Inspecting constant hangers and rigid holders in power stations has so far involved high personnel expenses. Technip, a globally operating plant manufacturer, uses HBM measurement technology to automate permanent load monitoring and thus ensure an increased level of safety and efficiency.
Piping in power stations needs to withstand considerable loads. Extreme temperatures and high pressure are not uncommon - conditions causing huge thermal strain and likely to overload the pipes. For this reason, so-called constant hangers are used for installing the pipes; they compensate for thermally induced movements.
However, force measurements on rigid holders are even more important. They permit integral evaluation of the load transfer by comparing the force differential between the cold and the hot state with preset values determined through system analyses carried out during the dimensioning of the plant. Deviations indicate imperfect load transfer (restricted movement due to the running of pipes, inadmissible hanger friction, distortion, etc.). Furthermore, force measurements on primary rigid supports enable the piping's current relaxation state to be assessed which is considered prerequisite to the required service life calculations on high-pressure piping.
Checking constant hangers and rigid holders in sensitive areas of a power station at regular intervals is already very complex and can only be carried out by well-trained specialists. Of course, the remaining risk resulting from visual inspection must not be underestimated: A false assessment might have far-reaching consequences.
It is relatively easy to eliminate the risk of a false assessment: just use HBM measurement technology. HBM offers two solutions for permanently monitoring the constant hangers and verifying the load transfer concept on the rigid supports (joint struts), i.e. for protecting the piping from overload:
- Load monitoring by installing type LY strain gages on the joint strut
- Load monitoring by installing a type U10M force transducer directly into the constant hanger's force flow.
Technip is a global leader in plant engineering for the power generation industry and uses both solutions for monitoring high-pressure piping in power stations.
The first method is ideal for retrofitting, because, for measuring the load, no changes have to be made to the design and thus the hanger does not require re-certification. In addition, installing the strain gages is very easy.
The second method provides even more accurate measurement results. The U10M is a rotationally symmetric, low-profile force transducer that guarantees high endurance strength even in the event of an extreme oscillation width of 200 percent. Due to its excellent linearity, it measures the forces acting on the constant hanger with high precision, even in the partial load range. Dr. Ulrich Reiners, project manager at Technip: "The force transducers stand out for their ruggedness which is required for use in power stations and they are easily installed." A further advantage when using the U10M is the integrated TEDS, the Transducer Electronic Data Sheet, which, in comparison to manual setup, makes configuring the complete measurement chain very easy and ensures minimum time expenditure and increased safety.
With both solutions, the MP30 carrier-frequency amplifier transmits the 4 to 20 mA signals common in power stations to a control station - over long distances and without quality loss. The MP30 belongs to HBM'sPME product family that stands for smart signal conditioning in industrial measurement technology. Using the MP30 has proven successful with both solutions. Dr. Ulrich Reiners: "The MP30 amplifier stands out for easy and fast programming and high accuracy. Another advantage is the fact that measured values are visualized in physical units directly on the instrument which has proven beneficial to maintenance and configuration."
Automated continuous monitoring provides increased safety and eliminates the need for complex manual inspection. HBM measurement technology increases efficiency and reduces costs.
Technip is represented with 23,000 employees in 46 countries worldwide. The company with headquarters in Paris/France is a global leader in plant engineering for the oil and gas industry.