An interlocked yard may have several track circuits depending upon the number of berthing tracks,
point zones and number of signals, siding etc. Each track circuit has to be bifurcated physically
from the adjacent track circuits by the means of insulated joints. Glued Joints bifurcate track
circuits physically and electrically too. Apart of that Glued Joints are having more mechanical
strength to retain insulation and to withstand rail creep mostly used along with Long Welded Rails.
The joints are fabricated in a workshop in 6.5 m Length and transported to the site for insertion in the track. Laying of these joints involves civil Engg. Works viz. distressing of welded rails, welding of the joints into running track etc.
The drawings for the same of different rail sections are:
| Sl.No. | Rail Section | G3(L) Type | Specification of Fish Plate |
|---|---|---|---|
| 1 | 52 Kg | RDSO/T-671 | IRS T-1-2012 |
| 2 | 60 Kg | RDSO/T-2572 | IRS T-1-2012 |
G3(L) type joints are of 6.5 m length and shall be used with Continuous Welded Rails and Long Welded Rails of 52 kg and 60 kg(UIC) rail sections in all temperature
Sleeper spacing: The sleeper spacing under glued joint shall be the same as
that of intermediate sleepers. The codal life insulated glued joints may taken as :
(i) 60 kg/60E1 rail section with 6 mm thick end post - 400 GMT
(ii) For 60kg/60E1 rail section with 10 mm thick end post and 52 kg with 6mm/10 mm thick end post - 200 GMT.
.
The insulating components viz. bushes, liners and end-posts are fabricated using glass cloth reinforcement and epoxy of an RDSO approved quality with hardener by a hand laying process or pressure moulding technique. These are built up layer after layer to achieve sufficient thickness.
Generally, end posts are made of 20 layers, liners of 4 layers and bushes of 5 layers.
After making a rectangular piece of glass cloth reinforcement and allowing it to cure, it is cut and profiled to the shape of an end post. The liners are fabricated in the hollow of a rail web. The bushes are cut to size from a long ferrule made by winding a wide piece of glass cloth on a bolt shank layer after layer with adhesive in between. The fabricated component is able to be separated from the surface on which it is made due to a coat of a releasing agent applied beforehand.
All the insulating components (Fig.1) of the joint are stuck in place with an adhesive layer and the bolts are tightened for a permanent setting. Glued Rail Joints are available in G3 (L) type having 6 bolts (L-Long)
(a) Material:
The requirement of material for fabrication of one Glued Joint is given in below. The input materials shall be procured from RDSO approved suppliers only. The list of approved suppliers of input materials is available in Master list of Approved Vendors issued by Quality Assurance (Civil) directorate of RDSO which is updated from time to time.
1. Materials Required for Fabrication of Glued Joints is tabulated below.
| No. | Description | Quantity G3(L) / G3(S) |
|---|---|---|
| 1 | Rail piece of required length | 1 No. / 1 No. |
| 2 | Fishplates | 2 Nos. / 2 Nos. |
| 3 | HTS bolts with nuts | 6 Nos./4 Nos. |
| 4 | Punched washers | 12 Nos./8 Nos. |
| 5 | Insulating bushes/sleeves** | 6 Nos./4 Nos. |
| 6 | Insulating liners** | 2 Nos./2 Nos. |
| 7 | Insulating end posts** | 1 No./1 No. |
| 8 | Glue | Glue consist of epoxy and hardener. The nomenclature of epoxy resin being: Ms CIBA-GEIGY of India’s ARALDITE LY 556; Ms SIP INDUSTRIES Ltd’s EPL 306 and Ms CIBATUL Ltd’s L aprox L-12. The nomenclature of the hardener being Ms CIBA-GEIGY of India’s HARDENER HY 951; Ms SIP INDUSTRIES Ltd’s HARDENER EH 301 and Ms CIBATUL HARDENER L aprox K-6. Hardener and resin shall be mixed in the ration 10:1 |
| 9 | Glass cloth carrier/(woven roving) | 4 pieces (15 x 100 cm)/4 pieces (15 x 66 cm) |
| 10 | Acetone or trichloroethylene or carbon tetrachloride or benzene (for cleaning tools, rails etc.) | Half lit approx. |
| 11 | Kerocleanse chemicals for cleaning hands | Half lit approx. |
| 12 | Release Agent | 25 gm Approx. |
| 13 | Sand (For sand blasting) | 0.2 cu.m/0.2 cu.m |
| 14 | Cotton waste or liners rags | 0.5 Kg approx. |
| 15 | Emry cloth no.2 | 2 sheets/2 sheets |
| 16 | Approved paint i.e. red, yellow and blue | As per requirement |
**The insulating components shall be made at the manufacturing site and shall not be procured from outside agencies.
2.PRE-FABRICATION WORK
(i) The glued joints shall be fabricated/assembled in a covered shed having clean,
dust free and well lit area, so that there is no possibility of extraneous particle
mixing with the glue.
(ii) The assembly jig shall be thoroughly cleaned of any dust using a brush before
taking up assembly.
(iii)One rail piece of minimum 6 m length shall be used for fabricating one glued
joint.
(iv)Rails required for fabrication of glued joints shall be straight and USFD tested.
These rails shall be issued by the consignee Zonal Railways to the
manufacturer. Old/Service rails shall not be used for fabrication of glued joints.
New rails need not to be USFD tested again by consignee Zonal Railways if
they have received the same from rail manufacturing plant duly USFD tested.
(v) The rail piece shall be cut in the middle with a rail cutting machine. It shall be
ensured that the cut is square and the rail ends are square, plane and smooth.
Since rail pieces taken from two separate rails are likely to have variations in
profile, it is, therefore, necessary that rail pieces cut from the same rail are
jointed together at the cut-end for fabrication of the joint. For this purpose, just
before cutting a rail-piece, necessary marking (such as A-A’ or 1-1’ etc.) shall
be put on the adjoining cut-ends with indelible paint and it shall be ensured that
the ends with corresponding mark only are jointed together.
(vi)The edges of the rail-ends of the two pieces at the cut shall be finished smooth
with a flat file. All burrs shall be removed.
(vii)Holes in rail pieces shall be drilled at locations following the relevant drawing
with a precision drill using jigs to ensure accuracy. It shall be ensured that the
holes drilled are not skew.
(viii)The burrs around holes shall be removed. The edges of the drilled holes shall
be chamfered using the chamfering tools.
(ix)The fish-plates shall have correct profile as per drawing so that contact with rail
on the fishing surfaces and web is proper. Drilling of holes in fishplates shall be
done by a precision drill using jigs. The edges of drilled holes shall be cleaned
of burrs. It shall be ensured that the holes drilled are not skew.
(x)The markings of rail designation, rolling details etc., occurring in the zone of
contact of rail and fishplates, shall be ground with a grinder so as to merge with
the parent profile/contour.
(xi)The matching surfaces of the rail and that of fish plate shall be sand blasted.
Sand blasted rail and fish plate surfaces shall be cleaned with the help of a
high speed revolving wire-brush (of about 500 revolutions per minute) and with
a blower to dislodge the metallic dust, caused during sand blasting, from the
cavities. Alternatively, the surfaces may be cleaned with the help of a brush
with hard nylon bristles.
(xii)The surfaces of rail, fishplates, insulating components, bolts, nuts & washers
shall then be finally cleaned using a suitable chemical such as
Trichloroethylene, Acetone, Carbon tetrachloride or Benzene. It shall be
ensured that the surfaces, after cleaning, are free from traces of oily
substances.
(xiii)The end-post, bushes/sleeves and insulating liners shall be roughened by
Emery Cloth No.2.
(xiv)The assembly work shall be commenced as soon as possible and in any case
within four hours of sand-blasting. If due to some reasons, the rails and the
fishplates could not be used within four hours of sand blasting, the sand
blasting operation should be repeated.
3. Special fish plates to be used in fabrication of Glued Insulated Rail Joints shall be inspected by purchaser Railway or its nominated inspecting agency (M/s RITES) at the premises offish plate manufacturer firm. Inspection should be done as per Para 19 of IRST-1 as amended from time to time. After inspection every accepted fish plate shall be plainly stamped with the inspecting officers stamp at one end of each fish plate on its outer side in the presence of Inspecting officer. The inspection certificate of inspecting agency shall be sent by manufacturer of special fish plate along with the supply to Glued Joint manufacturer. The Glued Joint manufacturer will check the supply with respect to the details mentioned in Inspection Certificate of inspecting agency and then only put these in use.
4. HTS bolts and nuts shall comply with the following specifications: -
a. "HTS Bolts - Material and manufacturing process of Hex bolts shall be as per IS: 1363 confirming to property clause 10.9 of IS: 1367."
b. "HTS Nuts- Material and manufacturing process of Hex nuts shall be as per IS: 1363 confirming to property clause 12.0 of IS: 1367."
c. "HTS HEX Bolts and Nuts to be used in fabrication of Glued Insulated Rail Joints shall be inspected by purchaser, Railway or its nominated inspecting agency (M/s RITES) at the premises of HTS HEX Bolts and Nuts manufacturer firm. The inspection certificate of inspecting agency shall be sent by manufacturer of HTS HEX Bolts and Nuts along with the supply to Glued Joint Manufacturer. The Glued Joint Manufacturer will check the supply with respect to the details mentioned in Inspection Certificate of inspecting agency and then only put these in use.
5. Glass- Cloth Carrier Reinforcement Glass- cloth carrier reinforcement shall conform to IS: 11273: 1992
(i) Nominal Weight: 360 ±_36 gm/sq. m
(ii) Nominal thickness: 300 ±30 microns
(iii) Construction: I) Ends per 100mm: 61 ±2.5%
II) Picks Weave per 100mm: 55.2 ±2.5 % plain
6. Glue: (for making insulating components)
Glue consists of resin and hardener. The nomenclature of resin & hardener manufactured by firms approved at present are as under:
| Firm's Name | Resin | Hardener |
|---|---|---|
| M/S Atul Ltd. | Epoxy Resin Lapox L-12 | Eposy Hardener Lapox K-6 |
| M/S. Huntsman Advanced Materials (India) Pvt. Ltd. | Araldite Ly-556 | Aradure HY-951 IN |
Resin and hardener shall be mixed in the ratio of 10: 1.
Specification and Quality Required of Glue: The tangential shear strength of glue is claimed to be about 120 kg/sq.cm by the manufacturer.
i) The Glue as developed by M/s Huntsman Advanced Materials (INDIA) Pvt Ltd for prefabricated type Glued Joints consists of ARALDITE XY 27 and hardener XY 28 IN to be mixed in proportion of 100:40. The approximate quantity of combined adhesive required for 52 Kg rail joint is 1.4Kg for 03 (L) and for 60Kg.rail joint is 1.68Kg for 03 (L).
(ii) Similarly; the Glue as developed by MIS ATUL Ltd for Prefabricated type Glued Joints consists of Epoxy resin Lapox A-83 and Hardener Lapox K-83 to be mixed in proportion of 100:40. The approximate quantity of combined adhesive required for 52 Kg rail joint is 1.4 Kg for 03 (L) and for 60kg rail joint is 1.68 Kg for 03 (L).
7. Quantity of raw materials required for insulating components for 52 kg G3 (L) and 60 kg G3 (L) Glued Joint, with10mm/6mm thick end post shall be approximately as under. However, in field performance of 10mm thick end post is not satisfactory so it is preferred to use 6 mm thick end post.
Marking of Glued Joints (by manufacturer)- Every Glued Joint shall have distinctive mark indicating the Glued Joint number, month and year of manufacturing and the code of the manufacturer as shown below. This marking should be embossed on the gauge and non-gauge face sides of the head of the rail of Glued Joint at 300 mm away from the one end of fish plate by punching without causing any damage to rail, in letters/digits of 6 mm height at a depth of 10mm from top of vertical face of rail, as indicated in figure
XX.XX MM YY AAA
The first four digits indicate the Glued Joint number starting from 0001 for first joint of every month, the next two digits’ month of manufacturing followed by last two digits of the year of manufacturing. The end letters shall be code of the manufacturer, assigned by the• Quality Assurance (Civil) directorate of RDSO.Marking of Glued Joints (by inspecting authority)- Every Glued Joint shall have distinctive inspection mark of inspecting agency. This marking should be embossed on the gauge and non gauge face sides of the head of the rail of Glued Joint at 300 mm away from the another end of fish plate by punching without causing any damage to- rail, in letters/digits –of 6 mm height a t a depth of 10 mm from top of vertical face of rail, as indicated in above figure.
Testing of Glued Insulated Joints
Electrical resistance test should be conducted and satisfy the following criteria –
In Dry Condition: - After preparation of Glued Joint, meggaring voltage of 100V DC shall be applied across the joint. The value of resistance shall not be less than 25 mega-ohms.
• In Wet Condition: -Glued joint is immersed in water for 48 hours and then insulation resistance is tested, the value of resistance shall not be less than 3 Kilo-ohms. Electricity resistance shall be checked annually during joint inspection by P. Way & Signal staff and a certificate recorded in the register.
Pull out Test:
The pull out test shall be conducted by suitably gripping the two rail pieces of the joint and subjecting the joint to axial tension. One method of conducting the test is to hold one end of the glued joint with the help of fishplates as fixed end. The other end of the glued joint is held to a moving frame with the help of a wedge inserted in slots cut in the glued joint through the moving frame brackets. the other method of conducting the test is to hold the glued joint with the help of fish plates at both ends of the testing frame. One end of the testing frame remains fixed and the other is moved with the help of two hydraulic jacks operated simultaneously. Manufacturer can adopt any other method also with prior approval of RDSO.
Acceptance Values:
The test joint shall be considered acceptable if there is no indication of separation between end posts and rail end(s) visible to the naked eye at the pull out load values given in the table below.
| Sl No. | Rail Section | Minimum pull out load in tonnes for G3(L)type joint | Minimum pull out load in tonnes for G3(S)type joint |
|---|---|---|---|
| 1 | 75 R | 110 | 70 |
| 2 | 90 R | 125 | 85 |
| 3 | 52 kg | 150 | 100 |
| 4 | 60 kg (UIC) | 170 | 110 |
The basis for acceptance/rejection of the lot with respect to pull out test shall be as follows:
Four joints should be randomly selected. Out of these four, two joints are to be subjected to pull out test. If
1. Both joints pass, lot is cleared for insulation resistance test in wet conditions.
2. Both joints fail, lot is rejected.
3. one joint fails, remaining two joints should be treated and if both pass, the lot is cleared for insulation resistance test in wet condition otherwise entire lot is rejected.
Laying of Glued Joint:
(a) Sleeper spacing: The sleeper spacing under glued joint shall be the same as that of intermediate sleepers.
(b) Before laying of the glued joint, it shall be ensured that at least ten sleepers on either side of the joint are properly packed to the correct level.
(c)Proper care shall be taken in transporting the joints to site of laying so that no damage is caused during loading, unloading and transportation.
(d) Liners & GJ Clip: Specially fabricated GFNL cut liners shall be used in glued joints due to space constraint of fish plates & to prevent short circuiting of track circuit due to rail clips as shown in fig. GJ clip shall be provided instead of J clip in glued joint area.
Maintenance of Glued Joints:
(a) The ballast used on track in the vicinity of these joints shall be cleaned to ensure efficient packing and drainage. Care must be taken to see that the ballast is clear of rails and rail fastenings. The clearance from the underside of rail must not be less than 50 mm.
(b) The joint does not need any special maintenance than that required for normal track. However, glued joint shall be kept clean to avoid accumulation of metal particles which leads to failure of Track Circuit.
(c) As in the case of standard insulated joints, the metal burrs at the ends of rails shall be removed well in time to avoid short circuiting through them. This work shall be done by Engineering staffs skillfully avoiding damage to end posts.
(d) Normally no relative movement occurs between rails and fish plates at these joints. In case failure occurs with separation of rail/fish plate surfaces and relative movement takes place, the damaged joint must be replaced soon. The electrical resistance of the joint does not decrease appreciably for a considerable time even after this separation.
(e) Between two successive tamping of Glued Joints by track machine, proper maintenance attentions and inputs should be given to Glued Joints for their upkeep and proper function.
(f) Use of GJ clip and cut liners along with GR Sole plate shall be ensured for proper toe load.
(g) Adequate spacing of sleepers at joint location shall be such so proper tamping by track machine shall be ensured.