The The Theacronym acronym acronym“STAMPED”, “STAMPED”, “STAMPED”,as as asused used usedfor for forhose hose hoseassemblies, assemblies, assemblies,is isisequally equally equallyas as asimportant important importantto to touse use usewhen when whendeveloping developing developing tube tube tube assemblies. assemblies. assemblies. The The Thesame same samefactors factors factorsapply; apply; apply;only only onlythe the thefabrication fabrication fabricationand and andinstallation installation installationwill will willvary. vary. vary. Flow Flow Flowand and andpressure pressure pressurecharts charts charts can can canbe be befound found foundfrom from fromthe the thesame same sametechnical technical technicalreferences. references. references. Typical Typical Typicaltubing tubing tubingcharts charts chartsare are areincluded included includedin ininTask Task Task7. 7. 7.
The
S T A MPE D
Size Size Sizeof ofoftthe he t hettubing ubing t ubingis isisbased based basedon: on: on: 1. 1. 1. Flow Flow Flow(GPM) (GPM) (GPM) 2. 2. 2. Flow Flow Flowvelocity velocity velocity(ft/sec) (ft/sec) (ft/sec) 3. 3.3. Pressure Pressure Pressure 4. 4. 4. External External Externalcorrosion corrosion corrosion All All Allhydraulic hydraulic hydraulictubing tubing tubingis isismeasured measured measuredon on onthe the theoutside outside outsidediameter diameter diameter(O.D.). (O.D.). (O.D.).The The Theflow flow flowvelocity velocity velocityis isisbased based basedon on onthe the thegalgalgallons lons lons per per per minute minute minute (GPM) (GPM) (GPM) flowing flowing flowing through through through the the the tube. tube. tube. This This This can can can be be be calculated calculated calculated or or or found found found on on on charts charts charts and and and in ininttechnical echnical t echnicalreferences. references. references. VVV= ==velocity velocity velocity(ft/sec) (ft/sec) (ft/sec) AAA= ==internal internal internalarea area area(sq. (sq. (sq.in.) in.) in.)(p (p (pxxxrr2r22)))or or or(D (D (D222xxx.7854) .7854) .7854) Q QQ= ==gallons gallons gallonsper per perminute minute minute(GPM) (GPM) (GPM) ppp= ==3.1416 3.1416 3.1416
Pressure Pressure Pressureis isisincluded included includedin ininsizing sizing sizinghere here hereas as aswell well wellas as asunder under undertthe he t he““P” “P”P”lat lat later ereron on onin inin““STAMPED”. “STAMPED”. STAMPED”. Flow Flow Flowlosses losses losses(pressure (pressure (pressure drop) drop) drop)can can canaffect affect affectsizing sizing sizingthe the thetubing. tubing. tubing.Length Length Lengthof ofofline line lineand and andconfiguration configuration configuration(elbows (elbows (elbowsand and andnumber number numberof ofoffittings) fittings) fittings)can can canadd add add ttoot opressure pressure pressurelosses losses lossesdict dict dictat atating ing ingaaalarger larger largerttube ube t ubeII.D. I.D. .D. Low Low Lowttem em t emperat perat peratures ures urescan can canalso also alsoaffect affect affectviscosit viscosit viscosityyywhich which whichin inintturn urn t urnwill will will affect affect affectpressure pressure pressuredrop. drop. drop. Wall Wall Wallthickness thickness thicknessat at atbent bent benttube tube tubesections sections sectionswill will willhave have havereduced reduced reducedwall wall wallsize. size. size. This This Thiswill will willrequire require requirethe the the designer designer designerto to todetermine determine determinethe the theamount amount amountof ofofreduction reduction reductionbased based basedon on onthe the thebend bend bendradius radius radiusand and andto to torecalculate recalculate recalculateallowable allowable allowableworkworkworking ing ingpressure pressure pressurefor for forthe the theparticular particular particularbend. bend. bend. On On Onsome some someapplications applications applicationswhere where wherecorrosion corrosion corrosionis isisanticipated, anticipated, anticipated,the the thelife life lifeof ofofthe the the system system systemcan can canbe be beextended extended extendedby by byincreasing increasing increasingthe the thewall wall wallthickness thickness thicknessto to tocompensate. compensate. compensate.
Method for Selecting Tubing and Fittings for a Metal Tube Assembly
Tem Tem Temperat perat perature ure urecan can canbe be beaaafactor factor factorwith with withtubing tubing tubingand and andfittings, fittings, fittings,but but butusually usually usuallynot not notuntil until untiltemperatures temperatures temperaturesare are areextreme extreme extreme(350° (350° (350°
A S S EMB LY CO MPO N EN T S EL EC T IF). O FFFto to to-45° -45° -45° F). F).N High High Highand and andlow low lowtemperatures temperatures temperaturescan can canaffect affect affectO-rings O-rings O-ringsin ininfittings fittings fittingsand and andthe the theselection selection selectionof ofoftubing. tubing. tubing.
Applicat Applicat ion: ion: ion:Determine Determine Determine where where the the thenew new newor or orreplacement replacement replacement tube tubeassembly assembly assemblyis isis to to tobe be beused. used. used. Most Most Mostoften, often, often,only only onlyaaadududuThe acronym STAMPED, as used for hose assemblies, is equallyApplicat as life. To fulfill where the requirements of the tube application, additional questions
9.0. Use the “STAMPED” method in selecting proper tubing and plicate plicate plicateof ofofthe the theoriginal original originalwill will willbe berequired required requiredprovided provided providedthe theoriginal original originalassembly assembly assemblygave gave gaveacceptable acceptable acceptableservice service servicelife. life. life. To To Tofulfill fulfill fulfill important to use when developing tube assemblies. The same factors may need to bebe answered such the as: the the therequirements requirements requirementsof ofofthe the theapplication, application, application,additional additional additionalquestions questions questionsmay may mayneed need needto to tobe be beanswered answered answeredsuch such suchas: as: as: gs for a metal tube assembly. apply; only the fabrication and installation will vary. Flow and pressure charts can be found from the same technical references.
Where Where Wherewill will willassem assem assembly bly blybe be beused used used
tcome 9.1. Design and specify tube assembly components. Working Working Workingand and andsurge surge surgepressures pressures pressures
S
Suct Suct Suction ion ionapplicat applicat application? ion? ion?
of the 1. Flow (GPM) as important to use when developing tube onym “STAMPED”, asize used for tubing hose assemblies, is equally Type Type Typeof ofofttubing ubing t ubing is based 2. Flowand velocity (ft/sec)will vary. Flow and pressure charts Fitting Fitting Fittingtype type type ies. The same factors apply;on: only the fabrication installation ound from the same technical references. 3. Typical tubing charts are included in Task 7. Pressure 4. External corrosion
Fluid/ambient Fluid/ambient Fluid/ambienttemp. temp. temp. Fluid Fluid Fluidcompatibility compatibility compatibility Environm Environm Environment ent ental alal Minim Minim Minimum um umbend bend bendradius radius radius Rout Rout Routing ing ing
Gov. Gov. Gov.& &&industry industry industrystandards standards standards Mechanical Mechanical Mechanicalloads loads loads Excessive Excessive Excessiveabrasion abrasion abrasion Expect Expect Expected ed edservice service servicelife life life Ext Ext External ernal ernalcorrosion corrosion corrosion
M
M MMat ataterial: erial: erial: Tube Tube Tubeselection selection selectionand and andfittings fittings fittingsmust must mustassure assure assurecompatibility compatibility compatibilitywith with withthe the thefluid fluid fluidto to tobe be becirculated circulated circulatedin ininthe the thesystem, system, system, aterial: Tube selection and fittings must be as as aswell well wellas as astthe he t heenvironm environm environment ent ental alalcondit condit conditions. ions. ions.
he t ubing is based on: compatible with the fluid to be circulated in the (GPM) N NNooott e: te:e:Many Many Manyswivel swivel swivel elbow elbow elbowfittings fittings fittings contain contain contain O-rings O-rings O-rings which which whichmust must mustbe be beconditions. compatible compatible compatiblewith with withthe the thefluid fluid fluidand and andenvironmental environmental environmental All hydraulic tubing is measured on the outside diameter (O.D.). system, as well as the environmental velocity (ft/sec) condit condit conditions. ions. ions. The flow velocity is based on the gallons per minute (GPM) flowing sure St StStudy udy udyManualManualManual-07/ 07/ 07/01/ 01/ 01/16 16 16 Connector Connector Connector& &&Conductor Conductor ConductorCetification• Cetification• Cetification•55 55 55 ressure: When selecting metal tube, it is vital to rnal corrosionthrough the tube. This can be calculated or found on charts and in aulic tubing is measured on the outside diameter (O.D.). The flow velocity is based on the galtechnical references. know the working pressure, including pressure r minute (GPM) flowing through the tube. This can be calculated or found on charts and spikes. Pressure spikes greater than the published cal references. working pressures will shorten the system service V = velocity (ft/sec) life and must be taken into consideration. PubA = internal area (sq. in.) (p x r 2 ) or (D2 x .7854) lished tube working pressures must be equal to Q = gallons per minute (GPM) p = 3.1416 or greater than the system pressure. Thinning of
Note: Many swivel elbow fittings contain O-rings that must be compatible with the fluid and environmental conditions.
P
the tube wall at bends must also be considered.
is included in sizing here as well as under t he “ P” lat er on in “ STAMPED”. Flow losses (pressure Pressure is included in sizing here as well as under the “P” later on Burst pressures are reference pressures intended for n affect sizing the tubing. Length of line and configuration (elbows and number of fittings) can add in STAMPED. Flow losses (pressure drop) can affect sizing the tubing. destructive testing purposes and design safety factors only. Typically, for ure losses dict at ing a larger t ube I .D. Low t em perat ures can also affect viscosit y which in t urn will of line and configuration (elbows andreduced numberwall of fittings) can dynamic essure drop.Length Wall thickness at bent tube sections will have size. This will require thehydraulic applications, the minimum burst pressure rating is add pressure dictating larger tuberadius I.D. Low temperatures fourworktimes that of the maximum working pressure rating. r to determine thetoamount of losses reduction based aon the bend and to recalculatecan allowable sure for the also particular On which some applications wherepressure corrosiondrop. is anticipated, affectbend. viscosity, in turn will affect Wall thick-the life of the can be extended wall thickness compensate. nds: Identify the tube end fittings nessby at increasing bent tube the sections will haveto reduced wall size. This will require
the designer to determine the amount of reduction based on the bend
E D
using manufacturers’ catalogs.
at ure can be a factor with tubing and fittings, but usually not until temperatures are extreme (350° radius and to recalculate allowable working pressure forselection the particular ° F). High and low temperatures can affect O-rings in fittings and the of tubing.
bend. On some applications where corrosion is anticipated, the life of the
elivery: Availability, time to assemble, special packaging, ship-
ion: Determine where the or replacement tube the assembly is to be to used. Most often, only a dusystem can benew extended by increasing wall thickness compensate. ping, and documentation. f the original will be required provided the original assembly gave acceptable service life. To fulfill irements of the application, additional questions may need to be answered such as:
T
emperature can be a factor with tubing and fittings, but usually not until temperatures are extreme (350° F to -45° F). High and Where will assem bly be used Fluid/ambient temp. Gov. & industry standards temperaturesFluid can compatibility affect O-rings in fittingsMechanical and the selection Working and surge low pressures loads ofion? tubing. Suct ion applicat Environm ent al Excessive abrasion
1. All hydraulic tubing is measured by its: pplication: Determine where the new or replacement tube assema. O.D. bly is to be used. Most often, only a duplicate of the original will be b. I.D. : Tube selection and fittings must assure compatibility with the fluid to be circulated in the system, required, provided the original assembly gave acceptable service c. Wall thickness. as t he environm ent al condit ions. d. Material hardness. any swivel elbow fittings contain O-rings which must be compatible with the fluid and environmental e. Material type. Type of t ubing Fitting type
A
Minim um bend radius Rout ing
Expect ed service life Ext ernal corrosion
ns.
nual- 07/ 01/ 16 6
AUGUST 2020
Connector & Conductor Cetification• 55
Test Your Skills 2. Anticipating a corrosion problem one could: a. Increase volume. b. Decrease volume. c. Increase pressure. d. Decrease wall thickness. e. Increase wall thickness. See correct answers on page 39.
