A double-headed tube structure comprises a tube body, a first tube head, an annular retaining member and a second tube head. The first tube head and a first end portion of the tube body are hermetically connected together. A second end portion of the tube body is sleeved on an outer circumference of the annular retaining member. The second end portion of the tube body, the annular retaining member and the second tube head are hermetically connected together. The annular retaining member communicates with the tube body and the second tube head. The first and second tube heads are sealedly welded at both ends of the tube body by a two-step forming process. Through the annular retaining member, the tube body is not deformed in the two-step forming process, thereby improving the welding and sealing effect.

A locking cap may be selectively locked into place within a tubular opening, such as the open end of a standpipe used to charge a building sprinkler system. The locking cap may have a plug portion. A friction load can be used to limit the unauthorized removal of the plug portion.

A locking cap may be selectively locked into place within a tubular opening, such as the open end of a standpipe used to charge a building sprinkler system. The locking cap may have a plug portion. A friction load can be used to limit the unauthorized removal of the plug portion.

A thread protector that has an external sleeve to protect pin threads disposed on a pin end of a tubular member. The thread protector also has flange disposed on a first end of the external sleeve to engage with the pin end of the tubular member. The thread protector further includes a securing apparatus extending from the flange to frictionally engage an inside portion of the tubular member to maintain position of the thread protector on the tubular member. A method of protecting the pin threads of the pin ends of the tubular members. The method includes screwing the thread protector on the pin threads of the pin end of the tubular member.

A double-headed tube structure and a double-headed tube structure are disclosed. The method includes the steps: a first tube head being sealedly welded to a first end portion of a tube body using a first mold, and then the first mold being removed; a second mold being inserted through the first tube head to a second end portion the tube body, the second end portion, an annular retaining member and a second tube head being sealedly welded together, and then the second mold being removed. The structure is that the second tube head is sealdedly welded to the tube body through the annular retaining member. The first and second tube heads are sealedly welded at both ends of the tube body by a two-step forming process. Through the annular retaining member, the tube body is not deformed in the two-step forming process, thereby improving the welding and sealing effect.

A double-headed tube structure and a double-headed tube structure are disclosed. The method includes the steps: a first tube head being sealedly welded to a first end portion of a tube body using a first mold, and then the first mold being removed; a second mold being inserted through the first tube head to a second end portion the tube body, the second end portion, an annular retaining member and a second tube head being sealedly welded together, and then the second mold being removed. The structure is that the second tube head is sealdedly welded to the tube body through the annular retaining member. The first and second tube heads are sealedly welded at both ends of the tube body by a two-step forming process. Through the annular retaining member, the tube body is not deformed in the two-step forming process, thereby improving the welding and sealing effect.

A thread protector that has an external sleeve to protect pin threads disposed on a pin end of a tubular member. The thread protector also has flange disposed on a first end of the external sleeve to engage with the pin end of the tubular member. The thread protector further includes a securing apparatus extending from the flange to frictionally engage an inside portion of the tubular member to maintain position of the thread protector on the tubular member. A method of protecting the pin threads of the pin ends of the tubular members. The method includes screwing the thread protector on the pin threads of the pin end of the tubular member.

According to one aspect, a non-roll end sleeve is configured to be disposed on a seamless cylindrical paper tube, said non-roll sleeve having a rectangular cross-section perpendicular to a central axis of the cylindrical paper tube when disposed on the cylindrical paper tube. According to another aspect, a container includes a seamless paper tube having at least one end provided with a shape in cross-section generally having N sides, where N is an integer selected from 3 to 8, which at least one end is closed by flaps of material between openings cut into the at least one end that have been folded inwardly and secured in place to form an end closure.

According to one aspect, a non-roll end sleeve is configured to be disposed on a seamless cylindrical paper tube, said non-roll sleeve having a rectangular cross-section perpendicular to a central axis of the cylindrical paper tube when disposed on the cylindrical paper tube. According to another aspect, a container includes a seamless paper tube having at least one end provided with a shape in cross-section generally having N sides, where N is an integer selected from 3 to 8, which at least one end is closed by flaps of material between openings cut into the at least one end that have been folded inwardly and secured in place to form an end closure.

This invention encompasses a system and a method used in the petrochemical and mechanical engineering area, more specifically in the area of protecting pipes or similarly shaped objects against external or internal damage or wear, which comprises a protective system for the ends and the inside of coated pipes, using the coating itself and other additional devices. The system is comprised of a cup (1), spacer (2), coating (3), external ring (4), and cap (5) used in the production line of the pipe-coating process, using the external coating itself, preventing corrosion and mechanical damage at the ends/bevel, in the sandblasted area of the collar and internal surface, from storage and transport to the location where it will be used, and welding in the field or on the vessel.