Preventive Maintenance Protects Your Investment

  Preventive Maintenance Protects Your Investment
 

In addition to scheduled thorough inspections, hoses should be routinely checked for wear and damage.

Look for the following:

  • External damage
  • Discoloration
  • Stiffness
  • Kinks
  • Exposed or rusted wire

A typical industrial hose is often subjected to physical abuse while in service, so the first step of a maintenance program is to educate operators on the elimination of avoidable misuse. You should strive to prevent a hose from being kinked or run over, and never use a hose above its rated working pressure. Two common causes of hose assembly damage are excessive pulling by the fittings and bending beyond the assembly's maximum bend radius. Operators must realize that the hose is part of the pressurized system and any damage created could result in an unsafe operation for them, as well as a reduction in the life of the hose.

To ensure safety, hose and fitting inspections should be regularly scheduled, since worn or damaged hoses can put workers and the environment in jeopardy. Periodic inspections, corrective actions and replacement are ultimately less expensive than unscheduled repairs and downtime. In addition, they can prevent unsafe conditions from occurring on the job site. Inspection frequency and requirements vary depending on hose application. In general, conditions to be considered are operating temperatures, operating pressures, the work environment and the hose application.

In addition to scheduled thorough inspections, a hose should be routinely inspected with eyes and hands to determine if it is suitable for continued service. Look for and correct:

  • Damage to a hose cover, such as cuts, cracks, abrasions and exposure of reinforcement
  • Color variations that may come from chemicals, ozone, heat and aging
  • Stiffness, which is usually the result of aging, environment, heat and chemical exposure
  • Kinks that restrict the flow of conveyed liquids and weaken the hose construction
  • Blisters on a cover that can break and expose reinforcement or lead to leakage
  • Damage to wire or fabric reinforcement, which results in weakened hose construction
  • Leakage, which can lead to peripheral damage or problems with attachments or couplings
  • Hose with exposed or rusted wire, which should be replaced immediately

Scheduled hose inspections require more thorough evaluations and accurate record retention. Detailed records should be kept for liability purposes, as well as to track any failure rates. Inspections should be scheduled at a minimum of every three months, with more demanding applications requiring much shorter intervals between inspections. Visual inspections should be performed before beginning each job. In addition, hydrostatic tests can be performed on a routine schedule (reference the procedure outlined in RMA publication The Hose Handbook). Fittings should also be surveyed during scheduled hose inspections. A hose should be removed from service if there is any sign of fitting movement from the hose, or if there is damage to the fitting that could prevent it from operating as intended (threads damaged, swivel does not work, excessive corrosion, etc.).

The following are guidelines to follow in order to properly maintain a hose and receive maximum expected service:

  • Never exceed the rated working pressure of a hose, except during a valid hydrostatic pressure test, as exceeding rated working pressure can cause the hose to burst prematurely.
  • Ambient and fluid temperatures should not exceed supplier recommendations.

(Manufacturers often supply the hose printed with the temperature and pressure limits. If this information cannot be found on the hose, contact the hose manufacturer to verify these critical operating parameters.)

  • Never exceed the specified minimum bend radius or pull a hose by its fitting. It could lead to kinking and loosened couplings. Consider using a kink guard near couplings.
  • Remember that a high-abrasion environment will be better served by a hose with a high-abrasion hose cover.
  • When storing rubber industrial hose, pay attention to temperature, humidity, ozone and sunlight. A room with moderate humidity and a temperature range of 50° to 75°F is recommended for storing most hose.
  • If exposed to freezing conditions, a stiff hose should be allowed to thaw and given additional inspections before being used.
  • Rotate stored hose stock to avoid exceeding its shelf life.

Ultimately, the storage, preventive maintenance, applications and replacement of hose are dictated by the work environment, end-user, manufacturer, fabricator, operator and many other factors. Giving careful consideration to hose selection, installation, care, maintenance and storage can provide optimum value, safety and performance, as well as a solid return on the investment.

[Next Article]  [Return to Table of Contents]  [Top of Page]