Flexible Metallic Hose

UL 536

1 Scope

1.1 These requirements cover flexible metallic hose having a nominal inside diameter of not more than 4 inches intended for use in piping systems carrying compressed gases, such as anhydrous ammonia, and flammable and combustible gases and liquids, at pressures not exceeding 500 psig (3.45 MPa) and temperatures not greater than 450 F (232 C) nor lower than minus 40 F (minus 40 C).

1.2 The terms flammable and combustible gases and liquids, as used herein, mean gases and liquids such as alcohol, fuel oil, gasoline, kerosene, liquefied petroleum gases, and manufactured and natural fuel gases. A combustible liquid has a flash point at or above 100 F (38 C). A flammable liquid has a flash point below 100 F and a vapor pressure not exceeding 40 psig (276 kPa) at 100 F.

1.3 Metallic hose intended to be used in chemical plants and petroleum refinery piping is intended for installation in accordance with requirements in Process Piping, ANSI/ASME B31.3-1996.

1.3.1 Flexible metal hose is not considered a substitute for standard pipe or tubing and its use should be confined to applications where flexible connections cannot be avoided. It should not be subjected to torsional, tensile, or excessive bending stresses and should be protected against mechanical injury.

1.3.1 added November 18, 1999

1.4 This standard does not apply to gas appliance connectors for handling fuel gases at 5 psig (34.5 kPa) or less, nor to metallic hose intended for use in oil-transportation piping or in gas-transmission and distribution-piping systems.

1.4.1 This standard does not apply to connectors used in natural gas processing plants, refineries, petrochemical plants, marine terminals, or gasoline service stations.

1.4.1 added November 18, 1999

1.5 Deleted June 9, 2003