Practical experience from the inspection of the OMV Schwechat refinery by Hans-Jürgen Bittermann
Refineries break down the "black gold" that is mineral oil and process its components for further use. The refinery's technology then also itself has to be "processed" at regular intervals. In shutdown maintenance such as this, cleaners,
greases, bonded coatings and assembly pastes play a role on practically every handle, as illustrated by the current example of the die service work at the OMV Schwechat refinery.
On the left a compressed air bolter hisses, while on the right fitters shout loud positioning instructions to the crane driver - a large heat exchanger is lowered slowly into the plant. Another special crane approaches from the front. How does the driver manage to manoeuvre in these narrow aisles? These days it's all happening at the otherwise peaceful site of the OMV Schwechat refinery, people and machines are moving around everywhere - and there is of course a reason for all this: It's time for the routine "planned shutdown", in other words servicing of the technical plant in August and September 2005. In concrete terms this means: Stop activities as specified in the Pressurised Equipment Monitoring Ordinance. This involves subjecting the plant technology to a comprehensive safety inspection, and also inspection and preventative maintenance work.
It's no wonder that so many people are actively involved in a shutdown service, as the maximum amount of work must be done in a very short time. And that's only possible with external help: In addition to the regular workforce of the OMV Schwechat refinery, some 1700 people - from serviceproviders and service personnel of the component manufacturers - are moving around the site. This thorough check-up costs the company around 32 million Euros.
At the same time, OMV is investing another 200 million Euros in increasing the capacity of the ethylene plant and in so doing is boosting monomer production from 650,000 to 900,000 tonnes annually. An additional 800 external specialists are actively involved in this - a total therefore of some 2500 people who must make the complex plant technology ready for production within the space of a few weeks.
At first glance it's astounding that in view of such an investment volume, thought is also given to the use of lubricants and assembly pastes. Normally, these consumables are regarded as being of low importance. This is not the case at OMV, which intentionally looks at these products as being most definitely important time management components.
Everyone at every level is aware that: Time is money, and every delay means high turnover losses for the refinery and the associated plastics production at the subsidiary company Borealis. This means that all procedures must be planned down to the most minute detail, every handle must be secure, and only the best tools and equipment are used.
Shutdown: Perfect planning and organisation required
The entire plant infrastructure must be inspected, serviced and if necessary repaired. Engineer Robert Pappenberger, head of Planning & Control and the shutdown supervisor, knows the specific figures by heart: 2 furnaces, 56 columns, 406 heat exchangers, 388 containers, 2800 valves, 1300 safety valves and 2400 measuring and control devices must be serviced. "In addition there are the necessary repairs to the pipelines, and investments
that can only be made when the plant is shut down".
For the shutdown, the refinery's external service-providers assume responsibility for over 95 per cent of all the work. Pappenberger explains that "as its core tasks, maintenance includes technical responsibility, longterm planning and also organisational and monitoring functions". Of course, besides setting the duration of the shutdown, from a safety and economy point of view ("that's the central, crucial point of every service!") this also includes incorporating knowledge gained from previous shutdowns with regard to safety, the length of the shutdown, the work sequence and costs, as well as the pre-planning of additional activities for future shutdowns."You need a lot of experience to be able to say on site at the plant that this needs doing now, but can wait until the next service," explains engineer Franz Cetl, head of Equipment and Mechanical Engineering. At the Schwechat refinery, that approach obviously succeeds well because mechanical availability is at an impressive 98 %.
Securing connections - and detaching them safely again
How problem-free the planned work sequences then actually run during theshort shutdowns depends on, among other things, the time taken for the assembly / disassembly of supply lines, apparatus and machines and the measuring and control devices.
Whatever connection method is selected: Perfect preparation (cleaning) of the surfaces and use of suitable bonded coating or the correct assembly paste ensures the reliability of the connection and makes its disassembly easier later on. At the Schwechat refinery, products from the OKS company of Munich are used for a number of applications (see interview). OKS, a subsidiary of Freudenberg Chemical Specialities KG, develops, produces and markets worldwide special lubricants as well as cleaning and corrosionprotection products for all types of service and maintenance work.
The invisible helper of the maintenance man
A brief glance into the world of tribology clearly shows the importance of such products in everyday work.
The functions of a lubricant can be varied and, depending on the particular application, can be necessary alone or in combination. Besides the primary demand placed on the lubricant - namely maximum power transfer combined with a minimum of friction and minimum wear - it is often necessary to fulfil various secondary properties such as water resistance, chemical resistance compatibility with plastics or corrosion protection.
Mineral oils, synthetic hydrocarbons, silicone oils, polyglycols, ester or similar synthetic liquids are used as the basis for high-performance lubricants. They differ in terms of, for example, their temperature behaviour, miscibility, lubrication capability, oxidation resistance, material compatibility and manufacturing costs. The choice of the viscosity of a
lubricating oil depends on the area in which the lubricant is used. The following basically applies: Low viscosity for low pressure stress and high sliding speeds, high viscosity for high pressure stress, low sliding speeds and high temperatures.... >> more