TB/T 1632.4-2014Welding of rails - Part 4: Gas pressure welding (English PDF)

3.5 in 2005 edition);

— MODIFY the requirements for hardness of welded joints (SEE 3.5 in this

edition and 3.5 in 2005 edition);

— MODIFY the inspection method (SEE Chapter 4 in this edition and

Chapter 4 in 2005 edition);

— MODIFY the inspection rules (SEE Chapter 5 in this edition and Chapter

3.1 Welding rail requirements

The rails for gas pressure welding shall meet the requirements of Chapter 4 in

TB/T 1632.1-2014.

3.2 Equipment and material requirements

3.2.1 Automated gas pressure welding equipment shall be adopted in

preference. In the welding process, it shall be able to automatically record the

change of parameters such as gas flow, rail-end pressure, etc. over time.

3.2.2 The purity of oxygen used for gas pressure welding of rails shall not be

less than 99.5%, while the purity of acetylene shall not be less than 98%.

3.3 Personnel requirements

Each welding operator shall hold a job training certificate issued by the technical

institution approved by the railway authority.

3.4 Process requirements

3.4.1 Welding environment requirements. The welding places shall have no

rain or heavy fog, at a temperature of not lower than 0°C. When the temperature

is below 0°C, measures of heat preservation shall be taken for the oxygen and

acetylene cylinders. Meanwhile, early drying shall be carried out within the

range of 400mm on each end face of the rails to be welded. Wind shall not be

greater than Level 5. In case of above Level 4, wind shielding measures shall

be taken.

3.4.2 POLISH the end faces of rails prior to welding. The allowable deviation

of the end face inclination shall be 0.2mm. SEE Figure 1.

3.4.3 For the alignment clamping operation of rails, alignment shall be based

on the working edges on the top of the rail and the side of the railhead.

3.4.4 The flame surface of the heater shall be parallel to the end face of the

rail.

3.4.5 The convex shearing process shall be carried out automatically. The

convex shearing process shall not cause damage to the joints and the rail

parent metal. After convex shearing, there shall be no macroscopic cracks on

or welding slag squeezed into the surfaces. The maximum convex shearing

allowance (the height of weld reinforcement after convex shearing) for each

part of the joint is as follows. 2mm for railhead; 2.5mm for railhead jaw; 2mm

for rail web; 1.5mm for rail flange.

reinforcement of the rail flange shall be under smooth transition. Longitudinal

grinding shall be carried out along the rails. It is not allowed to carry out

horizontal grinding. There shall be no grinding burn on the rail surfaces.

Misalignment in the vertical and horizontal directions on the non-working faces

of the welded joints shall be conducted with longitudinal grinding transition.

3.4.10 An imitation-type grinding machine shall be used to perform shape

finishing on the top surfaces of the rails and the working edges on the sides of

the railheads for the welded joints. Shape finishing shall maintain the contour

shape of railheads. The length of the shape finishing shall not exceed the limit

of 400mm on both sides of the weld center line. Shape finishing shall not cause

any mechanical or thermal damages to the welded joints or rails. Shape

finishing shall not be used correct the excessive flatness deviation and

excessive joint misalignment.

3.4.11 When a mobile gas pressure welding machine is used for CWR

(continuous welded rail) long rail welding, it shall be operated in coordination

with the CWR laying process. During locking welding, dwell convex shearing

shall be adopted. When the welded joints are cooled to below 300°C, it is

allowed to remove dwell pressure.

3.4.12 Mass production shall be carried out after passing the type inspection.

The production process shall be the same as the test specimens of the type

inspection.

3.4.13 The welded joints (finished products) of each rail shall be marked. The

markings shall be located on the same side of rail web of the welded long rails,

1m to 3m away from the welds. In addition, the markings shall be clear, upright

and identifiable for at least 5 years (or 1 overhaul cycle). The marking method

shall ensure that the welded joints (finished products) of each rail are traceable

based on the record sheet.

3.4.14 After welding, the following information shall be recorded (REFER to

Annex A).

a) rail markings, laying positions and welded joint markings;

b) environmental conditions (including temperature, wind, precipitation and

measures taken);

c) model of the welding machine;

d) welding and normalizing processes (including welding pressure, oxygen

and acetylene flow, heating time, swing frequency and width of the heater);

e) quality inspection and flaw detection results after welding;

f) welding operation group;

g) names of welders and inspectors;

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