Thermal Expansion and Piping Stress: Part 2, Stress Analysis and Proper Engineering Prevent Problems

Thermal Expansion and Piping Stress: Part 2, Stress Analysis and Proper Engineering Prevent Problems

This is the second in a three-part series on thermal expansion and piping stress. The first article provided a primer on the basics of the thermal expansion and contraction found in industrial facilities. This article focuses on the importance of proper stress analysis and good engineering to mitigate the risks of thermal expansion to piping and equipment.  The third article describes how to spot problems in your plant.

Piping systems are often complex, with lines running long distances to myriad pumps and tanks, and requiring numerous valves and instrumentation connections. These pipes may carry hot liquids or steam, which causes thermal expansion that increases the pipe’s length. Pipes carrying cold material experience thermal contraction.

Stress Analysis Overview

Stress analysis is the calculation of the forces created by thermal expansion. The stress analysis results are used to design the system flexibility that prevents damage from thermal expansion.  This includes determining the route for the piping and the type of supports to be used.

A detailed piping stress analysis based on the applicable piping codes is the key to the proper engineering design of a piping system. The calculations for piping stress, thermal expansion, and anticipated loading will guide the engineering decisions for the optimum pipe routing, piping materials, and piping supports.

It is very important that a stress analyzed line is installed as designed. If the route or the supports are modified, serious damage can occur.

Common failure modes for piping systems include brittle fracture, plastic deformation or instability, incremental collapse, and the peak stress limit caused by cyclic loading fatigue. Each failure mode is caused by a different type of stress that is defined in the piping codes.

Engineering Methods for Handling Thermal Expansion

Hot piping is typically not routed in long, straight runs. Instead, expansion loops are frequently used to absorb the thermal expansion.  These loops are commonly located in the pipe racks between major pieces of equipment.

Near pumps, tanks, and other equipment, the piping system may contain a series of elbows to prevent pipe growth from damaging the equipment—and to prevent equipment growth from breaking the pipe.

Yes, the thermal expansion of equipment must also be accounted for in the stress analysis. Equipment will expand and grow away from its anchor point—where it is attached to the floor ,wall or foundation.  A pump for hot service will be supported at the center of the casing. A vessel mounted at its base will grow up, while a vessel mounted at its midpoint will grow both up and down.  The extra elbows on the piping help handle this equipment movement.

Special pipe supports are used to control the direction of pipe expansion.

  • Anchors are welded in place to prevent pipe movement at that point. The piping will grow away from the anchor point in both directions.
  • Guide supports are installed wherever the pipe may be prone to lateral movement. A guide allows the pipe to grow in the direction of flow, but prevents movement to the side.
  • Spring supports are used when thermal expansion can cause the equipment or piping to grow vertically. Springs allow the pipe support to maintain contact across the entire range of temperatures. They are installed in the “cold” position. After installation, the “stops” are removed from the spring so that it is free to move up and down as the temperature changes

Insulated piping may rest on pipe shoes, which keep the hot pipe and its insulation from resting directly on the pipe rack steel. As the pipe expands, these shoes will also move. The engineering design must ensure that the shoes do not fall off the pipe rack steel as the pipe moves.

Next time, we’ll look at what you should be looking for to prevent thermal expansion problems in your facility.

Matrix Technologies is one of the largest independent process design, industrial automation engineering, and manufacturing operations management companies in North America. To learn more about thermal expansion and pipe stress analysis, contact Chris Mach, PE, Senior Consultant (Team Leader) in the Process & Electrical Design Department.

© Matrix Technologies, Inc.

How to Achieve Higher OEE Ratings with Data Integration

How to Achieve Higher OEE Ratings with Data Integration

Overall equipment effectiveness (OEE) is a key barometer of productivity in an industrial manufacturing plant because it provides a single measure of how well the manufacturing process is performing. Manufacturers want high OEE ratings that result from effective use of equipment at the required speed and efficiency while maintaining high levels of quality. When OEE ratings are lower, it means that one of the underlying metrics such as availability, performance, or quality is not where it needs to be.

Manufacturers often find that the data driving the underlying OEE metrics resides in many different data sources. This creates the need to pull together disparate information for OEE dashboards, as well as general reporting and visualization of the manufacturing operations.

Integration of heterogeneous data sources can be a complicated, confusing, multistep process. To obtain true manufacturing intelligence and insight for manufacturing operations management and decision-making, you need to combine business data with process data or gather more details into a process summary report for certain conditions.

Why One Interface is Better than Multiple Query Tools

Manufacturing intelligence can be simplified by using a single source to show the “single truth.” One simple way to accomplish this single source is to provide a common link or most common denominator. This is often as easy as using a database such as Oracle or SQL Server to link multiple data sources together.

Engineered solutions can use SQL Server Reporting Services to report on data from SQL databases and Oracle databases, while providing drill-down capabilities into process data from a Historian archive.

Such solutions can be extremely valuable. Not only does this save time, it also increases the integrity of the reports and provides an increased return on investment (ROI) in many cases.

How Seeing Data from All Configured Data Sources Can Improve OEE Ratings

For many manufacturers, having collective information readily available can be instrumental for making production changes, resolving issues, or providing details for change initiatives. Manufacturing intelligence is a driving force in maximizing the overall equipment effectiveness (OEE) rating in any process. Having data integrity and consistency in the reports is paramount when using a solution that does not involve manually pairing up data from multiple sources or multiple users.

Database reporting solutions can communicate with other systems and provide a common

communication tool to other systems. Instead of having to use a query tool for this database, an external open database connectivity (ODBC) query for that database, and yet another trend report for process data, you can use one interface to see data from all configured data sources. A well-trained analyst can query the Historian archives and then query the business system or some other database, all from the same interface. This speeds design and resolution time.

Starting with the big picture is usually the best approach. Understanding the flow of information and using documented data flow diagrams that shows data sources and data storage for the process is the key to architecting a tightly integrated plant information system.

This diagram of all the data sources and information flow makes it is easy to see the mappings and connectivity necessary to get the proper data in the right context. A connected system provides for the single source of manufacturing intelligence information and ensures the integrity of the Key Performance Indicators (KPIs), including OEE ratings.

Accurate, real-time OEE ratings give manufacturers the power to make informed decisions to keep operations running smoothly and efficiently. This level of concentric manufacturing intelligence enables you to make investments where needed to maximize returns in many cases. Having the “single truth” of data integrity also provides for powerful reporting and analysis to understand the “why” behind manufacturing operations.

Matrix Technologies is one of the largest independent process design, industrial automation engineering, and manufacturing operations management companies in North America. To learn more about our manufacturing operations management capabilities and manufacturing intelligence solutions, contact John Lee, Strategic Manager of Manufacturing Intelligence.

© Matrix Technologies, Inc.