Farr HD8625 - Illustration 2.F.1: Tong Suspension Relative To Axial Centre

2.12
hD8625 8-
5
/
8
” 35K Tong
Technical Manual
MCCOY DRILLING & COMPLETIONS ACCEPTS NO RESPONSIBILITY FOR DESIGNING AND
SELECTING AN ADEQUATE SUSPENSION AND RESTRAINT SYSTEM FOR YOUR DRILLING
EQUIPMENT
ALL SELECTED FASTENERS, SHACKLES, CLAMPS, ETC. USED FOR CONSTRUCTING THE
SUSPENSION AND SNUB LINES MUST BE RATED FOR THE CALCULATED FORCES.
Suspension & Restraint (Cont’d)
Ifyoudonotknowwhichspecificspringhangerisinuse,checkthespecificationpageinthismanualforinformationontherecom-
mendedspringhangerforthisapplication.McCoyDrilling&Completionswillnotguaranteeorspecifyspringhangersotherthanwhat
hasbeensuppliedbyMcCoy.
Manyapplicationsusealiftcylinderforadjustingtheheightofthetong.Ensuretheweightoftheliftcylinderisknownifithasnot
beenincludedinthetotalweightofthetong.
Allforcesuponthesuspensionlinemustbeconsideredwhencalculatingnecessarystrengthofthesuspensionline.Theweightof
thetong,theweightoftheliftcylinder,theweightofthespringhanger,andtheforceimpartedonthesuspensionlinebythespring
hanger must all be addedtogether in order toarrive at the totalforcesupported by the suspensionline. Select your suspension
linebaseduponthetotalforceandthemarginsofsafetydictatedbythepoliciesofyourcompanyandbyestablishedengineering
practices.Ultimately,calculatingtheforceonthesuspensionlineandselectionofthesuspensionlineisthecompleteresponsibility
ofthecustomer.
McCoyDrilling&Completionsrecommendsusingdualbackup(snub)linesofsufficientstrengthtowithstandtheforceimpartedby
themaximumratedtorqueofthetonginuse.Calculatetheforceonthesnublinesbydividingthemaximumtorqueofthetongby
thetong’storquearm(expressedinfeet).Forexample,a35,000lbs.-ft.tongwitha36inch(3ft.)torquearmwillgenerate11667lbs.
offorceagainstthesnubline.Selectyoursnublinesbaseduponthetotalforceandthemarginsofsafetydictatedbythepoliciesof
yourcompanyandbyestablishedengineeringpractices.Ultimately,calculatingtheforceonthesnublineandselectionofthesnub
lineisthecompleteresponsibilityofthecustomer.
Snublinesmustbesecurelyconnectedtotherearofthetong,andtiedofftoasuitableanchor.Onesnublinemustbesecuredto
theloadcell,whichisthensecuredtotherearofthetong.Thesideofthetongtheloadcellconnectstoisdependantuponwhether
make-uporbreak-outactivitiesareunderway.Toensureaccuratetorquemeasurement,thetorquemeasurementlinemustbecon-
nectedperpendiculartothelengthwiseaxisofthetong,andperpendiculartothehangline(seeillustrations2.F.1and2.F.2).Connect
thesecondsnublineontheoppositesideoftheloadcell,perpendiculartothelengthwiseaxisofthetongandperpendiculartothe
vertical.
IllustratIon 2.f.1: tong susPensIon relatIve to axIal Centre
seTup & operaTion
90
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