Do's and Don'ts | Flexible Braided Hoses
Bulletin 8773 Page 11
• DO protect the braided outer covering from damage.
DON'T FAIL TO ANCHOR . Anchor piping close to flexible connector, at end opposite source of vibration. Anchor flexible metal hose at the piping end, never at the equipment end. If hose is not securely anchored, it will transmit all vibration to the piping system. Not only that, it will often act like a spring and actually amplify the vibrations. Whenever possible, install flexible connector to vibrating equipment- before valves, pipe line, fittings so that most vibration is absorbed and isolated instead of being transmitted.
DON'T COMPRESS a flexible connector to make it fit! Installing it under compression stresses corrugated element, slackens braid pressure-restrainer, reduces further compressive movement, and generally results in early failure. DON'T FORCE-ROTATE one end of connector to match bolt holes in mating flange. This sets up residual torque-stress in connector, which causes cracking of corrugations or fitting joint. A flexible, connector absorbs vibration, or slow movement perpendicular to its axis. It is NOT capable of withstanding torque. • DO consider specifying one end with a Type "F" lap joint floating flange to minimize imposing torque stresses on the hose during installation. DON'T STRETCH connector to fit a gap longer than its factory- furnished length. Stretching places excessive residual stresses on braid and fittings. Result? Early rupture. • DO be sure to install it at exact normal free length as supplied. If connector is too long, shorten piping. DON'T IMPOSE TORQUE on connector when making up fittings and don't use a wrench on the ferrule or on the braid. Where a hex end is provided, use it. If not, use the wrench on the fitting length provided. Always use two wrenches, to keep the hose from being torqued as the joint is made up. DON'T let welding sparks hit the braid; they may burn some of the braid strands. Protect braid with nonflammable material in front of it when piping must be welded very close nearby.
• DO check for leaks and free movement after installation.
DON'T BEND HOSE sharply near fittings. Fitting end or flange face must always remain perfectly perpendicular to axis of hose. If piping meets at an angle, install hose with a shallow curve along its entire length, leaving small straight section at each end. This kind of installation generally requires a longer hose. DON'T LET HOSE support any weight except its own. Its light wall was designed to contain internal pressure, but not to carry external loads. Extra weight will stress and stretch it. • DO use hangers on all adjacent piping. Install hangers before installing hose, to be certain weight of pipe is on hangers. DON'T FORCE HOSE into too much lateral offset. This puts it under great strain. Also, it cannot then handle any movement of any kind. Avoid excessive force. • DO check the literature and do not exceed maximum permissible offset.
• DO use proper tools for installation. Only wrench on the proper fitting area of the assembly.
WARNING: Situations dangerous to personnel and property may exist with the operation and maintenance of any combustion equipment. The presence of fuels, oxidants, hot and cold combustion products, hot surfaces, electrical power in control and ignition circuits, etc., are inherent with any combustion application. Components in combustion systems may exceed 160°F (71°C) surface temperatures and present hot surface contact hazard. Fives North American Combustion, Inc. suggests the use of combustion systems that are in compliance with all Safety Codes, Standards, Regulations and Directives; and care in operation.
CONTACT fna.sales@fivesgroup.com T +1 800 626 3477 - F +1 216 373 4237
Fives North American Combustion, Inc. 4455 East 71st Street - Cleveland, OH 44105 - USA www.fivesgroup.com
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