DESC:FIELD OF THE INVENTION
The present invention relates to an improved thread protector. More particularly, the present invention relates to an improved thread protector for protecting the threads of connectors welded to casing pipes. Thread protector is also used for holding casing pipes with a box connector welded to one end of the pipe and a pin connector welded to the other end of the pipe during handling and transportation of the pipes.

BACKGROUND OF THE INVENTION
A thread protector is used to protect the threads of connectors welded to the ends of a pipe, also termed threads of the pipes in common language in the industry, during transportation and storage of the pipes. The threads play a very important role as if the threads get damaged on a pipe, it results in the rejection of the entire pipe section and then the pipe has to be replaced. Numerous constructions have been proposed as protective means for pipe threads using metal, fibrous, plastic parts or combinations of such materials but they generally suffer from the complexity of the protectors, the cost of fabrication and the cost of labor needed to assemble such protectors onto a threaded pipe. The danger of loosening or separation of the protector from the pipe is also a serious problem in view of the vibrations and various impacts that pipes with protectors suffer subjected to during loading, transporting and unloading.
US2893437 discloses the protectors to protect the threaded end portions of pipe and casing members during handling and shipping. It is basically a nipple type of thread protector which has a forward guide and alignment portion and a back securing portion which cooperate with each other to hold the nipple in position with respect to the casing and in such a manner as to prevent damage to threaded portions thereof and even if some relative pivotal movement is imparted between the nipple and the casing. The main drawback of this invention is the complicated design of the thread protector that uses several more parts and has to be threaded over the protected part which takes more time and efforts to assemble.
US6196270 B1 discloses a thread protector for protecting threads on the end of a pipe which includes a base portion, a threaded portion extending axially from a first end of the base portion and threadably engageable with the pipe and an elongated annular bumper extending axially from a second end of the base portion. The elongated bumper has an average length and width such that the ratio of the length to the width is at least 2. The base and elongated bumper have a total length of at least two inches. The main drawback of the invention is more complicated structure of the thread protector with a bumper designed for different considerations and features.
Therefore, in order to overcome the drawbacks of the prior arts, there is a need of a thread protector simple in design which protects the threads of the pipes and is useful for lifting the pipes during handling and transportation.

OBJECT OF THE INVENTION
The main object of the present invention is to provide an improved thread protector for a box connector and a pin connector.
Another main object of the present invention is to provide a thread protector for protecting the threads of the box connector and the pin connector during handling and transport.
Yet another object of the present invention is to provide a thread protector for protecting the threads of pipes and for quick and easy assembly of thread protectors over the pipe connectors using a grub screw.
Yet another object of the present invention is to provide a thread protector having an additional wall that comes inside the pin connector when the thread protector is screwed over the pin connector of the pipe. This additional wall on the inside of the thread protector for the pin connector provides protection to the pin connector against damage during lifting of the pipe with the thread protectors by using a sling over a U-type clamp, protection is more for the pin connector end of the pipe.
Yet another object of the present invention is to provide a thread protector made up of mild steel, and held by the grub screw, for protecting the box connector.
Yet another object of the present invention is to provide a thread protector having an additional wall inside the protector for the pin connector and made up of polypropylene material for protecting the pin connector.
Still another object of the present invention is to protect the box connector and the pin connector from damaging and wear at the time of transportation.

SUMMARY OF THE INVENTION
The present invention relates to an improved thread protector. More particularly, the present invention relates to improved thread protectors for protecting the threads of a box connector and a pin connector during handling and transport.
In a main embodiment, the present invention provides a thread protector made of mild steel to protect a box connector assembled using a grub screw. The grub screw is used for fixing the thread protector to the box connector. The grub screw helps in achieving a simple structure of the thread protector which is quick in assembling. The thread protector for the pin connector is also made of mild steel and is held by a grub screw.
In yet another embodiment, the present invention provides thread protectors for threads of pin connector and box connector made of polypropylene material to protect threads of the pin connector and the box connector. The thread protector for pin connector threads has an additional wall for supporting the pin connector which prevents the damage of thread as well as outer surface of pin connector during holding/lifting of the pipes with a pin connector welded at one end and a box connector welded at the other end. The additional wall for the thread protector for pin connector has a defined thickness so that it forms a packing for a U type clamp generally used for holding/lifting the pipes with the welded connectors.

BRIEF DESCRIPTION OF THE DRAWING
A complete understanding of the device and method of the present invention may be obtained by reference to the following drawing:
Figure 1 is a partial cross-sectional view of a thread protector of box connector in accordance to the present invention.
Figure 2 is a partial cross-sectional view of a thread protector of pin connector in accordance to the present invention.
Figure 3 is a diagrammatic representation of lifting condition of a casing pipe with connectors and thread protectors in accordance to a prior art.

DETAILED DESCRIPTION OF THE INVENTION
Many aspects of the invention can be better understood with references made to the drawings below. The components in the drawings are not necessarily drawn to scale. Instead, emphasis is placed upon clearly illustrating the components of the present invention. Moreover, like reference numerals designate corresponding parts through the several views in the drawings. Before explaining at least one embodiment of the invention, it is to be understood that the embodiments of the invention are not limited in their application to the details of construction and to the arrangement of the components set forth in the following description or illustrated in the drawings. The embodiments of the invention are capable of being practiced and carried out in various ways. In addition, the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.
The present invention relates to an improved thread protector. More particularly, the present invention relates to an improved thread protector for protecting the threads of a box connector and a pin connector during handling and transport of the pipes with a box connector welded at one end and a pin connector welded at the other end of the pipe.
In a main embodiment, the present invention provides a thread protector is double walled with a main wall and an additional wall preferably made of mild steel to protect a box connector, and held in place on the pipe by using a grub screw. A grub screw is also used for fixing another similar thread protector to the pin connector end of the pipe. The grub screw helps in achieving the simple structure of the thread protector.
In yet another embodiment, the present invention provides a thread protector made up of polypropylene material to protect a pin connector. The thread protector is double walled with a main wall and an additional wall for supporting the pin connector which prevents the damage of thread as well as outer surface of pin connector during holding/lifting of pipes with pin connector welded at one end and a box connector welded at the other end of the pipe. The additional wall has a defined thickness so that it forms a packing and protects threads and outer surface of the pin connector when U type clamps are used for holding/lifting the pipes with welded pin and box connectors.
Now referring to Figure 1, a partial cross-sectional view of a mild steel thread protector of box connector is shown. This figure shows thread protector held only on the box connector, but in actual use in the industry, the connector is welded to a casing pipe. A similar thread protector is used for protecting threads of the pin connector. The thread protector 1 comprises of a housing which is double walled with an additional wall 11 and a main wall 10 such that the box connector 2 fits between the walls 10, 11 of the thread protector 1 and tightened on the box connector 2 using grub screw 3 provided on the main wall 10. The inner diameter of the thread protector 1 depends on the outer diameter of the box connector 2. The thread protector 1 is held on to the box connector using a grub screw 3 on main wall 10. The grub screw 3 helps in achieving a simple structure of the thread protector 1 on a respective protected part which is quick in assembling. Said thread protector is made of a material including but not limited to mild steel, polypropylene and alike. The length of main wall 10 and additional wall 11 is in a ratio in the range of 1.65:1 to 1.45:1.
Now referring to Figure 2, a partial cross-sectional view of a polypropylene thread protector of pin connector is shown. This figure shows the thread protector only on the pin connector, but in actual use in the industry, the pin connector is welded to a casing pipe. A similar thread protector is used for protecting threads of the box connector for pipes with a pin connector welded at one end and a box connector welded at the other end of the pipe. The thread protector 4 comprises of a housing which is double walled and has a main wall 40 that has threads on the inner surface matching with the threads on the outer surface of the pin connector 5 and an additional wall 41 to support the pin connector 5. The thread protector 4 fits on the main wall 40 of the pin connector 5. The additional wall 41 of thread protector 4 supports the pin connector 5 from inside which prevents damage of threads as well as outer surface of the pin connector 5 during lifting and transportation of the pipes with a pin connector welded on one end and a box connector welded on the other end of the pipe. The additional wall 41 has a very little clearance from the inner surface of the pin connector 5 and the wall 41 extends to a defined depth inside the thread protector 4. The thread protector 4 is preferably made of polypropylene. The length of main wall 40 and additional wall 41 is approximately in a ratio of 2:1. The additional wall 41 also has a defined thickness lying in the range of 25-35mm and it forms packing for a U type clamp generally used for lifting/holding the pipes at the pin connector 5 end of the pipe with welded box and pin connectors.
The threads of the pin connector 5 and box connector 2 suffer excessive stress and get damaged during transportation and handling. The function of thread protector is to protect the threads of the pin connector 5 and the box connector 2 and reduces the threads from damaging and wear during transportation.
Now referring to Figure 3, diagrammatic presentation of lifting condition of a casing pipe in prior art as shown when the threads and outer surface of the pin connector gets damaged as the pipe is lifted using U- type clamps on each end. The U-type clamp 7 of the thread protector 4 is generally used for holding/lifting the pipe with welded connectors like a pin connector 5 at one end and a box connector 2 at the other end of the pipe. The thread protector 1 of the box connector 2 helps in protecting the threads of the box connector and for easy and quick assembly of the thread protector over the threaded ends of the pipe.
The foregoing description of embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principals of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated.
,CLAIMS:CLAIMS

We claim:
1. An improved thread protector (1) comprising:

a housing; and

at least one grub screw (3);

wherein,
said housing is double walled with a main wall (10) and an additional wall (11);

said thread protector (1) protects a box connector (2) as well as a pin connector;

said box connector (2) or pin connector fits between said main wall (10) and additional wall (11) and is tightened with said grub screw (3) attached to the main wall (10) to prevent damage to threads of the box connector (2) and pin connector.

2. The improved thread protector (1) as claimed in claim 1, wherein said thread protector (1) is made of a material including but not limited to mild steel, poly propylene (PP) and alike.

3. The improved thread protector (1) as claimed in claim 1, wherein said grub screw (3) enables a simple and fast assembly of thread protector (1).

4. The improved thread protector (1) as claimed in claim 1, wherein the length of main wall (10) and additional wall (11) is in a ratio in the range of 1.65:1 to 1.45:1.

5. An improved thread protector (4) comprises:

a housing; wherein,

said thread protector (4) protects a box connector as well as a pin connector (5);

said housing is double walled with a main wall (40) to protect threads of the pin connector (5) and box connector and an additional wall (41) to support the pin connector (5) or the box connector;

said main wall (40) has threads on its inner surface matching with threads of pin connector (5) or box connector; and

said additional wall (41) prevents damage to outer surface of pin connector (5).

6. The improved thread protector (4) as claimed in claim 5, wherein, said thread protector (4) is made of a material including but not limited to polypropylene.

7. The improved thread protector (4) as claimed in claim 5, wherein, said additional wall (41) has a defined thickness lying in the range of 25-35 mm.

8. The improved thread protector (4) as claimed in claim 5, wherein, the length of main wall (40) and additional wall (41) is in a ratio of approximately 2:1.