The Hydra-Lok® swaging system to make quick, reliable and low cost connections between piles and sleeves. The connection is for use on small relatively lightly loaded structures – 50 to 100 tonnes – with sleeves 1 metre long. The only preparation necessary is for pile and sleeve to have their longitudinal weld beads ground flush in the likely swaging area. After driving the pile the top 500 mm of the pile within the sleeve is swaged until it makes contact with and expands the surrounding sleeve. The swaging operation can be performed on any part of the pile so it is not necessary to drive the pile to a specific position relative to the sleeve, thus removing any problem due to pile under drive.The light weight Hydra-Lok® tools, being shorter than the normal swaging tools weigh between 4 and 8 tonnes and can be deployed from any suitable vessel from small DSV’s upwards. The operation to swage each pile takes between 20 and 30 minutes, allowing for stabbing and retrieval therefore; a 4 pile structure should be completed in 4 to 6 hours. The control and verification process is ongoing during the swaging operation by means of the pressure/volume (P/V) plot.
• Low cost 16" to 36" pile diameter
• Minimum preparation of pile and sleeve
• No requirement to drive to specific elevation
• Rapid connection-approx. 30 minutes/pile
• Immediate full connection strength-50 to 100
• It Operates at any depth |
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Light Weight Swaging Tool
Wellhead Protection Base Frame
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After stabbing the Hydra-Lok® tool into the pile the seals are inflated by water delivered through the umbilical to the surface. The inflated seals trap an annulus of water between them which is then pressurised to expand the pile. During the pressurisation process a measurement of Pressure verses Volume is made-the ‘P/V’ plot. The P/V plot gives an accurate picture of the operation as it is happening thus allowing the operator to monitor and control the connection procedure.
The P/V plot clearly shows the significant stages of the operation. Initially the pile elastically expands until it reaches its elastic limit at point A , it then plasticly deforms. The plastic deformation continues until the pile expands sufficiently to make contact with the surrounding sleeve at point B. On making contact with the sleeve the P/V plot clearly shows a significant change in gradient as the sleeve elastically deforms to its elastic limit at point C. The expansion is continued until the sleeve is, in turn plasticly deformed by a small amount to point D, this creates an interference fit between pile and sleeve. The operation, which takes between 20 and 30 minutes, is then complete. The tool and seals are depressurized and the tool is withdrawn and stabbed into the next pile to repeat the process. On completion of the operation P/V plot forms part of the connection As-Built documentation.
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Oil States Industries, Inc.
Oil States International, Inc.