CA1083052A

CA1083052A - Tubular element end protectors

Info

Publication number: CA1083052A
Application number: CA294,498A
Authority: CA
Inventors: Abdul H. Quraishi
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-01-07
Filing date: 1978-01-06
Publication date: 1980-08-05
Also published as: DE2800747A1; DE7800484U1; IE780024L; FR2376996B1; IT1103590B; JPS53124322A; IE46133B1; FR2376996A1; IT7847570A0

Abstract

"TUBULAR ELEMENT END PROTECTORS"
ABSTRACT

End protectors for inter alia the threaded ends of oil-well pipe assemblies. One such end protector comprises a urethane member moulded integrally with and bonded to a steel tubular member of uniform end-to-end cross-section, the protector engaging sealingly against the pipe assembly across transverse surfaces. Another such end protector comprises a foamed or cellular resilient member engaging sealingly against the pipe assembly across transverse surfaces.
Yet another such end protector comprises a resilient member having two axially spaced spaces, other than threads, extending in planes transverse to the axis of.
the and protector and adapted to engage sealingly against corresponding surfaces of the tubular element.

Description

~ ~ ~ 3~ ~ 2 BACKGROUND OF T~E INVENTION
This inven~ion relates to protectors for the ends of tubular elements (preferably tubular elements o~
annulc~r cross-section), hereinafter referred to as "end protectorsn. This invention is considered particularly~
but not exclusively, applicable to end protectors for screw-threaded pipe ends.
In the paqt, commercially available end protectors ~or the screw~threaded end~ of metal pipes have been constituted by a single homogeneous cap member o~ solid material e~g. ei-ther steel or a plastics or rubber material, the member bein~ ~rovided with a screw-thr~ad ~or mating coopcratiorl with the screw-~e~ded pipe end.
With a singl~ homogeneous cap member o~ solid plastics or rubber material, ~here is a danger that the end edg~ of the metal pipe will cut through the solld member when the latter ig subJected to imp~ot shock loads e.g. from sharp obJects such as stones on a rough ground during 3tackin~ operations Tha insu~iclent p~cture r~si~tance of thQ solid me~ber ca~, w~h some plastlcs ma~erials, cau8e ~le member to shatter ~he~ strongly impacted, whilst other plastics materials have a poor te~r ~trength or cut gro~h resista~ce, i.e. poor resigtance tQ tear onc~ a cut has been made. Such member~
are consequently limited to relatlvely llght duty use.

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~ ~ ~3~S2 For relatively heavy duty use, such as in the oil or gas exploration and/or extraction industry (e.g. off-shore drilling and mining), a steel end protector is commonly used. Although this overcomes the above-mentioned drawbacks of plasticq or rubber materials, the steel member must undergo a costl~
process of being carefully and precisely machined with the requlsite ma-ting screw-thread ~hich, to avoid galling (i.e. metal-to-metal welding o~ binding dua to friGtion), must provide ~or a loose fi~ on ~ pipe end. Even though ~he space between ~he steel end protQc-tor and metal pipe may ba packed with ~n anti-corro~lon agent such as a greRse, ingre~3 o~ corrosive elements can s-till occur during prolonged outdoor storage of the end protec-ted pipes. Furthermore, assembling steel end protec-tors on to the screw-threaded ends o~ metal pipes re~uires considerable care and skill by -the operatives -to avoid o~er-tigh~Qning or cross-thread~ng or an excQssiVe lnter~acial s~res~ a~ ~ace~ in metal-~o-metal cont~ct since any dc~mage c~nnot be readily detected at the ~actory but only on -~he s~.te or location o~ use ~hen ~he end pro-tectors are remo~ed. Re~ects or damage at this s-tago can have ecpensive consequence3 quite out o~ propor-tion ~ the intr~nsic replacament cost o~ the componen ~s involved ( a delay oî one day I n ~lfillln~ a contr~c~ on a Morth Sea oil rig can lnvolve .
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`` .` . ' ~ ~ 3~ ~ 2 a loss of several thousand pounds sterling)~ Moreover, there is a danger or likelihood that the steel end protector will t;ran~mit to t~e metal pipe end at least a substantial proportion of the shock~ compression and bending stresses to which it is subjected.
Another form of end protector which has bee~
propoc~ed comprise~ an open ring of rubber ha~ing a metal band within it, the two ends o~ t~le open ring being ~oroed towards one another by clamping means. Howe~er, such cm end protector leaves paxt o~ the metal pipe end open to corro~ive element~ through the gap betwe~n the ends of the open rlng and al~o ~ives rise to probl~mc~ in stack~g ~he pip~s p.rovidcd with ~uoh incompletely encompas~ing end protect~r~
Other proposals have been made for end protectors ~or ~he screw-threaded ends o~ met~l pipes, e.g. in USA
Patents No~ 2212423, 225~729, 3000402, 402~73 and 4020874, in which the end protector co!mprise~ t~io separat~ components of which one i~ rosillen~ ~nd is sandwich~d between th~ pipe 2Q ~hr~ad ~nd the other compon~nt which i~ a tubular metal ~ormation having radlally-directed flc~nge-llke portions o~erlying the pip~ ends. In generc~l it is necessar~ ~or the t~Yo cooponents to be sepRrated and se~uentially applied in ~Yo assembl~ steps~ So far a~ the applicant 15 awaxe, none of thes~ pro~osed two~component end protectors has been commerciall~ manu~act~ed or industrially adopted.

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. . -It is thought that this is due:
(a) to the likely labour cost of the two-step assembly sequence, and/or (b) to the likely manufacturing cost of producing two separate components (of which said other component must be provided with its particular special formation), and/or (c) to the likely difficulty of inserting a mandrel for testing the pipe's straightness, and/or ~cl) to the likely difficulty of removinq the end protector iE
the said other component is damaged and deEormed ~e,~, in the vicinity of the radially-directed flange-like poxtions), Furthermore~ none oE the prior art end protectors Eor the screw-threaded ends of metal pipes providQ3 a seal at each end Olr the protectclr that is transverse to the pipe axis, SUMMARY OF THE INVENTION
It is thus clearly desirable to provide for tubular ele-ments end protectors that are capable oE overcoming at least some of the disadvanta~e~ and drawbacks re;ferred to above in connection wi.th end protectors o the prior art, ~ccordin~ to a Eirst aspect o thàs invantion there is provided a composite, generally tubular end protector for the end Q~ a tubular element, comprising a rela-tively resilient member for intimately contacting the end o the tubular element when in use and or enga~in~ sealin~ly against the tubular element at at least ~,~ two axially spacod sealing 20rle5 ofwhich one is a radial end face of the tubular element, and a relatively rigid member in engagement ~ ;' .~,l;,, - : - : . -.
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with said relatively resilient member and consisting of a right cylinder of both uniform and constant cross-section from end to end thereoE, said relatively resilient member comprising an elas-tomeric material~formed in a mold oE which said relatively rigid men~)er is a part such as to be bonded to said relatively rigid member and be integral therewith without deformation of the rela-tively rigid member and without a separate adhesive.
Advantageously, the relatively rigid member has an elon~tion at break less than 30~ and the relatively resilient member has an elongation at break equal to or greater than 30 The said two members may be each of the same material or, as is preEerred, may he of diEferent materials.
~ or example, where the said two members ara each of tho ~am~ materi~l, the rclatively resilient member mny comprise a cellular plastics or rubber material and the relatively rigid member may comprise a substantially $mperforate skin of the same material on the relatively resil~ent memher.` Preferably in this case the cellular rnaterial is a plastics Eoam ~nd is sel~-skinn~d (e,~, solvent hlown in a mould such that the sQl~ent at -the ~" " ;~ . .
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mould surface does not blow but the solvent inwardly of the mould surface does blow).
~nhere the said two members are of different materials, these two materials preferabl~ have different values of Young's modulus of elasticity in compression.
Advantageously, the relatively rigid member has a value of Young's modulus of elasticity in compression that is at least appro~imately 10 times the corresponding value Q~ th~ relatively resilient ~ember. In accordance with the above criteria, the relatively resi1ie~t member and the relatively ri~id member may be selected, ~or example, ~rom the following: a rubber havlng a said modulu~ ~alue i~ the range 1.2 ~ 1~2 psi to l.5 x 103 ~si) a cro~s-linked urethane havlng a saicl modulus value of the order of 9 x 104 psi, a polyethylene ha~ing a said modulus ~alue in the range 1.5 x 104 p~l t~ 1.5 x 105 psi, a p.t.f.e.
material havin~ a said modulu~ v~lue in ~he range ~ x 104 psi to 4 ~ 104 psi1 a polyamide h~vlng a sald modulus ` value ln ~h~ X'an~Q C~ X 104 p'5i tV 2 X 105 pSi, a polycarbona~a havin~ a said modulus value in thQ range ~ x 105 to 2.5 x 105 psi, an acryllc r~sin ha~.ng a said modulus value of the ~rder o~ 3 x l05 pSi7 a rigid PVC
h~ing a said modulus v~lue o~ tha order o~ ~.5 x 105 p9i~
a fibr~ raln~orced vulcanised rubbar havin~ a said modulus va~ue l.n th~ r~nga 4 x 105 p~l to 9 x 105 psi, a glass .~ib~e r~l~eQrc~d polyester ha~rlng a said modulus value i~

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the range 9 x 105 psi to 5 x 106 pSi9 an ep~xy derived urethane rubber copolymer having a said modulus value in the range 1.5 x 104 psi to 8 x 104 psi, a metal or metal alloy having a said modulus value in the range 9 x 106 psi to 2 x 107 psi. Other combinations of materials ~or ~he relatively rigid and resilient members will be apparent to tho~ skilled Ln the art.
Pre~erably, the relatively resilient member comprises a thermosetting elastomeric material (adva~tageously o~ cellular form) having a high cut-~ro~t~ re~istance9 and ~he rela-tively rigid member comprlseq a metallic material.
In a pre~erred embodiment of this inwention ~h~
roln~tiv~r rQ~ilient meltlber comprise~ a urethane rubber copol~ner, e.g. epoxy derived, having a said modulus value 1~ in the range 102 psi to 8 x 104 psi ~preferablr 104 psi), and th~ relatively rigid mem~er comprises a sleeve of ~t~el, having a ~aid modulus ValUQ in the range 1.2 x 107 ps~ to 2 x 107 p9~ ~lterna~l~ely, th~ relativel~ rigid member may compris~ a sleev~ o~ gla~ ~ib~Q, th~ elastomeric material imprQgnating or being bonded to ~his sleeve during ~he moulding or ca~tlnv.
Advantageously~ the relatively resilient member o~
~lastomeric material is mouldad or cast to the relatively rigid me~er at low p~essure in a mould of which the relatively rigid member forms a part~

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According to a second aspect of this inven~ion there is provided an end protector ~or the end o~ a tubular element9 characterised in that the end protector comprises a resilient member o~ plastics orIubber material in cellular or foamed form, the resilient member being adapted and/or intended to engage sealingly against the tubular element.
Pre~erably the plastics or rubber mat~rial comprises an organic polymer.
Advan-tageously the said material comprises an elastomer or a rubber having a Shore hardness in the range A20 -to D8S on the durometer scale.
In a part.tcularl~ pre~erred embodiment said material aomprises a urethane polymer (advantageou,sly an epoxy derived urethane copolymer) having a Shore hardness in the range A20 to D85 on -the durometer scale and a Young's modulus o~ elasticity in compression in ~he range 10 psi to ~ x 104 p~i, pre~erably o~ the order of 104 psi.
In one arrangemen~ he said material ma~ be sel~
skinned ~.g~ solYent blo~nn ~n a mould such that the solvent at th~ mould sur~ace do~s not blow but the solvent inwardl~ o~ the mould sur~aae does blow). The skin thus ~ormed may have an elonga~ion at break less than 30%
whereas the cellular or foamed porti.on may have an elongation at break e~lal to or greater than ~0%. ',' '- - .' . . ~ . . - . -... ..
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~ 8 ~ 2 Preferably the cellular or foamed material has a density equal to or greater than 1.5 lbs/cu.ft.
~ere the end protector is for the screw-threaded end o~ a tubular element, the resilient member may be provided (e.g. by moulding) with a screw-thread to correspond with the screw-threaded end of the tubular element.
Accord~ng to a third aspect of this invention there is provided an end protector for the screw-threaded end o~ a tubular elemen-t, characterised in that the end proteotor comprises a resilient member ha~ing two axlally spaced surfaces, other than threads~ extending in planes transv~rse to the axi.s o~ th~ end protector and adapted to enl3age s~lingly a~ainst corresponding sur~aces o~ the tubular element.
According to a four~h aspect of this invention there i5 provided an end protector for the screw-threaded end o~ a tubular elemen~, cl~aracter~sed by the provision o~
OnQ or more tra~sverse holes through a generally cylindrical wall thereof whereby a tomm~-bar or like implement can be inserted ~or assisting the screwln~ on and/or Q~ of tho end protector.
BRIEF DESCRIPTIQN OF THE DRA~NGS.
By way of example~ embod~ment~ of ~h~s inven~ion will now b~ described wlth refarence to the accompanying drawings o~ which --1 0_ , , . ~ . .

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Figure 1 shows in longitudinal axial section an assembly of a pipe coupling and a hollow pipe of annular cross-section ~or use in an oil well;
Figure 2 shows an a~ial section through a first pin end protector according to this invention ~or the "pin end" of the assembly of Fig. 1;
Figure ~ is a plan vie~ of the end protector of Fig~ 2 ln the direction o~ arrow III;
Figure 4 shows in aYial sectlon a ~irst box end ~0 protector according to this invention ~or the "box end~
of the assembly o~ Fig~
Figure 5 is a plan ~iew o~ the bo;~ end protecto~
o Flg. 4 ln the dlr~o~on o~ nrrow Y
Figure 6 is a plan vi~w of a second p~n end protector according to this invent~on;
FiO~ure 7 sho~s in axial section a third pin end protector according to this inventlon;
Flgure 8 ~how~ ln ax~a~ ction a s~cond box ~nd protector according to this l~vention; and : .
FigurQ~ 9 and 10 ~how ~ur~her embodim~nts o~ thls lnve~*lon. ` ' DETAILED DESCRIPTION OF ~IBODIME~TS
The assembly illustrated in Fig. 1 comprises a hollow tubular steel pipe 1 o~ c~nnular cross-section provided at aach end 2, 3 with a tapar the an~le o~` ~hich l~ exag~eratad in the drawings ~or clarity o~ illus~ra-tlon.

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'` :` :` . . ~', z Each tapered pipe end 2,~ is provided with a screw-thread

4,5 respectively,the form of the taper and screw-thread being appropriate to that required for an oil ~ell pipe.
The assembly illustrated comprises a coupling 6 screwed on to the tapered pipe end 3 to provide a sealed connection, this coupling 6 ser~ing for the connection o~ like assemblies in series. The assembly thus has a so-called "pin end" provided by the -tapered threaded pipe end 2? and has a so-called "box end~ provided b~ the matingly tapèred and threaded coupling 6. Be~ore the assembly can bc despatched to a desired slt~ ~or installa-ticn in an oil well, ~hread protector~ for both tho pin end and the bo~
c~d mu3t ba fitted ln accord~cc with ~P;~ sp~cification 5~, ~a~tion 9.
Figures 2 and 3 illustrate a pin end protector 7 according to this invention~ and Figures 4 and 5 illustrate a box end protector 27 accord!ing to ~his in~ention.
Tho pin end p~otector 7 o~ Figs~ 2 ~nd 3 i~ a composite body comprlsing an outer tubular ~teel_m~ber 8 " that is bonded by it~ inner ~C~r~aco with the outer sur~ace o~ an i~ner tubulc~r resilien~ member ~. Pre~erably, but not ncce~saril~, the axial lengths o~ the two ~ember~ 8, 9 ar~ ~ubstantiallr equal to one another and to the pin end por~ion o~ the assembly o~ Fi~ The inner surface o~
tubular resi~ient me~nber 9 has a circular cross-section and i~ prov~d~d with an appropriate taper and screw-thread ~0 '' ~ ' ~ ,, " ' ., ' . ` ~ ~
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to correspond to the taper and screw-thread 4 of the pin end of the assembly~ The resilien~ mem~er 9 is also provided internally adjacent its smaller diameter end with a transverse9 e.g. radial, sealing surface 11 for resllient sur~acial sealing contact with the an~ular end ~ace 12 of the assembly's pin end (see Fig. 13. The geometry of sealing sur~ace 11 accords with that o~ the end o~ the pipe assembly, e.g. API, VAM9 Hydril~ BDS etc~
The re~llient member 9 i9 also provided i~ternally a~
its opposite, larger diameter end with a cylindrical ~ealing sur~ace 13 having a diameter ~ractionally less than tll~ outqide diametQr o~ the pip~ 1 so that this cyllndrlca~ sea~ing ~face 1~ can resilientl~ and sealingly contac-t the exterior surface portio~ 14 of the pipe 1 1l5 beyo~d the tapered thread 4.
` r~he pin end protector '7 i~ scre~ed on to the pLn end ... .
o~ the pipe assembly o~ Fig. 1 u~tll tho ~aling sur~ace~
-`` ` 11 a~d 1~ both mate with ~he corr~spondi~ sur~ac~s 12 and 14 r~spectively to provide resilien~ seals a~ains-~ the ingrQs o~ corr~slo~ produci~g age~ to the taper and ~hrcad 4 of said pin end, and simultaneQu~ly phy~ically isolating the taper and thread 4 o~ said pin end ~rom the exterior to protect ~t against damage dua to direct impact - and/or abrasion by a~ outside agency~ ~le transverse end sur~ac~ o~ member 9 adJacent sealing sur~ace 13 may also ~alingl~ ~ngage a corresponding transv~rse surface o~ the -13_ . :

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pipe assembly adjacent sur:Eace portion 14. The geometry of this transverse end surface will, li~e that of the surface 11, accord with the par-ticular geometry of the pipe assembly (e.g. EDS, VAM or Hyd~ril).
~ diametrically extending borehole 15 is provided through both members 8, 9 o~ the pin end protector 7 between the radial sealing surface 11 and the adjacent axial end o~ the pin end protector 7. This hole 15 serve~ as an eyelet ~or the insertion of a tommy-bar or other tool that may assist scre~ing the pin end protector 7 on to or off ~rom the pipe assembly~s pin end 2.
As is apparent ~rom Fig. 3, the tubular steel member 8 l~ o~ ~iform hexagonal cross-section from 0nd to end~
The ~Lats 16 pI~ovided by ~h~ hexagonal shape o~ member 8 enabl~3 the pipe assembly fitted with the pin end protector 7 t~ rest in states o~ st~le equilibrium and thereby reduce the likelihood or tendency o~ rolling of,the pin end protacted pipe assem~l~. Furthermore, the ~lat~ 16 a~sist in stacking a plurality o~ lik0 pin ~nd protected pipe assemblies in a convenient andIor space-savlng manner~
Similar ad~antages re~ult from the use of a pln end pro~ector 17 according to Fi~. 6 which is similar to the pin end protector o~ Figs~ 2 and 3 except that its tubular st~el member 1~ ls o~ generally triangular cross-section.
(It ~lill be appreciated that the degree of rounding-o~î or raùiusin~ o~ t.he corners o.~ the triangle ~n Fig. 6 can be :, - ` ~ .- ,., ' - - " ~. . - - -- ,' - . - - .

greater or less than that shown)~ The tubulclr steel member or sleeve of a pLn end protector according to this invention may have a cross-section o~ different shape providing one or more I~ats 16, e.g. other pol~gonal shapes or DLshaped, or providing cusp-shaped points to provide like state~ of stable equilibrium. Alternatively, the sleeve may be a right-cylinder of uniform annulc~r cross- -section from end to end. Advantageously such sleeves can be con~tituted by conventionc~lly formed pieces o~ pipe 1 a sectlon, e.g, scrap pipe end~ to mlnimlse e~pense, and thus require no ~urther shape-changl~g, forming or machining such as to provide inw~dly-directed flc~n~e~ e portions.
T~lo box end protector 27 of Fig~. 4 and 5 is a composite ~ody comprl~ing an :~ner tubul~r ~teel membQr 28 that is bonded by its outer st~face with ~he inner sur~ace o~ an o~er tubt~ar resiiient mem~er 29. Pre~erably9 but not necessarily, the axial lellgths o~ t~e two members 28,29 ~ .
are silbstantially e~ual ~o one another c~nd to the box end portion o~ the pipe assembly of Fig, 1~ The ou~er sur~ace o~ tubular resilient member 23 has a tapered portion of circular cro~-sectio~ ~hat ~3 provided with a screw-thread ~0 to correspond to ~he taper and screw-thread 5 of the box cnd of the pipe assembly. The resilient member 29 is also pro~ided e~ternally adjacent its larger diameter end with a trans~erse, e.g. radial, sealing sur~ace ~1 for resilient sur~acial sealing contact with the annular end face ~2 o~ -the ,, .. , ~ .-- .- .. .
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-pipe assembly's box end 6 (see Fig. 1). The resilient member 9 is also provided externally at its opposite smaller diameter end with a ~ransverse, e.g. radial, sealing surface 33 for resilie~t sur~acial sealing contact of the interior surface portion 34 of the coupling 6.
The box end protector 27 is screwed into the box end of the pipe assembly of Fig. 1 until the transverse sealing sur~aces 31 and 3~ both ma~e ~ith the corresponding transverse ~ur~aces 32 and 3~ respectively to provide resilient ~eals against the ingress of corrosion producing agents to the taper and t~ead 5 of said box end and its sealing faces ~, 34; and simultaneously physically `.
i~ola~ the taper and ~hread 5 and saLd ~aces 32~ 34 ~rom the ex-terlor to protect against damage due to direct impact and/or abrasion by an outside agency. With so-called premium ~oints such as BDS, VA~ and Hydril pipe assemblles, the sur~aces sealingly engaged by end protector surfaces 31, 33 ~i.e corresponding -to sur~aces 32, 34 o~
the illustrated pipe assem~ are spaced from the screw-~hread and are incllned a~ an anQle to th~ slope linQ o~
the threads 5~
A dlametrically extending borehole 35 i~ provided through both member~ ~3r 29 0~ the box end protector 27 be-tween -thQ radial sealing surface 31 and the ad~acen~
~5 axial end of tha box end pro tector 27. ~his hole 35 :ier~r~s as ;~n e~elet :Eor the insertion o:E a tommy-bar or .~ .. ..

~ ~3~ 5 other tool that may be used to assist the screwing o~
box end protector 27 into or out from ~he box end 6.
As is apparen~ ~rom Fig. 5, the tubular steel member 28 is a right-cylinder o~` uniform and ~onstant annular cross-section from end to end. The member 28 may be constituted by a conventionally formed piece o~ pipe section, e.g. a scrap pipe end, and require no ~urther shape-changing forming or machining, e.g. to pro~ide out-wardly~directed ~lange-like portions. The tubular resilient member 29 has the portion o~ its outer surface between its sealing sur~ace ~1 a~d ad~acent axial end ~ormed with a hexagonal cross-~ection pro~iding flats ~6. These ~lat~ ~6 ~nable th~ pipe a~iemblr ~i~ted with the box end protector 27 to rest ~n states o~ stabl~
equilibrium, thereby reducing the likel~hood or tendency o~ rolling o~ the box eI~ protected pipe assembly9 and assist in s~ack~n~ a pluralit~ Q~ like box end protected pipe as~emblie~ in a conveni~nt and/or sp~ce-~aving man~ex~.
Similar ad~antages can arise ~ formlng said resilient member portion with a different cro~s-sectional shape providing one or more flats 36, e.~. other polygonal shapes or ~-shaped, or with cusp-shaped points to pro~ide l~ke states o~ s~able equilibr~um. Alterna~ively said portion o~ the resillen~ member 29 ma~ have a cyli~drical outer sur~ace.

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The end protectors o~ Figs. 2 to 6 have their axial ends open, the opening being circular and of diameter "d". This diameter "d~ is arranged to provide the diametric clearance necess~y to enable à pipe assembl~
fitted wi-th these pln end and box end protectors to pass over a pipe-straightness testing-mandrel according to the relevant API specification ~for oil well use) without requiring that the end protec-tor~ be first unscrewed and removed from the pipe assembly. Thus the end protec-tors can be unscrewed and removed after the e~d protected pipe assemblr ha~ bee~ mounted on the mandrel and immedia~ely b~ore the pipe assembly is fed down the oll well.
However~ t~e present in~ention al~o contemplate~
the provision o~ end protectors with closed ends~
Preferred examples o~ such end protectors are ~hown in Figs. 7 and 8.
The pin end protector 37 of Flg~ 7 i~ similar to that described above with re~erence to Figs. 2 and 3 and~or to Fig. ~ and i9 a compo~ite body comprising an outQr tubular st~el member ~8 lntegral wi~h,and bo~ded by lts inner surface to, ~h~ outer surface of an inner hollow resilient member 39. However, ~he pin end protector 37 ls provided with a closure disc 40 integral with the resllie~t member 3g a~ the smaller diameter end of the resilien~ membe~ 39 where~y th~ latter has an axial cross-sec~ional shap~ of ~r~n~rally U-~orm.

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The box end protector 47 o~ Fig. 8 is similar -to tha~ described above with reference to Figso 4 and 5 and is a Gomposite body comprising an inner tubular steel member 48 that is bonded by its outer surface to the inner surface o~ an outer hollow resilient member 4~ so as to be integral therewith. However, the box end protector 47 i~ provided with a cup-shaped extension 50 Lntegral with the resi.lient member 49 at the smaller diameter end of the latter whereby ~ha lat~er has an axial cross-sectional shape of generally U-~orm~ Alternatively, the limbs of the cup-shaped extension 50 may be o~ 2ero extent 80 that lts diso-like radial bight wa:Ll 51 e~tends across ~hQ open:Ln~ ln con^tact with t~e ad~acen~ end o~ ~ember 48~ The radial disc-like wall 51 malJ even be disposed slightly in~lardly o~ member 48 so as to enable the ad~acent end of the proteotor 47 to seal resilien~ly aga~nst a ~rans~erse sur~ace such as 34 of the pipe as~embly o~ ~ig. 1.
~en th~ pin end and bo~ end prote~tor~ ~7 and 47 are fitted to a pipe assembly suoh as that o~ Fig. 1, they seal o~f tho whole o~ the inner sur~aca of thQ p~pQ
assembly aga~nst corroslve elements ~nd thus enable the end protected pipe assembl~ to be stored outdoors ~or long per~ods of tima wi~hout internal degradation~ ~
Furthermore, due to the resilienc~ of ~he ma-terial, the disc 40 c~d th~ radlal disc li~e wall 51 can ser~e as , : . . , ................. : . ~ .... .:

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:' ~' : ,. , ~ 2 flexible diaphragms to accommodate pressure changes in the air trapped within the sealed pipe assembly as the temperature varies. The box end protector 47 also allvws a lifting hook to be inserted into the box end without damaging the coupling or pipe lnterior, particularly the threads and sealing faces.
The integral closure disc 40 of pin end protec-tor 37 and the cup-shaped extension 50 (or at least wall 51) of box end protector 47 ma~ each be attached in a tear-away fashion to its associated resilient member 39, 49 ~or easy removal by or prior to insertion o~ the a~oresaid pipe-strai~ht~ess te~ting mandrel, leaving th~ remainder of rQsllie~nt m~mb~r 39, 49 in position on -~ e~ds of th~ pip~
assembly~ Alternativ~ly, ~Q closure disc 40 and the cup-shaped extension 50 may each be formed as a separate component a~tached (preferab]Ly in a readily removable mann~r~ to the resilient member ~9, 49.
I~ the abo~-d~scribed embodimen~s o~ thi5 inve~tion, the relatively ri~id member ~ 18, 28~ 38 and 48 was steel, pre~erabl~ mild steel. Oth~r composi-tions may however be employed ~or the rigid member. E~nples 1nclude glass fibre composi~ions and met~1 composi~ions such as bronze~
copper, brass, al~inlum and like metals and/or metal alloys.
The relatively resilient member 9, 2~, 39 or 49 is pre~erabl~ moulded or cast o~ a mouldable or castable elastomeric material) ad~antageously so as to have a cellular ` ` ` ~ - ' ' ` ~ ; ;:

`' ."` ' ' . . - - .

: ' .

~ 2 or foam construction. Preferably the moulding or casting opera~ion is by the pouring or low-pressure injection o~
the material into a mould that is partially formed by the relatively rigid member 8, 28, 38 or 48 respectively so that the two members are bonded to one another in the manner o~ a l~ainate. This casting or low-pressure injection moulding technique renders it unnecessary ~or the relatively rigid member to be accurately dimènsioned since, in thè absence o~ high pressure~ there i3 only a minimal seal ing re~uirement between the mould part~ - one o~ which is constituted by the relatively rigid member itsel~. The taper and threads o~ the resilien~ member are ~ormed by the mould as the mouldable material is being cast or moulded to ~orm the re~:LliQn~ m~mber ~ld bond it to th~ rigid member.
~l5 This mouldable material may be a natural rubber or a syntheti~
polymer e.g. a styrene butadiene rubber or a polyurethane ela~tomer. Other examples o~ suitable mouldable materials are organtc poly~er~ o~ the nature o~ thermoplastics te.g.
polyethylene, polypropyle~e and pol~styrene) or o~ a thermosetting nature (~.g~ a polyester~ urethane or epoxy).
Two espQcia~ly suitable mouldable thermoset ~ng elastomerlc materials are a ~ethane polymer and an epoxy derived urethane rubber copolymer such as those manu~actured by Wright & Sumner Limited (o~ 55 Argyll S-tree~, Ketteringy 2S Northant~ England) respQotively under the names CUE 02036 (cellular or non-cellul~r) and C~E 0203~; each is moulded :- . ,.. .::
.

', ' ~;

to have a Young's modulus of elasticity in compression in the range 102 psi to 8 x 104 psi~ preferabl~ of approxi-mately 104 psi.
The relatively resilient member 9, 29, 39 or 49 pre~erably has a value oP Young's modulus oP elasticity at least 10 time~ less than that o~ the relatively rigid member 8, 28, ~8 or 48 respectively, and preferably also has a vaLue of Shore hardness in the range A20 to D85 on the durometer scale. The Shore hardness D scale is an expanded ~cale oP the upper end o~ the Shore hardness A
scale (D45 is approximately e~ual to A92) which ranges from a minimum value o~ 0 to a maxlmum valuQ o~ 100.
Value~3 o~ Shore hardness on the A scale correspond numeri~all~ w~th clo~e approximatio:n to the value~ o~
har~le~3s on the InternationaL Rubber Hardness Scale which likewise ranges from a minim~lm value o~ 0 to a maximum value o~ 100. The American Society Por Testing Materials provides a mQthod (Dl415/62~') wh~reby a correlation can be obtained between the IRH ~alue and the valuQ o~ Young's 2Q modulus oP elasticit~ in com~ession.
~he propertles o~ tha t;wo materials oP the members 8, 9; 28, 29; ~8, 39 or 48, 49 are such that they each have a value o~ Young's modulus of elasticity in compression equal to or reater than 102 psi, th~ relatively rigid Z5 member h~vins an alongation at break less than 30~0 and the relatively reslllent member ha~ing an elongation at break equal ~o or greater than 30Y0.

' - , -' ' . ' ~ ' . ~ ' . , , ~ ~3~Z

Advantageously, the relatively resilient member 9, 29, 39 or 49 comprises an expanded polymer. The use of a foamed rubber or elastomer provides for increased resi:Liency and shock-absorbing properties, lightness of weigllt, economy and ease of manufacture. Each o~ the aforesaid urethane polymer ~UE 02036 and the epoxy derived urethane copolymer ~UE 02038 provides good results when expanded of the order of lOSo of i-ts original volume as well a~ when expanded up to 30 times its original Yolume.
Expanded polymers having an average density of between approximately 1.5 lbs/cu.~t. to 60 lbs~cu.ft~ e. a void to solid ratio between abou-t 98.2~o and 2:9~Yo) are considered ~uitable ~or the appllcatlon o~ thi~ i~e~tion. Method~
of polymer expansion lnto ~oams o~ appropriate density and cell structure te.g. open cells, closed cells, mlxed open/closed cells, ~oams with non-cellular skins, foams with non-skinning su~ce~s)9 ~oam laminates, etc.) are all well documented in the literaturc and will be apparent to one skilled in the art withiou~ ~lrther elaboration here.
I~ is considered that syntJaotic ~oams (including pre-formed hollow spheres) and lnner ~oams can be used with e~ual ease, such ~oams bei~g better able ~o absorb high impact loads.
For use in certain arduous service conditions it may be desirable to rein~orce the resilient member o~
mouldable mater;ial by incorporating into the la-tter -2~-- : . .

.

~ 8~ Sz adc~tional ~ibrous ancl/or particulate fillers. Examples of such fillers include marble flour, vermiculi-te, clay, `
sand, chalk, cc~bon blac~ glass fibre, carbon fibre, pre-impregnated means, mats, scrim, ~oven cloth and the like~
Other additives may be incorporated into the mouldable material or provided as separate coatings on the metal rigid member 8, 28, 38 or 48. Examples of such additives ;Lncl~e anti-oxidants, stabilisers, corrosion preventatives, adhesion promoting primer~ and the like~
The exemplary composite bodies described above with reference to thc drawin3s are each in the ~orm of a laminate having tWQ layers or plies ~ntQgral ~.ith one another~
Additional pli~8 or layer~ ~ay be provided of suitable material within the scope of the inYention.
It will also be apprec:iated that the two members ~orming plies or layers of t;he composite body constituting an end prot~ctor according to ~his lnYention need not be o~ dissimilar materials but can be of the s~me material.
Thi~ is exemplifled by ~he ~?nd protectors 57 and 67 of Figs. 9 and 10 according to thi~ invention ~herein the relatively rigid members 58 and 68 ar~? each in the form of an imper.~orate ski~ or layer o~ plastlcs or rubber m~uldabl~ or castable ma~terlal upon the surface o~ the relatively resllient member 59 or 69 which is a cellular or ~ca~ed form o~ the same plastics or ru~ber materialO
The relati~ely ri~id me~ber 58, 68 h~s an extension at - . - .

, . , ' . `' `
' ' - - ~ .
~, ~83~35;Z
break less than 30% whereas the relatively resilient member 59~ 69 has an extension at break equal to or greater than 30~. Ideally Ln such an arrange~ent, the cellular member 59 or 69 is a self-skLnned plastics material that has been solvent blo~n in a mould such that -the solvent at the mould sur~ace does not blow but the solvent inwardl~ o~ the mould surface doPs blow.
Advantageously the mouldable or castable material is a thermosetting elastomer, e.g. a urethane polymer~ or a foamed thermoplastic, e.g~ polyethylene or PV~.
It will be noted that ea~h o~ the above-described end protectors accordlng to this invention ~s o~ generally oyli~lrioal ~orm whereby when a pin end p~otector it ~ncompasses ~11 round the Qxterior surface o~ the p~n end of a pipe assembly a~d when a bo~ end protector it .
encompas~es all round the interior sur~ace o~ the box end of a ~lpe assembly (i.e~ i~ encompassed all round by the box end of the pipe assembl,y)~ Althoug~ the r~silient member o~ respectively the pin end and box end p~otectors extends ax~ally over at least the ma~orit~ o~ the pipe assembl~s thread~, the ~esilient memb,er's threads need not extend over ~he entire length o~ the resilie~t member itsel~l, This facilitates screwing on and o~ he protector, ~specially ~ere the pipe assembly ~hreads gradual1~ run out) i.e. decrease in depth along the taper~

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.. ..

It will be appreciated that end protectors accor~ing to this invention may be un~hreaded and/or untapered and smoothly cylindrical at their faces adapted and/or intended to coIltact the tubular element~ It will also be appreci~ted that this inve~tion is not restricted to end protectors ~or the ends o~ pipe assemblies as illustrated in Fig. 1, but that end protectors ~or other tubular element~ can be formed in accordance with thi~ i~ve~tio~.
Such tubular elements m3y be provided on or constituted by distillation columns, boilers, heat exchangers, riser pipe~, pipe lines, drill bits, oll-well production strin~, casin~s and drill pipes, and couplings. End protectors accordi~ to ~hi3 invention can be arranged to protcct tho end~ o~ such tub~lar e~ement~ a~ain~t dama~e during manu-facturing, ~tacking, storage, loading and~or unloading, shipment, transportation and. installation operations~
. .
There i5 no metal-to-metal ~on-tact between the above-describ~d and illus~rated e~!d ~rotector~ and~~he tub~lar element so that gallin~ and over-tightening o~ threads and sealing facQs cannot occur, there i`Q no danger o~ a burr . accidentally spoiling th~ pipe threadt lnter-metallic galvanic corrosion cannot arise, thQ end pro~ector~ can be `` removed and refitted ~y scre~ing on or off without dama~ing ~h~ thr~ad) and cross-th~eading damage cannot occur.

-~6-.: '::
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~ . ..

~ ~3~

Furthermore, it will be appreciated from the foregoing that the present invention also provides (a) an end protector for the end o~ a tubular element, wherein the end protector either comprises or is constituted by a resil:Lent member o~ cellular or foamed form~ and/or (b) an end protector f`or the threaded end of a tubular element~
wherein the end protector sealing engages the tubular elemen~
by two axially spaced surfaces, other than the threads, extending in planes transverse to the a~is of the end protector aDd tubular element, and/or (c~ an end protec~or ~or the screw-threaded end of a tubular element, characterizec by th~ ~ovision o~ one or mor~ trans~er~e holes through a gen~rally cylind~ioal wall t~r~o~` whQreby a tommy-bar or like implement can be insert;ed ~or assisting the screwing . on and/or o~f of the end protector.

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~ 27 `.

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,

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A composite, generally tubular end protector for the end of a tubular element, comprising a relatively resilient member for intimately contacting the end of the tubular element when in use and for engaging sealingly against the tubular element at at least two axially spaced sealing zones of which one is a radial end face of the tubular element; and a relatively rigid member in engagement with said relatively resilient member and consisting of a right cylinder of both uniform and constant cross-section from end to end thereof, said relatively resilient member comprising an elastomeric material formed in a mold of which said relatively rigid member is a part such as to be bonded to said relatively rigid member and be integral therewith with-out deformation of the relatively rigid member and without a separate adhesive.

2. An end protector according to claim 1, wherein the relatively rigid member has an elongation at break less than 30% and the relatively resilient member has an elongation at break equal to or greater than 30%.

3. An end protector according to claim 1 or claim 2, wherein said two members each have a Young's modulus of elasti-city in compression of at least 102 psi, and the relatively rigid member has a value of said modulus at least 10 times the value of said modulus for the relatively resilient member.

4. An end protector according to claim 1 wherein the relatively resilient member comprises an organic polymer.

5. An end protector according to claim 1 wherein the re-latively resilient member comprises a thermoplastic or a thermo-setting organic polymer.

6. An end protector according to claim 1 wherein the re-latively resilient member comprises an elastomer or a rubber having a Shore hardness in the range A20 to D85 on the durometer scale.

7. An end protector according to claim 1 wherein the elas-tomeric material of the relatively resilient member comprises a urethane polymer having a Shore hardness in the range A20 to D85 on the durometer scale.

8. An end protector according to claim 1 wherein the elas-tomeric material of said relatively resilient member comprises an epoxy derived urethane copolymer.

9. An end protector according to claim 1 wherein the elas-tomeric material of the relatively resilient member is in cellular, foamed or expanded form.

10. An end protector according to claim 9, wherein said elas-tomeric material has an average density equal -to or greater than 1.5 lbs/cu. ft.

11. An end protector according to claim 9 wherein the elas-tomeric material has an integral substantially imperforate or non-cellular skin on its surface.

12. An end protector according to claim 11 wherein said skin constitutes said relatively rigid member.

13. An end protector according to claim 1 wherein said relatively rigid member is a tube or sleeve comprising fibrous material.

14. An end protector according to claim 1 wherein said relatively rigid member is of metal, preferably mild steel.

15. An end protector according to claim 1 and for the screw-threaded end of a tubular element, wherein the relatively resilient member is moulded or cast with a screw-threaded surface enabling the end protector to be screw-threaded on to the said screw-threaded end of the tubular element.

16. An end protector according to claim 1 and adapted to encompass the end of a tubular element, wherein the relatively rigid member is shaped to provide at least one state of stable equilibrium for the tubular element fitted with said end protector.

17. An end protector according to claim 1 and adapted to be encompassed by the end of a tubular element, wherein the rela-tively resilient member has a portion to extend outwardly of the tubular member, which portion is shaped to provide at least one state of stable equilibrium for the tubular element fitted with said end protector.

18. An end protector according to claim 16 or claim 17 wherein said shape is polygonal, D-shaped or provided with pointed cusps.

19. An end protector according to claim 1 and for the screw-threaded end of a tubular element, wherein the end protector com-prises a resilient member having threads to engage the threads of said tubular element when in use and also having two axially spaced surfaces, other than threads, constituting said sealing zones and extending in planes transverse to the axis of the end protector for engaging sealingly against corresponding surfaces of the tubular element when in use, the threads of said resilient member being disposed between said two surfaces,

20. An end protector according to claim 1 wherein said elas-tomeric material comprises a mouldable or castable thermosetting elastomer.

21. An end protector according to claim 20, wherein said thermosetting elastomer comprises a urethane polymer.

22. An end protector according to claim 1 and for the screw-threaded end of a tubular element, including one or more transverse holes through a generally cylindrical wall thereof whereby a tommy-bar or like implement can be inserted for assisting the screwing on and/or off of the end protector.

23. A tubular element assembly comprising a tubular element and an end protector according to claim 1 fitted on an end thereof.