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SS 316 High performance fittings >Tube fittings > Overview


  Tube fittings
Overview
The selection of the optimal tube fitting for an application depends on the system operating parameters, tube construction and wall thickness, and other secondary considerations recommended or required by the specific application.
Operating Parameters
• Pressures – working and maximum service
• Temperature
• Vibration or system loading
• Severity of service or "mission criticality"
• Media or type of fluid in system or in surrounding environment
After determining the type of tubing, which is usually indicated by the working pressure & maximum service pressure of the hydraulic system, determining the fitting type best suited for the system based on the features listed in the accompanying table. When one or more tube fittings satisfy the system operating parameters, secondary considerations, such as specification conformance, existing practice, assembly considerations, and customer preference, should be considered.
 
Feature Soft-Seal ORFS (O-Ring Face Seal) SAE 37 Flared UltraFlare SAE Flareless
Pressures Very high Medium to high High Medium
Temperatures Nitrile/Buna: -30° to 250°F Stainless: -425° to 1200°F PTFE/Teflon: -100° to 450°F Stainless: -425° to 1200°F
  Viton: -15° to 400°F Brass: -40° to 400°F   Monel: -65° to 800°F
  Monel: -65° to 800°F      
Vibration Resistance Excellent Good Very good Good
       
Materials TSS 316/SS 316L stainless steel TSS 316/SS 316L stainless steel TSS 316/SS 316L stainless steel TSS 316/SS 316L stainless steel (17-4 ph stainless for ferrule)
    M405 Monel   M405 Monel
CA377/CA360/CA345 brass
Size Available NavSea: 1/8" - 2"   1/8" - 2" 1/4" - 1" 1/8" - 2"
(tubing OD) SAE: 1/4" - 1-1/2" 6 mm - 38 mm 6 mm - 25 mm  
Tube Welded or Seamless Welded or Seamless Welded or Seamless Seamless only
Compatibility Inch or metric Inch or metric Inch or metric Inch only
  All thickness Thin to medium thickness Thin to medium thickness Medium to heavy thickness
Seal Reliability Excellent Good Very good Very good
  Elastomeric seal Metal-to-metal seal PTFE seal reinforces metal-to- Metal to metal seal
High tolerance to minor sur- Low tolerance to minor surface metal seal Sealing surfaces are less
face imperfections and damage imperfections and damage Medium tolerance to surface prone to damage
High tolerance to assembly Low tolerance to assembly imperfections Low tolerance to assembly
variation variation Medium tolerance to assembly variation
    variation like under-flaring or  
torquing
Assembly 
Tubing Preparation Sleeve brazing or tube flanging Tube flaring Tube flaring Ferrule presetting
Ease of Assembly Excellent Good Very Good Good
  Minimal skill required once tail-piece/sleeve is affixed to tubing Requires skill and trained personnel Requires general knowledge of tube flaring & assembly, but forgiving of assembly variation Requires skill and trained personnel
Ease of Excellent Very good Very good Good
Maintenance "Zero-clearance" system means no tube entry into fitting body Small tube entry around fitting body Small tube entry around fitting body Large tube entry into fitting body
Specification SAE J1453 SAE J514 SAE J514 (partial) SAE J514
Conformance NavSea 710 MIL-F-18866 NASA GP-425 (partial) MIL-F-18866
  ISO 8434-2 ISO 8434-3