The presentation talks about various processes, code, equipment used in welding of steel piping in City gas distribution system

1. WELDINGWORKS IN
STEEL PIPING (CGD)
Mr.AkshayToraskar

2. EQUIPMENT , ACCESSORIES USED IN
WELDINGWORKS
• In Welding & associated activities, various inspection tools such
as welding gauge, filler gauge, tongue tester, high-low gauge,
pyrometer etc. is used on site with proper calibration certificate.
• Equipment used during NDT such as dosimeter, radiation survey
meter etc., is properly calibrated & verified on regular basis.

3. • Bridge cam type welding gauge is used to measured various
parameters of weld.

4. • Blade feeler gauge is used measured clearance between two
parts .

5. • HI-LO gauge is used to measured internal alignment of pipe
after fit-up / alignment, cuts radiographic rejects, pipe
thickness, fit-up gap, crown height.

6. • Tong tester is used to measured live-conductor without
damaging or powering down the circuit.The best thing about
this equipment is that it can measured high current without
shutting down circuit under test.

7. • Pyrometer Is used to measured temperature of various site
objects from distance.

8. • Radiation Survey Meter is used to detect & measure Ionizing
Radiation Field in dose or dose rate. It is mainly used to
radiography NDT test.

9. • Radiation dosimeter is used to measure continuous, short term
& pulse gamma, X ray radiation. It is mainly used in NDT
process.

10. QUAIFICATION OF WELDING PROCEDURE
• Welding procedure qualification is carried out only according to
requirements of API 1104.
• After visual inspection of weld coupon , if it is found satisfactory
it is examined by NDT method.
• Normally radiography test is carried out to check weld quality.
After radiographic acceptance, test coupon is further subjected
to destructive testing .

11. • Following destructive testing methods are used to check welding
procedure:
1. Tensile strength test
2.Nick break test
3. CharpyV-notch impact test
4.Bend test
5.Macro test
6.Hardness test

12. NICK BREAKTEST
• Nick break test reveals various internal defects such as slag
inclusions, gas pockects, lack of fusion etc.
• Specimen is cut transverse to weld by saw cutter.
• Fracture is made by striking specimen by single hammer blow.

13. Nick break test

14. Location of test specimen in pipe for weld

15. HARDNESSTEST
• The hardness test is done usingVickers method with 10 kg load
indentations made along traverses each approximately 1 mm
below the surface at both side of weld.

16. Vickers hardness method

17. • Codes used: ISO R146
• The hardness value obtained must not exceed 100hv more than
that of base metal.
• The advantages ofVickers test is that accurate readings can be
taken which can help in determining quality of weld, only one
type of indenter is used in testing of various types of base metal.

18. CHARPYV-NOTCH IMPACTTEST
• The specimen is taken fromArea 2 as show in figure of slide 14.
• CODE used: ISO R148
• Three test specimen is taken from each sample.The notch is
perpendicular to roller surface.
• Method:The specimen is submerged in thermostatic bath & kept at
the test temperature of 0 degreeCelsius for 15 minutes. They then
placed in testing machine & broken within 5 seconds.

19. Thermostatic bath equipment

20. CharpyV-Notch impact test

21. Acceptance criteria for Impact energy test

22. BENDTEST
• Preparation:
• Size of weld: Length: 230 mm, width: 25 mm
• Code: API 1104
• Radius of plunger: 2t (t= thickness of specimen)
• Radius of die : 3t + 1.6 mm
• Width of the die : 50.8 mm

23. Bend test

24. • Method:
• Bend specimen is bent in a guided-bend test jig shown in
figure. specimen is placed on die with weld at mid span. Face-
bend specimen is placed with face of the weld toward the gap.
• Plunger is forced into the gap until curvature of specimen is
approximately U-shaped.

25. WELDER QUALIFICATION
• The purpose of welder qualification test is to determine ability of
welders to make proper butt or fillet welds.
• Quality Engineer witnessed the test & certify qualification of
each welder separately.
• Welded joint is visually inspected & checked if it is free from
Cracks, inadequate penetration, lack of root fusion, burn-through
, presence of workman like appearance.

26. • Welder is qualified based onToughness or Impact test results.
• No welder is permitted to work without possession of
qualification card.
• If welder is found to perform type of welding or in position for
which he is not qualified, he would be disqualified from doing any
further work.