ANSI/CAN/UL 536:2021 STANDARD FOR SAFETY Flexible Metallic Hose
1 Scope
1.1 These requirements cover flexible metallic hose supplied with fittings on each end that facilitateconnection without twisting the hose. They have a corrugated metal core or a nonmetallic inner core whichare covered with a stainless steel braid.They have a nominal inside diameter of not more than 4 in (101mm) intended for use in piping systems carrying compressed gases, such as anhydrous ammonia, andcombustible fuel gases such as natural gas， liquefied petroleum gas, propane,and butane, at pressuresnot exceeding 500 psig (3.45 MPa) and temperatures not greater than 450 °F(232 C) or lower than-40 °F(-40°C).
1.2Flexible metallic hose is intended for aboveground applications and for underground applications notinvolving contact with soil.
1.3 Flexible metallic hose is not considered a substitute for standard pipe or tubing and its use should beconfined to applications where flexible connections cannot be avoided.
1.4 Flexible metallic hose is not intended to be subjected to excessive torsion, tension, compression,orbending stresses and shall be protected against physical damage and ignition sources.
1.5 This standard does not apply to hose connectors used in natural gas processing plants, refineries,petrochemical plants, marine terminals, or gas-transmission and distribution-piping systems.
1.6 These products have not been evaluated for use after fires, natural disasters such as earthquakes,or excessive physical damage beyond the expected assembly, installation and uses as identified in theserequirements.
1.7 These products are intended to be periodically inspected and maintained for continued service, ortaken out of service if necessary by qualified persons in accordance with industry recommended practicesandlor the manufacturer's instructions.
1.8 Products covered by these requirements are intended to be installed and used in systems inaccordance with the applicable Codes and Regulations as determined by the Authority Having Jurisdiction(AHJ), such as, but not limited to:
a) In the United States:
1) National Fuel Gas Code, NFPA 54/ANSIZ223.1;
2) Liquefied Petroleum Gas Code,NFPA 58; and
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