Preface
Pipe strain, an unwanted pressure or movement in piping systems, can significantly complicate alignment and cause substantial damage to machinery and systems. Understanding the causes and effects of pipe strain is crucial for anyone involved in the design, installation, and maintenance of piping systems. This comprehensive guide aims to provide insights into identifying, mitigating, and resolving pipe strain to ensure optimal system performance and longevity. Look carefully and make your best assessment prior to taking actions.
I. Possible Causes of Pipe Strain
Pipe strain arises from various factors, each contributing to the unwanted pressure or movement within the piping systems. Key causes include:
Improper Design or Installation: Incorrectly designed or poorly installed piping systems and machinery can lead to misalignment and strain.
Thermal or Pressure Changes: Fluctuations in temperature or pressure can cause pipes to expand or contract, resulting in unwanted movement.
Lack of Proper Support: Inadequate or improperly placed pipe supports can fail to hold the piping system securely, leading to strain.
Unaccounted Process Changes: Modifications in the process that were not considered during the initial design can introduce new stresses and strains.
II. Effects of Pipe Strain
The consequences of pipe strain can be severe, affecting both machinery and the overall system. Common effects include:
Misalignment of Coupled Machinery: Strain can shift components out of alignment, leading to operational inefficiencies and potential damage.
Machine Casing Distortion: Excessive pressure can deform the casing of machinery, compromising its integrity and performance.
Increased Load on Components: Bearings, seals, gears, and other parts may experience excessive thrust or radial loading, leading to premature wear and failure.
Vibration Issues: Pipe strain can cause excessive vibration in piping systems, which can transfer to buildings or adjacent machinery, creating noise and potential structural damage.
III. Proper Installation Practices
Effective installation practices are crucial in minimizing pipe strain. Here are some best practices:
A. Design Considerations:
- Account for induced moments and forces from piping and machinery during the design phase.
- Incorporate expansion and bellows joints to mitigate forces resulting from thermal and dynamic changes.
B. Machine Bases: Grout machine bases and allow adequate curing time before installing machinery. The curing period depends on the specific grouting material used. If installed look for soft foot and see if base has deteriorated and/or cracked concrete.
C. Installation Sequence:
Install piping starting at the pump and work backward to ensure proper alignment and support.
D. Avoid Common Pitfalls:
Prevent base-bound or bolt-bound situations.
Align flanges without relying on chain hoists or come-a-longs.
Ensure the piping system is designed rather than being improvised in the field.
Avoid making post-installation changes that could introduce new strains.
IV. Identifying Pipe Strain at the Pump
To determine if piping is inducing strain, follow these steps:
A. Check Each Flange:
Break the flange connection and use a dial indicator to measure movement across the flange in vertical, horizontal, and axial planes.
B. Shaft Alignment Measurements:
Take alignment measurements with the flange connected and then with it broken. Compare these measurements to assess the flange's influence on shaft alignment.
V. Inspecting Pipe Supports
Pipe supports are vital for maintaining the integrity of the piping system. When pipe strain is suspected, inspect the supports as follows:
A. Check Pipe Shoes:
Ensure all pipe shoes are correctly in place.
B. Inspect Hangers with Threaded Rods:
If threaded rods are moving or vibrating significantly, adjust them to ensure they provide proper tension and support.
C. Check Stiff Leg Supports:
Confirm that these supports are in contact with the floor and that the bolts are tight. Loosen and retighten bolts to relieve strain if necessary.
VI. When Pipe Strain or Excessive Pipe Movement is suspected
If you suspect pipe strain or excessive movement, take the following steps:
A. Inspect for Loose Supports:
Tighten bolts that may have loosened due to factors like concrete shrinkage.
B. Look for Recent System Changes:
- Check for new piping, valves, machines, or any components that have been recently removed and replaced.
C. Examine Thermal Changes:
Assess the system for any thermal changes that might impact the piping.
D. Check for Additional Bracing:
Determine if any additional bracing has been added that could influence the strain.
Summary: Solutions
Proper Design and Installation: Ensure that piping systems are properly designed, installed, and supported to minimize strain.
Regular Inspections: Conduct regular inspections and maintenance of pipe supports to confirm they are functioning correctly.
Consider Pipe Strain in Alignment: Always factor in pipe strain during precision shaft alignment, especially if there are recurring alignment issues.
By following these guidelines and best practices, you can effectively manage and mitigate pipe strain, ensuring the longevity and efficiency of your piping systems.
Disclaimer
The information in this paper came from previous communications with installers. At best it is utilized as issues the active installer needs to think about.
Your field problems may be different and there is nothing stated or implied herein that we have made any thorough investigations or given specific directions for your project.