No-waste slip joint range

DEMM Engineering & Manufacturing - - PRODUCT WATCH -

One of the sim­plest and most cost- ef­fi­cient con­cepts from a com­pany spe­cial­is­ing in com­mer­cial, in­dus­trial and public build­ing slip joints and bearings is also be­com­ing one of its most suc­cess­ful.

Aus­tralia’s Her­cules En­gi­neer­ing – the pro­ducer of Her­cules com­pos­ite slip joints and Her­cu­lon struc­tural bearings – spec­i­fies its Her­cules Gal­va­nized or Stain­less Steel Grease Slip joints (HGSJ) or (HSSJ) as a cost­sav­ing al­ter­na­tive to more ex­pen­sive com­pos­ite slip joints where their higher per­for­mance prop­er­ties are not re­quired and wasted on many jobs.

The eas­ily ap­plied grease slip joint types, typ­i­cally used on load- bear­ing brick­work and un­der con­crete slabs, are part of the broad range of Her­cules prod­ucts proven in mul­ti­ple ap­pli­ca­tions to help pro­tect and ex­tend the longevity of land­mark build­ings and ma­jor com­mer­cial, in­dus­trial and public build­ings and struc­tures through­out Aus­trala­sia and the Asia- Pa­cific.

Her­cules’ range of HGSJ and HSSJ Grease Slip Joints is de­lib­er­ately tai­lored to the needs of the con­struc­tion mar­ket as the essence of sim­plic­ity, says Mr David Booty, Man­ager, Her­cules En­gi­neer­ing (a di­vi­sion of Cut To Size Plas­tics).

“It’s horses for cour­ses when it comes to the pref­er­ences of ar­chi­tects, en­gi­neers and spec­i­fiers, who se­lect tech­nolo­gies in terms of ef­fi­cient con­struc­tion, ver­sa­til­ity and dura­bil­ity. Spec­i­fiers of these cost- ef­fi­cient slip joints get ex­actly what they need and don’t have to pay for per­for­mance fea­tures they don’t want,” says Booty, who has more than 30 years’ ex­pe­ri­ence in spec­i­fy­ing slip joints and bearings, in­clud­ing high per­for­mance types.

Un­like Her­cules’ more so­phis­ti­cated HSC, the HGSJ and HSSJ types are not re­quired to ac­com­mo­date slid­ing face ro­ta­tion of sup­ported struc­tures or to evenly dis­trib­ute their weight. Grease slip joints are also typ­i­cally not a slip joint from which per­ma­nent per­for­mance is re­quired, but rather one that can be used un­der cast-in-situ con­crete slabs and struc­tural com­po­nents to ac­com­mo­date +/- 5mm move­ment as the struc­ture set­tles and cures after con­struc­tion.

The slip joints (above) con­sist of a sandwich com­pris­ing two lay­ers of 0.55mm thick gal­va­nized steel or stain­less steel with molyb­de­num grease in- be­tween for slid­ing prop­er­ties and pro­tec­tion of slid­ing sur­faces. Bound strongly to­gether by in­dus­trial tape, ei­ther gal­vanised steel or Grade 304 Stain­less Steel is used for the reg­u­lar slip joints, while Grade 316SS is used in mod­i­fied types for ap­pli­ca­tions near the water or for the use in cor­ro­sive en­vi­ron­ments.

“Grease slip joints are sim­ply de­signed to ac­com­mo­date in­terim ex­pan­sions and sat­isfy the lin­ear sin­gle- plain slid­ing move­ment re­quire­ments, as op­posed to the ver­sa­tile, long de­sign life and on­go­ing re­li­a­bil­ity of com­pos­ite slip joints in­cor­po­rat­ing lay­ers of high­per­for­mance en­gi­neer­ing plas­tics and other high grade ma­te­ri­als.

“They do the job they are re­quired to do dur­ing the con­struc­tion and fin­ish­ing phase, after which their slip per­for­mance is no longer re­quired and they be­come part of the in­te­grated struc­ture. Their huge pluses are cost- ef­fi­ciency, sim­plic­ity and dura­bil­ity – they can be drilled to ac­com­mo­date po­si­tion­ing dow­els to lock a slab, for ex­am­ple – a process that would frac­ture and de­stroy more elab­o­rate and ex­pen­sive joints.”

Re­cent ap­pli­ca­tions where they have ex­celled in­clude health care ap­pli­ca­tions, where they have been in­cor­po­rated into re­tire­ment vil­lage con­struc­tion.

Other ap­pli­ca­tions in­clude carparks and high rise apart­ments. Cav­ity bridge types (be­low) are also avail­able where pre­ci­sion slab po­si­tion­ing is re­quired.

De­sign spec­i­fi­ca­tions rec­om­mended in­clude: • Co­ef­fi­cient of fric­tion* 0.04

( Zinc-Zinc) - 0.16 (Steel-Steel). • Ex­pan­sion ca­pac­ity ±2 to

±5mm. • Rec­om­mended con­tact

stress** 100 – 150MPa. • Op­er­at­ing Tem­per­a­ture Range

-25°C to +120°C (peak +130°C). • Drop­ping Point for Grease +175°C. Her­cules En­gi­neer­ing has pro­vided a broad range of lon­glast­ing slip joints and struc­tural bearings for use in struc­tures as di­verse as the Sydney Opera House, the Hang Seng bank in Hong Kong, Aus­tralia’s New Par­lia­ment House in Can­berra and the world’s largest cop­per mine, Kansan­shi, in Zam­bia. The com­pany has just re­leased a new tech­ni­cal brochure which in­cludes rec­om­mended slip joint so­lu­tions for op­ti­mum cost- ef­fi­ciency and dura­bil­ity for build­ings rang­ing from hos­pi­tals, health care struc­tures and shop­ping cen­tres, carparks, trans­port ter­mi­nals, of­fice tow­ers and ware­houses through to fac­to­ries, stor­age tanks, si­los, boil­ers and in­dus­trial and re­sources plants. * Co­ef­fi­cient of fric­tion has been ob­tained by com­par­i­son of sev­eral in­de­pen­dent sources and it is an ap­prox­i­mate value for greased sur­faces of spec­i­fied ma­te­ri­als. A prob­lem oc­curs with the value con­cern­ing the type of grease used. Con­sid­er­a­tions should be made in us­ing this value un­til fur­ther no­tice. ** The rec­om­mended con­tact stress is a prac­ti­cal value range for com­mon ap­pli­ca­tion sce­nar­ios. The ul­ti­mate load would be sig­nif­i­cantly higher in a range be­tween 150-200MPa and it is lim­ited by the Grease lu­bri­cat­ing ca­pac­ity and steel prop­er­ties. www.demm.co.nz/reader- en­quiry #170207

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