4 General Technical Specification of Bhilai Steel Plant, SAIL ...

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General Technical Specification
- The parts to be degreased should be cleaned and dried by blowing air.
- Outer surface of pipes is degreased by wiping with cloth dipped in solvent and
then dried till smell of solvent disappears.
- For degreasing inner surface of pipes, pipe shall be plugged at one end, filled
with solvent and closed at the other end. Pipe shall be kept in horizontal position,
rotated about axis at least once in a minute. After continuing the process for
about 15 minutes, the solvent shall be drained and pipe blown with dry oil free
air or nitrogen for at least 5 minutes.
- Drying after degreasing can also be done in open air for at least 24 hours.
- Vapour degreasing method can also be applied for pipes.
- For degreasing of valves, fittings and other components, the same shall be
dismantled and parts dipped in solvent for 5 to 10 minutes. After degreasing, the
parts shall be dried in open air till smell of solvent is eliminated.
- Gaskets and packing material shall be degreased by dipping in solvent for 1.5 to
2 hours after which these shall be dried in open air for 24 hours.
- Degreasing operation shall be done in open air.
- The workers should use safety masks to prevent hazards due to inhaling of the
solvent vapours. Solvent contact with skin shall also be avoided.
- Safety aspects regarding handling of solvents shall be kept in mind during
degreasing process.
006 Erection
007 Testing
- Erection of oxygen pipelines shall be done as per approved drawings and
general guidelines for erection of pipelines.
- Gas welding or electric arc welding shall be used for erection of pipelines.
Welding shall be done by qualified welders.
- Qualifying tests for welding, welding procedures and quality control etc. shall be
generally as per IS: 2825, ‘ code of Practice for Unfired pressure Vessels’.
- Radiographic examination of 100% welds for oxygen pipelines with working
pressure over 6 kgf/ cm 2 (g) and OD above 76 mm shall carried out.
Interpretation of radiographs shall be done by a competent agency like Lloyds
Register of Shipping. Proper identification marking for welds and their
corresponding radiographs shall be carried out by the contractor.
- For pipelines having working pressure below 6 kgf/ cm 2 (g), 40% welds shall be
tested by radiography.
- Cleanliness of personnel as well as tools and tackles shall be ensured.
- All erected pipelines shall be tested for strength and leakage using dry and oil
free air or nitrogen.
- Before testing, the pipeline shall be degreased by vapour degreasing method.
- After degreasing, the pipelines shall be blown with dry and oil free nitrogen.
During blowing, velocity in the pipeline shall not be less than 20 m/ sec.
- Blowing shall be done for a period of at least 1 hour to remove all particles of
dust, scale etc. from the system. Cleanliness shall be checked by holding a
piece of white paper at the air outlet.
Gases & Liquid Fluids
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GS-02