Thread protector

Sept. 19, 1961

Μ. M. BOWMAN, JR

THREAD PROTECTOR

3,000,402

Filed Feb. 12, 1958

Sheets-Sheet 1

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A T FORNEYS

Sept. 19, 1961

Μ. M. BOWMAN, JR

THREAD PROTECTOR

3,000,402

Filed Feb. 12, 1958

Sheets-Sheet 2

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INVENTOR.

MARK M. BOWMAN JR

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ATTORNEYS

United States Patent Office

3,000,402

Patented Sept. 19, 1961 prises steel shell 23 and plastic body 24 having threads 25 adapted to coact with the pipe threads 21 so as to secure the thread protector in place with the end of the pipe 22 in contact with shoulder 26. Ribs 27 of body 24 provide a close fit with body 24 and shell 23. Shell 23 is crimped over plastic body 24 as shown at 28.

In FIGURE 3 thread protector 30 is shown applied to the threaded end 31 of pipe 32. Thread protector 30 comprises metal shell 33 and plastic body 34 having threads 35 adapted to coact with threads 31 on the pipe to secure the thread protector 30 to the end of pipe 32 with the end of the pipe in contact with shoulder 36. The metal shell 33 is crimped over the plastic body as shown at 37. The plastic body has a plurality of lateral perforations indicated at 38.

FIGURE 4 shows an embodiment of the thread protector of this invention wherein the thread protector 40 is applied to the threaded end 41 of pipe 42. Thread protector 40 is composed of cylinder 43 having internal threads 44 and cylinder 45 having crimped edge 46. Corrugated sleeve 47 is positioned in the annulus between the cylindrical members 43 and 45 and is confined in the annulus by the end plates 48. An annular space 50 in end plate 48 allows cylinder 45 and sleeve 47 to absorb impact blows. Cylinder members 43 and 45 can be welded together at the junction of the cylinders.

FIGURE 5 shows a modification of the thread protector of FIGURE 4 wherein the corrugated sleeve 47 of FIGURE 4 is replaced by a coil of a resilient tubing material indicated at 49.

In the embodiment of the invention shown in FIGURES 4 and 5 the cylindrical members are preferably made of thin gage metal, such as steel, but can be made of a non-metal such as rigid polyethylene.

The corrugated sleeve of FIGURE 4 can be made of metal, or rigid polyethylene or any substantially rigid material capable of absorbing an impact blow. Similarly the spiral or coil of tubing of FIGURE 5 can be of solid polyethylene or a soft metal such as copper, aluminum, lead, etc.

The energy absorbing material of the embodiment of FIGURES 1,. 2 and 3 can be a pliable material such as rigid plastic materials, rubber, etc. which is sufficiently rigid for formation of threads therein and which has sufficient pliability to absorb impact blows encountered in the normal handling of the threaded article.

Rigid plastic materials are generally preferred over rubber for the reason that rubber normally does not possess sufficient rigidity to absorb severe impact blows and normally does not have sufficient rigidity to form satisfactory threads. Rigid plastic materials which are applicable for use in the present invention include polyethylene, polyvinylchloride, polytetrafluoroethylene, and the like. Particularly applicable for use in the present invention is a polymer of ethylene or other 1-olefin prepared according to patent application Serial No. 573,877, filed March 26, 1956, by J. P. Hogan, et al., now U.S* Patent 2,825,721, issued March 4, 1958. As set forth in that application .in more detail unique polymers and copolymers, can be produced by contacting one or more olefins with a catalyst comprising, as an essential ingredient, chromium oxide, preferably including a substantial amount of hexavalent chromium. The chromium oxide is ordinarily associated with at least one other oxide, particularly at least one oxide selected from the group consisting of silica, alumina, zirconia, and thoria. One satisfactory method for producing the catalyst com70 prises the use of a steam-aged commercial cracking catalyst comprising a coprecipitated gel containing approximately 90 weight percent silica and 10 weight per3,000,402 , THREAD PROTECTOR ^*?jk M. Bowman, Jr., Bartlesville, Okla., assignor to Phillips Petroleum Company, a corporation of Delaware

Filed Feb. 12,1958, Ser. No. 714,810 7 Claims. (Cl. 138—96)

This invention relates to thread protectors and more particularly to thread protectors used on threaded articles to cover and protect threads during handling and storage of the threaded article. In one of its aspects the invention relates to a novel thread protector which combines the rigidity of metal with the flexiblity of a rigid plastic material such as solid polyethylene to produce an improved thread protector.

A principal object of the invention is to provide a thread protector which will absorb impact blows. Another object of the invention is to provide a· thread protector which can be fabricated easily. and economically. It is also an object of the invention to provide a thread protector which combines resistance to high impact loads with resistance to cutting by contact with sharp objects. The provision of a thread protector which is both easily and rapidly removed from the threads at the site of use 25 with no danger to workmen of splinters or bruises is still another object of the invention. Other and further objects and advantages of the invention will be apparent to one skilled in the art upon reading the detailed description of the invention and the appended drawing.

FIGURE 1 of the drawing is a view of an externally threaded pipe end partially in axial cross-section and partially in perspective with a preferred embodiment of the thread protector of the invention applied thereto;

FIGURE 2 is a view of a modification of the thread 35 protector of FIGURE 1;

FIGURE 3 is a view of a modification of the thread protector of FIGURE 1;

FIGURE 4 is an axial sectional view of a pipe end haying a thread protector applied thereto which com- 40 prises, another embodiment of the present invention; and

FIGURE 5 shows a modification of the thread orotector of FIGURE 4.

I have .provided a thread protector which combines the. elasticity and plasticity of solid polyethylene with the 45 rigidity of metal, such as steel, and utilizes these features in combination to provide an improved thread protector. My improved thread protector is made by encasing a cylinder of a pliable material such as rigid polyethylene in a thin metal cup. The pliable material is threaded to mate with the thread on a pipe or other object where the threads are to be protected.

I have also provided a thread protector comprising a cup of double wall construction with a resilient filler between the walls. The resilient member between the two walls of the thread protector absorbs impact loads so as to protect the threads. The resilient means between the walls of the thread protector can be of metal or can be of plastic materials such as rigid polyethylene.

Referring now to the drawing and particularly to ®θ FIGURE 1, thread protector 10 is shown applied to the threaded end 11 of pipe 12. The thread protector comprises metal shell 13 containing the plastic body 14 having longitudinal perforations 15 therethrough. Threads 16 of the plastic body 14 coact with threads 11 of the ⁶⁵pipe to secure the thread protector in place so as to butt the end of the pipe against the shoulder 17. The metal shell 13 of the thread protector is crimped over the plastic body as shown at 18.

FIGURE 2 shows thread protector 20 applied to the threaded end 21 of pipe 22. Thread protector 20 com3,000,402 ing a plurality of ridges of polyethylene separated by void spaces and, FIGURE 3 shows a plurality of radial perforations in the polyethylene cylinder..

A satisfactory ratio of void space to rigid polyethylene is from about 30 percent to about 60 percent void space. The void space in the modifications, shown in FIGURES 1 and 3, will preferably be about 30 percent whereas the void space in the modification of FIGURE 2 can be from 50 to 60 percent.

The polyethylene cylinder should have an overall wall thickness of from W to about % of an inch. For most applications the wall thickness will properly be in the range of about % to about % inch because this amount of polyethylene will provide adequate protection without adding undue bulk to the thread protector. In this respect, polyethylene is superior to rubber because a greater mass of rubber will be required to provide the same impact absorbing characteristics as the required amount of polyethylene. The thread protector provides a smooth, flush fit with the inside of the pipe ends so that water is not retained in the pipe which often is stacked out of doors with the result that opportunity of corrosion of the threads is reduced.

Reasonable variations and modifications are .possible within the scope of this disclosure without departing from the spirit and scope of the invention.