Pipe clamp

Details Pipe clamp Pipe clamp

1996-09-30

1998-10-06

Heinrich, Samuel M.

Metal fusion bonding

With means to handle work or product

Including means to orient work or position work portion...

228212, 269 481, B23K 37053

Patent

active

058164758

DESCRIPTION:

BRIEF SUMMARY
DESCRIPTION OF INVENTION

This invention relates to an internal clamping device for holding adjacent pipe sections rigidly in end-to-end relationship to enable a circumferential weld to be completed around the adjacent pipe ends to secure the pipe sections together.
Such general types of clamping devices are known in the art such as for example the internal pneumatic line-up clamp manufactured by CRC-Evans Pipeline International Inc of Houston Texas. This type of clamping device is self-propelled for movement within pipe sections and has two independently operable clamping mechanisms each of which is engageable with a respective adjacent end of two pipe sections which are to be welded together. Each of the clamping mechanisms comprises a plurality of circumferentially spaced apart radially extendible and retractable clamping shoes. The shoes in each mechanism are pneumatically operated by means of a double acting pneumatic piston movable on the centreline of the device to actuate the clamping shoes by means of a toggle linkage connected between the piston and the shoes. The two sets of clamping shoes are axially spaced apart so that one set may be radially outwardly extended into clamping engagement with the interior wall of a pipe section adjacent one end whilst the other set of clamping shoes may be similarly radially outwardly extended into clamping engagement with the interior wall of an adjacent pipe section adjacent one end so that the respective ends of the pipe sections may be rigidly held preparatory to being welded together. Subsequent to completion of a circumferential weld around the pipe section ends, the clamping shoes may be radially inwardly retracted and the device may be self propelled along one of the pipe sections to the other end thereof where a similar clamping and welding operation may be performed to secure another pipe section whereby an extended pipeline may be built up of a plurality of pipe sections.
When automatic circumferential welding processes are utilised it is usual to position the adjacent ends of pipe sections to be welded together so as to leave a small annular axial spacing therebetween. It will be appreciated that such spacing will be located intermediate the positions at which each of the respective pipe sections is clamped whereby, during the welding operation, welding detritus may fall through the spacing onto the clamping device. Also, after the welding has been completed, an extremely rough circumferential weld line may remain internally of the pipe sections.
In order to overcome the aforesaid problem it has been proposed to utilise what are known as back-up shoes, usually made of copper, and which are either attached to or used in lieu of one of the sets of clamping shoes. Such copper back-up shoes comprise segments of two differing configurations arranged alternately circumferentially and having respective circumferentially and radially overlapping chamfered end faces so as to present a radially outer circumferentially continuous cylindrical surface in both the fully retracted and fully extended positions of the back-up shoes. In use, if for example the copper back-up shoes are attached to or utilised in lieu of the front clamping shoes, the rear clamping shoes will firstly be radially outwardly extended into clamping engagement with an end of one of the pipe sections and the copper back-up shoes will then be radially outwardly extended into engagement with the other pipe section and also to bridge the annular spacing between the adjacent pipe section ends. This bridging is enabled because each of the back-up shoes has an axial dimension considerably in excess of the axial spacing between the pipe section ends which is required for welding purposes and thus when the back-up shoes are in clamping engagement with the pipe sections the shoes effectively provide a continuous supporting surface immediately adjacent the interior walls of the pipe sections. Thus, during the welding operation, welding detritus is contained within the annular channel bounded by the end

REFERENCES:
patent: 4165831 (1979-08-01), Connell
patent: 4177914 (1979-12-01), Clavin
patent: 4201326 (1980-05-01), Connell
patent: 4285458 (1981-08-01), Slavens
patent: 4363954 (1982-12-01), Rinaldi
patent: 5110031 (1992-05-01), Rinaldi
patent: 5356067 (1994-10-01), Leduc
The Passo Welding System, Saipem, Brochure.
Brochure of SAIPEM (date unknown).

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