Did you know that over 95% of through wall failures reported in high-energy piping systems are related to applied bending stresses from external or off design conditions?
Often times these stresses are the result of improperly designed or malfunctioning hanger supports. To ensure that the piping systems are being supporting as predicted and intended by the designer, hot and cold condition walkdowns of the hanger supports of high energy piping systems should be audited annually. The condition of the supports provides an accurate barometer of the overall condition of the applicable high-energy piping system.
Unfortunately, so many plant managers and engineers get HUNG UP on hangers and simply don’t perform the necessary annual walkdowns. Performing this one simple annual inspection can alleviate the risk of so many preventable failures down the road.
Here are a few things to keep in mind when performing pipe support walkdowns:
- Design of expansion and contraction of the system as it heats up and cools down. Ideally, these systems should be allowed to expand vertically from cold to hot and be contained horizontally. The top section of the pipe systems should be moving in an upward direction while the bottom sections should be allowed some downward movement. (This is a generalized statement and is intended to provide an example of typical pipe movement scenarios) A rigid type hanger will typically be located along the vertical riser section of the pipe that separates the upward expansion design from the downward expansion design. Guides and snubbers along the pipe systems allow for horizontal containment.
- Supports should be moving within the design range – not necessarily at the design settings. i.e. : not topped out or bottomed out and moving in the correct direction.
- In a base loaded unit we are mostly concerned with hot condition readings, as this is where the system spends most of it’s time.
- Load adjustments should only be made in the hot condition and only by qualified individuals.
If during your periodic walkdowns of your pipe supports, you find that you have any of the following conditions, hanger adjustments or replacements may be necessary.
- Bottomed out spring hangers
- Hangers exceeding travel range
- Loose or Broken Locknuts
- Sagging high-temperature steam lines
- Broken hanger components
- High energy steam lines “jumping” during startup/shutdown (water hammer events)
When the above conditions exist, further evaluation of the systems is required to determine the significance of any deficiencies and develop recommendations. Such evaluations may include load testing and stress analysis. Travel adjustments can then be made to attempt to bring the support system to its optimum condition. Support load testing is performed after adjustment to assure the pipe supports are set to the recommended loads and are within the allowable range.
On occasion, there are issues that prevent obtaining the optimum load and travel setting such as insufficient adjustment remaining in the hanger, insufficient rod length, or damage to hanger bolts, bearing or other components which affect the reliability of the adjustments. If these conditions are apparent, the replacement of the hanger may be deemed necessary. The procurement of replacement hangers can be a tedious task and should be handled by an experienced hanger professional who understands the requirements and specifications needed to provide the proper support. Once the hanger components have been procured, the installation process involves careful attention to ensure temporary support of the system in order to remove the existing hanger. Many times an on-site evaluation must be made to determine the best way to hang and attach the newly supplied hanger.
Because healthy pipe support systems can increase the longevity of your piping systems, Thielsch Engineering’s pipe support program encompasses all considerations to the ongoing health of your pipe supports. These considerations include inspection, adjustment, and repair of pipe supports. In addition, if it is determined that a pipe support requires replacement, Thielsch Engineering also handles the procurement and installation of the appropriate hanger components, making our hanger services completely turnkey. Thielsch is currently involved in over a dozen projects across the nation that involve the adjustment and or replacement of high energy piping supports.
If you would like more information on failures associated with Hanger Supports or would like Thielsch Engineering to develop a scope of work for an engineering inspection and evaluation or adjustment, please feel free to contact the following experts:
Corporate Office: Mr. Peter Kennefick at firstname.lastname@example.org
Ohio and Florida Regional Offices: Mr. Robert Smoske at email@example.com