FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See Section 10; rule 13)

TITLE OF THE INVENTION
A GLAND FOR UNDERWATER STRAIN GAUGING

APPLICANTS
LARSEN & TOUBRO LIMITED, an Indian company having its registered office at PRDH, Powai Works, Saki Vihar Road, P.O. Box 8901, Mumbai 400 072, Maharashtra, India

INVENTORS
Rajeev V. Kulkarni and Raj an Khakhar both Indian nationals of Larsen & Toubro Limited, an Indian company having its registered office at PRDH, Powai Works, Saki Vihar Road, P.O. Box 8901, Mumbai 400 072, Maharashtra, India

PREAMBLE TO THE DESCRIPTION
The following Complete specification particularly describes the invention and the manner in
which it is to be performed.

Field of Invention
The invention relates to a gland for strain gauging for which strain measurements are required on the surfaces of the equipment exposed to liquids.
Background of Invention
Strain measurements on equipments using foil type resistance wire strain gauges form an important input for testing and quality assurance. This strain gauge measurement system and its applications are very sensitive which gives output strains in microns.
For critical equipments, strain measurements may be required even on the inside surfaces of the equipment filled with liquid. Each strain gauge contains three wires and there could be a plurality of such strain gauges required on the inside surface of the equipment. The strain gauge lead wires need to be taken out from the inside to the outside to be connected to the strain measurements instruments. The strain gauge output signal is very sensitive and gets affected by certain factors such as difference/change in lead wire resistance, stretching of the wire, temperature variations etc. Presently, the gland used to take out wires from the inside to the outside requires bare solid wire with insulation coating. Figure 1 illustrates the gland used at present for strain measurements. The gland requires the strain gauge lead wires with additional joints, water proofing requirements and change in wire types and hence are more susceptible to failures and inaccurate results.
In order to overcome the above-mentioned drawbacks, a gland is configured which allows the lead wire from the strain gauges to be passed through the gland and directly connected to the strain measurement instruments outside the equipment.
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Such a gland should be leak proof even at high pressures and the sealing arrangement in the gland should not cause the stretching/squeezing of the wires, which could affect the output readings. In case of an accidental leakage additional
provision to contain the leakage needs to be provided.
Summary of the Invention
The present invention overcomes the limitations of the prior art. The above requirements are satisfied with the gland according to the present invention. The wires that come out of the strain gauge are passed to the outside strain measuring instruments through individual holes that are provided on a plate integral with gland body. Such a perforated plate is designed to withstand the pressure requirements. The perforated plate also provides mechanical support to the sealant. The gland body comprises at least an inside and an outside cavity. The inside cavity is conical and has "V" notches. This cavity with "V" notches is filled with sealant like silicon sealant, which, after curing gives a soft rubber like property that prevents leakage due to the conical shape and the additional grip provided by the material in the "V" notches. Suitable combination of sealant and wire coating should be used, for instance, cross-linked vinyl resin sheathed wire coating and silicon sealant, but not restricted to the same.
In another embodiment, there is an arrangement provided in case of leakage. On the outer side of the gland a cavity is provided wherein a quick setting adhesive could be filled in and the cover tightened in order to plug the leakage.
This whole gland assembly is fitted on the equipment with suitable threading and gasket arrangement.
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Brief Description of the Drawings
The invention will now be explained with reference to the drawings.
Figure 1 shows the details of the gland presently used in underwater strain gauge
measurements (prior art).
Figure 2A shows the plan view of the gland according to the present invention
Figure 2B shows the sectional view at A-A of Fig. 2A
Figure 2C shows the details at 'C of Fig. 2B
Figure 2D shows the details at 'D' of Fig. 2C
Figure 2E shows the plan view of the gland according to the present invention
Figure 2F shows the sectional view at B-B of Fig. 2E
Figure 3 shows the schematic view of the gland fitted on a vessel
Detailed description of the drawings
The constructional features of the presently used gland for underwater strain
gauging and their drawbacks as illustrated in Figure 1 have already been discussed in the background of the invention.
The present invention will be described with reference to Figures 2A, 2B, 2C, 2D, 2E, 2F and 3 of the accompanying drawings.
The wires coming out of the strain gauges (not shown) are passed through individually through each hole (10) provided in the perforated plate (11). The perforated plate (11) is designed and manufactured to withstand the pressure requirements. The gland body (1) is provided with an outer cavity (3) and an inner cavity (2). The inner cavity (2) is conical in shape and is provided with "V" notches (4) as shown in the figure. The Cavity (2) and "V" notches (4) are filled
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with sealants such as silicon sealants which after curing possesses excellent soft rubber like properties to prevent leakages. Thus the conical shape of the inner cavity (2) and the material in the "V" notches (4) aid in leak-resistance for the gland.
In a further embodiment, in the event of a slight leakage a secondary sealing arrangement is provided. On the outer cavity (3) a quick-setting adhesive is filled in and a cover (8) tightened in order to plug the leakage. The provision of the cover (8) aids in the mechanical support for the secondary sealant. The wires are bundled and passed through groove (7). Internal threads (6) are provided in the gland to screw the cover (8) over the gland.
In another embodiment, the individual holes (10) are chamfered (5) to provide further leak-tightness to aid in a strong leak-proof arrangement.
A suitable combination of wire coating and sealant may be, but not restricted to, a cross linked vinyl resin sheathed wire coating and silicon sealant.
The whole gland assembly is fitted to the equipment (14) and suitable threading (12) and gasket (13) arrangement.
The invention as described above provides numerous advantages over the prior art. This construction is user friendly and simple. There are no additional joints on the lead wires. Provision of perforated plates enables efficient mechanical support to the sealant. The provision of a secondary sealing arrangement enables leak resistance in the event of slight leakages. The provision of a cover plate provides mechanical support to the secondary sealant. The provision of chamfers at the individual holes and "V" notches in the cavity further enables the leak resistance.
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We Claim
1. A gland (1) for underwater strain gauging comprising an inner cavity (2) and an outer cavity (3); a plate (11) with a plurality of holes (10) for passing the individual wires from a strain gauge to the strain measuring instruments through each of the individual holes (10) in the said plate (11).
2. The gland as claimed in claim 1, wherein said inner cavity (2) is conical in shape and is provided with "V" shaped notches (4) filled with sealant to provide leak resistance for the gland.
3. The gland as claimed in claim 1 or 2, wherein a quick-setting adhesive is filled in the outer cavity (3) of the said gland and a cover (8) is fitted on the said outer cavity (3) to plug the leakage.
4. The gland as claimed in any one of the preceding claims, wherein the said holes (10) provided on the plate (11) are chamfered (5) to enable a leak-proof arrangement.
5. The gland as claimed in claim 2, wherein the sealant is a silicon sealant.
6. The gland as claimed in any one of the preceding claims, wherein internal threads (6) are provided in the glands to screw the cover (8) over the outer cavity (3) of the gland.
7. The gland as claimed in any one of the preceding claims, wherein a threading (12) and gasket (13) arrangement is provided to fit the gland assembly onto the surface of the equipment (14) that requires strain measurement.
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8. The gland for underwater strain gauging, substantially as herein described, with reference to the accompanying drawings.
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Dated this 31st day of January 2007


ABSTRACT
TITLE: A GLAND FOR UNDERWATER STRAIN GAUGING
The present invention relates to a gland for underwater strain gauging. The gland body is provided with an outer cavity, inner cavity and a perforated plate. The inner cavity is conical in shape and is provided with "V" notches The wires coming out of the strain gauges are passed through individually through each hole provided in the perforated plate. The perforated plate is designed and manufactured to withstand the pressure requirements. The Cavity and "V" notches are filled with sealants such as silicon sealants, which after curing possesses excellent soft rubber like properties to prevent leakages. Thus the conical shape of the inner cavity and the material in the "V" notches aid in leak-resistance for the gland.