GUIDELINES ON FABRICATION OF STEEL STRUCTURE OF FOOT OVER BRIDGES PDF

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GUIDELINES ON FABRICATION OF STEEL STRUCTURE OF FOOT OVER BRIDGES 1.0 Introduction : Foot over bridges over the Indian Railways are used by pedes trian traffic to cross the Railway track safely. 1.1 Specification for steel: i) IRS BI – 2001 (Fabrication Specification) Para 8.1 s tipulates as under: ...

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GUIDELINES ON FABRICATION OF STEEL STRUCTURE OF FOOT OVER BRIDGES mukesh bahlani

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GUIDELINES ON FABRICATION OF STEEL STRUCTURE OF FOOT OVER BRIDGES 1.0

Introduction : Foot over bridges over the Indian Railways are used by pedes trian traffic to cross the Railway track safely.

1.1

Specification for steel: i)

IRS BI – 2001 (Fabrication Specification) Para 8.1 s tipulates as under: “IS:2062 Grade “A” as rolled semi-killed or killed s hall be used for foot-over-bridges and other s tructures s ubjected to non-critical loading.”

ii) 1.2

The rolling and cutting tolerances s hall be in accordance with IS:1852.

Flattening and Straightening of steel: IRS BI – 2001 (Fabrication Specification) Para 15 s tipulates as under: “15.1 All s teel materials plates and s tructural s hall have s traight edges , flat s urfaces and be free from twis t. If necess ary, they shall be cold straightened or flattened by pressure before being worked or assem bled unless they required to be of curvilinear form . Press ure applied for straightening or flattening shall be such as it would not injure the material and adjacent surfaces or edges s hall be in close contact or at uniform dis tance throughout. 15.2 Flattening and s traightening under hot condition s hall not be carried out unless authorized and approved by the Ins pecting Officer.”

1.3

Cutting of steel: IRS BI – 2001 (Fabrication Specification) Para 17 s tipulates as under: “17.1 Flame cutting by mechanically controlled torch/torches s hall be accepted. Provided the edge as given by the torch is reasonable clean and s traight, plates may be cut to s hape and beams and other s ections cut to length with a gas cutting torch, preferably oxyacetylene gas should be us ed.

1

17.2 All flame cut edges shall be ground to obtain reasonably clean square and true edges . Draglines produced by flam e cut s hould be removed.” 1.4

Approval of Quality Assurance Plan (QAP): Stagewise m anufacturing process from raw material indicating various steps , tes t checks and their frequency, sampling plan, authority for grant of clearance, s tage like tem plating and lay out of foot over bridge, fixture/jig m anufacturing, drilling of com ponent/welding of component initial assem bly, final finis hing, final ins pection, s urface preparation and painting etc. are clearly s hown and signed by m anufacturer, indenting Railway authority and approved by com petent authority.

1.5

1.6

Lay out : i)

The layout of s tructure on tem plate floor is the m os t important operation in fabrication. It is essential that the template floor is perfectly level with adequate lighting arrangem ent. Steel flooring is des irable, as it would also minimize variation in dim ens ions due to tem perature changes . The m arking tools and ins trum ents like square, divider, punches , s teel s criber s hould be of good quality.

ii)

Calibrated tape for meas urement of lay out m ust be used.

Jigs and fixtures : Jig is the device us ed in the m ass production to locate the jo b and guide the tool for drilling etc. While a fixture is a s im ply a device for holdin g the work in true s hape during process in g. The use of steel tem plates , jigs and fixtures is preferable to help in achieving econom y, increasing production, reducing man power, reducing hum an errors , increasing accuracy and eliminatin g s pecial m atch m arking.

1.7

Drilling of holes : Quality of fabrication s hall be improved if jigs are us ed during fabrication. Drilling of the com ponent may be done through jigs . All burrs left by the drill and s harp edges of the holes shall be rem oved.

1.8

Welding Process and Positions : i)

Welding shall be carried out in accordance with the approved welding procedure, specifications by approved welders , process es and positions. Proform a for welding procedure s pecification and welding procedure qualification records are enclos ed as Annexure-I and II.

2

1.9

ii)

All welding should be preferably done in flat pos ition (horizontal). Welding s hould be done as per drawing ens uring proper size of weld. Over s ize welding may lead to excess ive heat affected zone which may lead to failure of m aterial. Welding should be carried-out in a warm and dry place s o that the rainwater or other atmospheric elem ents m ay not come in contact while welding is in progress.

iii)

Electrodes s hall confirm to Class A2 of IRSM-28 and wire for CO2 welding s hall confirm to Class 1 of IRSM-46.

iv)

All cons umable shall be s tored and handled with care and in accordance with the m anufacturer’s recomm endations .

Riveting : i)

Before riveting is commenced the permanent s urface of components shall be painted with two coats of red oxide zinc chrom e priming to IS 2074.

ii)

IRS BI – 2001 (Fabrication Specification) Para 23 s tipulates as under: “23.1 The dimension on the drawings referred to the diam eters of the rivet holes and their finis hed rivets. The rivet holes s hall be 1.5mm greater than the diam eter of the rivet bars used. The rivet shall be made to IS:1929. The s hanks of the undriven rivets s hall be made of a length s ufficie nt to fill the holes thoroughly and form the head. The clearance i.e. the difference in diam eter between the rivets meas ured under head before being heated and the rivet hole shall not be less than 0.75 mm . Before riveting is comm enced, all works shall be properly bolted so that the s ection riveted are in clos e contact throughout. Rivet s hall completely filled the holes and shall be machine driven by means of pressure or percuss ion riveters of approved design. 23.2 All rivets s hall be properly heated to s traw heat for the full length of the s hank, firmly backed and clos ed. The head of the rivet, particularly in long rivets , s hall be heated more than the point be heated, m ore than the head. Sparking or burnt rivets s hall not be us ed. Whereas it is im poss ible to back up by normal m ethod of holding up, ‘double gunning’ m ay be res orted to. Alternatively pneumatic hold ing device may us ed. 23.3 Gauges for rivet dimens ions and contours s hall be provided by contractor for the us e of the Inspecting Officer. 23.4 Rivets when driven shall com pletely fill the holes , have the heads concentric with the shanks and shall be in full contact with 3

the s urface. Driven rivets when s truck sharply on the head with the 110-gm. rivet tes ting hammer, shall be free from movement or vibration. 23.6 All loose and burnt rivets and rivets with cracks badly formed eccentric or deficient heads s hall be cut out and replaced. Permissible deviation of driven rivets shall be as per Annexure-III. Rivets s hall also be cut out when required for the examination of the work. Actual method of cutting out s hall be approved by the Engineer. Recouping and caulking shall in no circums tances be resorted to. 23.8 iii)

1.10

All field rivets s hall be tes ted.

All defective rivets and loose rivets shall be m arked on their heads with paint and prom ptly replaced. Rivets in any com ponents should be tes ted 100% in shop by a respons ible supervisor and maintain the record of the same.

Final Cutting and Finishing of component : Final finis hing of length, profile and notches etc. it is accom plis hed by accurate m arking with the help of templates , m eas urement and gauge wherever necess itates and than by gas cutting (Chipping, grin ding) as the case may be. Excessive metal is normally chipped off or gas cut (more than 3 mm ) and the exact finishing or profiling is achieved by fine and accurate grinding.

1.11

Inspection Stages : (a)

Before fabrication

(b)

During fabrication

(c )

After fabrication

(a)

Before Fabrication : • Quality As surance Plan s hall be prepared and got approved. • Raw m aterial s uch as channels and plates etc. to be ins pected as per s pecificatio n m entioned agains t each items and rolling Mark Certificates . • Lamination, piping, pitting rolli ng defects and Straightness of m aterial to be checked before fabrication.

4

•

Cons um ables s uch as, rivets, welding electrodes and paints etc. are as per s tandard s pecification.

• Welding Procedure Specifications need to be approved. • Welders approval as per Welding Procedure Specification. (b)

During Fabrication : • Lay out, jigs and fixtures and profile to be checked. • Welding by qualified weld ers as per approved WPSS. • Welding parameters are to be set & checked during welding. • Riveting by qualified and s killed personal with approved work ins tructions.

(c )

After Fabrication : • Verify rolling Mark num ber of steel s ections us ed for fabrication, from Certificate issued by manufacturer. Check the regis ter m aintained by firm. • Surface defects shall be checked vis ually. • Qualify of welds with respect to specified s izes , length and any vis ual defects . • Quality of rivets to be checked visually and with the help of riveting hamm er. • Dye Penetration Tes t for Welds • Leading dim ensions i.e. overall length, hole dimens ions, end finishing etc. s hall be checked. For this purpos e detail m eas urement sheet s hall be prepared for.

1.12

Connection Details : Some of the connection details comm only us ed in fabrication of FOB has been s hown as Annexure-IV.

5

ANNEXURE-I (Ref. Clause 26) 1.

Proforma for Welding Procedure Specification Sheet

Name and address of Fabricator: Welding procedure specification No. 1.0 2.0 3.0 4.0 5.0 5.1

Weld joint description : Base Metal Welding Process Welding position Welding consumables : Electrode/wire

: : : Class

: Dia Drying method Class Dia Drying method

5.2

Flux

5.3.1 6.0 6.1

Shielding gas : Base Metal preparation : Joint design details : (Give sketch showing arrangement of parts, welding groove details, weld passe s & their sequence etc.) Joint preparation : Welding current : Type : Polarity Welder qualification : Welding parameters and technique: Welding Parameters :

6.2 7.0 8. 9. 9.1 Weld Pass No.

Electrodes/ w ire dia. (mm)

Current (amp)

Arc Voltage (volt)

1

2

3

4

9.2 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0

: : : : :

:

Wire feed speed (m/min) 5

Trav el speed (m/min)

Electrical stick out (mm)

Gas flow rate (litre/min.)

6

7

8

Welding sequence and technique : (Give sketch showing sequence and direction of welding). Provision of run in and run-off tabs: Cleaning of weld bead before laying next weld bead: Root preparation before welding other side of groove weld: Preheating and inter pass temperature: Peening: Post weld treatment: Rectification of weld defects: Inspection of weld: Any other relevant details: Prepared by Signature ____________________________ Designation ____________________________ Date ____________________________ (for & on behalf of Fabricator)

ANNEXURE-II 1.

Proforma for Welding Procedure Qualification Record

Name and address of Fabricator 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0

Description of Weld Welding procedure specification no. Name of welder Date of preparation of test piece Dimensions of test piece Base Metal Welding Process Welding position Welding Current

10.0 11.0 11.1

Weld joint design details Welding consumables Electrode/wire

11.2

Flux

11.3 12.0 Weld Pass No. 1 13.0 14.1

Shielding gas Welding parameters Electrodes/ Current Arc w ire dia. (amp) Voltage (mm) (v olt) 2 3 4 Preheating and interpass temperature: Results of Qualification Tests: Test 1 Non-destructive tests i) Visual examination: ii) Dye penetrant test: iii) Magnetic particle test: iv) Radiographic/Ultrasonic test: Destructive tests: i) Macro-examination: ii) Hardness survey: iii) Fillet weld fracture test: iv) Transverse tensile test: Tensile strength Yield Stress Location of fracture v) All-weld tensile test: Tensile strength Yield Stress Elongation % vi) Guided bend test: Root bend test Face bend test Side bend test vii) Any other tests

: : : : : : : : : T ype : Polarity : : : Class : Dia : Brand : Class : Type : Brand : : : Wire feed speed (m/min) 5

Trav el speed (m/min) 6

Specimen No. 2

Electrical stick out (mm) 7

Shielding gas flow rate (lit/min.) 8

Result 3

Signature ____________________________ Designation ____________________________ Date ____________________________ (for & on behalf of Fabricator)

8

9

Tele DOT- 91-0522-2450398 Rly .-42120(O) 43120(Res.)

Fax 91-0522-2450398 E-mail : edbs@ rdso.railnet.gov.in

No. CBS/FOB I. II.

III.

226011 Government of India-Ministry of Railways Research Design & Standards Organisation Lucknow- 226011

Dated

-03-2008

Director, IRICEN, Pune-410001. Principal Chief En gineer: 1. Central Railway , Mumbai CST-400 001. 2. Eastern Railway , Fairlie Place, Kolk ata-700 001. 3. East Central Railway , Hazip ur-844 101. 4. East-Coast Railway, Bhubaneshwar-751 016. 5. Northern Railway , Baroda House, New Delhi- 110 001. 6. North-Central Railway , Allahabad-211 001. 7. North Eastern Railway , Gorakhp ur-273 001. 8.. North-Western Railway , Jaip ur-302 001. 9. Northeast Frontier Railway, M aligaon, Guwahati-781 011. 10. Southern Railway , Park Town, Chennai-600 003. 11. South Central Railway , Rail Nilayam, Secunderabad-500 371. 12. South East Central Railway, Bilaspur-495 004 13. South Eastern Railway , Garden Reach, Kolk ata-700 043 14. South-West Railway , Hubli-580 023. 15. Western Railway , Mumbai-400 020. 16. West-Central Railway , Jabalp ur-482 001. Executive Director Civil En gg.(B &S), R ailway Board, Rail Bhavan, New Delh i01. Sub: Guidelin es on Fabrication of Steel Structure of Foot Over Bridges. Ref: Railway Board’s letter no. 2004/CE-I/BR/Domibivali dated 24-10-07. *******

RDSO has develop ed guidelines on Fabrication of Steel Structure of Foot over Bridges. These guid elines are bein g sent for information and necessary action p lease. DA: As Abo ve (Total 9 pages).. (Piy ush Agarwal) Executive Director (B&S) For Director General...