How to Get Your Plant Piping Design Right with Accurate Stress Analysis

Piping design plays a crucial role in plants and hence it requires precision with design. The operational agility and efficiency of any facility depend greatly on the robustness and ability of the pipes. While these pipes look static, they are surprisingly dynamic. Constantly fluctuating loads, extreme temperature differences, varying pressures, and the weight of components exert a lot of stress that can damage the pipes and cause them to shift.

And when the substances flowing through these pipes are hazardous, the consequences can be perilous for the people working the plant and also for the equipment installed. Accurate pipe stress analysis can help you diagnose issues and arrive at a safe and reliable fix for the plant environment.

This article explains the importance of stress analysis for a safe and efficient plant design, delves into the design basics of pipe stress, and lists some common piping design mistakes along with fixes.  

The Significance of Pipe Flexibility & Rigidity

An accurate pipe stress design requires you to create a perfect balance between its rigidity and flexibility. Pipes tend to expand when subjected to thermal stresses. They also shrink when the temperature drops drastically. This has a direct impact on the connected equipment.

If there is no room for expansion or movement, the pressure is exerted on the pipes and the supporting machinery, until something gives way. The best way to address this issue is by enhancing the agility of the system with flexible supports, expansion joints, or flexible loops that lend elasticity.

However, too much flexibility is also not desired. It leaves the pipes susceptible to natural and transient forces like hurricanes, earthquakes, steam hammering, and vibrations.

This is where rigidity has a vital role to play. Anchors add rigidity to pipes. They break the system into independent sections by blocking any movements or forces from impacting the other side. They also make the piping systems much easier to modify and fix when problems arise. However, overuse of anchors magnifies thermal loads and that is why you need to place them only in sections with minimal thermal displacements.

Fundamentals of Piping Stress Design  
To achieve a perfect balance between pipe rigidity and flexibility, you need to follow these three basic rules of detailed engineering design:

• Keep the pipe stresses below their permissible code limits to avoid pipe damage
• Allow large displacements to avoid collision with adjacent objects
• Keep all the forces at pipe-machinery connections well below the permissible limits stated by the manufacturer

If you follow these fundamental principles, you are likely to achieve the desired balance. However, the combination of pipe routes and supports is complex, the number of fitting options and bends is also extensive. Even if you have the commitment and intent, you cannot control the environmental variables. This is where the experience and technology expertise of an agency offering detailed engineering services can help!

Whether you are building a manufacturing facility from the ground up or constructing a petroleum refinery, they can help you design a piping system that ensures complete safety of your workforce and infrastructure.

How to Get Piping Stress Analysis Right the First Time

Experience can make a massive difference when it comes to piping stress analysis. Experienced companies providing detailed  engineering services are familiar with the codes, compliance regulations and processes and they are also equipped with stress analysis software like Bentley and AutoPIPE. This not only reduces the time and cost but also ensures accuracy, safety, efficiency, and a compliant piping design.

From accounting for every load to ensuring component strength to making calculations for a wide variety of pipe layouts, they accomplish all the competing goals with complete precision. Their team also investigates potential causes for impending failures and brainstorms possible solutions. Their proficiency and the advanced capabilities of the best software solutions combine to ensure that your design decisions are reliable and right.

Common Mistakes in Piping Design & How to Fix Them

1. Trapping of pipe between two connections
This happens when two adjacent pieces of equipment are secured to the floor and the length of pipe running between them expands due to heat and there is no room to grow.
Fix – Stress does no take a straight route. Adding a U-shaped bend or an expansion loop to the run will enable the pipe to flex & grow while relieving the stress.

2. Expansion around a corner when pipe guide is used
A straight and long section of any pipe is often held up using a series of guide supports. These supports are made using pipe shoes that feature guiding clips on the side to facilitate forward and backward movement. Any bend in this pipe disrupts the expansion after the bend.
Fix – To enable growth, it is best to cut the clips located near the corners. This gives the pipe freedom to move in both directions simultaneously.

3. Expansion joints moving far apart
When you have a straight pipe with insufficient space to incorporate an expansion loop, using a joint can be beneficial. This accordion-like joint renders flexibility to the pipe under pressure. However, when this pipe is subjected to high pressure, it pushes the joint outward in both directions.
Fix – You can consider adding anchors before & after the section that expands and is attached to the joints. This will eliminate any possibility of potential danger.

4. Support Lift-off  
Pipes that travel long distances vertically need supports at the top & bottom to safely manage the weight of the pipe. In the case of thermal growth, it is bound to lift off the support placed at the top. If the top lift-off occurs, the bottom support suffers damage due to overloading.
Fix – The best solution, in this case, is to avoid any long vertical runs. This can be achieved by breaking down a long vertical run and allowing each section a little room for expansion so none of the support lift-off and cause any damage.

5. Damage caused to a piece of equipment by a connection in the vertical pipe
In the case of sensitive equipment, even a small vertical run is enough to create misalignment and cause damage. Such issues are challenging to solve.
Fix – The best solution for this issue is to avoid connecting a vertically laid pipe to any sensitive section. If this is not possible, a cold spring or a spring can make for a feasible solution.

Conclusion
Challenges and pitfalls are unavoidable when it comes to piping design. But the biggest challenges arise when there is a lack of proper planning. Making calculated decisions to safeguard the plant and equipment is not possible without the assistance of an external agency providing detailed engineering services.

Whether it is a single line of pipe or hundreds of intricate lines, an experienced partner can help you prepare thoroughly, plan thoughtfully, think critically, and design precisely. With a trusted team, you will end up with a much safer plant that will keep your operations up and running at peak efficiency.