Products and solutions, 2005-12-21, 09:00 AM
Four trades from a single source
Floorcoverings, rain jackets and beverage packages - PVC is very much here to stay in our everyday lives. One of the biggest European manufacturers is the Scandinavian company Hydro Polymers, which recently decided to enlarge its plants in Norway and Sweden. And ThyssenKrupp Xervon is involved in the extension of an ethylene plant belonging to its subsidiary Noretyl in Rafnes. The engineering company in charge of extension work is Linde.
The two companies have already worked together on the extension of a natural gas processing plant in Kolsnes, where ThyssenKrupp Xervon was responsible for the trades of corrosion protection and scaffold erection. This time, Noretyl is receiving insulation and fire protection as well from the same source. Worth roughly EUR 5.1 million, this contract is the biggest international order ever awarded to ThyssenKrupp Xervon by the chemical plant engineering sector.
"The client was impressed by our wide-ranging experience in the performance of international projects together with the strategy of uniform site management with a single contact for several trades," says Regional Manager Michael Steins, revealing the secret of success. "We relish the opportunity, if only because this is the first time that we are providing four trades as a single-source supplier."
The coordination of the logistics enjoys top priority. About 1,000 metric tons of scaffold materials are in use, 30,000 square meters of insulating materials and fire protection systems are being applied, and 300 tons of pipelines are being coated. A total of 90 to 100 employees from Germany are in action on site, and work is scheduled for completion in December. September was the critical month in this project, because this was when the existing parts of the plant were shut down and connected to the new ones. "This means we had a clear-cut timetable," Steins explains. "The shutdown could not be postponed and, consequently, all the preparatory work had to be completed by September."
To be able to respond more flexibly to any deadline problems, the corrosion protectors therefore started coating the small parts in advance at home in Gelsenkirchen. In the company's own blast-cleaning shop, all the pipes with a rated diameter of 25 to 600 inches were sand-blasted and - depending on their purpose - coated accordingly. The existence of this blast-cleaning shop with its capacity for large and small parts was one of the factors that clinched the contract from the pipeline construction company, as weather conditions in Norway are unpredictable. The available capacity in Germany was therefore gladly exploited. Applied were a simple rust protection coating for the cold water pipes, and a high-performance special coating for pipes exposed to temperatures up to 500°C. Security-sensitive parts of the plant, and particularly load-bearing and supporting elements, were also given a fire-resistant coating of Chartek F 90, which means that they resist fire for over one and a half hours in a blaze with extreme heat stressing. In Norway itself, only the welds and any transport damage have to be treated and various items of equipment such as standing frames or heat exchangers have to be coated.
In the company's own workshop in Germany, sheet-metal parts were prefabricated with one of the most advanced sheet/plate metalworking machines to the dimensions supplied from Norway. Sheet metal that has been plastic-coated on both sides represents a special challenge in this context.
The insulation specialists then take the coated pipes from their workmates in Gelsenkirchen and expertly insulate them immediately after their assembly on site. In Rafnes most of the pipes requiring insulation have temperatures of well below zero.
To prevent icing and the penetration of moisture into the insulation, multi-layer insulation of PIR rigid foam shells is being employed. Because of the material's cellular structure and its particularly good heat conductivity, this material satisfies best the requirements of the ethylene plant. The individually layers are laid with offset joints and butt-jointed with adhesive, and for extra protection from penetrating moisture the PIR shells are also laminated with special sheeting. This sheeting consists of three layers - 25 percent polyethylene, 50 percent aluminum and a further 25 percent polyethylene - and has a particularly high vapor diffusion density. Since the pipes are noisy due to the media flowing in them, they are also insulated with a 50 to 150 millimeter thick layer (depending on the noise level) of sound-absorbent mineral fiber matting.
As surface protection the insulation is given a jacket of galvanized steel sheeting with a pigmented PE coating, which is additionally lined on the sound-insulated pipelines with a bonded anti-drumming sheet. This highly complex insulation can achieved overall insulation thicknesses of up to 325 millimeters. A pipeline with an outer diameter of 219 millimeters thus has an insulated diameter of 870 millimeters.
The three plate heat exchangers, on the other hand, require special insulation treatment. These are particularly heat-sensitive packs of stainless steel and aluminum plates through which fresh cold water and already used heating water flow in separate chambers and exchange heat. These plate heat exchangers are given cold insulation with an additional fire protection system that has to resist fire for 90 minutes and also keep the temperature of the plate heat exchanger below 150°C.
Fire protection finish
The insulation specialists from ThyssenKrupp Xervon came up a special coating system for this application. The plate heat exchanger is first lagged with 50 millimeter thick mineral fiber matting, which is then clad with a metal jacket of 1 millimeter thick galvanized steel sheet. The cold insulation, consisting of 100 millimeter thick PIR panels with offset joints, is then bonded to this sheet steel jacket. Like the pipelines, these plates are laminated with the special sheeting. After this, a hard cover of 4 millimeter thick steel sheet is built around this insulation for protection from direct exposure to fire. Since this steel sheet is extremely heavy, the housing is composed of many individual panels cut to size and edged by a specialist company with computer-controlled laser cutting machines.
After installation on site, the up to 6.5 ton insulation housing is given a Chartek fire-resistant coating. In the event of a fire, the flames are initially resisted by the hard cover with the fire-resistant coating. If the temperature inside the housing rises, the PIR insulation, which is only employed as cold insulation, offers no resistance as it only tolerates temperatures up to 100°C. However, the next metal-jacketed layer of insulation matting prevents a rapid temperature rise within the demanded 90-minute fire resistance time. This is a result that is scarcely conceivable without the efficient interaction of all the trades from planning through to execution.
Hydro Polymers produces various PVC plastics. To this end, liquefied North Sea gas and common salt are used for the production of ethylene, chlorine, caustic soda and hydrochloric acid. The ethylene is then mixed with chlorine, and the intermediate products of ethylene dichloride (EDC) and vinyl chloride monomer (VCM) are processed with the addition of caustic soda and hydrochloric acid into polyvinyl chloride (PVC). The plants in Rafnes in Norway and in Stenungsund in Sweden produce all the VCM required for Hydro's PVC production.