Hoses used for loading or unloading ammonia into or from the refrigeration system have a limited life. The user must be alert to signs of hose deterioration before failure occurs. This page describes some inspection and testing procedures, work practices, and hose selection criteria to ensure the safe transfer of ammonia.

Potential Hazards

Figure 1. Unloading a railcar

• Hose failure, leading to a release of ammonia.

Possible Controls

• Provide information pertaining to the hazards of ammonia to workers. [29 CFR 1910.119(d)(1)]
  
  
  • For more information see Properties of Ammonia.
• Use hoses that are designed according to generally accepted good engineering practices. [29 CFR 1910.119(d)(3)]
  
  
  • Use hoses that are commonly used for ammonia, such as:
    
    
    • Stainless steel braided
      
      
    • Nylon braided
       
  • Use hoses that:
    
    
    • Indicate suitability for ammonia.
      
      
    • Have a working pressure of at least 350 psi and a burst pressure of at least 1750 psi.
      
      
    • Mark at least every 5 feet the manufacturers name, the words Anhydrous Ammonia, the working pressure, and the year of manufacture.
      
      
    • Make up hose assembly that is capable of withstanding a test pressure of 500 psi.
  • Replace hoses according to the manufacturers recommendations.
    
    
  • Do not use old, damaged, or mistreated hoses.
     
• Ensure employees are trained in the proper care and maintenance of hoses. [29 CFR 1910.119(g)]
  
  
  • Implement the following recommendations for the use of hoses:
    
    
    • Do not drag hoses over sharp or abrasive surfaces, unless specifically designed for such.
      
      
    • Protect hoses from severe end loads.
      
      
    • Ensure the pressure in the hoses is at or below its rated working pressure.
      
      
    • Change pressure gradually to prevent excessive surge pressures.
      
      
    • Do not run over hose with equipment.
      
      
    • Do not kink hoses.
      
      
    • Use dollies to handle large size hose.
       
  • Storage of hoses
    
    
    • Protect hose from:
      
      
      • Extreme temperatures
      • Too high or low humidity
      • Ozone
      • Sunlight
      • Oils
      • Solvents
      • Corrosive liquids and fumes
      • Insects
      • Rodents
      • Radioactive materials
    • Avoid stacking hoses in such a way that the weight of the stack creates distortions on the hose at the bottom.
      
      
    • Store hoses in the original shipping container if possible.
       
• Conduct routine inspections or testing for hoses as part of a Mechanical Integrity Program. [29 CFR 1910.119(j)]
  
  
  • Inspect hoses and connectors prior to each use. Look for:
    
    
    • Loose covers
      
      
    • Kinks
      
      
    • Soft spots, which may indicate broken or displaced reinforcement
       
  • Perform a hydrostatic test periodically:
    
    
    • Test for one minute at 150 percent of the recommended working pressure.
      
      
    • Test hoses when they are straight, not coiled, or kinked.
      
      
    • Flush hoses with alcohol to remove traces of moisture.
      
      
    • Never use a compressible gas for the test due to the explosive action of the hose should failure occur.
      
      
    • Bleed air through an outlet valve while filling it with the test medium.
      
      
    • Place steel rods at ends and at approximately 10 foot intervals to prevent "whipping" should failure occur.
      
      
    • Bulwark the outlet end of the hose to stop blown-out fittings.
      
      
    • Protect testing personnel from the forces of the testing media should failure occur.
      
      
    • Do not stand in front of or in back of the ends of the hose being pressure tested.
       
  • Inspect the couplings or fittings.

Additional Information

• Specifications for Anhydrous Ammonia Hose, 7th Ed. Rubber Manufacturer's Association (RMA) Publication IP-14, (2003). Covers hose, three-inch inside diameter and smaller, commonly referred to as "pressure transfer hose", used to convey anhydrous ammonia liquid or to convey anhydrous ammonia gas where the gas is in contact with liquid ammonia.
  
  
• Safety Standard for Refrigeration Systems. ANSI/ASHRAE 15-2001, (2001). This document specifies safe design, construction, installation and operation of refrigerating systems. This establishes safeguards for life, health and property and prescribes safety standards. This applies to new installations and modifications of existing installations. See the Table of Contents.
  
  
• Hose Technical Bulletin - Manual for Use, Maintenance, Testing, and Inspection of Anhydrous Ammonia Hose, 4th Ed. Rubber Manufacturer's Association (RMA) Publication IP-11-2, (1997). 
  
  
• A Guide for Developing a Training Program for Anhydrous Ammonia Workers. National Institute for Occupational Safety and Health (NIOSH) Publication No. 79-119 (1978). Primarily emphasizes safety in the operation of facilities that handle anhydrous ammonia for agricultural purposes; however, the information included should interest all who handle anhydrous ammonia at other permanent installations. See the Table of Contents.