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Technical Report

TECHNICAL REPORT - T022
Subject: Low Temperature Hose Service
By: Hose Master
Date: February 2009


One of the advantages metal hose has over rubber or plastic hose is it's ability to withstand low and cryogenic temperatures. However, it is still necessary to match the assembly components to the anticipated application temperature. An incorrect alloy used for a low temperature application may result in premature failure. Some metals, particularly ferrous (iron-based) alloys such as carbon steel, are susceptible to losing their normal ductile properties and becoming brittle at relatively moderate temperatures.1

Example: ASTM A53 Type F carbon steel, which is a common material for pipe and TOE nipples, is rate service only down to 20°F.

Fortunately, the yield2 and tensile3 strengths of austenitic4 stainless steels, nickel alloys such as 276, and many copper based alloys such as bronze, significantly increase as the temperature decreases. The material ductility5 decreases, but not sufficiently to preclude their use for most applications.

The fatigue strength of 300-series stainless steels actually increases at lower temperatures and there is a corresponding decrease in fatigue crack growth rates. With 300-series stainless steel corrugated metal hose applications, as the temperature drops:

  • The strength of the hose increases.
  • The resistance of the hose to fatigue fracture initiation increases.
  • Fatigue cracks progress through the hose wall at reduced rates from those at ambient temperature.


A mandatory requirement: If a customer is requesting hose for low temperature service, determine what the temperature actually is. The terms, "cryogenic" and "absolute zero" are sometimes used by the end-user or distributor, but these are not sufficiently specific for accurately defining an application:

Terminology:

  • "Cryogenic" does not define a temperature. The term is actually rather loose and can vary substantially depending on the source. Definitions generally range from -148°F to -237°F.
  • "Absolute Zero" is -459.67°F. It a theoretical temperature and cannot actually be achieved.

Chart 1 - Low Temperature Metal Limits per ASME B31.3 - Process Piping
ProductAlloyASTMLow Temp Rating (F°)
Hose300 Series
C276
A240
B575
-425
-325
Braid300 Series
C276
A478
B575
-425
-325
TOE/PipeCS
300 Series
C276
A53, types F
A312
B574
20
-425
-325
TOE/PipeCS
300 Series
C276
A105
A182
B574
-20
-425
-325
"A" Stub300 Series
C276
A403
B366
-425
-325
"C" Stub300 SeriesA403-425
To determine the low temperature limit for an assembly component not listed in Chart 1:
  1. Determine, from the component vendor if necessary, the specific ASTM standard to which it was manufactured.
  2. Refer to 31.3 Table A-1 (Book 24 in the Hose Master Standards library.)


Notes:

1 The temperature at which the metal becomes brittle is termed the "Ductile to Brittle Transformation Temperature" (DBTT)
2 Yield Strength is the point at which a stressed (deformed) metal will not return to its original shape.
3 Tensile Strength is the maximum amount of pulling stress a metal can accommodate before failure.
4 Austenitic Stainless Steels includes 300 series stainless steel (i.e. 304, 316…).
5 Ductility is the ability to form or change the shape of metal.
6 The European Standard BS EN 14585-1:2006 "Pressurized Corrugated Metal Hose Assembly for Pressure Applications, Part 1: Requirements" contains a guideline for the use of various alloys at two temperature limits (See Chart 2)

Rev. A; Date: 2/10/09

T022 Location:s/procs/sales eng.