Process Of The Welding Process

10.5. Welding

10.5.1. Welding equipment:

No welding process or procedure should be adopted without prior approval of Engineer-in charge. Unless otherwise specified, welding should be done in accordance with the codes API-1104.All welding machines, transformers/Diesel generators as may be required, line up clamps, beveling machines and other equipment used in connection with the welding work must be satisfactory and must be kept in good mechanical condition so as to produce sound welds.

10.5.2 Welding Process:

• Welding under this specification should be done with following welding process subject to the approval of Engineer-in-charge / representatives.

• Manual metal arc process

• Oxy - acetylene Welding process

• Automatic or semiautomatic welding should be made only with the specific approval of the Engineer-in-charge, of the entire procedure and material.

• Combination of the welding process of usage of electrodes of different classes or makes in a particular joint shall be adopted only after the welding procedure has been duly qualified and approved by the Engineer-in-charge.

10.5.3 Root Pass:

• Root Pass should be made with respective electrodes mentioned in the electrodes specifications. The size of the electrode should not be greater than 3.25 mm. Welding should be done with direct current with due regards to polarity and current values recommended by the electrode manufacturers. Upward techniques should be adopted for welding pipes horizontally fixed in position. For thickness less than 3 mm and pipe size 50 mm NB and below Oxy-acetylene welding is recommended.

• The soundness of weld depends to a large extent on complete fusion of the root edges. Hence the root pass of butt joints should be such ...

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...ent gasket unless otherwise specified.

• All piping system to be tested shall have high point vent and low point drain. The pressure gauge used for testing shall be located as close to the lowest point as possible

• Test pressure shall be maintained for at sufficient time to facilitate completion of inspection. Minimum duration of test shall be 4 hr. unless otherwise specified. Pressurizing equipment shall be isolated after the piping system attains the test pressure. After successful completion of hydro test, the piping shall be depressurized.

• Test Record

Contractor shall submit test records in duplicate for all the lines tested. The test records shall as minimum include following information.

Date of test

Identification of line tested and test result

Test medium & Test pressure

Sr. No. of the pressure gauge along with copy of calibration certificate