Plant managers and engineers may oversee multiple systems of industrial hoses throughout their facility. Deciding when to replace those hoses can be complicated. Failures can occur if the hose is replaced too late, but replacing it too early, when it is not yet necessary, can cost the facility time and money. Regular inspections and detailed record-keeping can therefore provide the necessary data to increase uptime and reduce overall costs.
By Alice Chin, Field Engineer Supervisor, North America, Swagelok Company.
To ensure hoses are changed at the proper time, a preventive maintenance schedule should be established. A preventive maintenance plan will allow managers to monitor individual hoses more carefully over time. Inspecting each hose frequently and replacing hoses proactively as needed can help prevent failures that could derail an entire operation. Though developing a plan can be time-consuming at first, the money it will save facilities over time will offset the upfront investment of time and resources. It is important to understand that no two hose maintenance schedules will be identical because each hose undergoes different stresses during operation. Replacement intervals should be based on a hose’s particular environment, including elements like pressure, fluid type, movement demands, and nearby equipment.
To provide a real-world example: If a particular application uses 50 identical hoses, plant managers may steam clean half of them and wear them out after a year, while the other half may not be cleaned at all, and last up to five years. Putting all 50 hoses on a five-year maintenance plan does not make sense because it could lead to significant failures in the hoses that usually wear out in a year. On the other hand, replacing all the hoses yearly is not the best solution because it incurs unnecessary expenses both in equipment and downtime. By identifying and implementing the right maintenance schedule for both sets of hoses significant cost savings could occur.
How to Create an Effective Preventive Hose Maintenance Plan
Though general inspection and replacement guidelines should be provided by a hose supplier, specific maintenance intervals will vary. In other words, the replacement intervals cannot be standardized and must be established through observation and record-keeping.
1: Identify All Your Hoses
The first step toward developing an effective preventive hose maintenance plan is to complete a full plant audit, which includes identifying and tagging each hose, see Figure 1. Carefully log each hose thoroughly, noting the hose type, part number, process fluid, pressure or temperature ratings, and the supplier’s name and contact information.
Other information that should be collected during the audit and logged in a spreadsheet includes each hose’s length, size, core material and construction, reinforcement layers, end connections, mounting, cover type, operating conditions, and cleaning procedures. Plant managers should also mark the date the hose was installed and when its scheduled replacement date is. Having an accurate log of all hoses in a plant will be a valuable addition to a plant’s operation. If there is uncertainty about where to begin, consult with the hose supplier, who should be able to visit the plant and offer advice on how to best log the hoses.
2: Track the Life Cycle of Each Hose
Once the audit is complete, it is important to set specific inspection schedules for each hose based on the recommendations of the supplier, see Figure 7. Generally, these regular inspections are strictly visual and do not require a system shutdown. During these inspections plant managers should pay attention to signs of wear, including scrapes, cuts, corrosion, kinks, and general deterioration. If any of these signs are present, the hose should likely be replaced.
Make sure to record all such observations on the spreadsheet. If it is time to replace the hose, be sure to note the service interval so it can be used in the future to ensure the hose remains viable at all times. In the unfortunate event that a hose fails during operation, it is critical to document every detail, including the location of the failure, its severity, and how the hose was mounted. By taking copious notes on the failure and working with the supplier, it may be possible to prevent such failures in the future.
3: Eliminate Hose Strain
It is important to understand and note what environmental factors are placing the hoses under stress, so it is recommended to complete some inspections while the system is in operation to identify potential problems before they become significant. Check to see if a hose is rubbing against other equipment, experiencing pulses, is subjected to external heat sources, or is installed in such a way that may cause unnecessary stress. When these conditions are discovered, they should immediately be fixed. Failure to resolve these issues could result in catastrophic failures or shorten the service life of the hose. Figures 2 to 6 depict the most common types of hose strain.
4: Assess the Need for a Protective Cover
Under certain circumstances, protective covers for hoses are necessary. Typical covers include:
- Thermosleeve materials protect hoses from weld spatter and deterioration caused by UV light.
- Fire jacketing provides insulation from internal system fluid temperature extremes.
- Spiral guards can protect against abrasion.
- Armor Guards keep hoses from kinking while also limiting abrasion damage.
- Spring guards also prevent kinking and protect against abrasion.
Hose covers do not affect hose technical data, but it is critical to understand each cover’s operation temperature and primary purpose. For example, a thermosleeve does not resist abrasion, though it does an excellent job of protecting against weld spatter.
5: Follow Inspection and Replacement Protocols
Once a hose’s replacement interval has been established, a preventive maintenance plan will naturally emerge. That does not remove the responsibility from plant managers to inspect the hoses periodically in case changes in system parameters put additional, unforeseen strain on the hoses.
6: Analyze Your Data
Having a spreadsheet with the maintenance data in it is not enough. Once the information has been collected, it is incumbent on plant managers and engineers to analyze the data and compare it to real-life hose inspection and replacement frequencies. Only with this additional step can it be determined if any intervals should be shortened or lengthened, either for safety or budgetary reasons. Sometimes, it is necessary to perform destructive tests on a replaced hose to see if it was replaced too soon or too late. Regular data analysis will also provide insights into whether the right hose is being used for the application. If a hose is being replaced more often than expected, alternative designs should be considered that may be more appropriate for the specific application. As always, do a cost-benefit analysis to ensure the hose being used serves the plant’s overall best interests.
7: Be Prepared with Spares
One of the biggest advantages of establishing regular replacement intervals for hoses within a plan is that replacements can be ordered before they are needed. In some cases, plants should have extra hoses in inventory at the plant in case they are needed quickly. For example:
- Hoses for Critical Safety or Process Applications: It is imperative to keep readily available spares to correct hose applications that present critical safety hazards or severe downtime potential.
- Hoses that are Likely to Fail: When a hose’s operating environment presents a high likelihood of premature failure, it is beneficial to have an extra hose on hand to accommodate frequent replacements. For example, hoses that kink, move in two planes, or experience vibration will likely fail earlier than others.
A better practice may be to find a more suitable hose for the application or adjust the system completely to remove strain on the hose.
- Hoses for Special Applications: Keep spares of any hoses that are difficult to source due to special materials, lengths, end connections, and other variables. If a special order hose has a three-week lead time, it may be beneficial to inventory two spares for good measure.
While setting up an effective preventive maintenance schedule requires regular inspections and careful recordkeeping, implementing a hose maintenance plan could improve safety for its employees. These plans allow operators to replace hoses less often and mitigate the risk of failure. With less downtime and enhanced safety, the profitability of the plant could increase significantly. In the long run, keeping track of the hoses in a facility will show in real terms the value of the investment.