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Jointing Systems

Electrosteel D.I. Pipes and Fittings are available with following types of jointing systems:

  • Socket & Spigot Flexible Push-on Joints
  • Restrained Joint Push-on Type
  • Mechanical Flexible Joints (only fittings)
  • Flanged Joint

Socket & Spigot Flexible Push-on Joints

Socket and Spigot Flexible Joints are assembled with synthetic (Ethylene Propylene Diene Monomer / Styrene-Butadiene-Rubber) rubber gaskets of special shape. The gasket has a hard ‘Heel’ and a soft ‘Bulb’. In Push-on joint the soft bulb of the rubber gasket is compressed when the spigot is inserted into the socket. The ‘Heel’ locks the position of the gasket and does not allow the gasket to get displaced when the spigot is pushed in. The joint becomes tighter with the increase in internal pressure of water. The rubber is confined in a place and cannot blow out.

Permissible Deflection at Socket and Spigot Joints

Where it is necessary to deflect the pipeline from a straight line, either in the vertical or horizontal plane, to avoid obstructions etc., deflection at joint should not exceed the following:

Push on Joint Maximum Deflection Angle
80-150 mm
200-300 mm
900-1000mm 1½°

Electrosteel ductile iron pipe Joints are type tested

Electrosteel's design of the socket and the rubber gasket ensures guaranteed leak-tight joint through Type Test as per BSEN:545/ EN598 and ISO:2531. Type Test is testing the pipe and pipe joint at extreme working conditions (the product and use) to ensure satisfactory performance for a long time.

Jointing of Pipes

Step 1: Clean the socket grooves and outside spigot end.
Step 2: Hold the gasket as shown and place inside the socket
Step 3: Apply lubricant on the gasket. Do not use petroleum based lubricant.
Step 4: Apply lubricant on the spigot also. Please check that the spigot end is properly champhered.
Step 5: Properly align both the pipes.
Step 6: Gently push the spigot into the socket with suitable mechanical means.

Rubber Gasket

The absence of sunlight and oxygen, presence of moisture/water, relatively lower and uniform surrounding temperature in buried conditions help in preservation of rubber gaskets. Thus this type of joint is expected to last for more than 100 years.

  • Good quality Synthetic rubber gaskets made either of SBR (Styrene Butadyne Rubber) or EPDM (Ethylene Propylene Diene Monomer) conforming to IS:5382 are used with Ductile Iron push-on joint pipes.
  • Gasket should be stored in a cool & dry place. Direct exposure to sunlight should be avoided.
  • It is advised that the users should obtain gaskets through Electrosteel only.

Jointing Tips

  • The sockets should face uphill while pipeline is laid on a slope.
  • The direction of flow has nothing to do with direction of the socket.
  • Never use petroleum based lubricant during jointing. It damages the gasket.
  • All Fittings should be suitably anchored against displacement as recommended in the laying specification.
  • Spigots should be inserted into the socket up to the white insertion mark to ensure proper jointing.
  • The joint deflection should not be more than the recommended deflection.

Restrained Joint Push-on Type for Buried Pipes

Restrained Joints are special jointing system, which can take care of axial movement in case of thrust. Hydraulic thrust forces occur in pressurized mains, when there is any change in direction (bends, tees) or any change of diameter (tapers, valves) or any pipeline end (blank flanges or caps). These special joints are necessary on fittings and a few pipes adjacent to the fittings. Restrained Joints eliminate use of concrete anchor blocks, which are costly and delay the progress of laying operation.

Type of Restrained Joint

  • Tooth gasket Restrained Joint
  • Bolted Restrained Joint
  • Electrolock Restrained Joint


  • Restrained joints are for Underground Application.
  • All pipes in the pipeline need not be restrained.
  • Restraining length depends on Soil type, back fill compaction, Pipeline Profile and Working Pressure.
  • All Bends, Reducers End blocks and Tees with its adjacent restraining lengths are to be with Restrained Joints.
  • Joints on both sides of the fittings ore to be restrained

Tooth Gasket Restrained Joint

  • Can be used on any Push on Joint Socket & Spigot pipe.
  • Need specially manufactured Steel teeth Inserted Gasket in place of normal Gasket.
  • Gasket has to be set in the Socket Groove like any other gasket.
  • Like any other pipe the steel teeth allow the spigot to be pushed into the socket.
  • Once the Spigot is fully inserted, teeth bite in to the spigot and restrict the spigot to come out.
  • This specially designed gasket performs the dual role of water sealing and restraining.
  • After assembly, pull bock the pipe to ensure engagement of teeth
DN (mm) Deflection Angle  (Degree) Class K9 or equivalent
PFA (bar) PMA (bar) PEA (bar)
80 3 27 32 37
100 3 27 32 37
125 3 20 25 30
150 3 20 25 30
200 3 20 25 30
250 3 20 25 30
300 3 20 25 30
350 3 11 16 21
400 3 11 16 21
450 3 11 16 21
500 3 11 16 21
600 3 11 16 21

Bolted Restrained Joint

  • Can withstand very high pressure.
  • Need specially manufactured pipes, with Factory manufactured Hood on the socket and Weld Bead on spigot.
  • Need special accessories like Gland, Split Retainer Ring and Nuts/ Hook Bolts
  • The water sealing and restraining are in two different systems.
  • Normal gasket to be used for sea li ng.
  • The Hook Bolts with the support from socket hood hold the gland and the socket together. The welding bead on the other pipe's spigot cannot pass through Retainer Ring housed in the gland, ensures restraining axial movement between the two pipes.
  • Easy to assemble and disassemble when required.
DN (mm) PFA (bar) PMA (bar) PEA (bar) Deflection Angle  (Degree)
80 64 77 80 5
100 64 77 80 5
125 64 77 80 5
150 55 66 71 5
200 44 53 58 4
250 39 47 52 4
300 37 44 49 4
350 32 38 43 3
400 30 36 41 3
450 30 36 41 3
500 30 36 41 3
600 27 32 37 3
700 25 30 35 2
800 16 19 24 2
900 16 19 24 2
1000 16 19 24 2

Electrolock Restrained Joint

  • Can withstand very high pressure.
  • Need Factory manufacture Long Socket Pipes with two chambers one for normal sealing and the other for restraining  axial  movement.
  • The water sealing is done by Push-on gasket and restraining is done by Weld Bead and Locking Bar.
  • Normal Push on joint gasket to be used for sealing.
  • After assembly, the locking bars in parts are to be inserted in the Locking Chamber. The weld bead on the spigot gets locked with the locking bar against separation force.
  • Con be used for trench less applications where all pipes with such joints are used in the trenchless portion.
  • Easy to assemble and disassemble when required.
  • Please contact us for Snow Application.
DN (mm) Angular Deflection (degree) Standard Application High Pressure Application
PFA (bar) PMA (bar) PEA (bar) PFA (bar) PMA (bar) PEA (bar)
80 5   76 81 110 132 137
100 5 64 76 81 110 132 137
125 5 64 76 81 110 132 137
150 5 55 66 71 75 90 95
200 4 44 52 57 63 75 80
250 4 39 46 51 44 52 57
300 4 37 44 49 40 48 53
400 3 30 36 41 33 39 44
450 3 30 36 41 33 39 44
500 3 30 36 41 33 39 44
600 3 27 32 37 30 36 41
700 3 25 30 35 28 33 38

Jointing of Flanged Pipes

Over ground and specialized applications require restrained joints where Flanged pipes are used. Flanged Pipes have the following advantages:

  • Acts as self-restrained Joint reducing the requirement of thrust blocks.
  • Ideal for over-ground and Exposed Installations
  • Flanged Pipes are ideal for Vertical pipelines.
  • Used for Temporary Installations (over pillars) where pipelines need to be disengaged or displaced.
  • Widely used for interconnection in Pump House and Treatment Plant.
Flanged Pipe type Diameter Range and lengths Available PN Ratings
Welded Flanged Pipes
Flanges are welded on either side of a Class K9 barrel From 80DN to 1000DN lengths up to 5.0 m. PN 10, PN 16, PN 25, PN 40
Screwed Flanged Pipes
Flanged are screwed-fit on either side of a Class K9 From 80DN to 300DN diameter, in lengths up to 5.0 m. PN 10, PN 16
Cast Flanged Pipes
Flanged Pipe is cast as a single unit using advanced Lost Foam method. From 80DN to 200DN up to 700mm length and 250DN to 700DN up to 1.2 m length PN 10, PN 16, PN 25, PN 40

Flanged Joints

Jointing of Flanged Joints

  • Properly align the pipes
  • Clean flange faces and remove rust and dirt
  • Position the gasket. Use 3 mm. thick moulded rubber gaskets with quality conforming to IS 5382.
  • Lubricate bolt threads, all mating surface and flanges
  • Use automotive grade oil / grease
  • Insert the nut-bolts one by one. Tighten diametrically opposite bolts to the recommended torque
  • If necessary, re-tighten bolts before pressure testing

Electrosteel manufactures Flanged Pipes using all the three methods, that is, Welded Flanged Pipes, Screwed Flanged Pipes and integrally Cast Flanged Pipes (short lengths). Other types of coating and lining to the Flanged Pipes are also available. All flanged pipes are normally lined with Cement Mortar and has outside Zinc and Bitumen Coating.


  • Buried installation of flanged pipe is not recommended.
  • Flanged joint being a rigid joint, perfect alignment of the flange faces during jointing and bolt tightening is absolutely vital.
  • Use of duck foot bend at bottom of vertical flange pipe line is necessary.
  • For high pressure application, flanged pipeline needs thrust block / support at bends / tees.