner companies and provide office space for planning and coordination tasks. The containers also accommodate mobile warehouses, counters for issuing tools and PPE, and common rooms. The team from TÜV SÜD Chemie Service has likewise set up its base for the next few weeks in these containers. In the conference room, the turnaround managers and inspectors review the agenda for the upcoming inspections, which follow an exact sequence and schedule. Nothing is left to chance; there is no time for inefficiency. "For every single day of the turnaround, we have defined an exact route along which we guide the engineers to the prepared components", says Turnaround Manager Marcel Hohnroth.
Comprehensive preparations are required before the turnaround engineers can complete their tasks smoothly and within the intended timeframe. The cracker plant must be completely scaffolded, and certain parts of the plant — reactors, pressure vessels, columns, heat exchangers, valves, piping — must be made accessible. Numerous components have had to be cleaned and prepared for inspection. "Every component must be inspected separately", explains Klaus-Dieter Peschel, manager, plant safety & inspection at the Dormagen location of TÜV SÜD Chemie Service. The inspection and test plan of his team of 10 comprises a total of 1,000 components.
Turnaround Engineer Peter Löffler says: "When time is of the essence, coordination of all maintenance and inspection plans is imperative. Computer-controlled management of inspection intervals is indispensable in our line of work. It enables us to call up inspection reports of high data quality at any time and keep an eye on inspection intervals. This saves time and reduces costs for plant managers and owners."
Precision work with dual control
The scaffolded cracker plant uses many cranes during the shutdown.
On their way to the cracker plant, the TÜV SÜD team members pass the catering tent, which covers a floor space of 150 sq m and provides food and drink for up to 1,250 people on site on every single day of the turnaround.
The inspection engineers from TÜV SÜD Chemie Service test the pressure load and tightness of a heat exchanger. The test does not reveal any safety-relevant weaknesses, and the welds and connections satisfy the requirements. Nevertheless, one more test is required. Even if all individual components have successfully passed the test, the team must still carry out final approval of the entire component. Only when this has been done is the test completed. A brief phone call is made before the turnaround engineer leads the TÜV SÜD Chemie Service team to a storage area, where the hood of the heat exchanger stands next to various other components. Now, the heat exchanger can be approved in its entirety. Every step is documented. "We maintain a second documentation list parallel to that of our client, to ensure we do not overlook any test items," says Peschel, whose team also reviews and checks this list internally at the end of each turnaround day, thus extending the usual two-man rule to a three-man rule.
At a length of 4 m, a diameter of 70 cm, and a weight of 1.6 tonnes, the inspected heat exchanger is relatively small. Larger heat exchangers can weigh up to 100 tonnes. The transport of these types of components and parts to their destinations calls for appropriate lifting equipment, which frequently involves heavy-duty cranes. On every single day of the turnaround, a total of 40 cranes, including the red crawler crane, are employed to overcome the force of gravity at the site of the turnaround.
Modern test methods
Throughout the two-month turnaround, around 1,250 employees were busy cleaning, maintaining, and inspecting the cracker plant.
The turnaround at the chemical plant, which takes place every five years, focuses not only on maintenance and servicing activities to maintain the value of the chemical plant, but also on opportunities for expansion and optimization. The petrochemical processes at INEOS are gradually improved with every shutdown. "Applying innovative test methods and long-standing experience gained in previous large-scale turnarounds, we can support plant managers and owners in the best possible manner when it comes to the implementation of safety-relevant measures," says Peschel. High-resolution digital images of possible inhomogeneities in welded materials, plant components, or complex geometries enable more specific measures that combine maximum safety and cost-effectiveness. To this end, the test engineers apply innovative ultrasonic and radiographic test methods and bring experience from previous plant shutdowns at INEOS in Cologne to determine whether and how a component has changed and whether it may have to be replaced.
If repairs are necessary, the test engineers will take on further responsibilities — from defining the scope of repairs, providing the necessary calculations, and approving the inspection and test plans to monitoring the repairs. All experts work to the common goal of ensuring the deadline for the startup of the cracker can be met. On this day of the turnaround all components are found to be in compliance with the requirements.
After two months of shutdown the plant is started up again as scheduled. The scaffolding is disassembled and the pressures in the systems are built up again. The plant is brought back to operating temperature. Fluids and gases flow into the systems. One-and-a-half years of preparations and around 75,000 hours of planning thus find a successful completion. "This was the largest turnaround that we have ever had at our site in Cologne," says Dr. Anne-Gret Iturriaga Abarzua, communications manager at INEOS.