Stud tensioning systems

As a specialist in the design, construction, supply and maintenance of highly automated stud tensioners, we offer our clientele requirements-oriented solutions for opening and closing pressurized water reactors (PWR) and boiling water reactors (BWR) as well as other primary and secondary circuit components in nuclear power plants.
Our range of supplies and services includes single and multiple stud tensioners, stud turning and handling systems, stud and blind hole cleaning systems. The automated stud tensioners are equipped with state-of-the-art control technology. The use of the stud tensioner reduces the operating time on the critical path when opening and closing reactor pressure vessels, the number of operators and duration of stay at the reactor, thus significantly reducing radiation exposure.
Our stud and the blind hole cleaning machines ensure smooth operation of the stud turning equipment, as the reactor studs/bolts as well as the blind holes of the reactor flange are optimally dry cleaned, inspected and greased. Damage to the threads is detected, recorded and repaired where required, if necessary. The use of our cleaning systems on the reactor or the cleaning of the reactor studs is the optimal preparation for the use of the stud turning equipment and the stud tensioning device. In addition to designing and manufacturing the equipment for customer applications, we offer a comprehensive after-sales service for our products in international range. The after-sales service carries out not only the operation of the equipment, but also the maintenance of the components. If necessary, existing old tensioning devices are modernized and upgraded with the latest control technology to ensure the necessary high availability on the critical path again.

Experience from 60 years of stud tensioning technology

Due to the increased construction of nuclear power plants in the 1960s, the first hydraulic multiple stud tensioning system was developed. The concept of the machine was based on the experience of our predecessor company in the field of hydraulics for mining equipment.

In 1964, the first hydraulic multiple stud tensioning machine (MST), which allowed the simultaneous stretching of 36 RPV studs, was used at the Obrigheim NPP. Obrigheim was the first NPP to opt for this stud tensioning system, as special equipment was needed to open and close the reactor pressure vessel, meeting the highest safety standards. Response times were significantly reduced.

Keeping the original product idea, 60 years of intensive development work and customer contacts with resulting experience lead to the latest generation of MST, where simultaneous hydraulic stretching of the reactor studs is only one of many functions. Remote and automatic turning of reactor studs and cover nuts are now integrated functions, as well are measurement, recording and registration of relevant operating conditions and parameters. With today's MSTs, it is also possible to transport RPV studs and nuts, thus reducing inspection times.

state of the art technology

In the many years of operation of a stud tensioning machine, rapid development was achieved in mechanical engineering, high-pressure hydraulics and especially automation technology. We bring your stud tensioning machine up to the current state of the art.

We have implemented more than 30 modernization projects of stud tensioning systems worldwide, often with a more than 50% reduction of the time required for RV opening and closing.

Our services for a modernization project include planning, concept development, calculation, design, delivery, installation, commissioning, training of the NPP personnel as well as service for RV opening and closing.

International service - 24/7

The commissioning of new deliveries and modernized stud tensioning systems are a matter of course for us and our customer service staff. Our long-standing and constantly improved quality management system guarantees a high-quality standard.

At fixed intervals, our service staff will carry out the mandatory required maintenance on your stud tensioning systems. Within the scope of these revisions of all mechanical components that are subject to wear over time, we carry out, for example, the replacement of seals, batteries, etc. In this context, we also carry out repairs on stud tensioning systems. In the case of new deliveries and maintenance, calculations and component analyses based on the finite element method, such as stability verifications, are also prepared on the customer's request.

You can count on our support 24 hours a day - we are always there for you.

More flexibility through our service staff

Our service staff is constantly active in nuclear plants worldwide for RV opening and closing with our stud tensioning systems. The use of our service engineers for opening and closing primary circuit components guarantees you safety and speed on the critical path. We provide you with specialists with many years of international experience, high qualifications and continuous training. This creates more flexibility for you in the deployment of NPP internal personnel.

Well trained staff for safe handling

Qualified and well-trained personnel are a cornerstone for the profitability of your plant. Our training courses, which we conduct for initial deliveries and modernizations of stud tensioning systems, form a significant contribution to safe and effective handling. Depending on the customer's requirements, we perform our operator training directly in your nuclear plant or during the functional test of the stud tensioning systems in the test stand at our premises in Lünen. Depending on the complexity of the respective stud tensioning system, the training duration is between 2 and 3 days for small tensioners and up to approx. 14 days for big RV stud tensioning systems.

Training contents are: Functional principle of the machine, operator training, trouble shooting, control and software training, maintenance and transport of the tensioning system.